Reactor apparatus

Abstract

A mechanism for tumble stirring fluid within a plurality of vials 118, each vial containing a magnetic stirring element 133, comprises a magnet carrier member 115 having a first element 113a and a sec

Description

Field of the invention The invention relates to the field of automated chemistry research. Specifically, the invention relates to apparatus, devices and methods for performing chemical reactions in multiple vials while providing the capability to monitor the reaction through sampling and / or non-invasive optical assessment and to stir the contents of each of the vials. Background Chemistry research is increasingly automated to increase throughput and improve the control of reaction conditions. Typically, automated chemistry is conducted in glass vials in which small amounts of powder and liquids are combined. To perform a reaction the contents of the vial are stirred to mix the components and then energy is added, commonly in the form of heat or light but possibly via pressure, electricity or mechanical means. Chemists then analyse the sample post-reaction to analyse what compounds have been created or consumed. For many workflows, reactions may be sampled and analysed periodically during the reaction to understand the ‘reaction kinetics’ (i.e. the rate at which the reaction is taking place). Conventionally, automated chemistry reactions take place in a rectangular array of vials known as an SBS rack / plate, with the array typically numbering 24, 48 or 96 vials. This standardised ‘footprint’ allows long established laboratory robotics to pick, place and process vials as a batch. While the rectangular array of samples is good for compatibility with existing laboratory robotics, it does provide some challenges to optimised chemistry reactions. Specifically, the uniformity of stirring and temperature control is challenging as the vials in the corner of the rectangular array experience different conditions and stirring to those in the centre. The rectangular array also poses challenges for photochemistry (adding energy to the reaction using light). Using a rectangular array of vials necessitates that light energy is directed from above or below, however the vials are generally capped (obscuring the top) and access is required from beneath to effect magnetic stirring. Understanding reaction kinetics traditionally relies on sub-sampling (liquid, gas or solids) from the reaction vial and then analysing that sub-sample using techniques such as liquid chromatography. Increasingly, non-invasive optical methods to assess reaction kinetics are being adopted, for example, imaging, hyperspectral imaging, RAMAN spectroscopy, or IR spectroscopy. This myriad of techniques all require optical access to individual reaction vials which is not easily achieved in a rectangular array of vials. Additionally, stirring of fluid within a vial is traditionally conducted by a cylindrical stir bar disposed in the bottom of the vial and rotated about a vertical axis. However, this stirring method, particularly in the case of small vials, may fail to create even mixing throughout the vial. The present invention aims to address these deficiencies by departing from such conventional stirring arrangements and by departing from the convention of a rectangular array of vials. Summary of the invention In one aspect, there is provided a mechanism for tumble stirring fluid within a plurality of vials, each vial containing a magnetic stirring element disposed in the fluid, the stirring mechanism comprising: a magnet carrier member having a first element with a first magnetic axis and a second element having a second magnetic axis, each magnetic axis extending from a south magnetic pole to a north magnetic pole, the first element and second element being arranged sequentially on the magnet carrier member such that the first magnetic axis and second magnetic axis are antiparallel to each other, wherein a position of the magnetic poles can be moved about a substantially circular path defined by the magnet carrier member whereby to create an alternating magnetic field that can induce rotation, about a horizontal axis, of a magnetic stirring element disposed in a vial offset vertically from the magnet carrier member. The circular path defined by the magnet carrier member may lie in a horizontal plane, and the first magnetic axis and second magnetic axis may be orthogonal to said horizontal plane. The first and second elements may be arranged such that the north magnetic pole of the first element and the south magnetic pole of the second element are aligned on a common horizontal plane, relative to the magnet carrier member. The first element and second element may together form a pair of first and second elements on the magnet carrier member. The magnet carrier member may comprise a plurality of said pairs of first and second elements. Said plurality of pairs of first and second elements may be arranged sequentially on the magnet carrier member such that the magnetic axes of adjacent elements are antiparallel. The magnet carrier member may comprise between 2 and 100 pairs of said first and second elements, preferably between 2 and 50 pairs, and more preferably about 10 pairs of said first and second elements. The mechanism may comprise a third element having a third magnetic axis and a fourth element having a fourth magnetic axis. The third and fourth magnetic axes may be antiparallel to each other. The third and fourth magnetic axes may be orthogonal to the first and second magnetic axes. The first, second, third, and fourth elements may be arranged sequentially in a Halbach configuration. The mechanism may comprise a magnet drive assembly configured to rotate the magnet carrier member such that the first and second elements move continuously along the substantially circular path. The magnet drive assembly may also be configured to rotate the magnet carrier member such that the third and fourth elements move continuously along the substantially circular path. The magnet drive assembly may be configured to rotate the magnet carrier member at (a predetermined rate of) “X” revolutions per minute and the magnet carrier member may have (a predetermined) “Y” number of pairs of said first and second elements, such that a product of “X” and “Y” is between 100 and 3000, and preferably between 1000 and 2000, and more preferably about 1200. The magnet drive assembly may be configured to drive the magnet carrier at between 5 and 300 revolutions per minute and preferably between 50 rpm and 200 rpm, and more preferably at about 120 rpm. The first and second elements may be static electromagnetic coils configured to be electrically controlled whereby to invert a direction of their magnetic axes and create the alternating magnetic field about the circular path. According to another aspect there is provided a method of tumble stirring a fluid within a vial, the method comprising: providing a magnet carrier member having a first element with a first magnetic axis and a second element having a second magnetic axis, each magnetic axis extending from a south magnetic pole to a north magnetic pole, the first element and second element being arranged sequentially on the magnet carrier member such that the first magnetic axis and second magnetic axis are antiparallel to each other, providing a vial containing fluid with a magnetic stirring element disposed therein, the vial located at a position offset vertically from the magnet carrier member, and rotating the magnet carrier member such that the first and second elements move continuously along the substantially circular path in a substantially horizontal plane, thereby creating an alternating magnetic field which induces rotation, about a horizontal axis, of the magnetic stirring element disposed in the vial. According to another aspect there is provided a vial holding assembly for a reactor apparatus, comprising a mechanism for tumble stirring fluid as defined above and herein, and a vial carousel including a plurality of vial holders. The magnet carrier member of the mechanism may be positioned beneath the vial holders. The vial carousel may be configured to be rotated such that the vial holders follow a substantially circular path. The vial holding assembly may comprise a vial drive assembly configured to rotate the vial carousel. The substantially circular path of the first and second elements may be below the substantially circular path of the vial holders. Additionally, or alternatively, the substantially circular path of the first and second elements may be coaxial with the substantially circular path of the vial holders. The first element and the second element may be arranged to be spaced from a base of a vial held in one of said plurality of vial holders by a distance of between 1 mm and 20 mm. The vial carousel may be housed within an enclosure defining an internal volume. The enclosure may comprise: a removable lid portion. The enclosure may comprise a base portion arranged beneath the vial holders; and a sidewall that surrounds the vial carousel and extends up from a perimeter of the base portion. The removeable lid portion may comprise at least one opening in alignment with at least one of the plurality of vial holders when the lid portion is mounted to the vial holding assembly. The vial holding assembly may comprise one or more fluid conduits configured to allow an external supply of fluid to flow into the enclosure. The vial holding assembly may comprise a fluid flow controller configured to control at least one of a temperature and a flow rate of the fluid. The fluid flow controller may comprise at least one of a heating element and a cooling element configured to control a temperature inside the enclosure, whereby the fluid flow controller is configured to circulate a flow of fluid through the enclosure via said heating element or cooling element. The vial holding assembly may comprise at least one analysis station comprising apparatus configured to interact with one or more vials held in the vial holders when aligned with the analysis station. The at least one analysis station may comprise a camera disposed adjacent the vial carousel. The camera may be configured to view the contents of a vial held in a vial holder. The at least one analysis station may comprise at least one of a RAMAN or IR spectrometer. The vial holding assembly may comprise a sidewall that surrounds the vial carousel, wherein the sidewall has at least one aperture though which analysis of the contents of one or more vials held in said plurality of vial holders can be performed by analysis apparatus positioned in alignment with the aperture. The vial holding assembly may comprise one or more light sources. The one or more light