Device for analyzing a small amount of liquid

Abstract

Device (1, 100, 200, 300) for the analysis, fluorescence measurement, luminescence measurement, phosphorescence measurement, Raman scattering measurement or absorption measurement of a small amount, for example a drop, of a liquid sample (P) by means of light which can be guided through the sample (P) and can then be detected or analyzed according to the said measuring methods, wherein the device (1, 100, 200, 300) has an upper sample holder (3, 103, 203, 303) in the use position with a receiving point (4, 304, 304') for applying or dropping the sample (P) and a light inlet (5, 205, 305) for excitation light, which is horizontally oriented in the use position and is located below the sample holder (3, 103, 203, 303), characterized in that the device has a first device (7, 207, 307) located in the beam path behind the light inlet (5, 205, 305) for deflecting the light upwards to a position (Q) provided in the sample holder next to the receiving point (4, 304, 304') and a second light deflection (8, 108, 218, 308) which deflects the light beam coming from below into the sample (P) to be analyzed.

Description

INTRODUCTION

[0001] The invention relates to a device for the analysis, fluorescence measurement, luminescence measurement, phosphorescence measurement, measurement of Raman scattering or absorption measurement of a small amount, for example a drop, of a liquid sample with the aid of light which is guided through the sample and can then be detected or analyzed according to the aforementioned measuring methods, wherein the device has, in the use position, an upper flat receiving point for applying or dropping the sample, a light inlet into its housing which is oriented horizontally in the use position and located below the receiving point and a first device located in the beam path behind the light inlet for deflecting the light upwards to the receiving point, as well as a second light deflection which directs the light beam coming from below into the sample to be analyzed. STATE OF THE ART

[0002] A similar device is described in the German patent DE 10 2004 023 178 B4 and has proven itself in practice as a universal accessory for absorption measurements. However, it has been shown, in particular, that in fluorescence measurements, the direct deflection of the excitation light toward the detector by means of the detachably attachable reflector results in the detector being overexposed with an excessive amount of light. This can cause the detector to become saturated and potentially damaged. At the very least, the excitation radiation cannot be distinguished from the fluorescence radiation, which is significantly weaker in intensity, and therefore, evaluation of the measurement signal is not possible.

[0003] The similar solution known from German patent DE 10 2005 036 898 B4 has also proven successful, as the availability of a lower height for universal applicability as an accessory has proven to be a critical success factor. However, the same undesirable effects occur during fluorescence measurements as previously described.

[0004] EP 0 660 106 A1 discloses a device that allows measurements to be taken at greater distances using a conventional spectrophotometer that has a slot for inserting a measuring cuvette. The device has the external dimensions of such a cuvette and thus fits into the slot of the spectrophotometer. The device incorporates light deflectors in the form of prisms or mirrors, which initially deflect the incoming light to a first light guide, which leads to a remote measuring point on a probe. The light is returned via a second light guide and, within the device, is guided by a second deflector in the form of a prism or mirror to the point where, in the case of a measuring cuvette, the light passing through it exits towards a detector.

[0005] In commercially available fluorimeters and spectrofluorimeters, as well as in the fluorescence cuvettes used to hold and hold the liquid samples to be analyzed, an angle of 90° has been established for decoupling the excitation and emission radiation of a fluorescent sample. In principle, any other angle that decouples the numerical aperture of the excitation and emission radiation would also be suitable. The disadvantage of this approach is the required sample volumes, ranging from at least 20 µL to one or more milliliters.

[0006] US Pat. No. 7,397,036 B2 describes a variant of the 90° arrangement of excitation radiation and received emission radiation, which enables the fluorimetric analysis of small sample volumes of approximately 2 µL. The sample to be analyzed is held in a special sample holding device as a liquid column solely by the surface tension between two plungers. The sample volume examined depends on the pipetting accuracy or on the amount of sample remaining in the liquid column, which is determined by its respective surface tension. Therefore, the measurement of conventional organic-based samples is largely impossible. Due to the open arrangement of the sample holding device, the required protection against stray light is not adequately guaranteed. From US 2009 / 0156429 A1 a device for pulsed excitation and measurement of fluorescence spectra is known, in which the excitation light is directed by means of steering mirrors to a point on an input-side prism, which lies completely outside the sample holder. Description of the invention

[0007] The task is therefore to create a universally applicable device of the type described above, in which its advantages of being able to easily place small, precisely defined sample quantities of a liquid sample, even with low surface tension, at a measuring point and to carry out reliable and simple cleaning after the measurement are retained equally with large and small installation heights, but now a fluorescence measurement with sufficient differentiation of excitation radiation and emission radiation is possible.

