Stirring device for an autosampler for analyzing finely dispersed suspensions

Abstract

A stirring device for a sample holder for automatically analyzing a multiplicity of samples, comprising: a sample holder frame for regularly arranging a multiplicity of sample vessels; a sample holder base plate, which is arranged under the sample holder frame and comprises at least one channel or a recess for receiving a temperature control medium such that the temperature of a sample vessel arranged in the sample holder frame can be controlled; an agitator, arranged in or under the sample holder base plate and configured to set a stirring rod comprising a ferromagnetic material in rotation in the sample vessel in a contactless manner when the sample vessel and the agitator are arranged one above the other, such that a finely dispersed material contained in a fluid in the sample vessel is suspended; and a drive unit, configured to change a position of the sample vessel in relation to the agitator or a position of the agitator in relation to the sample vessel such that, in a first position set by the drive unit, a first sample vessel can be arranged above the agitator and, in a second position set by the drive unit, a second sample vessel can be arranged above the agitator.

Description

Stirring device for an autosampler for the analysis of finely dispersed suspensions Technical area

[0001] The invention lies in the field of sample preparation and sample collection technology for the analysis of finely dispersed systems, such as soil samples, sewage sludge, wastewater fractions, ceramic slurries, pigment suspensions, wheat beer, and suspension cell cultures. The invention potentially relates to the fields of chemical analysis, environmental monitoring, food technology, and biotechnology.

[0002] In other words, the invention relates to a stirring device for an autosampler for reproducible sample collection from finely dispersed suspensions (samples) for automatic analysis, in particular a stirring device for a slurry autosampler. Slurry is understood here as a suspension of finely dispersed material that is unstable due to at least partial sedimentation of sample components and must therefore be completely resuspended immediately before analysis to ensure the reproducibility of the measured data. Previously known state of the art

[0003] The spatially ordered provision of a large number of sample vessels in specially adapted sample holders (also called sample racks), sample carousels and sample receiving tables for automatic sample collection from corresponding, similar vessels containing the samples, sample vials (e.g. so-called autosampler vials), is widespread and used in various areas of analysis, in particular liquid chromatography (e.g. HPLC) and spectrometry (e.g. Atomic absorption spectrometry (AAS or atomic emission spectrometry (AES)) is common. Disadvantages of the state of the art

[0004] However, previously known solutions only rarely provide for automatic homogenization or automatic resuspension of the contents of the sample vials immediately before automatic sample aspiration by the autosampler of the corresponding measuring device.

[0005] The analysis of suspensions of finely dispersed materials is reserved for specialized applications anyway. Surfactants are typically used as stabilizers to stabilize the suspensions. These surfactants are subject to high chemical purity requirements. On the other hand, the stabilizer should not impair the signal-to-noise ratio that would otherwise be achievable when detecting sample components of interest. The addition of surfactants or inert fillers can impair the sensitivity of an analytical method and should therefore be avoided.

[0006] The previously known use of ultrasound to resuspend sedimented sample components prior to automatic sample collection by an autosampler can also be detrimental to the comparability and reproducibility of analytical results due to the potentially additional disruption caused, for example, by the mechanical destruction of sample components. Therefore, samples taken (automatically) by the autosampler typically have to be mixed, shaken, or stirred manually beforehand.

[0007] Furthermore, no separate temperature control of the samples or the sample vessels containing them is usually provided other than the passive, inevitable temperature control provided solely by the ambient (laboratory) air. Likewise, hermetic sealing of the sample vessels arranged for automatic sample collection is rarely used. Only in selected cases, for example in gas chromatography or high-performance liquid chromatography (HPLC), are samples present in organic solvents, the evaporation of which is prevented by a cap or a separate septum. Well-established analysis techniques for inorganic materials, such as AAS, are rather conservative in this regard, relying on the use of aqueous solutions that are held unsealed in a comparatively simple sample holder for sample collection.Typically, the autosampler of a corresponding measuring device is set up to sequentially supply samples arranged in the sample holder for analysis. Against this backdrop, existing solutions are only partially satisfactory and require significant manual and / or technical effort, resulting in correspondingly high costs. Typically, the advantage of automated sample aspiration and analysis is offset by the indispensable effort of continued manual sample handling. Exploiting the potential of automated sample aspiration (and analysis) over a period exceeding an 8-hour workday is therefore associated with high personnel costs and practically impossible. Thus, the potential of existing autosamplers generally remains untapped. Problem

[0008] It is therefore an object of the present invention to provide an autosampler and / or a device for an autosampler which enables manual resuspension of sedimented or partially sedimented sample components before automatic sample aspiration by the autosampler, in particular for the analysis of suspensions of finely dispersed materials.

[0009] Since, for certain applications, thermostatting of the sample is a prerequisite for maintaining its integrity and thus for the reliability of the analytical data collected, it is also desirable to maintain a constant temperature of the sample vessels arranged in the sample holder and the samples contained therein, at least until the time of sample collection by the autosampler. Inventive solution

[0010] The stated objects are achieved by a device according to claim 1. Further embodiments, modifications and improvements will become apparent from the following description and the appended claims.

[0011] According to one embodiment, a stirring device for a sample holder of an autosampler for automatic analysis of a plurality of samples is proposed, comprising the following: 1) a sample holder frame for a regular arrangement of a plurality of sample vessels, i.e. a frame that ensures or enforces the regular arrangement of the plurality of sample vessels. A corresponding arrangement is typically predetermined by the measuring instrument used. 2) a sample holder base plate, for example made of aluminum or another material with good heat conduction, e.g. brass, arranged beneath the sample holder frame, wherein the sample holder base plate comprises at least one, for example loop-shaped, channel. Likewise, instead of the upwardly closed channel, an upwardly open recess can also be provided.The channel and the recess are each adapted to receive and guide a temperature control medium, so that a sample vessel arranged in the sample holder frame can be temperature controlled in contact with the sample holder base plate or at least in spatial proximity to this. In other words, the described sample holder base plate fulfils the function of a temperature control unit. 3) an agitator arranged in or below the sample holder base plate (the temperature control unit), which is configured to set a stirring rod comprising a ferromagnetic material in motion in the sample vessel without contact, for example into rotation, when the sample vessel and the agitator are arranged in close proximity to one another, for example one above the other, so that a sample vessel arranged in the. A sample vessel is used to suspend finely dispersed material arranged in a fluid. The finely dispersed material has, for example, an average particle size (assuming typically spherical or approximately spherical or granular materials, said particle size corresponds to an average particle diameter) of a maximum of 0.25 mm, 0.5 mm, or even 1 mm. 4) a drive unit configured to change a position of the movable sample vessel with respect to the rigidly arranged agitator or a position of the positionable agitator with respect to the sample vessel such that, in a first position set by the drive unit, a first sample vessel can be arranged above the agitator, and, in a second position set by the drive unit, a second sample vessel can be arranged in its place above the agitator.

[0012] The described device advantageously allows the resuspension of finely dispersed materials from a liquid sample immediately before automatic sample aspiration, with the sample also being temperature-controlled. This typically avoids the disadvantages described above of the previously conventional addition of dispersing agents (e.g., surfactants) to the sample or exposure to ultrasound.

[0013] According to one embodiment, the sample holder frame additionally comprises a retaining means configured to fix or retain a sample vessel arranged in the sample holder frame. In particular, the sample vessels are held so firmly that they remain in the sample holder frame when a sample collection cannula or needle of an autosampler is retracted into the respective sample vessel for sample collection and are not pulled out of the frame or lifted along with the retracted autosampler needle.