source may be configured to illuminate one or more vials held in said plurality of vial holders. The one or more light sources may comprise a plurality of LEDs positioned concentrically with the vial carousel. The LEDs may be configured to laterally illuminate one or more vials held in the plurality of vial holders. According to another aspect, there is provided a reactor apparatus comprising a vial holding assembly as described above and herein. The reactor apparatus may comprise a robotic device configured to interact with the one or more vials held in the plurality of vial holders. The robotic device may be configured for movement above the vial holding assembly. The robotic device may be operable to pick a vial from a position remote from the plurality of vial holders and place said vial in one of the plurality of vial holders. The robotic device may comprise a needle apparatus configured to perform at least one of: dosing the one or more vials held in the plurality of vial holders with a liquid reagent; and sampling fluid contained in the one or more vials. Thus, described herein are devices, apparatus and methods for performing and analysing chemical reactions. Traditionally, a magnetic stirring element disposed in fluid in a vial is rotated around a vertical axis; however, for small vials better mixing has been demonstrated by using ‘tumble’ stirring, which flips the magnetic stirring element in the fluid about a horizontal axis. An advantage of the invention is that vials are arranged in a configuration that allows consistent tumble stirring across a plurality of vials at the same time. Brief description of the drawings One or more embodiments of the invention will now be described, purely by way of example, with reference to the accompanying figures, in which: Figure 1 shows an isometric view of a vial holding assembly for a reactor apparatus according to the present invention; Figure 2 shows an isometric view of the vial holding assembly of Figure 1 with its top cover removed; Figure 3 shows a cut-away part sideview of the vial holding assembly of Figure 1 illustrating the vial carousel, carousel drive assembly and the magnetic stirring mechanism of the vial holding assembly; Figures 4A and 4B show a cross-sectional view of a magnetic tumble stirring mechanism of the vial holding assembly of Figure 1; Figures 4C and 4D show a cross-sectional view of an alternative magnetic tumble stirring mechanism suitable for the vial holding assembly of Figure 1, the magnetic tumble stirring mechanism having a Halbach configuration; Figure 4E depicts an embodiment of a magnetic tumble stirring element suitable for use with the magnetic stirring mechanisms of Figures 4B and 4D. Figures 5A and 5B show a top view and a cross-sectional side view of the vial holding assembly of Figure 1, illustrating the vial drive assembly and the magnet drive assembly of the vial holding assembly; Figures 6Aand 6B show a top view and a cross-sectional view of the vial holding assembly of Figure 1, illustrating an airflow arrangement of the vial holding assembly; Figures 7A and 7B show a top view and a cut-away view of the vial holding assembly of Figure 1; Figure 8 shows an isometric view of the airflow distribution system of the vial holding assembly of Figure 1; Figure 9 shows a reactor apparatus comprising the vial holding assembly of Figure 1; Figures 10A and 10B show a side view and a cross-sectional plan view of the reactor apparatus of Figure 9; and Figure 11 shows a schematic plan of the reactor apparatus of Figure 9. Detailed description An example of a vial holding assembly 100 for a reactor apparatus 500 is shown in Figure 1. The vial holding assembly 100 comprises a vial carousel 103 (not shown in Figure 1) configured to hold or support one or more (e.g. a plurality of) vials 118, by way of one or more vial holders 134 or otherwise. The vial carousel 103 (and thus vials 118 held by the vial carousel 103) may be disposed in a substantially enclosed cavity or space 132. The space 132 may also be referred to as an enclosure 132. The space 132 may define an internal volume. The internal volume of the space 132 may be defined, at least in part, by a lid 107 and sidewall 131 of the vial holding assembly 100. The lid 107 may be removable. The lid 107 may also be referred to as a top cover or lid portion. The internal volume may also be defined, at least in part, by a base portion of the vial holding assembly 100. The base portion may comprise the vial carousel 103 (as depicted in Figure 6B) or may be arranged below the vial carousel 103 (for example, the base portion may comprise the motor baseplate 109). The vials 118 may be placed on, or retrieved from, the carousel 103 (or otherwise accessed) from above. In the embodiment of Figure 1, the vials 118 may be accessed by removing the lid 107. Additionally, or alternatively the vial 118 may be accessed through one or more openings 128 in the lid 107. An opening 128 may be positioned in the lid 107 such that the opening 128 aligns with a vial holder 134 of the vial carousel 103 (and thus may align with a vial 118 on the vial carousel 103) when the lid 107 is mounted to the vial holding assembly 100. The opening 128 may be shaped and / or sized to allow a vial 118 to pass vertically through the opening 128. The sidewall(s) 131 may comprise one or more external recessed portions 141 delimited by one or more ribs 142. The recessed portions 141 may provide space for external analysis stations 106. External analysis stations 106 may include, for example, a RAMAN probe 126 for performing RAMAN spectroscopic analysis on the vials 118 and their contents. Additionally, or alternatively, an analysis station 106 may include a camera 125 for imaging the vials 118 and their contents. It will be appreciated, however, that many other appropriate types of external analysis station 106 may be used with the assembly 100. Further examples will be discussed in connection with Figures 9 to 11. Providing the external analysis stations 106 in recessed portions 141 of the sidewall 131 may advantageously reduce the footprint and size of the vial holding assembly 100. The ribs 142 may delimit between different external analysis stations 106. For example, where external analysis stations 106 involve optical analysis, the ribs 142 may inhibit one station 106 from illuminating another. The ribs 142 may also serve to support the structure of the vial holding assembly 100. For example, the ribs 142 may support the lid 107. The vial holding assembly 100 may further comprise an air temperature control unit 122 configured to control the temperature of air (or another fluid) in the cavity 132 defined by the sidewalls 131 and the lid 107. The air temperature control unit 122 may be external to the cavity 132 containing the vial carousel 103 and fluidly connected to said cavity 132 by one or more external ducts 121. The air temperature control unit 122 will be discussed in more detail in connection with Figure 8. Figure 2 shows the vial holding assembly 100 of Figure 1 with its lid 107 removed, exposing the vial carousel 103. In Figure 2, the vial carousel 103 is shown holding a plurality of vials 118. In the embodiment of Figure 2, the vial carousel 103 is substantially circular. A circular configuration may be advantageous as the rotational symmetry of the vials 118 on the vial carousel 103 helps ensure that each vial 118 experiences the same conditions and / or environment. For example, in a circular configuration, each vial 118 is equidistant from the outlet 105a of the central air pipe 105, and therefore should experience the same heating or cooling effects from air ejected from the central air pipe 105. Therefore, a circular vial carousel 103 promotes the even heating or cooling of vials 118 on the vial carousel 103, thus promoting temperature uniformity between different vials 118. The vial carousel 103 may be configured to move vials 118 about a continuous (e.g. cyclical) predetermined path defined by the carousel 103. The predetermined path of the vials 118 in Figure 2 is ideally substantially circular; however, the carousel 103 may be another shape (e.g. pentagon, square or other suitable polygon) that allows vials 118 to follow a continuous path. Such a non-circular shape may still facilitate a circular vial path in that the vial holders 134 (and thus the vials) may be located at the corner of the shape (e.g. a square) and the shape may be rotated. As long as the vial holders 134 are each equidistant from a central axis of rotation, a circular path for the vials may be defined. In the embodiment of Figure 2, the vial carousel 103 is configured as an annular ring (or annular disc). Such a configuration may be more suited to embodiments where the predetermined path of the vials 118 is a circular path. The vial carousel 103 may be formed of a single component or adjoining segments, which might better facilitate predetermined paths that are non-circular. The vial carousel 103 may be rotated within the vial holding assembly 100 by a vial drive assembly 150. In embodiments where the carousel 103 is circular (or the carousel 103 is non-circular but nevertheless defines a circular vial path), the term ‘rotating’ preferably means rotating the carousel 103 about an axis of rotation. In embodiments where the carousel 103 is not circular, the term ‘rotating’ may refer to the process of driving the vials 118 about the path defined by the carousel 103. Rotating the vial carousel 103 may enable individual vials 118 to be selectively positioned at processing or analysis stations (e.g. internal and external analysis stations 104, 106). Rotating the vial carousel 103 may also advantageously improve the uniformity of the amount of energy (e.g. thermal or light) that each vial 118 receives. Continual rotation of the vial carousel 103 ensures that any hot spots or brights spots within the cavity 132 of the assembly 100 are ‘averaged out’ in respect of the vials 118 by the movement of said vials 118. Therefore, a moving or rotating vial carousel 103 may promote thermal and / or optical uniformity between different vials 118. Other physical characteristics of the environment experienced by the vials 118 may also be averaged out by the moving or rotating vial carousel 103. The cavity 132 in which the vials 118 are located may have a substantially annular profile. The outer perimeter of the cavity 132 may be defined by the sidewalls 131 of the vial holding assembly 100 and the inner perimeter of the cavity 132 may be defined by one or more internal analysis stations 104. A plurality of internal analysis stations 104 may be arranged in an annular configuration with the central air pipe 105 extending through the centre of the arrangement. Accordingly, an arrangement of