[0008] This object is achieved with a device for the analysis, fluorescence measurement, luminescence measurement, phosphorescence measurement, Raman scattering measurement, or absorption measurement of a small amount of a liquid sample having the features of claim 1. Advantageous developments of the invention are defined in the subclaims.

[0009] To solve this problem, the device defined above provides a first device located in the beam path behind the light inlet for deflecting the light (light deflection) upwards to a position lateral to the receiving point, as well as a second light deflection that directs the light beam coming from below into the sample to be analyzed (toward the receiving point). The second deflection can be arranged laterally in the area of ​​the sample holder and directs the light into the liquid sample at a suitable angle so that no portion of the excitation radiation is directed toward the detector, thus separating the emission beam path and excitation beam path.In contrast to the device defined at the beginning, not only the side of the sample receiving point facing the detector is designed to be translucent, but also its lateral boundaries, whereby the term translucent refers to the excitation and signal radiation used.

[0010] To minimize losses during transport within the device, it is advantageous to integrate the second light deflection into the lateral boundaries of the sample holder, so that it is suitable for directing the excitation light horizontally into the sample (to the sample receiving point) to excite fluorescence. Accordingly, with horizontal excitation, the fluorescence is emitted at 90° in a vertical direction upwards and downwards. Due to the second light deflection located next to the sample receiving point, it is perpendicular to the excitation radiation in the sample and thus spatially separated from it.

[0011] If the beams run essentially vertically due to the design of the first light-deflecting element and the subsequent beam guidance to the recording point and a corresponding beam guidance from the recording point back towards the detector, the height of the device can be varied as desired within a wide range, since the second light deflection does not influence the function at the actual measuring point, namely the well-shaped, recessed sample recording point.

[0012] The sample receiving location is preferably a recess in the sample holder. This recess can be flat and horizontal and has a circumferential side border. Cup-shaped recesses with sloping side walls, cylindrical recesses with vertical side walls, or other shapes of sample receiving location are equally suitable, as long as they allow for a precise definition of the sample volume at the receiving location.

[0013] Since it can be important, depending on the application, to know the exact volume of the sample being analyzed, even for fluorescence measurements, the sampling point is preferably closed or limited at the top. This limitation can be provided by a lid and is preferably flush. It is also possible for the sampling point to be limited by a reflector with a horizontal reflection surface for fluorescence radiation, also preferably flush. The reflector can also be integrated into the lid and thus limit the sampling point in the manner described. The sample sampling point, which is precisely defined in terms of its size and volume, is particularly advantageous because it results in a measuring chamber that is geometrically defined in all spatial directions. This ensures that organic media with only a low surface tension remain in the measuring chamber and, at the same time, the volume is clearly defined.This also eliminates the dependence on pipetting accuracy, since the volume examined depends solely on the geometry of the measuring chamber.

[0014] The sample collection area can be designed as a square, similar to a fluorescence cuvette. However, for ease of cleaning, it is preferable to design the area cylindrical or in the shape of a truncated cone. This shape is irrelevant for the optical function.

[0015] The reflector could also be replaced by another element defining the measurement chamber. However, it can increase the solid angle of the fluorescent light captured for the measurement and thus amplify the signal. Alternatively to a flat reflector, a transparent element defining the measurement chamber is also conceivable. It has a curved, for example, spherical, reflecting surface on its back that reflects the emitted fluorescent light toward the detector.

[0016] Because the reflector is preferably located in a lid-like element, the sample collection point is protected from stray light. Stray light can prevent accurate measurement results, especially with weak fluorescence signals.

[0017] All components delimiting the measuring chamber should advantageously be designed in such a way that the materials used are free of fluorescence and their edges and surfaces, due to their nature, do not generate any scattering that can reach the detector.

[0018] The first light redirection can take the form of totally reflecting prisms or other reflective components, for example metal-coated mirrors.

[0019] The light can be guided from the first deflection point to the acquisition point using light-guide rods, large-cross-section optical fibers, or fiber bundles. With well-collimated excitation radiation, such as that conceivable with a laser radiation source, light-guided components can, in principle, be dispensed with, and the excitation radiation can be transported directly from the first deflection point to the second deflection point.

[0020] The light guide from the floor of the acquisition point to the first detector light deflector, which redirects the light toward the detector, functions in a similar manner. Due to the need to direct a sufficiently strong light signal from the actual measurement point toward the detector, light guidance using light-conducting components in this line is likely to be indispensable in practice.

[0021] The first detector light deflection can again be achieved by a totally reflecting prism or another reflective component. It is also conceivable to integrate the prism, for example, into the end of the light guide rod by providing its end with a reflective surface arranged at an angle.