[0014] Advantageously, the retaining means can comprise a simple perforated disc whose holes correspond to the arrangement of the sample vessels in the sample holder frame and whose holes have a smaller diameter than the sample vessels. For example, the retaining means can comprise a sieve plate whose meshes easily allow the sample collection cannula of the autosampler to pass through, whereby the sieve plate, as a closed net, covers and reliably holds the sample vessels arranged in the frame. Likewise, the retaining means can be a perforated plate made of an elastic material, for example a silicone film. The diameters of the holes in the perforated plate correspond to the diameter of the sample vessels or the holes are somewhat smaller, so that the sample vessels can only be placed in the frame against a certain resistance and cannot be easily lifted within the frame or even removed from the frame all that easily.In this way, the restraint device prevents unintentional lifting and removal of the. Sample vessels through the automatic sampler with the retraction of the sample collection capillary.

[0015] According to one embodiment, the stirring device further comprises a control unit, wherein a change between the first position and the second position of the sample vessels takes place after an automatic sample pickup from a (first) sample vessel by the autosampler.

[0016] Typically, the autosampler is freely programmable, so that any sample vessel can be specifically moved to for sample collection. The order in which samples are taken from the sample vessels arranged in the frame, or the processing of a sequence of analyses of the numerous samples in a numerous sample vessels, is therefore not necessarily predetermined by their spatial arrangement within the frame. However, an additional control unit, in the simplest case a light barrier, can expediently register the sample change and, for example, start or stop the operation of a respective assigned agitator. This means that - on the one hand - a sample arranged in the sample vessel is reliably resuspended and thus homogenized before sample collection, and - on the other hand - the respective agitator is only operated for as long as is actually necessary.

[0017] According to one embodiment, the temperature control unit (the sample holder base plate) comprises a channel and the temperature control means is a temperature-controlled fluid, wherein the channel has terminal connection means for supplying the temperature-controlled fluid and for discharging the temperature-controlled fluid.

[0018] Advantageously, a commercially available temperature-controlled water bath, which typically has a pump, can allow the temperature-controlled water to flow through the channel of the sample holder base plate, temperature-control it and thus ensure reliable temperature control of the samples arranged in the sample holder.

[0019] According to one embodiment, the sample holder base plate comprises a recess instead of the channel or in addition to it, and the temperature control means is, for example, an electrical resistance heater or, for example, a Peltier element. The temperature control means in question is arranged and controllable in such a way that a target temperature can be set in a sample vessel arranged above it.

[0020] An electrical resistance heater is advantageously easy to control. By combining a heating coil arranged in the recess and a heating element in the channel flowing cooling liquid, the constancy of the desired temperature of the samples can be easily achieved with a comparatively simple control.

[0021] According to one embodiment, the agitator is configured to generate a magnetic field rotating about a rotation axis, wherein an axis of symmetry of the sample vessel arranged above the agitator is substantially aligned with a rotation axis of the agitator or corresponds to a rotation axis of the agitator.

[0022] Advantageously, a stirring bar made of a ferromagnetic material arranged in the sample vessel can be set in rotation by means of the stirrer. The rotating stirring bar mixes the sample and redisperses sedimented sample components. Likewise, any phase separation that may occur between different sample components of a heterogeneous sample while the sample is standing can be eliminated. This ensures the reproducibility of the collected analytical data and thus the reliability of the analytical method.

[0023] According to one embodiment, the rotating magnetic field is generated by a bar magnet mounted orthogonally to the rotation axis and rotatable about this axis, or by at least two permanent magnets oriented oppositely with respect to their polarity, which are mounted rotatably about the rotation axis of the drive unit in such a way that their diametrically opposed magnetic poles of opposite polarity rotate in a plane that is oriented parallel to a main extension plane of the sample holder base plate.

[0024] It is advantageous to set a stirring rod arranged in the sample vessel, for example a nickel wire of appropriate length, into rotation so that previously sedimented sample components are redispersed or resuspended.

[0025] According to one embodiment, the regular arrangement of the plurality of sample vessels in the sample holder frame is selected from a concentric, a linear - for example in the form of a spiral line - and / or a gridded arrangement - for example in rows and columns.

[0026] This advantageously facilitates proper sample collection. Sample containers can also be provided with a machine-readable code, so that the analysis results obtained can be precisely assigned to a specific sample.

[0027] According to one embodiment, the sample holder frame equipped with sample vessels causes a linear arrangement of adjacent sample vessels along one or more concentrically running lines or paths, wherein at least the sample holder frame and optionally the sample holder base plate (temperature control unit) firmly connected to the sample holder frame are mounted so as to be rotatable about a central axis of rotation.

[0028] Advantageously, the sample holder frame, which appears as a sample carousel, can be reproducibly adjusted step by step by means of a comparatively simple drive, so that sample vessels arranged in concentric circles or paths can be guided under the sample holder of an autosampler, thus enabling sequential sample aspiration.

[0029] According to one embodiment, the sample holder frame provides an arrangement of adjacent sample vessels along a spiral line, with at least the sample holder frame being rotatably mounted about a central axis of rotation. For easily understandable reasons, the sample holder base plate, if it has temperature-control ribs, is typically firmly connected to the sample holder frame.

[0030] A spiral arrangement of the sample vessels also advantageously enables sequential sample collection, as the sampler is gradually brought closer to the sample carrier's center of rotation as it advances. Naturally, as in the previously described embodiment, the aim is to achieve a largely centered arrangement of the sampler's cannula over the sample vessel intended for sample collection (relative to the respective sample vessel).

[0031] According to one embodiment, the sample holder frame is firmly connected, for example rigidly connected, to the sample holder base plate.

[0032] This advantageously results in a compact design. Optionally, the sample holder base plate can be detachably connected to the sample holder frame with conveniently arranged stirrers. This allows a commercially available autosampler to be advantageously equipped with the temperature control and resuspension unit described above and below.

[0033] According to one embodiment, the sample holder base plate has tempering ribs arranged on the upper side of the sample holder base plate such that at least one side of the sample vessels arranged in the sample holder frame is positioned adjacent to the tempering rib.

[0034] This advantageously facilitates reliable temperature control of the samples contained in the sample vessels.

[0035] According to one embodiment, the agitator is arranged below the sample holder base plate and is movable relative to it, so that it can always be arranged below a sample vessel provided for automatic sample reception.

[0036] Advantageously, the sample holder frame is not moved with the samples, but the sampler (with its sampler cannula) and the agitator move synchronously or with a time delay so that the sample is mixed before the sample is taken.

[0037] According to one embodiment, a number of agitators corresponds to a number of concentrically extending lines or paths along which the sample vessels are arranged. This line essentially originates from the rotational axis of the sample holder frame. The sampling cannula is then arranged or can be arranged at the intersection points of this line with the projections of the concentrically extending lines / paths, i.e., the respective centers of the successively arranged sample vessels, resulting from a top-down projection.

[0038] Advantageously, with comparatively little structural effort, a large number of samples can be resuspended as required immediately before the sample is taken by the automatic sampler.

[0039] According to one embodiment, the drive unit has an electric drive comprising a stepper motor, a linear motor, a conveyor belt and / or a drive belt, e.g. a toothed belt.

[0040] These drive systems have proven to be highly controllable. They ensure a reproducibly adjustable step size when advancing the samples or the agitator(s).