vial holders 134 in a single, continuous row (i.e. the vials are not arranged side-by-side in multiple concentric rows) allows for the vials 118 to be laterally accessed from two sides: an outer perimeter of the vial carousel 103 and an inner perimeter of the vial carousel 103. This arrangement enables the vial holding assembly 100 to monitor reactions in the vials 118 at more locations, by way of multiple different analysis stations (e.g. internal and external analysis stations 104, 106). The analysis stations 104, 106 may be configured to vertically access the vials 118. For example, the cap of a vial 118 may be removed at an analysis station 104,106. The same analysis (or processing) station or a different one may thus access the contents of the vial 118, to sample said contents, through the top of vial 118. The analysis stations 104, 106 may also be configured to view the contents of a vial 118 held in a vial holder 134. The analysis stations 104, 106 may be configured to view the contents of a vial 118 held in a vial holder 134 through a side of a vial 118. As can be seen in Figure 2, external analysis stations 106 (such as the RAMAN probe 126) may be in alignment with apertures 127 in the sidewalls 131. The external analysis stations 106 in alignment with the apertures 127 may optically access the vials 118 by way of the apertures 127. These access apertures 127 may be in the recessed portions 141 of the sidewalls 131. Figure 3 shows the internal components of the vial holding assembly 100 in more detail. As shown in Figure 3, the vial carousel 103 may be configured as an annular disc. The vial holders 134 of the vial carousel 103 may comprise one or more openings or indented (or recessed) portions 134 configured to receive a base (i.e. the bottom) of a vial 118 held in the vial carousel 103. In the embodiment of Figure 3, the indented portions 134 are formed in said annular disc. The vial carousel 103 may further comprise a supporting member 116 configured to support a portion of the vials 118 vertically above their respective bases. The supporting member 116 may be positioned vertically above the base of the vial carousel 103. The supporting member 116 may rotate in synchronisation with the vial carousel 103. In the embodiment of Figure 3, the supporting member 116 may comprise an annular disc 116 having substantially the same profile as the annular ring (annular disc) 103 of the vial carousel 103 and having openings 116a which align with the indented portions 134 of the carousel 103. The openings 116a of the supporting member 116 may be shaped and sized to receive a top portion 118a of the vials 118. The supporting member 116 may inhibit the vials 118 from tipping over when the vial carousel 103 is rotated. The motion of the vial carousel 103 may be driven by the vial drive assembly 150. The vial drive assembly 150 may comprise a vial carousel motor 114, such as a DC motor connected to a power supply (not shown). The vial drive assembly 150 may comprise one or more geared arrangements. Additionally, or alternatively, the vial drive assembly 150 may comprise (and thus drive the vial carousel 103 via) one or more of belts, linkages, or a friction drive mechanism. The vial carousel 103 may even be directly driven by the vial carousel motor 114. It will be appreciated that many other appropriate drive mechanisms may be used in the vial holding assembly 100. In the geared arrangement 170 depicted in the embodiment of Figure 3, the vial carousel motor 114 may have a vial carousel drive pinion 120 mounted to its shaft and the drive pinion 120 may be meshed with, and thus configured to drive, a vial carousel drive gear 108. The vial carousel drive gear 108 may be coupled to the vial carousel 103 by an additional geared arrangement (not shown). Additionally, or alternatively, the vial drive gear 108 may be coaxial with and directly coupled to the vial carousel 103. In the embodiment of Figures, the vial carousel drive gear 108 is coupled to the vial carousel 103 by way of a vial carousel base 102 (shown in more detail in Figure 5B). When the vial holding assembly 100 comprises a vial supporting member 116, the vial supporting member 116 may be driven by the vial drive assembly 150 in the same manner as the vial carousel 103. To that end, the vial supporting member 116 may be directly coupled to the vial carousel 103, or otherwise configured to be driven by the vial carousel motor 114. The vial holding assembly 100 may also comprise a stirring mechanism 300 configured to tumble stir the contents of (e.g. fluid within) the vials 118, by way of magnetic stirring elements 133 (not shown in Figure 3) disposed in fluid in the vials 118 (i.e. each vial 118 may contain a single stirring element 133). As shown in Figure 3, the magnet carrier 115 may be configured as a magnet carrier base 115 configured to support the two or more magnetic elements thereupon. The magnet carrier 115 may also be referred to as a magnet carrier member 115. In the embodiment of Figure 3, the magnetic elements (which may also be referred to herein simply as ‘elements’) are permanent magnets 113. However, it will be appreciated that where magnets 113 are referred to herein, they may be replaced by any other suitable element, such as electromagnets. Therefore, any references to magnets 113 are not intended to limit the present disclosure to the use of only permanent magnets. Other suitable arrangements will be discussed in more detail in connection with Figures 4A to 4D. The magnets 113 may be configured to provide at least one north magnetic pole and at least one south magnetic pole by having their magnetic axes arranged antiparallel to each other (i.e. substantially parallel but in opposite directions such that their poles align N-S-N-S). The magnetic axes of the magnets 113 may be substantially orthogonal to the magnet carrier 115 (i.e. orthogonal to the path of the magnets 113 defined by the carrier). The magnetic axes of the magnets 113 may additionally or alternatively be orthogonal to the vial carousel 103 (i.e. orthogonal to a plane containing the path of the vial holders 134) such that the poles of the magnets 113 ‘face’ the vial carousel 103. Therefore, the vial carousel 103 ‘sees’ alternating north and south poles about the magnet carousel 103. The magnet carrier 115 and / or the magnet base 115 may define a continuous (i.e. cyclical) predetermined path about which the magnets 113 may move or travel. In the embodiment of Figure 3, this is achieved by the magnets 113 being located about the perimeter of an annular disc (the magnet base 115). Thus, the path of the magnets 113 in Figure 3 is circular, however the magnet carrier 115 may define a circular path by other means or may define path of any other continuous shape (e.g. pentagon, square or other suitable polygon or other shape) about which the magnets 113 may move. A circular magnet path may promote the uniformity of the magnetic field created, thus promoting uniform stirring of fluid within different vials 118, by the induced rotation of the stirring elements 133 disposed therein. The magnet base 115 is configured to support the magnets 113 such that they are located atop the magnet base 115. The magnet base 115 may be formed as a single member such a disc, an annular disc or a ring. Such arrangements may be more suited to embodiments where the predetermined path of the magnets 113 is circular. Alternatively, the magnet base 115 may be formed of adjoining segments, which might better facilitate predetermined paths that are non-circular. In other embodiments, the magnet carrier 115 may support, carry or house the magnets 113 in an alternative configuration. For example, the magnets 113 may be positioned about a central shaft (of the magnet carrier 115) and supported by spokes which extend from said central shaft. The magnets 113 may be affixed to the magnet base 115 via one or more fixing elements, such as bolts (not shown). The fixing elements may extend through the body of a given magnet 113 and through one or more corresponding through-holes in the magnet base 115. The magnets 113 may also be retained on the magnet base 115 via one or more clamping elements (not shown), such as a bracket bolted (or otherwise fixed) to the magnet carrier. The magnets 113, when they are permanent magnets, may comprise any suitable magnetic material. Examples include neodymium, ferrite magnets and alnico magnets. The magnetic stirring mechanism 300 of the vial holding assembly 100 may also comprise a magnet drive assembly 160 configured to drive the magnet carrier 115 such that the at least one north magnetic pole of a magnet 113 and at least one south magnetic pole of a magnet 113 move along the predetermined path. The at least one north magnetic pole and at least one south magnetic pole may move continuously along the predetermined path. In the embodiment of Figure 3, the magnet drive assembly 160 is configured to rotate the magnet carrier base 115 such that the magnets 113 move about a circular path defined by a perimeter of the magnet carrier base 115. The magnet drive assembly 160 may comprise a magnet carrier motor 112 which may be a DC motor connected to a power supply (not shown). The magnet drive assembly 160 may comprise one or more geared arrangements. Additionally, or alternatively, the magnet drive assembly may comprise (and thus drive the vial carousel 103 via) belts, linkages, or a friction drive mechanism. The magnet carrier 115 may even be directly driven by the magnet carrier motor 112 and it will be appreciated that many other appropriate drive mechanisms may be used in the vial holding assembly 100. When the magnet drive assembly 160 comprises a geared arrangement 170, as depicted in Figure 3, the magnet carrier motor 112 may have a magnet carrier drive pinion 130 mounted to its shaft and the drive pinion 130 may be meshed with, and thus configured to drive a magnet carrier drive gear 138. The magnet carrier drive gear 138 may be coupled to the magnet carrier 115 by an additional geared arrangement (not shown). Additionally, or alternatively, the magnet carrier drive gear 138 may be coaxial with and directly coupled to the magnet carrier. In the embodiment of Figure 3, the magnet carrier drive gear 138 is coupled directly to the magnet base 115 which is shown in more detail in Figure 5B. As will be set out in connection with Figure 4, for the magnetic stirring mechanism 300 to function, the magnetic stirring elements 133 must experience a changing or alternating magnetic field. In the embodiment of Figure 3, this alternating magnetic field can be created by the magnets 113 moving relative to the vials 118. Therefore, in embodiments where both the magnet carrier 115 and the vial carousel 103 are configured to