[0022] As already described, in the present device, the actual measuring point has been relocated to the upper receiving area, where the angular arrangement of the excitation beam and emission beam is favorable for fluorescence measurement. This reveals, as a key aspect of the described invention, the independence from the device-side arrangement of the excitation radiation and the necessary orientation of the emission radiation toward the detector.

[0023] On the one hand, it is preferable to choose fluorescence measuring instruments as the location for the device. In commercially available devices, the arrangement of the excitation radiation and the necessary alignment of the emission radiation toward the detector are typically at an angle of 90°, although other angles are conceivable.

[0024] Equally, it is now possible to use some photometers or spectrophotometers for fluorescence measurements that are actually intended for absorption measurements or transmission measurements, respectively. Particularly obvious and universally applicable devices are those with a polychromator on the detector side, so-called diode array devices, or devices that can select the wavelength range to be analyzed using spectral filters. On the excitation radiation side, the excitation wavelength can then be determined at the output of the lamp module using simple spectral filters, which are inexpensively available as catalog items from Edmund Optics, for example.

[0025] In addition to the possibility of measuring fluorescence, a structural variant according to a second embodiment of the present invention also provides the possibility of carrying out transmission measurements by using two different deflection elements in the lid.

[0026] In this case, the second deflection is not integrated into the lateral boundaries of the recording point, but is provided at a suitable location so that it is suitable for directing the excitation light further horizontally into the sample.

[0027] For fluorescence measurement, the second deflection device can now be conveniently attached to a lid. However, it continues to function in the same way, directing the excitation light coming from below through the translucent side walls of the sample holder onto the sample to be analyzed.

[0028] On the other hand, an alternative second light deflection can be provided for measuring the transmission. This second light deflection is suitable for directing the excitation light into the recording point and vertically downwards through the sample by multiple reflection. In other words, excitation is no longer horizontal, but vertically, and the radiation for transmission measurement is taken from the sample in the same way. For such transmission measurements, a roof prism, a truncated cone prism, or another beam-deflecting component is used, for example, in which the radiation is deflected onto the sample to be analyzed by multiple deflections in such a way that the radiation passes through the sample and can interact with it, whereby the optical axis of the excitation radiation coincides with the optical axis of the radiation guided towards the detector.

[0029] For practical purposes, both second deflections are simultaneously integrated into a lid that can be placed on top of the sample holder, so that, for example, by rotating the lid by a structurally defined angle around its rotation axis, it is possible to easily switch from transmission measurement to fluorescence measurement or vice versa.

[0030] In this way, it is possible to use fluorimeters and spectrofluorimeters not only for fluorescence measurement but also for transmission measurement.

[0031] As already mentioned, it is therefore possible to use some photometers or spectrophotometers for fluorescence measurement that are actually intended for absorption measurements or transmission measurements.

[0032] In a third embodiment, the invention can be used equally for measuring transmission in a transmission measuring device and fluorescence in a fluorescence measuring device, wherein the components are arranged in such a way without rotating the cover. Here, the second light deflection is suitable for directing the excitation light coming from the first light deflection into the receiving location and vertically downward through the sample by multiple reflection. A lateral boundary of the sample holder, which limits it in a direction at right angles to the aforementioned position, is designed as a bevel of the sample holder that totally reflects the fluorescent light.

[0033] The advantage of this approach is the use of the respective instruments for transmission measurements and fluorescence measurements without the need to adapt any measurement routine or procedure. However, the availability of both types of instruments is required.

[0034] When setting up a combination device for both transmission and fluorescence measurements, for example using individual modules, both measurement modes can be operated simultaneously. This is possible by modifying the arrangement of the beam deflection components.

[0035] In a fourth embodiment of the present invention, in addition to the receiving point in the sample holder, a third light deflector is further integrated. This third light deflector is arranged horizontally opposite the second light deflector and is suitable for directing the light coming from the second light deflector, which has passed through the sample, downwards for measuring the transmission. As a result, the device according to the invention is equally suitable for measuring transmission in a transmission measuring device and fluorescence in a fluorescence measuring device. By designing the sample receiving point differently and integrating the second beam deflector into the light-permeable lateral boundaries of the sample receiving point, corresponding components arranged in the lid can be dispensed with.