[0041] According to one embodiment, the control unit is configured to trigger the operation of the agitator when a sampler of the autosampler is approached to a sample vessel for the purpose of taking a sample or is on a path to the sample vessel from which a sample to be resuspended is to be taken with the aid of the sampler for the subsequent automatic analysis, after a first sample has previously been analyzed, i.e. now the second sample following the first sample is to be taken.

[0042] The non-continuous operation of the agitator motors advantageously extends the service life of the agitators. The control unit can also be adapted to a slow To start up the agitator and gradually increase the speed of the agitator so that sedimented sample components can be reliably resuspended.

[0043] According to one embodiment, the control unit comprises a sensor. The sensor can comprise, for example, a light barrier or a distance sensor, wherein the light barrier and the distance sensor detect a sample vessel change, i.e., a replacement of the first sample vessel with the second sample vessel before a sample is taken by the sampler, and—in interaction with the control unit—trigger or start the operation of the agitator.

[0044] The sensor advantageously allows the precise determination of the time at which the next sample will be drawn up. This allows the precise location of the sample vessel to be made available. Based on this, the "stirring time" required for complete resuspension, i.e. the operating time of the agitator, can be determined. Once this time has elapsed, which can be specified, for example, by a control program implemented via the control device, automatic sample aspiration is initiated. Since the analysis of a sample typically takes longer than the time required for sample aspiration, the agitator can be switched off after sample aspiration. In this respect, the data determined by the sensor can serve as trigger points in the automatic analysis process. Operating the relevant agitator motors only before and optionally during sample aspiration extends their service life.

[0045] According to one embodiment, the control unit is configured such that the agitator is stopped after the sample has been taken up by the sampler until the next sample vessel is made available for analysis.

[0046] This advantageously extends the effective service life of the drive means used to operate the agitator, such as motors, and reduces operating costs.

[0047] According to one embodiment, the agitator has a drive selected from an electric, a hydraulic and a pneumatic drive.

[0048] According to one embodiment, the agitator is driven electrically and comprises a brushless electric motor.

[0049] Brushless electric motors have the advantage of being particularly low-maintenance and reliable.

[0050] According to one embodiment, an automatic analysis of the samples suspended by means of the agitator comprises one of: viscosity measurement, particle size measurement, particle analysis, for example by means of ICP-TOF-MS, thermogravimetry and atomic absorption spectrometry (AAS).

[0051] These analytical techniques are specifically aimed at analyzing samples containing particles or even individual particles, so the proposed method is of great use here.

[0052] According to one embodiment, the temperature control medium is a fluid, in particular thermostatted water.

[0053] Water is known to be an effective tempering agent.

[0054] According to one embodiment, the stirring device is used for elemental analysis of a sample by means of AAS.

[0055] Advantageously, AAS can also be used to reliably analyze complex sample mixtures that include both organic and inorganic sample components.

[0056] According to one embodiment, a kit or assembly for retrofitting an autosampler of a measuring device comprising a sample holder and a sample receiver is proposed. The kit or assembly comprises a sample holder baseplate adapted for placement beneath the sample holder of the autosampler. For example, the sample holder baseplate is adapted with regard to its length, width, and / or height, in particular by its diameter and height—if the sample holder is a stepwise rotating sample carousel. Optionally, the kit further comprises a control unit comprising a sensor, in particular a light barrier and / or a distance sensor.The sample holder base plate has an agitator configured to move a stirring rod comprising a ferromagnetic material in a sample vessel in a contactless manner using a magnetic field when the sample vessel is arranged above the agitator, such that a finely dispersed material arranged in a fluid in the sample vessel can be suspended with the stirring rod. The optionally present control unit is configured to activate the agitator for a predeterminable time when the sample vessel is changed. The predeterminable time can be selected such that the sample is completely (re-)suspended at the time the sample is taken up by the sample holder.

[0057] The described kit advantageously enables the easy retrofitting of a commercially available autosampler, for example for particle analysis or AAS.

[0058] According to one embodiment, the sample holder base plate further comprises at least one channel or a recess for receiving a temperature control medium, so that the sample vessel which can be arranged above the sample holder base plate or the sample arranged therein can be temperature controlled.

[0059] Advantageously, the sample can be tempered, for example cooled, in order to reduce evaporation of a suspension medium / the sample and to preserve or largely preserve a concentration or integrity of an analyte in the sample.

[0060] According to one embodiment, the kit further comprises a sample collection cannula, in particular a tapered cannula.

[0061] Advantageously, the cannula, which is tapered at the end, can be used to replace the sample collection capillary, which is usually blunt-ended, so that a sample can be collected from a sample vessel sealed with a septum without the function of the septum being lost due to the sample collection, namely to prevent contamination and / or evaporation of the sample.

[0062] According to one embodiment, the kit further comprises a retaining means adapted to retain and / or fix the sample vessel in the sample holder.

[0063] For example, the retaining means can be a silicone disc that, similar to the perforated plate of the sample holder, has holes corresponding to the sample vessels, with the diameter of the holes in the silicone disc being slightly smaller than the diameter of the holes in the sample holder. This retaining means is expediently arranged on or below the corresponding perforated plate of the sample holder. For this purpose, the silicone plate can have an adhesive layer on one side, be self-adhesive, or be removably attached to or below the perforated plate of the sample holder using a fastener, such as screws or clamps.

[0064] The embodiments described above can be combined with each other as desired.

[0065] Before an embodiment is explained in more detail below with reference to the figures, it is pointed out that the same elements in the figures have the same or similar reference numerals, and a repeated description of these elements is omitted here. Furthermore, the figures are not necessarily to scale; rather, the focus is on explaining the basic principle of the proposed technical solution. Figures

[0066] Figure 1 shows a schematic diagram of a stirring device for an autosampler.

[0067] Figure 2 shows a sample holder frame fully equipped with sample vessels with the sampler immediately before the sample is taken using a sampling cannula from a sample vessel closed with a septum.

[0068] Figure 3 shows an embodiment of a sample holder base plate with stirrers arranged therein.

[0069] Figure 4 shows the embodiment of the sample holder base plate shown in Fig. 3 in a plan view and in a sectional view.

[0070] Figure 5 shows perspective views of various embodiments of a sample holder base plate.

[0071] Figure 6 shows an exploded view of an autosampler.

[0072] Figure 7 shows an embodiment of a sample carrier frame with a retaining means arranged between two holding plates in the form of a perforated disc comprising an elastomer.

[0073] Figure 8 shows an embodiment of a sample holder with spirally arranged holes and corresponding tempering ribs of the associated sample holder base plate.

[0074] Figure 9 shows a box-shaped sample holder frame for arranging the samples in the form of an array, in “rows” and “columns”.

[0075] Figure 10 shows an embodiment of an agitator.

[0076] Figure 11 shows a schematic sectional view of a sample vessel containing a finely dispersed sample and stirring rod.

[0077] Figure 12 shows test results on recovery rates / recovery values ​​as a function of the length of the stirring rods used using the reference material BAM-U110 as an example.

[0078] Figure 13 shows the absorbance measurement results of a total of 182 measurements of different samples that were automatically recorded over a period of 800 minutes.

[0079] Figure 14 shows the recovery rates (mean ± c) for the dispersed samples, which are present as stabilized suspensions or slurry, which were determined on three consecutive days.