move, they must be able to move at different speeds (e.g. with different revolutions per minute). In some embodiments the magnet carrier 115 and the vial carousel 103 may have a common drive assembly (not shown). Additionally, or alternatively, the magnet drive assembly 160 and vial drive assembly 150 may share common components. However, in such embodiments, the magnet carrier and the vial carousel 103 are ideally driven at different speeds. For example, the magnet drive assembly 160 and vial drive assembly 150 may share a common motor but, via one or more geared arrangements, may be configured to move at different speeds. Preferably the magnet carrier 115 is driven at a higher speed than the vial carousel 103. In some embodiments it may be advantageous to move the vial carousel 103 completely independently from the magnet carrier 115. This may allow vials 118 to be selectively positioned at different analysis stations 104, 106 and remain stationary at those stations for a selected amount of time, without impacting the motion of the magnet carrier 115, and thus not interfering with the stirring mechanism 300. To this end, it may be advantageous to have two independent motors 114, 122, as shown in the vial holding assembly 100 in Figure 3. In the embodiment of Figure 3, the magnet drive assembly 160 is vertically offset from the vial drive assembly 150. This may allow the two assemblies 150, 160 to operate independently. The vial carousel motor 114 is the lower motor, and its shaft extends through an opening 139 in the motor baseplate 109. The vial carousel drive pinion 120 therefore sits above, but adjacent the motor baseplate 109. The vial carousel drive pinion 120 meshes with the vial carousel drive gear 108, which may be adjacent the motor baseplate 109 and located below the magnet carrier drive gear 138. The magnet carrier motor 112 may be located above the motor baseplate 109. The magnet carrier motor 112 may be mounted atop the motor baseplate 109 by way of the motor mounting bracket 117. The motor mounting bracket 117 may be coupled to the motor baseplate by one or more fixings (not shown) at one or more fixing points in the motor baseplate 109. The magnet carrier drive pinion 130, mounted to the shaft of the magnet carrier motor 112 is therefore meshed with the magnet carrier drive gear 138. For the two drive gears 108, 138 to not interfere with each other, the carousel drive gear 108 may be concentrically inwards (in addition to or instead of) being below the magnet carrier drive gear 138 (or vice versa). As previously mentioned, the magnet carrier drive gear 138 may be directly coupled to the magnet carrier 115 (which may be above and adjacent the magnet carrier drive gear 138). Both the magnet carrier drive gear 138 and the magnet carrier 115 may be annular. Therefore, the vial carousel base 102, which is coupled to the carousel drive gear 108 may extend through centres of the magnet carrier drive gear 138 and the magnet carrier 115 and thus attach to the vial carousel 103. This arrangement is shown in more detail in Figure 5B. In this way, the magnet carrier 115 and the vial carousel 103 of Figure 3 may rotate coaxially with one another but be moveable independently of each other. It will be appreciated that many other suitable coaxial but independent arrangements may be used in the vial holding assembly 100. Figure 4A shows an overhead view of a vial holding assembly 100, indicating a circular cross-section 0-0 and Figure 4B shows the magnetic stirring mechanism 300, when viewed about the circular cross section O-O. The rightwards pointing arrow on the lefthand side of Figure 4A therefore indicates motion about this circular 0-0 cross section. As shown in Figure 4B, the magnetic stirring mechanism 300 may comprise at least two magnetic elements (e.g. magnets 113) configured to provide at least one north magnetic pole and at least one south magnetic pole arranged about a substantially circular path (e.g. the circular path indicated by cross-section O-O). A magnetic element which provides a north magnetic pole may be in the form of a magnet 113a which has its north pole as the uppermost pole, and its south pole positioned below the north pole (thus the magnetic axis of said magnet 113a is substantially vertical). Therefore, the upwards-facing north pole may be adjacent the vial carousel and adjacent the magnetic stirring elements 133. A magnetic stirring element 133 most adjacent a north pole of a magnet 113a will align its south pole with the north pole of the magnet 113a, in accordance with the magnetic field created by the magnet 113a. A magnetic element which provides a south magnetic pole may be in the form of a magnet 113b having the opposite orientation. Its magnetic axis may also be substantially vertical, but its south pole will be the uppermost pole. A magnetic stirring element 133 most adjacent a south pole of a magnet 113b (i.e. a magnetic stirring element 133 ‘facing’ a south pole) will align its north pole with the south pole of the magnet 113b, in accordance with the magnetic field created by the magnet 113b. Each magnet 113 has a magnetic axis extending from its south magnetic pole to its north magnetic pole. The pole of a magnet 113 most adjacent to the vial carousel 103 may be referred to as the pole ‘seen’ by the magnetic stirring element 133. In some embodiments, the magnets 113 may be arranged sequentially on the magnet carrier 115 such that magnetic axes of adjacent magnets 113 are anti parallel to each other. However, it will be evident from Figure 4D that embodiments exist where this is not strictly the case. In such embodiments, the magnetic stirring mechanism 300 may still comprise antiparallel pairs of magnets 113 (such as magnets 113a and 113b), but these magnets 113 may be interspersed with magnets 113 having axes with different orientations (such as magnets 113c and 113d). This will be discussed in more detail in connection with Figure 4D. Each antiparallel pair of magnetic elements may comprise a first magnetic element (e.g. magnet 113a) having a first magnetic axis and a second magnetic element (e.g. magnet 113b) having a second magnetic axis, the first magnetic axis being antiparallel to the first. Therefore, the first magnetic element (e.g. magnet 113a) may provide a north magnetic pole and the second magnetic element (e.g. magnet 113b) may provide a south magnetic pole. The pairs 113a, 113b should be arranged such that the magnetic poles seen by the magnetic stirring elements 133 in the vials 118 alternate (north-south-north-south) about the magnet carrier 115. Thus, the magnetic elements are configured to provide an alternating magnetic field to the magnetic stirring elements 133 disposed in the vials 118. The alternating field should induce rotation of the magnetic stirring elements 133 in the vials 118 about a horizontal axis. The magnetic stirring elements 133 may be provided in the form of traditional ‘stir bars’ which may be substantially cylindrical. However, as the magnetic stirring elements 133 of the present invention are configured to ‘tumble stir’ (i.e. stir the contents of a vial 133 via rotation about a substantially horizontal axis) rather than spin (i.e. stir via rotation about a substantially vertical axis), a disc-shaped magnetic stirring element 133 may be preferable. Tumble stirring is advantageous over this traditional ‘spin’ stirring (i.e. stirring about a vertical axis) as it may result in more uniform mixing over a vertical axis of a vial and a disc-shaped magnetic stirring element 133 may further promote uniform mixing. An exemplar magnetic stirring element 133, provided in the form of a magnetic disc, is illustrated in Figure 4E. By moving the north and south poles of the magnets 113 underneath (or above, in some embodiments) the magnetic stirring elements 133, the magnetic stirring elements 133 will see alternating poles from the magnets 113 of the magnet carrier 115. The magnetic stirring elements 133 will flip or rotate (to correctly align with the poles of the magnets 113 moving underneath them) continuously about a horizontal axis in accordance with the alternating magnetic field created by the moving north and south magnetic poles, thus tumble stirring any fluid within the vials 118. As the magnetic stirring element 133 needs to see a south pole, followed by a north pole, followed by a south pole again (or vice versa) in order to complete a full rotation, it will be appreciated that in embodiments where the magnets 113 have fixed orientations, a minimum of two magnets 113 (one to provide a north pole and the other to provide a south) is necessary for the magnetic stirring mechanism 300 to function. The magnetic axes of the magnets 113 may be orthogonal to the plane containing the path of the magnets 113. Additionally, or alternatively, the magnetic axes of the magnets 113 may be substantially orthogonal (or, at least, not parallel) to the plane in which the vial carousel 103 lies. These planes may preferably be horizontal. Therefore, the magnetic axes of the magnets 113a and 113b may preferably be vertical. Arranging the magnetic axes orthogonal to the vial carousel 103 advantageously promotes tumble stirring. For example, were the magnets 113 to be provided in a similar configuration to that of Figure 4B, but oriented horizontally (i.e. having horizontal magnetic axes, rather than vertical), the magnetic stirring elements 133 would be induced to stir by rotating about a vertical axis (i.e. stir by ‘spinning’), and thus not tumble stir. This would also be the case were the magnets 113 to be horizontal and the vial carousel 103 placed concentrically about (or concentrically inward of) the magnet carrier 115. In the embodiment of Figure 4B, the magnet carrier 115 is provided as annular magnet carrier base 115. The magnet carrier base 115 may be located beneath vial holders 134 of the vial carousel 103. In some embodiments, the magnet carrier base 115 may be located directly beneath and coaxial with the vial carousel 103. Therefore, the magnets 113 are located below and coaxial with the vials 118 and the magnetic stirring elements 133 disposed in those vials 118. Preferably the path of the magnets 113 is such that the magnets 113 pass underneath the centre (i.e. through the central vertical axis) of each vial 118. This arrangement may be preferable as placing the magnets 113 directly beneath the stirring elements 133 allows the stirring elements 133 to experience a greater magnetic field strength than they would in an alternative position. Advantageously, the coaxial arrangement also ensures that each magnetic stirring element 133 will experience the same magnetic field strengths (i.e. the same magnetic field strength profile as the magnetic field alternates). This