[0036] The sample receiving point can preferably be designed to be interchangeable in order to be able to use different optical layer thicknesses for the transmission measurement. Short description of the drawings Fig. 1A is a vertical sectional view of a first embodiment of the present invention; Fig. 1B is a compared to Fig. 1A vertical sectional view rotated by 90°; Fig. Figure 1C is a horizontal section along line AA in Fig. 1A; Fig. 2A shows an enlarged view of the actual measuring point of the Fig. 1A; Fig. 2B corresponds to Fig. 2A, in which, however, some light rays are also drawn to illustrate the light guidance; Fig. Figure 3A is a horizontal sectional view along line AA of the Fig. 1A with the beam arrangement of 90° typical for fluorimeters; Fig. 3B is a Fig. 3A corresponding alternative sectional view with the beam arrangement of 180° typical for photometers for transmission measurement; Fig. 4A shows an enlarged view of the actual measuring point in a second embodiment of the invention with a rotatable lid, with the lid in a position for fluorescence measurement; Fig. 4B shows an enlarged view of the actual measuring point of the second embodiment in a cover position for transmission measurement; Fig. 5A and Fig. 5B are horizontal sectional views corresponding to the Fig. 3A and Fig. 3B, each with a beam arrangement of 90° typical for fluorimeters and with a beam arrangement of 180° typical for photometers for transmission measurements; Fig. 6A shows an enlarged view of the actual measuring point in a third embodiment of the invention during transmission measurement; Fig. 6B shows an enlarged view of the actual measuring point of the third embodiment in fluorescence measurement; Fig. Figure 6C is a cross-sectional view taken along line AA of the Fig. 1A with a non-rotatable lid, whereby the device must be inserted into a different device to allow transmission measurements or fluorescence measurements; Fig. 7A shows an enlarged view of the actual measuring point in a fourth embodiment of the invention which is suitable for transmission measurement and fluorescence measurement; Fig. Figure 7B is a cross-sectional view taken along the line AA of the Fig. 1A with a non-rotatable lid, whereby the device must be used with a different device to allow transmission measurements or fluorescence measurements; and Fig. 8A to 8D show variants of the sample holders and mounting locations. Ways to implement the invention

[0037] Fig. 1A shows a vertical sectional view of the analysis device according to a first embodiment of the invention and Fig. Figure 1B shows a vertical sectional view which, compared to Fig. 1A is rotated by 90° around the vertical axis shown. The analysis device 1 comprises a vertically elongated housing with a square cross-section (see Fig. 1C), which has on its upper side a sample holder 3 with a cup-like depression 4 for receiving a small amount of a liquid sample P, such as a drop, wherein the order of magnitude of the applied volume of the sample is in the range of 10 µl or less. In this view, as well as the corresponding views of the embodiments discussed below, the analysis device 1 is already shown in its normal position of use, in which the liquid sample P is introduced into the sample holder 4 from above and held there by gravity. The sample holder 3 is made of a material that is transparent to the excitation light and the fluorescence signal generated in the sample thereby, or other types of signals such as Raman scattering, in this case of a suitable glass such as synthetic quartz glass.However, not all boundary surfaces of the sample holder 3 necessarily have to be transparent in this way, but only those surfaces which are crossed by the excitation light and the signal to be measured.

[0038] The device is closed at the top by a lid 11, in which a reflector 10 is inserted centrally above the sample receiving point 4, which reflector delimits the sample receiving point 4 at the top. Although the device shown in the present embodiment is delimited at the top by a reflector 10, it is also conceivable to delimit the sample receiving point 4 only by the lid 11 in order to be able to precisely define the very small sample volumes. The reflector 10 of the present embodiment protrudes slightly into the receiving point in order to prevent the liquid sample from leaking out when the lid 11 is closed. Nevertheless, it is possible to design the reflector flush with the top side of the sample holder 3, whereby the same applies to the alternative design option in which the sample receiving point 4 is delimited only by the lid 11.

[0039] The analysis device 1 is intended to be inserted into a holder of a conventional spectral analysis device, wherein suitable analysis devices include spectrophotometers, fluorimeters, Raman spectrometers, absorption measuring devices, and the like, which can measure the fluorescence, luminescence, phosphorescence, Raman scattering, or absorption of the liquid sample P. For this purpose, the analysis device 1 is provided in its lower region, i.e., in the position of use below the sample holder, with a horizontally oriented light inlet 5 for excitation light, which is located in a suitable position so that excitation light from the aforementioned measuring devices can be coupled in through the light inlet opening 5 when the analysis device 1 is inserted. The analysis device also comprises a suitably placed light outlet 6 for coupling the signal light to the measuring device.