[0080] Figure 15 allows the comparison of stirred and unstirred dispersions of microplastics depending on the type of dispersant used. Detailed description

[0081] The stirring device 100 for an autosampler 60, shown schematically in Fig. 1, comprises a sample carrier 20 comprising a circular sample carrier frame 21 with a total of four circular, concentrically arranged rows of holes for receiving circular-cylindrical sample vessels 26. The sample carrier 20 comprises a sample carrier base plate 22 with stirrers 2 arranged therein. The sample carrier base plate has connections 3a, 3b in the form of hose connectors for the supply and removal of a temperature control medium 5. In order to detect a change in the position of the sample vessels, a sensor 70, for example a light barrier 70, an optical, capacitive or ultrasonic-based distance sensor 70, is arranged laterally next to the sample carrier 20.

[0082] Fig. 2 shows the sample carrier 20 of the same embodiment 100 with the sampler 66 comprising a sample receiving cannula 67. The cannula 67 can be positioned precisely over the septum (not visible here) of the sample container 26 from which the next sample is to be taken, before the next sample is taken from the subsequent second, third, etc. sample vessels 26a, 26b, 26c, etc., by means of a coordinated rotational position of the sample carrier 20 and the sample receiver 66.

[0083] Fig. 3 shows the sample carrier base plate 24 of this embodiment with four agitators 2 arranged therein. The agitator 2 is supplied or removed via the connecting pieces 3a and 3b. The discharged temperature control medium 5 ensures, via the temperature control ribs 25, a temperature control of the sample vessels 26, 26a, 26b, 26c held in the sample carrier frame 21. Their change can be detected by means of the sensor 70.

[0084] Fig. 4 shows a plan view of the sample carrier base plate 24 comprising tempering ribs 25 and a circumferential channel 3. The channel 3 can have a cross-section of any shape and can be, for example, square (below) or circular (above).

[0085] Fig. 5 shows various embodiments of the sample carrier base plate 24a, 24b, and 24c with recesses 4 of different cross-sections and shapes. The spiral-shaped recess 4 (groove) of embodiment 24b is adapted, for example, to accommodate a heating wire (not shown) surrounded by ceramic sleeves or embedded in a ceramic mass or glass wool. Likewise, the recess can be closed at the top and serve to circulate a temperature-controlled fluid. The recess 4 of embodiment 24a, on the other hand, can serve, for example, to accommodate a Peltier element.

[0086] The components of an autosampler 60 shown in Fig. 6 are the sample carrier frame 21 with base plate 24, sampler 66 and sampler cannula 67 which serves to take samples from sample vessels (not shown), the contents of which are dispersed by means of the stirrers 2 immediately before the sample is taken.

[0087] Fig. 7 shows the structure of a sample carrier 21 comprising a first or upper perforated plate 21a and a second or lower perforated plate 21d and a retaining means in the form of an elastomer perforated disc 21c arranged between these two. The holes in all of the perforated plates are arranged concentrically to one another. The holes in the elastomer perforated disc 21c have a smaller diameter than those of the upper and lower perforated plates 21a and 21d used for sample guidance. The elastomer perforated plate 21c is held by a perforated plate 21b and 21d arranged above and below it, or can be clamped between them. Since its hole diameters are slightly smaller than the diameters of the sample vessels 26a, 26b, 26c used. . .circular diameter, the sample vessels are held in their position in the sample carrier 21 and cannot be lifted or even pulled out of the sample carrier 21 by a retracted sample receiving cannula 67 of the sampler 66.

[0088] Fig. 8 shows an embodiment 22 of a sample holder with holes arranged spirally around a central axis of rotation 13 and corresponding tempering ribs 25 of the associated sample holder base plate 24d.

[0089] Fig. 9 shows a box-shaped sample holder frame 23 for arranging the samples 26, 26a, 26b, 26c... in the form of an array, in "rows" and "columns" with a sample holder base plate 24e closing the frame 23 at the bottom.

[0090] Fig. 10 shows an embodiment of a stirrer 2. The stirrer 2 comprises an electric motor (hidden) and a magnet carrier rotatable about a rotation axis 12 of the stirring rod 29 in the sample vessel 26, on which two permanent magnets 10 are arranged diametrically opposite one another in such a way that they point with different magnetic poles N, S upwards or towards the sample vessel 26 with the stirring rod 29.

[0091] Fig. 11 shows a typically used sample vessel 26 containing a sample 50 of a finely dispersed material and a stirring rod 29. The sample vessel 26 is sealed by a septum 28 pressed onto its opening by means of a closure cap 27. The septum 28 is made of an elastomer, for example, a polyurethane or silicone, which is designed to automatically seal an opening caused by a cannula puncture after the cannula is withdrawn. This reliably protects the sample 50 against evaporation.

[0092] Fig. 12 shows experimental results on recovery rates / recovery values ​​as a function of the length of the stirrer bars 29 used for the reference material BAM-U110 for various nickel stirrer bar sizes (m = 5, error bars = standard deviation). For reference, both the mean value (line) and the uncertainty (dotted lines) of the reference material used are given.

[0093] Fig. 13 shows absorbance measurement results from a total of 184 measurements of different samples, which were automatically recorded over a period of 800 minutes. The 184 individual measurements are represented by blank values, quality control standards (C), and the values ​​determined to create the calibration curve at 720 minutes. Only four outliers were detected within this measurement (Grubb's test, a = 0.05). The device used thus reliably delivers consistent values. Excluding the four outliers, the recovery rate is 105% ± 13%.

[0094] Figure 14 shows the recovery rates (mean ± G) for the dispersed samples (slurry) measured on three consecutive days. The values ​​were 96% ± 11%, 94% ± 13%, and 92% ± 11%, respectively. The recovery of the ionic quality control standards was in a similar range of 96% ± 7%. This result demonstrates that the proposed device ensures daily stability in terms of accuracy and precision.

[0095] Fig. 15 shows recovery rates for stirred and unstirred dispersions of microplastics depending on the type of dispersant used. In the measurements, the recovery for the reference material from the triplicates (N = 3) per solvent is 42% ± 29% for MeOH ( <p(MeOH) = 99 %), 43 % ± 11 % für EtOH (<p(EtOH) = 99 %), 104 % ± 11 % für ACN (<p(ACN) = 99 %) und 66 % ± 33 % für Reinstwasser (<p(H2O) = 99 %). Diese Ergebnisse bestätigen die Bedeutung der Wahl eines geeigneten Dispersionsmittels. Examples of implementation

[0096] First, factors influencing the stability of the dispersion (slurry) were investigated. The stirrer bar used proved to be crucial for the resuspension and stability of the dispersion, as well as for potential contamination. A key requirement for the stirrer bar is that it be magnetic. This property limits the possibilities to a few materials. Pure nickel wire was chosen as an example because this material is magnetic, inexpensive, stable to many chemicals, and easily accessible in high purity. To investigate the influence of the stirrer bar on the stability of the suspension, various diameters (1 mm and 2 mm) and lengths (4 mm to 9 mm) were tested. The test material was the soil reference material BAM-Ul 10 (w (Cd) = 7.3 mg / kg ± 0.6 mg / kg) in pure water using AAS (Analytik Jena contrAA 800 HR-CS-AAS System; Analytik Jena GmbH, Germany).The mass concentration for this study was set to (Cd) = 1.5 pg / L. The influence of the different stir bar sizes is evident in the recovery values ​​shown in Fig. 12. The error bars represent the standard deviation of n = 5.

[0097] Without stirring, recovery ranges from 12% to 21%, highlighting the need to resuspend the samples. When a stir bar is used, recovery ranges from 91% to 106%, with a standard deviation of less than 10%. This recovery rate fits perfectly within the range of the reference material. Furthermore, no influence of the stir bar size is observed, demonstrating the high robustness of the achieved mixing. Furthermore, the stability of the soil slurry in pure water is already stable enough for quick and easy analysis.