allows each vial 118 to experience substantially the same speed and strength of mixing. Ensuring that vials 118 experience consistent mixing allows for chemical analysis performed on different vials 118 to be better compared. The arrangements disclosed herein allow uniform mixing to be achieved even in embodiments where the vial carousel 103 is static. In the embodiment of Figure 4a, the magnets 113 are provided in a circular configuration, which may further promote even mixing between different vials 118. The pairs of magnetic elements (e.g. magnets 113a and 113b) may also be arranged such that the north magnetic pole of the first element (e.g. magnet 113a) and the south magnetic pole of the second element (e.g. magnet 113b) are aligned on a common horizontal plane, relative to the magnet carrier 115. In this way, the poles of the magnets 113 which are adjacent the vial carousel 103 may be equidistance from the carousel 103. In some embodiments, the magnetic elements (e.g. magnets 113) are arranged to be spaced from a base of a vial 118 held in one of the plurality of vial holders 134 by a distance of between 0.5 mm and 100 mm, and preferably by a distance of between 1 mm and 20 mm. While two magnetic elements may be a lower limit of the number necessary, the magnetic stirring mechanism 300 may preferably comprise more than two magnetic elements. The more magnetic elements provided via the magnet carrier 115, the more rotations a magnetic stirring element 133 will undergo in one revolution of the magnet carrier 103. For example, in an embodiment where the magnet carrier 115 has 20 magnets 113 (i.e. 10 pairs of magnetic elements), 10 magnets 113 having their north poles facing the vial carousel 103 and 10 magnets 113 having their south poles facing the vial carousel 103 (where the north and south poles alternate) a magnetic stirring element 133 adjacent the magnet carrier would undergo 10 full rotations per revolution of the magnet carrier 115. Ideally, the magnets 113 are arranged such that their upwards-facing poles alternate between north and south (i.e. they are arranged N-S-N-S). Therefore, the magnet carrier 115 ideally comprises an even number of magnets 113, where half are configured to provide a north magnetic pole and half are configured to provide a south magnetic pole. When the magnet drive assembly 160 is configured to drive the magnet carrier at “X” revolutions per minute and the magnetic stirring mechanism comprises “Y” number of magnetic elements, a product of “X” and “Y” may be between 10 and 12000, between 10 and 6000, between 100 and 6000, between 200 and 6000, between 2000 and 4000, between 200 and 3000, between 1000 and 2000, or any value therebetween, such as about 2400, or about 1600, or about 1200. Viewed in another way, when the magnets 113 are considered as pairs, the number of number of pairs of first and second magnetic elements may be predetermined as “Y”. In this case, a product of “X” and “Y” may be between 5 and 6000, between 5 and 3000, between 50 and 3000, between 100 and 3000, between 1000 and 2000, between 100 and 1500, between 500 and 1000 or any value therebetween, such as about 1200, or about 800, or about 600. Accordingly, the number of magnetic elements (i.e. the value of “Y”) may be predetermined (although, where the magnetic elements are provided as electromagnets, this number may be dynamically determined). The rate of rotation of the magnet carrier 115 (i.e. the value of “X”) may also be predetermined to set the product of “X” and “Y” to the desired value. The product of “X” and “Y” may determine the rate of rotation of the magnetic stirring elements 133 disposed in the vials 118. In some embodiments, the rate at which the magnetic stirring elements 133 are caused to rotate within the vials 118 may be at about “Z” rpm (revolutions per minute) where “Z” is about half of the product of “X” and “Y” (where “Y” is the number of magnetic elements). This may apply in the case where each magnetic element has its magnetic axis oriented vertically (such as in Figure 4B). In some embodiments, the rate at which the magnetic stirring elements are caused to rotate within the vials 118 may be at about “Z” rpm (revolutions per minute) where “Z” is about a quarter of the product of “X” and “Y”. This may apply in the case where the magnetic elements are arranged in a Halbach configuration (such as in Figure 4D). In some embodiments, the rate at which the magnetic stirring elements 133 are caused to rotate in the vials 118 may be at about “Z” rpm (revolutions per minute) where “Z” is about the product of “X” and “Y” (where “Y” is the number of pairs of first and second magnetic elements). The rate at which the magnetic stirring elements 133 are caused to rotate within the vials 118 may be between 10 rpm and 6000 rpm, between 50 rpm and 3000 rpm, between 100 rpm and 1500 rpm, between 500 rpm and 1000 rpm, or any value therebetween, such as about 1200 rpm, or about 800 rpm, or about 600 rpm. The magnet drive assembly 160 may be configured to drive the magnet carrier 115 at between 5 rpm and 300 rpm, between 10 rpm and 150 rpm, between 50 rpm and 100 rpm, or any value therebetween, such as about 120 rpm, or about 60 rpm. The magnet stirring mechanism 300 may comprise between 2 and 100 pairs of the first and second magnetic elements, preferably between 2 and 50 pairs, and more preferably about 10 pairs. Therefore, in embodiments such as that of Figure 4B, where the magnet stirring mechanism 300 comprises only vertically arranged magnets 113 (i.e. only the magnets 113a and 113b of the pairs of the first and second magnetic elements), the magnet stirring mechanism 300 may comprise between 2 and 200 magnetic elements, between 2 and 100, between 10 and 50, or any number therebetween such as about 20 magnetic elements. In other configurations, the magnet stirring mechanism may comprise additional magnetic elements, as will be discussed in further detail in connection with Figure 4D. As previously mentioned, in some embodiments, the magnets 113 may be permanent magnets 113 and have fixed orientations (i.e. a given magnet 113 should always have its magnetic axis pointing in the same direction). However, the stirring mechanism 300 relies on the magnetic stirring elements 133 experiencing an alternating magnetic field. The field lines should point vertically and field lines due to adjacent magnetic elements should point antiparallel to each other. A single magnetic element should experience such an alternating magnetic field which alternates in time. Therefore, any magnetic arrangement which can produce such an alternating magnetic field in this manner is suitable. Therefore, additionally, or alternatively, some or all the magnets 113 may be electromagnets. Using electromagnets may allow an operator to dynamically select the number of magnets 113 included in the system as only a selected portion of the electromagnets can be powered at a given time. A user may also select the direction of the poles (and thus the direction of the magnet field lines) of a given electromagnet by reversing the current through the electromagnet. The magnetic field strengths of the electromagnets could also dynamically controlled. Therefore, using electromagnets may allow for more precise control of the magnetic field, and thus for more precise control of the induced motion of magnetic stirring elements 133 disposed in the vials 118. The electromagnets may provide an alternating magnetic field by providing them via a rotating magnet carrier 115, as shown in Figure 3. However, the electromagnets may alternatively be static and their magnetic field strengths (and directions) may be controlled electrically. For example, the current through the electromagnets may be controlled to create a changing magnetic field which simulates an arrangement where permanent magnets 113 are moved about the predetermined path. This effect may be achieved by varying the current through a first electromagnet in time, such that the direction of the poles (i.e. the direction of the magnetic axis) of that first electromagnet alternates in time. Further electromagnets, adjacent that first electromagnet may similarly be controlled such that they too have alternating poles, but the direction of their poles always opposes (i.e. is antiparallel to) that of the first electromagnet. In this way, a north pole (adjacent the vial carousel 103) may appear to ‘move’ from one electromagnet to the next, thus mimicking an arrangement where permanent magnets 113 physically move about a path, while the electromagnets (i.e. the electromagnetic coils which, when a voltage is applied, form said electromagnets) may be stationary. Such arrangements may reduce the number of moving parts in the overall system, thus reducing complexity. Many other arrangements which would create a suitable alternating magnetic field are also possible and may be used as the magnetic stirring mechanism 300 of the vial holding assembly 100. For example, Figures 4C and 4D depict an arrangement where the magnets 113 are arranged in a Halbach configuration (array). The directions of the magnetic axes of the magnets 113 in Figure 4D are indicated by arrows, where the arrows point from the south pole of a magnet 113 towards its north pole. In a Halbach array, the vertically arranged magnets (i.e. magnets 113a and 113b of the previously discussed pairs of first and second magnetic elements) are interspersed with horizontally arranged magnets (i.e. magnets 113c and 113d). The direction of the magnetic axes of the horizontally arranged magnets 113c and 113d are similarly alternating (i.e. antiparallel to each other). A magnetic stirring mechanism 300 comprising a Halbach array therefore may comprise a third magnetic element 113c having a third magnetic axis and a fourth magnetic element 113d having a fourth magnetic axis, the third and fourth magnetic axes being antiparallel to each other and orthogonal to the first and second magnetic axes. The first, second, third, and fourth magnetic elements may be arranged sequentially in a Halbach configuration. Advantageously, a Halbach configuration (array) creates a stronger magnetic field compared to an arrangement of magnets 113 of the same strength which only alternate in the vertical direction (as in Figure 4B). For instance, the magnetic field strength created by the arrangement of Figure 4D would be greater than that of Figure 4B (assuming similar magnets 113 were used). Additionally, the magnetic field strength below the Halbach array is substantially suppressed. This may inhibit the magnetic field from interfering with any components positioned below the Halbach array, such as motors or otherwise. As previously mentioned, in embodiments such as that of Figure 4D, where the magnet stirring