[0040] In the beam path behind the light inlet 5, a reflective prism 7 is provided as the first light deflection device, which couples the excitation light beam from the horizontal into a light guide 13, for example an optical fiber, provided vertically in the housing 2 of the device 1. It is also possible to use other light deflection elements, such as mirrors, instead of reflective prisms. The excitation light is thus guided by the deflection or reflection at the prism 7 and - in this embodiment - by the light guide 13 upwards to a position lateral to the recording point 4. However, it is also possible to dispense with a light guide and guide the excitation beam, for example, through a hollow housing interior to the position next to the recording point 4.

[0041] Furthermore, in the present embodiment, a bevel 8 formed in the side wall of the sample holder 3 is located above the end of the light guide at the position laterally to the receiving point 4 as a second light deflection 8, which deflects the excitation light beam by total reflection into the horizontal to the sample P in the sample holder 4 (see Fig. 1A). The excitation light generates, for example, fluorescence in the sample P, which is emitted at a narrow solid angle essentially perpendicular (90°) to the direction of incidence of the excitation light in the sample P. In the present description, fluorescence is used merely as an example for the generation of emission, since the design of the analysis device 1 does not result in any differences for the analysis compared to other types of emission such as luminescence, phosphorescence, or Raman scattering, which are also observed at an angle to the direction of the excitation light in order to separate the very weak signals from the high intensity of the excitation light. It should also be understood that, for practical reasons, the observation or discharge of the emission light takes place at 90° to the excitation direction, but in principle it is also possible to use other angles that ensure sufficient spatial separation of the excitation light and signal light.

[0042] A portion of said fluorescent light is emitted upwards and reflected back downwards by the reflector 10. Together with the downwardly emitted portion, the fluorescent light is coupled through the bottom or the lower surface boundary of the sample holder 4 into a second light guide 14, which guides the fluorescent light to a reflection prism 9, also located in the lower region of the device, as the first detector-side light deflector, which in turn deflects the fluorescent light beam to the detector located in the fluorescence measuring device. For this purpose, a light exit opening 6 is provided in the housing 2 of the analysis device 1. This light exit opening 6 is also horizontally oriented and, corresponding to the beam guidance of fluorescence measuring devices, is arranged at an angle of 90° to the light inlet 5, as can be seen from Fig. 1B and Fig. 1C can be seen.

[0043] In the Fig. 2A and Fig. 2B, the upper area of ​​the analysis device 1 is shown again in an enlarged manner, with Fig. 2B shows exemplary light rays which are coupled as excitation light through the light guide 13 laterally next to the sample holder 4 into the sample holder 3, are totally reflected by the bevel 8 as a second light deflection and are guided horizontally into the sample P. The fluorescence radiation (emission) is then guided downwards at a right angle by the light guide 14 from the sample holder 4 of the sample holder 3.

[0044] In Fig. 3A is again one of the Fig. 1C corresponding sectional view along the line AA of the Fig. 1A. However, the invention alternatively provides for coupling the fluorescence emission out of the analysis device 1 in alignment with the excitation radiation instead of at a right angle to the direction of the excitation radiation. For this purpose, the corresponding Fig. 3B, the light exit opening 6' is formed in the side of the analysis device 1 opposite the light entry opening 5. In this way, it is possible to use some commercially available photometers or spectrophotometers, which are actually designed for absorption measurement, also for the measurement of fluorescence, since the Fig. With the arrangement shown in Figure 3B, the fluorescence radiation can be coupled out of the analysis device 1 in alignment with the excitation radiation and coupled into the photometer or spectrophotometer according to their aligned excitation and signal beam paths. Thus, fluorescence measurements can be performed independently of the device-side arrangement of the excitation beam path and emission beam path.

[0045] The Fig. 4A and Fig. 4B show a second embodiment of the analysis device according to the invention, which can be used both for measuring fluorescence and for measuring the absorption properties of the liquid sample P in the sample receiving point 4. Fig. 4A shows a detailed view of the upper part of the analysis device 100, in which the second light deflection is achieved by two alternatively usable optical deflection elements 108 and 118. One deflection element is designed as an externally reflecting prism 108, which is mounted laterally and below in the cover 111 of the device 100 such that its base 108a is arranged above the light guide 113 for the excitation light and deflects the excitation light beam by 90° in order to introduce it horizontally into the sample in the sample holder 4. In contrast to the first embodiment, the sample holder 103 does not extend into the area above the light guide 113 for the excitation light; instead, the light exits the light guide 113 at the end of the housing 102 of the device 100 before being deflected horizontally by the reflector prism 108. In this case, the end of the light guide 113 is expediently provided with a lens orlens-shaped surface 123 to focus the excitation light beam. In this way, according to the same principle as the first embodiment, the sample liquid in the sample holder 4 is excited to emit fluorescence, wherein the emitted fluorescent radiation is guided vertically downwards by a light guide 114, as in the first embodiment, in order to be guided horizontally to a detector in the lower region of the device 100 again by the first detector-side light deflection 9. Optionally, a lens or lens-like curved surface 124 can also be formed at the lower end of the light guide 114.