[0098] For routine analysis, both intraday and interday precision and accuracy are important parameters. Therefore, automated measurements of soil reference material BAM-Ul 10 (w (Cd) = 7.3 mg / kg ± 0.6 mg / kg) in pure water were performed using AAS over a period of approximately twelve hours. The mass concentration for this study was set to approximately (Cd) = 1.5 pg / L. Nickel stir bars with a diameter of 2 mm and a length of approximately 7 mm were used for this experiment. The same mass concentration was used as in the previous experiment. The data from this study are presented as mean normalized absorbance in Figure 13.

[0099] The interday stability measurements with water were carried out on consecutive days, and on the fourth day, the experiment with MeOH was carried out. The results are shown in Fig. 14. For each day, 125 individual measurements were carried out. To reduce fluctuation, the data were corrected where necessary using QC standards (Quality Control Standard) in water (Cd) = 1.5 pg / L. A single-element cadmium standard (p(Cd) = 1000 mg L') was used. 1, Certipur, Merck KGaA, Germany). Type I ultrapure water from a Milli-Q system (>18.2 Mfi cm; Merck Millipore, Germany) was used for dilution, as the QC also showed some drift during the measurements. The observed drift may have been caused by changing the oven or changing the lamp intensity of the AAS apparatus. One measurement on each day took approximately twelve hours. As in the previous experiment, outliers were determined using the Grubb test (α = 0.05).

[0100] The recovery rates (mean ± c) for the soil slurries for the three days were 96% ± 11%, 94% ± 13%, and 92% ± 11%, respectively. The recovery of the ionic quality control (QC) standards was in a similar range of 96% ± 7%. This result demonstrates that daily stability in terms of accuracy and precision is maintained. Furthermore, the experiment shows that the standard deviations of the replicates are close to those of the ionic standard, which means that the major standard deviation is not caused by the autosampler stirring device described here, but by the AAS method itself. This assumption is supported by the fact that the standard deviation and recovery of the samples prepared in MeOH / ultrapure water mixture ( <p(MeOH) = 96 %) suspendierten Proben 96 % ± 7 % beträgt. Diese Standardabweichung ist identisch mit deijenigen der ionischen Standards und zeigt, dass dieser Wert nicht reduziert werden kann.These results demonstrate that perfectly suitable values ​​in terms of precision and accuracy can be achieved with virtually no sample or solution preparation. Thus, the stirring device proposed here and used as described allows for the rapid and reliable determination of the mass fraction of contaminants in soil samples using AAS.

[0101] To determine the detection limit, limit of quantification, and linear range for cadmium in soil samples using the described stirring device, the upper limit of the linear range of the method used was first determined. This limit was up to p(Cd) = 3 pg / L (sample both as slurry and as ionic calibration). Higher concentrations resulted in a nonlinear calibration curve. The instrumental detection limit (LOD) was calculated as three times the standard deviation of ten blank measurements taken on three different days. The limit of quantification (LOQ) was calculated based on the same blank measurements using ten times the standard deviation. Using these calculations, the LOD for Cd using the described stirring device is 0.04 pg / L ± 0.02 pg / L and the LOQ is 0.15 pg / L ± 0.08 pg / L.

[0102] To investigate the influence of the sample matrix on the analytical values, Cd was determined in acrylonitrile butadiene styrene (ABS). This method involves the elemental analysis of microplastics. ABS is of considerable interest because the assessment of toxic metals in polymers, such as ABS, is particularly relevant due to its frequent use in electronics and toys. However, microplastics (MP) can also be considered a vector for pollutants other than cadmium. To account for the high solubility of ABS in organic solvents, the proposed stirring device was tested using sample containers sealed with septa and sample collection from the organic solvents acetonitrile (ACN) and methanol (MeOH). The cooling enables high stability of the solvents, i.e., low evaporation and thus unadulterated concentration over long measurement times.

[0103] Anthropogenic waste, especially highly persistent plastic waste, has become a global problem. The hypothesis that microplastics (MP) can be a vector for potentially harmful chemicals ("Trojan horse effect") has achieved "paradigm status" among scientists studying the occurrence and effects of MP.

[0104] While, for example, agglomerates were visible in ultrapure water, the particles in ACN were stabilized, as could be observed under the light microscope. This problem is particularly evident when measuring the triplicate. The standard deviation within a measurement (m = 5) is in a range of more than 100%. For ACN, it is in the same range as for the measured soil sample. This indicates that either a larger agglomerate or almost no sample was measured. This finding confirms the necessity of a cooled and closed sample container. Since methanol and ACN have a high vapor pressure, the corresponding solvent would evaporate during long-term measurements. The combination of several technical features described in the invention, which in retrospect and in isolation may appear simple, enables the reliable acquisition of valid measurement data using volatile solvents, the use of which is particularly indicated in the case of environmental samples (soil or water samples) contaminated with microplastics.

[0105] Although specific embodiments have been illustrated and described herein, it is within the scope of the present invention to appropriately modify the illustrated embodiments without departing from the scope of the present invention. The following claims represent a first, non-binding attempt to broadly define the invention.

[0106] Additional objects, advantages, and novel features of the present invention will become apparent upon consideration of the following examples, which are not intended to be limiting. Furthermore, each of the various embodiments and aspects of the present invention, as described above and claimed in the claims, will find experimental support in the following examples, which are offered to illustrate the invention, but not to limit it.

[0107] The main challenge with slurry sampling is maintaining the stability of the suspension (sample) being measured. This can be achieved through chemical means such as surfactants or physical processes such as ultrasonication. However, the use of surfactants is problematic because it potentially introduces a new source of contamination, adds an additional step to the workflow, and requires the optimization of a suitable stabilizer mixture for each specific matrix or suspension. Even with optimization measures, the suspension can collapse within a few hours, preventing overnight measurements and thus limiting throughput.

[0108] On the other hand, the installation of physical stabilization units requires space in the autosampler and introduces an additional source of contamination to the sample when using stir bars ("stirring fish"). In particular, the physical space required by the slurry stabilization unit impacts throughput, as the number of sample positions in the autosampler is significantly reduced. Furthermore, this adaptation usually requires structural changes to the autosampler, which limits the versatility of the modified measurement equipment. Materials, reagents, standards and methods

[0109] For calibration, a single element cadmium standard (p(Cd) = 1000 mg L' 1Certipur, Merck KGaA, Germany). Class I ultrapure water from a Milli-Q system (>18.2 Mfi cm; Merck Millipore, Germany) was used for dilution. Nitric acid (CO(HN03) = 65%) was used to stabilize the ionic standard. Palladium and magnesium ICP-MS standard solutions were used as auxiliary agents for the HR-CS-AAS measurement (p(Mg) = 10,000 mg L'). 1 ; p(Pd) = 10000 mg L' 1 , Certipur, Merck KGaA, Germany). Two different reference materials were used to characterize the newly developed autosampler system: BAM-H010 (Acrylonitrile butadiene styrene (ABS), granulate, Federal Institute for Materials Research and -test (BAM), Germany) and BAM-Ul 10 (contaminated soil, BAM). The ABS reference material was further ground under the addition of liquid nitrogen. To obtain small plastic particles, two steps (500 pm and 150 pm sieves) were performed using a centrifuge mill (ZM 200, Retsch GmbH, Germany). HPLC vials with PTFE / silicone septa were used as sample containers. The organic solvents used (methanol (MeOH, LC-MS grade 99.95%), ethanol (EtOH, for analysis, 99.9%), acetonitrile (CAN, LC-MS grade, 99.95%)) were purchased from Th. Geyer (CHEMSOLUTE, Th. Geyer GmbH & Co. KG, Germany).