mechanism 300 comprises magnets in addition to the vertically arranged of the pairs of the first and second magnetic elements, the magnet stirring mechanism 300 may comprise between 2 and 800 magnetic elements, between 2 and 400, between 40 and 200, or any number therebetween such as about 40 magnetic elements or about 20 magnetic elements. Figures 5A and 5B show a top view and a cross-sectional side view of the vial holding assembly 100 of Figure 1. As previously mentioned, Figure 5B shows further details of the vial drive assembly 150 and the magnet drive assembly 160. As depicted, each of the vial carousel drive gear 108, the vial carousel base 102, the magnet carrier base 115, and the vial carousel 103 may be arranged about a central tube 101. A portion of the vial carousel base 102 may be positioned between the vial carousel drive gear 108 and the central tube 101. A lower portion of the vial carousel base 102 may mesh with and thereby be driven by the vial carousel drive gear 108. One or more bearings 110 may be positioned between the central tube 101 and the vial carousel base 102 to allow the vial carousel base 102 to rotate about the central tube 101. The vial carousel base 102 may extend along an outer surface of the central tube 101. The vial carousel base 102 may extend between the central tube 101 and the magnet carrier base 115 to contact and thereby drive the vial carousel 103. A bearing 111 may be positioned between the vial carousel base 102 and the magnet carrier base 115 to facilitate independent rotation of those two components. The vial holding assembly 100 may also comprise a light source configured to illuminate or irradiate vials 118 held in the vial holding assembly 100. The light source may be an array of light emitting diodes (LEDs) 123 located adjacent the vial holders 134. For example, the LEDs 123 may be provided as an annular ring of LEDs 123 located concentric with and inwards of the vial carousel 103. The LEDs may be provided as an array on one or more printed circuit boards (PCBs). The LEDs 123 may be positioned on or outwardly of the internal analysis stations 104. The LEDs 123 may be positioned to emit light radially such that substantially the entire side of a reaction vial 118 is irradiated. The light source (e.g. LEDs 123) may be configured to emit light having wavelengths specific to the chemistry being performed. Exemplar wavelengths include 360 nm, 365 nm, 420 nm, 440 nm, or 455 nm. The light source may be configured to illuminate each vial 118 held in the vial holding assembly 100 substantially evenly. In other embodiments, where the illumination is not even, rotation of the vial carousel 103 may average out any inconsistencies in the illumination of the vials 118. The vial holding assembly 100 may also comprise one or more light source blocking panels 124 positioned to occlude the light source (e.g. positioned over the LEDs 123) at certain positions. The light source blocking panels 124 may inhibit vials 118 at said positions form being illuminated by the light source 123. Therefore, the blocking panels 124 may be positioned at locations where the vials 118 would otherwise be optically imaged. For example, as depicted in Figure 7B, the blocking panels 123 coincide with an external analysis station 106 having a camera 125. In this case, the blocking panels 124 may prevent the LEDs 123 from inhibiting the imaging of the camera 125. Figures 6A and 6B show a top view and a cross-sectional view of the vial holding assembly 100 of Figure 1, illustrating an airflow arrangement of the vial holding assembly 100. The vial holding assembly 100 may comprise one or more fluid conduits configured to allow an external supply of fluid to flow into the space (enclosure) 132. The one or more fluid conduits may include one or more of: the central air pipe 105; the lateral air duct 119; the outlet conduit 142; and external air ducts 121. Air (or another fluid) may enter the space 132 of the vial holding assembly 100 via the central air pipe 105 which may extend into a base (such as the previously mentioned base portion) of the vial holding assembly 100, through the motor baseplate 109 and the central tube 101 to the space 132. Air may then exit the space 132 via an outlet. The outlet may be provided as the lateral air duct 119 (see Figures 3 or 7B). The outlet (e.g. the lateral air duct 119) is preferably positioned across the vial carousel from the central air pipe 105 such that circulated air is forced to flow over the vials 118 and promote complete mixing of the fluid in the space 132. The outlet 105a of central air pipe 105 (i.e. where the central air pipe 105 connects to the space 132) in the embodiment of Figure 6B is positioned centrally, in the middle of the vial carousel 103. Therefore, the lateral air duct 119 is positioned outward of the vial carousel 103. In the embodiment of Figure 6B, the lateral air duct 119 is located at the base of the sidewalls 131, near an outer perimeter of the vial carousel 103. The lateral air duct 119 may be provided as a continuous annular ring about the vial carousel 103 (see Figure 3, for example). Figures 7A and 7B show a top view and a cut-away view of the vial holding assembly 100 of Figure 1. As shown therein the lateral air duct 119 may extend downwards, outwardly of the vial and magnet drive assemblies 150, 160. The lateral air duct 119 may connect to external air ducts 121. While a top portion of the lateral air duct 119 may be an annular ring having a continuous opening in fluid communication with space 132, a lower portion of the lateral air duct 119 may form one or more conduits which extend downward to connect with the external airducts 121. As previously mentioned, Figure 7B also depicts an embodiment where a light source is provided as an annular ring of LEDs 123, provided on PCBs, inside of and facing the vial carousel. Figure 7B depicts the camera 125 and the RAMAN probe 126 in further detail. Other suitable analysis or processing stations (e.g. internal 104 or external 106 analysis stations) may include an IR spectrometer or a hyperspectral camera. It will be appreciated that any exemplar analysis stations discussed in connection with the external analysis stations 106 may also be provided via the internal analysis stations 104, or vice versa. Figure 8 shows an isometric view of an airflow distribution system 200 for a vial holding assembly 100. The airflow distribution system 200 may also be referred to as a fluid distribution system and while it may be discussed herein in reference to controlling the flow of atmospheric air, it will be appreciated that, in some embodiments, the airflow distribution system 200 may be connected to an alternative supply of fluid (such as an inert gas, e.g. argon, or even a liquid). In such embodiments, the airflow distribution system 200 may also comprise an external gas (or liquid) supply (not shown) containing said supply of gas or fluid. As depicted in Figure 8, the external air ducts 121 may connect to and be in fluid communication with the air temperature control unit 122, thus putting the air temperature control unit 122 into fluid communication with the space 132. The air temperature control unit 122 may also be referred to as a fluid flow controller. The fluid flow controller may also control a flow rate of the fluid, as it is circulated through the space 132 and fluid conduits in fluid communication with said space 132. The enclosed volume of the vial holding assembly 100 which contains the vial carousel 103 (i.e. the space 132) may be temperature controlled. Preferably the temperature inside the space 132 may be controlled to be at any selected temperature between -20C and 120C. The temperature inside the space 132 may be controlled by controlling the temperature of a fluid which is (re)circulated though said space 132. Temperature control of the (re)circulated fluids may be achieved by recirculating fluid through electrical heating and / or cooling element(s) housed in the air temperature control unit 122. The air temperature control unit 122 may additionally or alternatively comprise other suitable heating or cooling mechanisms. For example, the (re)circulated fluids may be temperature controlled by way of a secondary fluid and a heat exchanger. The temperature in the enclosed volume (e.g. space 132) containing the vials 118 may be controlled to be a selected temperature using feedback from a temperature sensor (not shown), disposed in the enclosed volume (e.g. space 132), and a control system (not shown) to change the power supplied to the heating and / or cooling elements accordingly. Additionally, or alternatively, other heating and / or cooling arrangements may be employed. For example, the vial holding assembly 100 may comprise a heating element 513 disposed adjacent the magnet carousel (see Figure 11, for example). The heating element 513 may be provided as one or more rings located concentrically with the vial carousel 103. Such an arrangement may promote even heating or cooling of the vials 118. The flow path of the (re)circulated fluids may be as follows. Fluid may be heated and / or cooled by the air temperature control unit 122. An outlet conduit 142 may convey fluid from the air temperature control unit 122 to the central air pipe 105. An outlet 205a of the central air pipe 105 acts as a fluid inlet for the space 132 and thus circulares fluid into the space 132. The fluid is forced to flow over the top of the internal analysis stations 104, in the space between said stations 104 and the lid 107. The fluid flows over the top of the vials 118 on the carousel and to an outlet which is located outwardly of the vial carousel. The outlet may be provided at the lateral air ducts 119, which form an annular opening about the vial carousel. The fluid is conveyed, via this opening, into the duct 119. A lower portion of the duct 119 may form one or more conduits, which convey the fluid from the space 132 to the external air ducts 121 which, in turn, circulate the fluid back into the air temperature control unit 122. That fluid may then be recirculated anew through the fluid flow system 200 of the vial holding assembly 100. Figure 9 shows a reactor apparatus 500 comprising a vial holding assembly 100. Above the vial carousel 103 may be provided a range of optional equipment to access vials from above. The equipment may be static or moveable. As previously discussed, the vial holding assembly 100 may comprise analysis stations 104, 106 comprising apparatus configured to interact with one or more vials 118 held in the vial holders 134 when aligned with the analysis station 104, 106. The reactor apparatus 500 may comprise further analysis or processing equipment or apparatus, moveable or otherwise, configured to interact