[0046] Furthermore, a roof prism 118 is mounted off-center under the cover 111, which closes off or limits the sample holder 4 with its wider underside. For this purpose, the roof prism 118 is expediently provided with a small projection on its underside portion 118a located above the sample holder 4, which projection prevents the sample liquid from escaping from the cup-like depression 4. (For the sake of better visibility, the projection is not shown as extending to the edges of the sample holder.) The Fig. The left part 118b of the underside of the roof prism 118 visible in Figure 4A does not lie on the sample holder 4.

[0047] If the cover 111 is now turned by 180° (see Fig. 4B, which shows the same sectional view, not rotated by 90°, as the Fig. 4A), the part 118b of the underside of the roof prism 118 which was previously not located above the sample holder 4 comes to lie above the light guide 113 supplying the excitation radiation, so that the light beam emerging from the light guide 113, after passing through a short intermediate space 119 located laterally next to the sample holder 4, enters the roof prism 118 through the surface 118b, is totally reflected from a bevelled side 118c of the prism 118 into the horizontal, this reflected excitation light is then reflected vertically downwards above the sample holder 4 from the other bevelled side 118d of the roof prism 118 and thus enters the sample holder 4 vertically and is transmitted through the sample P.The transmitted light entering the light guide 114 through the bottom of the sample holder 4 now contains the absorption signature of the sample P and can thus be evaluated to determine the absorption properties of the sample P. It should be noted that the values ​​shown in the . Fig. 4A and Fig. It should be understood that the arrangements of the reflection prism 108 and the roof prism 118 shown in Figure 4B, as well as their integration into the cover 111, are merely exemplary, and that other deflection elements, such as a mirror at the positions of the surfaces 108a, 118c, and 118d, can also be provided. It is also possible to arrange these optical deflection elements at other angular arrangements, so that the cover can be rotated around the vertical axis by angles other than 180° to switch from the fluorescence measurement configuration to the absorption measurement configuration.

[0048] As already mentioned in the first embodiment of the Fig. 3A and Fig. 3B can also be used in the embodiment of the Fig. 4A and Fig. 4B the light exit opening is arranged at 90° to the light incidence opening in the housing of the analysis device 1 ( Fig. 5A), whereby the device 100 is then suitable for insertion into conventional fluorescence measuring devices. Alternatively, the light exit opening 6' can also be arranged at 180°, i.e., aligned with the light entry opening on the opposite side of the housing of the device 100, so that the measurements of fluorescence / luminescence ( Fig. 4A) and absorption ( Fig. 4B) can be carried out in a photometer or spectrophotometer ( Fig. 5B).

[0049] Fig. 6A to 6C show a third embodiment of the present invention. It should be noted that now Fig. 6A and Fig. 6B again like the Fig. 1A and Fig. 1B represent sectional views rotated by 90°. In this embodiment, the analysis device 200, like the first and second embodiments, comprises a light guide 213, which guides the excitation light from the first light deflection 207 next to the sample holder 4. Above the sample holder 203, a truncated cone prism 218 is arranged off-center, which, as a second light deflection, similar to the second embodiment, deflects the excitation light such that it is directed vertically into the sample holder 4 and transmitted through the sample P. Accordingly, a light guide 214 is again provided along the vertical axis of the device 200, which (as in the operating mode of the Fig. 4B of the second embodiment) guides the transmitted light carrying the absorption signature vertically downward. There, it is deflected horizontally by a second detector-side light deflector 209' and coupled out of the analysis device 200 through a light exit opening 206', which is arranged in alignment with the light entry opening 205 on the opposite side of the housing.

[0050] At the same time, in this embodiment, the sample holder 203 comprises on a side wall as a third light deflection a bevel 228, which is located at a position rotated by 90° to the position to which the excitation light coming from the first light deflection is guided by the light guide 213 next to the sample holder 4 (see Fig. 6B and Fig. 6C). This bevel 228 is also located laterally next to the sample holder 4 at the same horizontal level as the latter and serves to reflect the fluorescence generated in the sample by the excitation light beam passing vertically through it, which is emitted horizontally essentially at 90° to the excitation light beam in the sample, vertically downwards by total internal reflection in the sample holder 203. This fluorescence light exits the sample holder 203 vertically through its lower boundary surface and into a third light guide 215, which guides the fluorescence emission downwards to a second detector-side light deflection 209, which deflects the fluorescence emission radiation horizontally and couples it out through a light exit opening 206. This light exit opening 206 is in turn arranged at 90° to the light entry opening, as is expedient for fluorescence measurements. The third light deflection, like the first orThe second detector-side light deflection of this embodiment can again be represented by deflection prisms, mirrors or other suitable light-deflecting elements.