[0110] The newly developed autosampler system described here was named Automated Slurry Analyzer (ASA) and is shown in Fig. 6. The system is specifically adapted for stabilizing suspensions to enable reproducible analysis of slurry samples. For this purpose, four brushless motors (type 0703B 15000 KV, Racerstar Electronic Technology Co., Ltd., China) are used as magnetic stirrers by attaching neodymium magnets (diameter 3 mm, height 1 mm) to them. The modified stirring units are placed below the positions where the autosampler needle withdraws the sample. To protect them from possible spills, the motors are covered with a thin glass fiber reinforced epoxy (FR-4) laminate.

[0111] To avoid contamination, Ni ekel wire pieces (99.2%, Evek GmbH, Germany) of different diameters (1 mm and 2 mm) and lengths were used as stirring rods.

[0112] According to one embodiment, the autosampler is designed for ease of handling to accommodate standard HPLC vials with a volume of 1.5 mL. To keep these vials stable and prevent them from being lifted, To avoid sample vials being damaged, the turntable (sample holder) was designed in three layers of PVC / silicone / PVC. The two PVC layers hold the vials in position, while the silicone layer acts as a retaining element to prevent the vials from being lifted by the needle after sample collection. As a further modification, a cannula was attached to the autosampler to penetrate the septum of the HPLC vials used and maintain the low dead volume in the system.

[0113] By cooling the aluminum base plate of the autosampler and using closed HPLC vials, the potential loss of solvents is drastically reduced and the uninterrupted operation time (measurement times) is considerably extended without the need to manually close the vials, e.g., with Parafilm, as reported by Metzger M. et al., 2019 (Screening method for extractable organically bound fluorine (EOF) in river water samples using high-resolution-continuum source graphite furnace molecular absorption spectrometry (HR-CS GF MAS)“, Anal Bioanal Chem, 411, 4647-4660). A Cool-Care 8-16 unit (Van Der Heijden Labortechnik GmbH, Germany) was used as a cooler (thermostat).

[0114] The photoelectric sensor used enables precise motor start-up, thus reducing the time the motors are only rotating, thus extending their service life. The system is designed to be installed on an AAS autosampler within minutes and removed again if necessary—no parts need to be connected, and the use of the photoelectric sensor allows the movement of the autosampler to be used instead of a direct electrical connection between these two parts of the measurement setup. This enables fast, user-friendly, and reproducible analysis of slurry samples, for example, using AAS.

[0115] In addition to using the slurry function, the developed autosampler can also be used without stirring to prevent solvent evaporation and thus make measurements more reliable. Furthermore, the integrated water management can be used not only for cooling but also for targeted heating of sample vessels before sample collection, for example, to trigger reactions before the sample is taken. This wide range of options in a highly automated form makes this autosampler, i.e., the system consisting of a temperature control unit with integrated agitator and photoelectric detection of the rotation of a sample carousel, perfectly suited for routine measurements.

[0116] The analysis of cadmium was performed on an Analytik Jena contrAA 800 HR-CS AAS system (Analytik Jena GmbH, Germany). Pyrolytic Coated graphite tubes with a PIN platform (Analytik Jena) were used. The temperature program used for the AAS and the injection sequence were adapted according to Borges AR et al. 2011 (Method development for the determination of cadmium in fertilizer samples using high-resolution continuum source graphite furnace atomic absorption spectrometry and slurry sampling, Spectrochimica Acta Part B: Atomic Spectroscopy, 66, pp. 529-535). According to the autosampler's analysis routine, sampling was carried out as follows: 10 pL ultrapure water, 25 pL sample, and 5 pL Pd / Mg mixture (p(Pd) = 1.0 g / L, p(Mg) = 0.6 g / L). The temperature program is summarized in Table 1.

[0117] Table 1: Temperature program used for the determination of cadmium by HR-CS-GF-AAS.

[0118] In the autosampler described, the stirring rod used is a key component with regard to the stability of the sludge and its potential contamination. A key requirement for the stirring rod is that it is magnetic. This property limits the selection to a few materials. Here, pure nickel wires were chosen because this material is magnetic, inexpensive, stable against many chemicals, and readily available in high purity. To investigate the influence of the stirring rod on the stability of the sludge, stirring rods of various diameters (1 mm and 2 mm) and lengths (4 mm to 9 mm) were tested. The test material was the soil reference material "BAM-Ul 10" (w(Cd) = 7.3 mg / kg ± 0.6 mg / kg) in pure water. This soil is from a floodplain north of the city of Halle / Saale, which, as a floodplain of the Saale River, had been exposed to fluvial immissions of pollutants for decades (cf.Description of the certified reference material BAM-Ul 10 "contaminated soil" of the Federal Institute for Materials Research, Berlin; Germany; publication date December 2006). The mass concentration of cadmium was adjusted to approximately p(Cd) = 1.5 pg / L. The values ​​obtained with these different stir bar sizes. Results are presented as recoveries in Fig. 12. The error bars represent the standard deviation of 5 replicate measurements on the same sample.

[0119] Without stirring, the recovery ranges from 12% to 21%, demonstrating the need to stabilize the suspensions. When a stir bar is used, the recovery ranges from 91% to 106%, with a standard deviation below 10%. This recovery fits perfectly within the range of the reference material. Furthermore, no trends related to the stir bar size are evident, demonstrating the high robustness of the method. Furthermore, the stability of the samples in the form of the material dispersed in water is already sufficient for rapid and simple analysis. Daily precision and accuracy are important parameters for routine analyses. Therefore, a sequence of measurements was performed over a period of approximately twelve hours. Nickel stir bars with a diameter of 2 mm and a length of approximately 7 mm were used for this experiment. The same mass concentration was used as for the previous experiment.The data from this series of experiments are presented as mean normalized absorbance in Fig. 13. The graph represents 184 individual measurements—this includes blank values, quality control standards (QC), and the calibration curve over approximately 720 minutes of measurement time. Only four outliers were generated within this measurement (Grubbs test, α = 0.05). Thus, the method is extremely stable. Excluding the four outliers, the recovery rate is 105% ± 13% (mean ± G).

[0120] Day-to-day stability with water was performed on consecutive days, and on the fourth day, the experiment with MeOH was conducted. The results are shown in Figure 14. 125 individual measurements were performed for each day. To account for instrument drift, the data were corrected against QC standards where necessary, as the QC also exhibited some drift during the measurements. Drift can occur when the oven heating power fluctuates or the lamp intensities change. Each measurement lasts approximately twelve hours. As with the previous experiment, outliers were identified using Grubb's test (α = 0.05).

[0121] The recovery rates (mean ± G) for the slurry samples on the three days were 96% ± 11%, 94% ± 13%, and 92% ± 11%, respectively. The recovery of the ionic quality control standards was in a similar range of 96% ± 7%. This result demonstrates day-to-day stability in terms of accuracy and precision. Furthermore, the experiment demonstrates that the standard deviations of the replicates are close to those of the ionic standard used, indicating that the major standard deviation is not caused by the developed autosampler extension, but by the AAS method itself. This assumption is supported by the fact that the standard deviation and recovery of the sample suspended in MeOH / ultrapure water ( <p(MeOH) = 96 %) 96 % ± 7 % betragen. Diese Standardabweichung ist identisch mit derjenigen der ionischen Standards und zeigt, dass dieser Wert allein durch eine Änderung des Autosamplers nicht reduziert werden kann. Diese Ergebnisse zeigen, dass mit nahezu keiner Probenvorbereitung oder Lösungszubereitung perfekt geeignete Werte in Bezug auf Präzision und Genauigkeit erreicht werden können. Somit kann eine schnelle und zuverlässige Methode angewendet werden, um den Massenanteil von Verunreinigungen in Bodenproben zu bestimmen.