with one or more vials 118 held in the vial holders 134. For example, the reactor apparatus 500 may include a needle array 504 including one or more sampling needles configured to sample one or more of liquids, gases or solids contained within the vials 118. The lid 107 may comprise additional openings 128a which align with the one or more sampling needles of the needle array 504. The openings 128a may allow the one or more needles to access vials 118 held in the vial holding assembly 100. In the embodiment of Figure 9, the needle array 504 is fixed and may access different vials 118 by the vial carousel 103 moving with respect to the static needle array 504. Although the needle array 504 is fixed, the sampling needles may be moveable in the vertical direction, to extend into and retract from the vials. Alternatively, the needle array 504 could be moveable laterally, as well as vertically. The reactor apparatus 500 may comprise a vial capping station 506 configured to place caps on, and / or remove caps from vials 118 held in the vial holding assembly 100. The vial capping station 506 may access the vials 118 via an opening 128. In the embodiment of Figure 9, the capping station 506 is fixed, and may access different vials by the vial carousel 103 moving with respect to the static capping station 506. Therefore, the capping station 506 might be moveable vertically. Additionally, or alternatively, the capping station 506 could be moveable laterally. The reactor apparatus 500 may comprise an immersion probe (not shown), configured to conduct analysis via immersion in fluid contained in the vials 118. The immersion probe may be provided in a similar manner to the sampling needles of the needle array 504. The reactor apparatus 500 may comprise a dispensing needle and / or a solids dosing hopper configured to dose vials 188 with liquid supplied to the liquid dispensing needle or solids supplied to the solids dosing hopper. The dispensing needle and / or a solids dosing hopper may be fixed with the respect to the vial carousel 103. For example, the dispensing needle and / or a solids dosing hopper may be provided with the needle array 504. Additionally, or alternatively, the dispensing needle and / or a solids dosing hopper is located overhead the vial holding assembly 100 and moveable. For example, the dispensing needle and / or a solids dosing hopper may be provided via a moveable device 505. The moveable device 505 may be configured for movement above the vial holding assembly 100. The moveable device 505 may comprise a robotic device. In some embodiments, the moveable device 505 may be mounted to an overhead gantry 501. The gantry 501 may be configured to move the device 505 laterally in one or two directions. For example, the gantry 501 may move in one lateral direction by way of rails 511 mounted to a base of the reactor apparatus 500. The gantry 501 may be configured to move the device 505 vertically. Additionally, or alternatively, the moveable device 505 may be mounted to a base of the reactor apparatus 500 or mounted external to the reactor apparatus 500 and moveable as one or more articulated robotic arms. For example, the moveable device 505 may be configured as a SCARA (Selective Compliance Articulated Robot Arm) robot. The reactor apparatus 500 may comprise one or more moveable devices 505. Providing more than one moveable device 505 may allow additional analysis apparatus to be mounted to moveable devices 505. Said analysis apparatus, in being mounted to separate moveable devices 505, may thus be moved independently of each other. The device 505 may also comprise a vial gripper (not shown) configured to pick up a vial 118 from a first selected location and place said vial at a second selected location (or vice versa). The first location may be a vial holder 134 of the vial carousel 103. The second location may be an SBS plate rack 510 located in or adjacent the reactor apparatus 500. The vial gripper may access the vial carousel 103 (to pick or place vials therefrom or thereon) via one or more openings 128. Additionally, or alternatively, access to the vials 118 may be allowed by the removal of the lid 107. The vial gripper may be configured as a vial pick and place robot. The vial gripper may allow vials 118 to automatically be loaded and unloaded between the vial carousel and SBS plate racks 510 (or another suitable vial 118 storage means). The reactor apparatus 500 may further comprise a wash station 509 for needles. The moveable device 505 may be configured to wash needles or other sampling devices at the wash station 509 in between sampling (or dispensing reactants into) different vials 118. As previously mentioned, the reactor apparatus 500 may comprise one more sampling needles configured to extract, thereby sampling, fluid or other matter from the vials 118. The sampling needles may be provided with the needle array 504. Additionally, or alternatively, the moveable device 505 may comprise one more sampling needles. The sampling needle(s) may be configured to store the sampled fluid for later analysis, or to deliver the sampled fluid to an analysis station in the reactor apparatus 500. The sampling needle may be fluidically coupled to said analysis station, or configured to be moveable between the vials 118 and the analysis station. The reactor apparatus 500 may further comprise an overhead compartment 507 having a sliding lid 507. The overhead compartment may house features including electronics; fluid reservoirs for supplying dispensing needles, receiving fluid from the sampling needles, or otherwise; or a solids container for supplying material (e.g. solid powders) to the solids dosing hopper. A sliding lid may allow access to the overhead compartment. The gantry 501 supporting the moveable device 505 may be mounted to or in an underside of the overhead compartment 507. The reactor apparatus 500 may further comprise a base compartment 503 configured to house the vial holding assembly 100. The components of the reactor apparatus 500 may be enclosed by a fume hood (not shown) configured to substantially seal the volume of the reactor apparatus 500 from the atmosphere. The sealed volume may be limited to the space (or enclosure) 132. Additionally, or alternatively, the sealed volume may comprise the space defined between the overhead compartment 506 and the base compartment 503 of the reactor assembly 500. Some or all of the sealed volume may be configured to be flooded with a gas or a liquid. While certain components described herein are described as static and some as being mounted to the moveable device 505, it will be appreciated that any static component could be mounted to the moveable device and any of the moveable components may similarly be static. Static components may be mounted to a base (such as a top surface of the base compartment 503) of the reactor apparatus 500 or otherwise. Figures 10A and 10B show a side view and a cross-sectional plan view of the reactor apparatus 500 of Figure 9. As depicted therein, the reactor assembly 500 may comprise SBS plate racks 510 (or a surface configured to receive said SBS plate racks 510). The SBS plate racks 510 may be located at a forward position in the reactor assembly 500 such that a user or a robot may place vials 118 on said racks 510 (or remove vials 118 from the racks 510) without interfering with the other components of the assembly 500. As previously mentioned, the reactor assembly 500 may comprise one or more fluid reservoirs 512 configured to supply fluid to the dispensing needles, or other analysis apparatus. The fluid reservoirs 512 may be provided on a lateral side of the reactor assembly 500, as depicted in Figure 10B. Alternatively, the fluid reservoirs 512 may be provided in the body of the assembly 500, such as in the base compartment 503 or the overhead compartment 507. Figure 11 shows a schematic plan of the reactor apparatus of Figure 9. As depicted therein, the reactor assembly 500 may comprise an injection port 514. The injection port 514 may be configured to receive fluid sampled (i.e. sub-sampled) from the vials 118. For example, the sampling needle(s) may be configured to sample fluid from a vial 118 held in the vial carousel 103 and deliver that fluid to the injection port 514. As previously described, the sampling needle(s) may be provided as a part of the moveable device 505 and thus movable between the vials 118 and the injection port 514. The injection port 514 may be configured to transfer the fluid sampled from the reaction vials 118 to analytical apparatus (not shown). Said analytical apparatus may be housed in the reactor assembly 500. For example, the analytical apparatus may be housed in the overhead compartment 507 or the base compartment 503. Additionally, or alternatively, the analytical apparatus may be external to the reactor apparatus 500. The analytic apparatus may be an HPLC (high-performance liquid chromatography) instrument. The area camera 125a of Figure 11 may be the same as the camera 125 of Figure 2. The area camera 125a may also be an additional or alternative camera configured to image the volume of the reactor apparatus 500, as opposed to imaging individual vials 118. The lighting and internal photochemistry (photochem) array 123a may comprise the previously described light source (e.g. LEDs 123). The lighting and internal photochemistry (photochem) array 123a may additionally or alternatively comprise other light sources or photochemical apparatus. The clockwise arrow extending along the inner side of the vial carousel 103 indicates an exemplary direction of motion of the vial carousel 103 (the vial carousel 103 may alternatively rotate anticlockwise). The vial carousel 103 may be rotated in order to position a selected vial 118 at a selected processing or analysis station (or analysis apparatus). For example, a vial 118 may be positioned at the ‘pick at place’ position 515 (which coincides with the pick and place robot) in order to be removed from the vial carousel 103. In another example, a vial 118 may be positioned at a location on the carousel coinciding with the vial capping station 506 in order to be capped or de-capped. Eash analysis or processing station 104, 106 or apparatus may define one vial position which the station or apparatus is configured to interact with (i.e. the station or apparatus may interact with a vial 118 at that vial position). Some analysis stations may define more than one vial position which they are configured to interact with. In the case of the needle array 504, the analysis station may be static and simply define multiple positions in which vials 118 may be analysed. In other cases, the analysis stations or apparatus may be moveable, by way of the moveable device 505 or otherwise.