[0051] Fig. 7A and Fig. 7B show a fourth embodiment of the present invention. This embodiment shows a variant of the third embodiment, in which the sample holder 303 has two bevels 308, 328 located on opposite boundary sides. The Fig. The bevel 308 shown on the right in Figure 7A serves, as previously in the first embodiment, for the total reflection of the excitation light supplied by a light guide 313 and directs this excitation light beam horizontally to the sample holder 4 and through the sample P. The fluorescence / luminescence thus excited in the sample is again captured at 90° by a light guide 314 and guided vertically downwards to a first detector-side light deflection 309. The excitation light beam that has passed horizontally through the sample is further guided in the sample holder to the second bevel 328, which also deflects the transmitted light beam, now provided with the absorption signature, vertically downwards and couples it into a light guide 315. This guides the transmitted light to a second detector-side light deflection 309'.The first detector-side light deflector 309 directs the light beam with the fluorescence signal horizontally through a light exit aperture 306, which is arranged at 90° to the direction of the excitation light beam and the light entrance aperture 305. The second detector-side light deflector 309', on the other hand, directs the transmitted light beam (absorption spectrum) horizontally through a light exit aperture 306' arranged opposite the light entrance aperture 305.

[0052] Thus, the third and fourth embodiments of the analysis device 200 and 300, respectively, can be used as needed for the analysis of the transmitted light (absorption) or the emitted light (fluorescence, luminescence, Raman scattering, etc.) in the corresponding measuring devices without having to make changes to the analysis device, for example, rotating the lid.

[0053] The Fig. 8A to 8D finally show structural variants of the test receptacle according to the invention, wherein the Fig. 8A shows an alternative sample holder 303' suitable for the fourth embodiment with a cup-like sample receiving point 304' instead of a cylindrical one in side view and top view, which Fig. 8B shows a sample holder 203' suitable for the third embodiment. These two variants each have a round cross-section. In the Fig. 8C and Fig. 8D, however, shows octagonal cross-sectionally shaped sample holders 203'' and 303'', where the Fig. 8C is again suitable for the third embodiment and has a cup-like depression, while the sample holder of the Fig. 8D has a sample holder suitable for the fourth embodiment.

[0054] It should be understood that in the embodiments described above, the horizontal cross-section along line AA does not necessarily have to be square, but can also have other shapes, such as octagonal or round, depending on the requirements of the recordings in the respective measuring instruments. Thus, the analysis device preferably has the external dimensions of a cuvette that can be inserted into a photometer, spectrophotometer, fluorimeter, or spectrofluorimeter and can be exposed to their light. The external dimensions of the cross-section of the analysis device thus correspond, for example, to those of a standard cuvette and are in particular 12.5 mm x 12.5 mm, because the majority of photometers or similar measuring instruments are designed for such dimensions.The devices for light supply or light deflection arranged inside the analysis device are expediently located at the point on the analysis device where, in conventional cuvettes, entrance and exit windows for the light used for measurement are provided. The first light deflection deflects the light radiated by the photometer or the like to the sample receiving point, and the detector-side light deflection(s) deflect the light returning from the sample receiving point to the detector. By cleverly selecting the dimensions of the analysis device according to the invention, it can thus be integrated into conventional photometers, spectrophotometers, fluorimeters, or spectrofluorimeters, so that it can be used to measure even very small samples of a medium.

[0055] It should also be understood that the above description does not list all signatures to be analyzed when detecting emission radiation at 90° to the excitation radiation, but these will be understandable to those skilled in the art. For example, Raman scattering at 90° to the incident excitation radiation is also measured, as are fluorescence and luminescence.

[0056] The assignment of excitation and emission radiation to components, as well as the orientation of the beams, shown in the figures and in the explanations, represents only a preferred assignment that allows all of the described advantages to be utilized. In principle, the analysis device can also be operated in reverse. Industrial applicability

[0057] In addition to UV / Vis spectroscopy, fluorescence for very small volumes is used in molecular biology, among other areas, because the high measurement sensitivity of the method significantly lowers the detection limit for nucleic acids and proteins (from the lower ng / µl to the lower pg / µl range).

[0058] In addition, by carefully selecting fluorescent dyes, such as SYBR Green, it is possible to differentiate between nucleic acids (dsDNA, ssDNA, RNA), which is not possible using UV measurement at 260nm alone, since all nucleic acids absorb exactly at this wavelength.