[0122] Detection limit, quantification limit and linear range The upper limit of the linear range of the method used was up to p(Cd) = 3 pg / L (both as a sludge sample and as an ionic calibration). Higher concentrations resulted in nonlinear behavior of the calibration points. The instrumental limit of detection (LOD) was calculated as three times the standard deviation of ten blank measurements on three different days. The limit of quantification (LOQ) was calculated based on the same blank values ​​using ten times the standard deviation. Using these calculations, the LOD for cadmium is 0.04 pg / L ± 0.02 pg / L and the LOQ is 0.15 pg / L ± 0.08 pg / L.

[0123] A polymer, acrylonitrile butadiene styrene (ABS), was used as the second matrix. Due to the challenging digestion process for polymers, direct sampling of such sample matrices is of great interest, as they are found in many everyday products. Due to the particle size of the selected reference material (BAM-H010), which is too large for the developed injection system, the material was ground prior to analysis.

[0124] Milling was carried out in a two-step process, using a centrifugal mill with a 500 pm (first step) and a 150 pm (second step) sieve, and using liquid nitrogen to prevent melting of the polymer. After milling, no further steps were performed, and the samples were weighed directly, with tests performed using four different solvents (MeOH, EtOH, ACN, water). All other parameters, such as the oven program and the stir bar, were kept identical to those for the soil samples.

[0125] Since organic solvents with a high vapor pressure are used, the closed vessel system is also adapted and cooling comes into play. Evaporation is drastically reduced, and no concentration is produced as a result of the Evaporation is expected. Since three organic solvents with high vapor pressures were included in this study, sample containers sealed with septa were used and the samples were cooled. This drastically reduced the evaporation of the solvents used and prevented a previously detectable concentration resulting from evaporation.

[0126] In the measurements shown in Fig. 15, the recovery rate (mean ± G) for the reference material (BAM-H010) from the triplicates (N = 3, m = 5) per solvent is 42% ± 29% for MeOH ( <p(MeOH) = 99 %), 43 % ± 11 % für EtOH (<p(EtOH) = 99 %), 104 % ± 11 % für ACN (<p(ACN) = 99 %) und 66 % ± 33 % für ultrareines Wasser (<p(H2O) = 99 %). Um das Auftreten der hohen Standardabweichung für drei der untersuchten Lösungsmittel zu untersuchen, wurden die Suspensionen unter Verwendung eines Lichtmikroskops untersucht. Hier waren zum Beispiel in ultra-reinem Wasser Agglomerate sichtbar, während in den ACN-Proben keine Agglomerate beobachtet werden konnten. Dies deutet darauf hin, dass entweder ein größeres Agglomerat gemessen wurde oder fast keine Probe vorhanden war. Es ist auch deutlich sichtbar, dass das Rühren das Ergebnis in allen Fällen verbessert.

[0127] However, these results highlight that even with physical stabilization methods such as stirring, solvent selection is crucial. Nevertheless, the presented autosampler does not require any mixtures or surfactants to stabilize the suspension. Consequently, the risk of contamination is minimized, and all solvents used can be purchased in high purity. This finding confirms the necessity of cooled and sealed sample vessels. Since ACN, like methanol, has a high vapor pressure and would therefore evaporate during long measurements, adaptations to the autosampler are necessary to obtain valid data in volatile solvents, as practiced here.

[0128] The stirring device described above can be advantageously used, for example, as an autosampler extension for a GF-AAS apparatus (graphite furnace atomic absorption spectrophotometry / / AAS with electrothermal heating) and is a useful tool for simplifying complex and error-prone sample preparation, particularly the digestion of solid samples. This extension offers a cost-effective alternative for the precise, accurate, economical, and rapid determination of the metal content in solid samples. The flexibility and adaptability of the system are evident within the two exemplary matrices (soil and polymer), as it can be easily adapted to different matrices by simply changing the solvent. Furthermore, the system is designed to control the temperature and is based on on the use of sealable sample containers, which are readily available from various suppliers, which facilitates the use of organic solvents.

[0129] The use of the stirrer used according to the invention, described here as an example using a commercially available AAS device, with the temperature-controlled sample holder for sample vials sealed with a septum and an optical sensor, enables access to emerging markets, such as the fully automated analysis of electronic waste using spectroscopic methods. The elemental analysis of electronic waste is extremely challenging using conventional techniques due to its complex composition of glass, polymers, and various other matrix components that are difficult to digest. Furthermore, the resulting system enables the determination not only of extractable organic fluorine (EOF) but also of adsorbable organic fluorine (AOF) using activated carbon suspensions.This capability allows a comparison and complementary investigation of these two parameters in the increasingly worrying area of ​​new pollutants, in particular per- and polyfluorinated substances (PFAS).

[0130] According to exemplary embodiments, the present disclosure relates to a tempering and stirring device for an autosampler of a measuring apparatus, for example an AAS or particle analysis apparatus equipped with an autosampler.

[0131] As mentioned at the beginning, the proposed stirring device is also suitable for sample collection and sample preparation during the analysis of a wide variety of finely dispersed systems, such as soil samples, sewage sludge, wastewater fractions, ceramic slurries, pigment suspensions, wheat beer and suspension cell cultures, and thus concerns applications in chemical analysis, environmental monitoring, food technology and biotechnology. List of reference symbols 1 drive unit 2 agitator (motor with magnetic carrier) 3 channel 3a, 3b Connection means for supplying or discharging a tempered fluid 4 Recess 5 Tempering agents 10 permanent magnet(s) 12 Rotation axis of the stirrer (and the stirring rod in the sample vessel above) 13 Rotation axis of the sample holder frame 20 sample holders 21, 22, 23 Sample holder frames 21a upper guide plate 21b upper clamping plate 21c Silicone perforated disc, retaining device 21d lower clamping plate 24, 24a, 24b, 24c, 24d, 24e Sample holder base plate, temperature control unit 25 Tempering rib 26, 26a, 26b, 26c. . . Sample container 27 Cap 28 Septum 29 Stirring rod, “stirring fish” 50 finely dispersed material in the sample vessel 60 autosamplers 66 samplers 67 Cannula, sample collector cannula 70 Sensor, e.g. light barrier or distance sensor 80 electric motor 100 stirring device

Claims

Claims 1. Stirring device (100) for a sample holder (20) for an automatic analysis of a plurality of samples, comprising: a sample holder frame (21, 22, 23) for a regular arrangement of a plurality of sample vessels (26, 26a, 26b, 26c...), a sample holder base plate (24, 24a, 24b, 24c, 24d, 24e...) which is arranged below the sample holder frame (21, 22, 23), wherein the sample holder base plate (24, 24a, 24b, 24c, 24d, 24e...) comprises at least one channel (3) or a recess (4) for receiving a temperature control medium (5), so that a sample vessel (26, 26a, 26b, 26c...) arranged in the sample holder frame (21, 22, 23) .) is temperature-controlled; a stirrer (2) arranged in or below the sample holder base plate (24, 24a, 24b, 24c, 24d, 24e...), which is configured to set a stirring rod (29) comprising a ferromagnetic material in the sample vessel (26, 26a, 26b, 26c. . .) into contactless movement by means of a magnetic field when the sample vessel (26, 26a, 26b, 26c.. .) and the agitator (2) are arranged one above the other, so that a finely dispersed material (50) arranged in a fluid in the sample vessel (26, 26a, 26b, 26c. . .) is suspended; and a drive unit (1) which is configured to change a position of the sample vessel (26, 26a, 26b, 26c. . .) in relation to the agitator (2) or a position of the agitator (2) in relation to the sample vessel (26, 26a, 26b, 26c. . .) such that in a first position set by the drive unit (1), a first sample vessel (26, 26a, 26b, 26c. . .) can be arranged above the agitator (2), and in a second position set by the drive unit (1), a second sample vessel (26a, 26b, 26c, 26d. . . .) can be arranged.