Claims

1015LO CXI i— i—CO20 1—2.

1. A vial holding assembly for a reactor apparatus, comprising:a vial carousel including a plurality of vial holders, the vial carousel configured to 5 be rotated such that the vial holders follow a substantially circular path; anda mechanism for tumble stirring fluid within a plurality of vials disposed within the plurality of vial holders, each vial containing a magnetic stirring element disposed in the fluid, the stirring mechanism comprising:a magnet carrier member having a first element with a first magnetic axis and a second element having a second magnetic axis, each magnetic axis extending from a south magnetic pole to a north magnetic pole,the first element and second element being arranged sequentially on the magnet carrier member such that the first magnetic axis and second magnetic axis are antiparallel to each other,wherein a position of the magnetic poles can be moved about a substantially circular path defined by the magnet carrier member whereby to create an alternating magnetic field that can induce rotation, about a horizontal axis, of a magnetic stirring element disposed in a vial offset vertically from the magnet carrier member, andwherein the substantially circular path of the first and second elements is below and coaxial with the substantially circular path of the vial holders.The assembly of claim 1, wherein the circular path defined by the magnet carriermember lies in a horizonal plane, and the first magnetic axis and second magnetic axis 25 are orthogonal to said horizontal plane.

3. The assembly of claim 1 or 2, wherein the first and second elements are arranged such that the north magnetic pole of the first element and the south magnetic pole of the second element are aligned on a common horizontal plane, relative to the magnet carrier 30 member.

4. The assembly of any of claims 1 to 3, wherein the first element and second elementtogether form a pair of first and second elements on the magnet carrier member, wherein the magnet carrier member comprises a plurality of said pairs of first and second elements.3513 11 255. The assembly of any preceding claim, wherein said plurality of pairs of first and second elements are arranged sequentially on the magnet carrier member such that the magnetic axes of adjacent elements are antiparallel.5 6. The assembly of claim 5, wherein the magnet carrier member has between 2 and100 pairs of said first and second elements.

7. The assembly of any of claims 1 to 4, further comprising a third element having a third magnetic axis and a fourth element having a fourth magnetic axis, the third and fourth 10 magnetic axes being antiparallel to each other and orthogonal to the first and second magnetic axes and the first, second, third, and fourth elements being arranged sequentially in a Halbach configuration.

8. The assembly of any preceding claim, further comprising a magnet drive assembly 15 configured to rotate the magnet carrier member such that the first and second elements move continuously along the substantially circular path.

9. The assembly of claim 8, wherein the magnet drive assembly is configured to rotate the magnet carrier member at “X” revolutions per minute and the magnet carrier member 20 has “Y” number of pairs of said first and second elements, such that a product of “X” and “Y” is between 100 and 3000.

10. The assembly of claim 8 or 9, wherein the magnet drive assembly is configured to drive the magnet carrier at between 5 and 300 revolutions per minute.2511. The assembly of any of claims 1 to 7, wherein the first and second elements are static electromagnetic coils configured to be electrically controlled whereby to invert a direction of their magnetic axes and create the alternating magnetic field about the circular path.3012. The assembly of any preceding claim, wherein the magnet carrier member of the mechanism is positioned beneath the vial holders.

13. The assembly of any preceding claim, wherein the vial holding assembly further 35 comprises a vial drive assembly configured to rotate the vial carousel.13 11 2514. The assembly of any preceding claim, wherein the first element and the second element are arranged to be spaced from a base of a vial held in one of said plurality of vial holders by a distance of between 1 mm and 20 mm.

515. The assembly of any preceding claim, wherein the vial carousel is housed within an enclosure defining an internal volume.

16. The assembly of claim 15, wherein the enclosure comprises a removable lid 10 portion.

17. The assembly of claim 16, wherein the removeable lid portion comprises at least one opening in alignment with at least one of the plurality of vial holders, when the lid portion is mounted to the vial holding assembly.1518. The assembly of any one of claims 15 to 17, further comprising one or more fluid conduits configured to allow an external supply of fluid to flow into the enclosure, and a fluid flow controller configured to control at least one of a temperature and a flow rate of the fluid.2019. The assembly of claim 18, wherein the fluid flow controller comprises at least one of a heating element and a cooling element configured to control a temperature inside the enclosure, whereby the fluid flow controller is configured to circulate a flow of fluid through the enclosure via said heating element or cooling element.2520. The assembly of any preceding claim, further comprising at least one analysis station comprising apparatus configured to interact with one or more vials held in the vial holders when aligned with the analysis station.30 21. The assembly of claim 20, wherein the at least one analysis station comprises acamera disposed adjacent the vial carousel, the camera being configured to view the contents of a vial held in a vial holder.

22. The assembly of claim 20 or 21, wherein the at least one analysis station comprises 35 at least one of a RAMAN or IR spectrometer.13 11 2523. The assembly of any of claims 15 to 22, further comprising a sidewall that surrounds the vial carousel, wherein the sidewall has at least one aperture though which analysis of the contents of one or more vials held in said plurality of vial holders can be 5 performed by analysis apparatus positioned in alignment with the aperture.

24. The assembly of any preceding claim, further comprising one or more light sources configured to illuminate one or more vials held in said plurality of vial holders.10 25. The assembly of claim 24, wherein the one or more light source comprises aplurality of LEDs positioned concentrically with the vial carousel, the LEDs configured to laterally illuminate one or more vials held in the plurality of vial holders.

26. A reactor apparatus comprising:15 a vial holding assembly according to any preceding claim, anda robotic device configured to interact with the one or more vials held in the plurality of vial holders,wherein the robotic device is configured for movement above the vial holding assembly.2027. The reactor apparatus of claim 26, wherein the robotic device is operable to pick a vial from a position remote from the plurality of vial holders and place said vial in one of the plurality of vial holders.25 28. The reactor apparatus of claim 26 or 27, wherein the robotic device may comprisea needle apparatus configured to perform at least one of:dosing the one or more vials held in the plurality of vial holders with a liquid reagent; andsampling fluid contained in the one or more vials.3029. A method of tumble stirring a fluid within a vial, the method comprising:providing a magnet carrier member having a first element with a first magnetic axis and a second element having a second magnetic axis, each magnetic axis extending from a south magnetic pole to a north magnetic pole,5 the first element and second element being arranged sequentially on the magnetcarrier member such that the first magnetic axis and second magnetic axis are antiparallel to each other,providing a vial carousel including a plurality of vial holders, at least one vial holder holding a vial containing fluid with a magnetic stirring element disposed therein, the vial 10 carousel configured such that the vial is located at a position offset vertically from the magnet carrier member,rotating the vial carousel such that the vial holders follow a substantially circular path in a substantially horizontal plane, androtating the magnet carrier member such that the first and second elements move15 continuously along a corresponding substantially circular path in a substantially horizontal plane, thereby creating an alternating magnetic field which induces rotation, about a horizontal axis, of the magnetic stirring element disposed in the vial,wherein the substantially circular path of the first and second elements is below and coaxial with the substantially circular path of the vial holders and wherein the vial 20 carousel and magnet carrier member rotate at different speeds.13 11 25

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