2. Stirring device (100) according to claim 1, wherein the sample holder frame (21, 22, 23) comprises a retaining means which is configured to hold a sample vessel (26, 26a, 26b, 26c. . .) arranged in the sample holder frame so firmly that it can be withdrawn when a sample is withdrawn into the sample vessel (26, 26a, 26b, 26c. . .) penetrating sample receiving cannula (67) of an autosampler (60) remains in the sample holder frame (21, 22, 23).

3. Stirring device (100) according to claim 1 or 2, further comprising a control unit, wherein a change between the first position and the second position occurs after an automatic sample pickup from the first sample vessel (26, 26a, 26b, 26c. . .) and the control unit is adapted to control the operation of the stirrer.

4. Stirring device (100) according to one of claims 1 to 3, wherein the sample holder base plate (24, 24a, 24b, 24c, 24d, 24e...) comprises a channel (3), and the temperature control means (5) comprises a temperature-controlled fluid, and the channel (3) a terminal connection means (3a) for supplying the tempered fluid and a terminal connection means (3b) for discharging the tempered fluid.

5. Stirring device (100) according to one of claims 1 to 3, wherein the sample holder base plate (24, 24a, 24b, 24c, 24d, 24e...) has a recess (4), and the temperature control means (5) is a Peltier element or a resistance heater, wherein the Peltier element is arranged and controllable such that a target temperature can be reached in a sample vessel (26, 26a, 26b, 26c. . . .) arranged above the Peltier element or above the resistance heater.

6. Stirring device (100) according to one of claims 1 to 5, wherein the magnetic field is generated by a bar magnet mounted orthogonally to a rotation axis (12) and rotatable about this, or the magnetic field is generated by at least two oppositely oriented permanent magnets (10) which are rotatably mounted about the rotation axis (12) such that their diametrically opposed magnetic poles of opposite polarity rotate in a plane which is oriented parallel to a main extension plane of the sample holder base plate (24, 24a, 24b, 24c, 24d, 24e...).

7. Stirring device (100) according to at least one of claims 1 to 6, wherein the regular arrangement of the plurality of sample vessels (26, 26a, 26b, 26c. . .) in Sample holder frame (21, 22, 23) is selected from a concentric, a linear and / or a gridded arrangement.

8. Stirring device (100) according to claim 7, wherein the sample holder frame (21) equipped with sample vessels (26, 26a, 26b, 26c. . .) provides an arrangement of adjacent sample vessels (26, 26a, 26b, 26c. . .) along concentric lines, and wherein at least the sample holder frame (21) is rotatably mounted about a central axis of rotation (13).

9. Stirring device (100) according to one of claims 1 to 8, wherein the sample holder frame (21, 22, 23) is fixedly connected to the sample holder base plate (24, 24a, 24b, 24c, 24d, 24e...).

10. Stirring device (100) according to one of claims 1 to 9, wherein the sample holder base plate (24, 24a, 24b, 24c, 24d, 24e...) comprises tempering ribs (25) which are arranged on an upper side of the sample holder base plate (24, 24a, 24b, 24c, 24d, 24e...) such that at least one side of sample vessels (26, 26a, 26b, 26c...) arranged in the sample holder frame (21, 22, 23) is adjacent to the tempering rib (25).

11. Stirring device (100) according to one of claims 1 to 10, wherein the agitator (2) is arranged below the sample holder base plate (24, 24a, 24b, 24c, 24d, 24e...) and is movable relative to the latter, so that it can always be arranged below a sample vessel (26, 26a, 26b, 26c...) provided for automatic sample reception.

12. Stirring device according to one of claims 8 to 11, wherein a number of stirrers (2) is equal to a number of the concentrically extending lines, and the stirrers (2) are arranged substantially along a line emanating from the rotational axis (13) of the sample holder frame (21, 21a) at intersection points of this line with the concentrically extending lines.

13. Stirring device (100) according to at least one of claims 3 - 12, wherein the control unit is arranged to trigger the operation of the stirrer (2) when a sampler (66) approaches to take a sample or is on its way to the sample vessel (26, 26a, 26b, 26c. . .) from which a resuspended sample is to be taken with the aid of the sampler (66) for subsequent automatic analysis.

14. Stirring device (100) according to claim 13, further comprising a light barrier (70) or a distance sensor (70), wherein the light barrier (70) and the distance sensor (70) detect a replacement of the first sample vessel (26, 26a, 26b, 26c. . .) by the second sample vessel (25a, 25b, 25c. . . .) before a sample is taken by the sampler (66) and triggers operation of the agitator (2).

15. Stirring device (100) according to at least one of claims 1 to 14, wherein the agitator (2) has a drive which is selected from an electric, a hydraulic and a pneumatic drive, in particular from an electric drive and a brushless electric motor (80).

16. Use of a stirring device (100) according to at least one of claims 1 to 15 during an automatic measuring method selected from a viscosity measurement, a particle size measurement, a thermogravimetry, a particle analysis, in particular an AAS.

17. Kit for retrofitting an autosampler (60) having a sample holder (20) and a sample receiver (66), comprising: - a sample holder base plate (24, 24a, 24b, 24c, 24d, 24e...) adapted to be arranged below the sample holder (20) of the autosampler (60); - and optionally a control unit comprising a sensor (70), in particular a light barrier and / or a distance sensor; wherein the sample holder base plate (24, 24a, 24b, 24c, 24d, 24e...) has an agitator (2) configured to set a stirring rod (29) comprising a ferromagnetic material in a sample vessel (26, 26a, 26b, 26c...) into motion without contact by means of a magnetic field when the sample vessel (26, 26a, 26b, 26c...) and the agitator (2) are arranged one above the other, such that a finely dispersed material (50) arranged in a fluid in the sample vessel (26, 26a, 26b, 26c...) can be suspended.

18. Kit according to claim 17, wherein the sample holder base plate (24, 24a, 24b, 24c, 24d, 24e...) further comprises at least one channel (3) or a recess (4) for receiving a temperature control means (5), so that the sample vessel (26, 26a, 26b, 26c...) which can be arranged above the sample holder base plate (24, 24a, 24b, 24c, 24d, 24e...) can be temperature controlled.

19. Kit according to claim 17 or 18, further comprising a sample receiving cannula (67), so that a sample receiving capillary of the sample receiver (66) can be replaced by the sample receiving cannula (67) and a sample can be received from the sample vessel (26, 26a, 26b, 26c. . .) closed with a septum (28).

20. Kit according to any one of claims 17 to 19, comprising: - a retaining means adapted to retain and / or fix the sample vessel (26, 26a, 26b, 26c. . .) in the sample holder (20).

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