[0059] The combination of UV / Vis spectroscopy and fluorescence in a single measuring head offers users significant savings potential through lower investment requirements and significantly reduced space requirements in the laboratory. At the same time, users only need to learn how to operate one device, as they can now optimally cover both methods with a single measuring device.

Claims

[1] Device (1, 100, 200, 300) for the analysis, fluorescence measurement, luminescence measurement, phosphorescence measurement, Raman scattering measurement or absorption measurement of a small amount, for example a drop, of a liquid sample (P) by means of light which can be guided through the sample (P) and can then be detected or analyzed according to the measuring methods mentioned, wherein the device (1, 100, 200, 300) has an upper sample holder (3, 103, 203, 303) in the use position with a receiving point (4, 304, 304') for applying or dropping the sample (P) and a light inlet (5, 205, 305) for excitation light, which is horizontally oriented in the use position and is located below the sample holder (3, 103, 203, 303), characterized bythat the device has a first device (7, 207, 307) located in the beam path behind the light inlet (5, 205, 305) for deflecting the light upwards to a position (Q) provided in the sample holder next to the receiving point (4, 304, 304') and a second light deflection (8, 108, 218, 308) which deflects the light beam coming from below into the sample (P) to be analyzed. [2] Device according to claim 1, wherein the second light deflection (8, 308) is integrated into the sample holder (3, 303) at the position (Q) next to the receiving point (4) and is suitable for directing the excitation light horizontally into the sample (P) for exciting fluorescence. [3] Device according to claim 2, wherein the second light deflection (8, 308) is integrated into a lateral boundary of the sample holder (3, 303) and is designed as a bevel (8, 308) of the sample holder which totally reflects the excitation light coming from the first light deflection (7, 307). [4] Device according to one of the preceding claims, wherein the receiving location is a recess (4, 304, 304') in the sample holder (3, 103, 203, 303) and is preferably closed at the top. [5] Device according to one of the preceding claims, wherein the device (1, 300) further comprises a detachable reflector (10, 310) with a horizontal reflection surface for fluorescent radiation, which delimits the receiving point (4, 304) at the top. [6] Device according to claim 1, wherein an alternative second light deflection (118) is additionally provided for measuring the transmission, which is suitable for directing the excitation light by multiple reflection into the receiving point (4) and vertically downwards through the sample (P). [7] Device according to claim 6, wherein the second light deflection (108) and the alternative second light deflection (118) are integrated into a cover (111) which can be placed on top of the sample holder (103) and which is designed to be rotatable so that it is possible to switch between the second light deflection (108) for measuring the fluorescence and the alternative second light deflection (118) for measuring the transmission. [8] Device according to claim 1, wherein a third light deflection (228, 328) is further provided next to the sample receiving point (4), which is suitable for directing signal light coming horizontally from the sample (P) downwards. [9] Device according to claim 8, wherein the second light deflection (218) is suitable for directing the excitation light coming from the first light deflection (207) by multiple reflection into the receiving location (4) and vertically downwards through the sample, and wherein the third light deflection (228) is integrated into a lateral boundary of the sample holder (203), which bounds the sample holder at a right angle to the said position (Q) in the horizontal direction. [10] Device according to claim 8, wherein the third light deflection (328) is integrated into a lateral boundary of the sample holder, which is arranged horizontally opposite the second light deflection (308) and is suitable for directing the light coming from the second light deflection (308) and passing through the sample (P) downwards for measuring the transmission. [11] Device according to one of claims 1 to 7, wherein the device has a first detector light deflection (9) located in the beam path below the receiving point (4), which is suitable for deflecting the signal light coming from the sample (P) in a horizontal direction in the use position to a detector. [12] Device according to one of claims 8 to 10, wherein the device has a first detector light deflection (9, 209', 309) located in the beam path below the recording point (3, 203, 303), which is suitable for deflecting the signal light coming from the sample (P) in a horizontal direction in the use position to a detector, and a second detector light deflection (209, 309') located in the beam path below the third light deflection (328), which is suitable for deflecting the signal light coming from the sample and deflected by the third light deflection in a horizontal direction in the use position to a detector. [13] Device according to claim 11, wherein further in the beam path after the first detector light deflection (9) a light exit (6, 6') is provided, the horizontal direction of which defined by the first detector light deflection is arranged at 90° to the direction of incidence of the excitation light or is arranged in alignment with the direction of incidence of the excitation light. [14] Device according to claim 12, wherein furthermore in the beam path after the first detector light deflection (209', 309) a first light exit (206, 306) is provided, the horizontal direction of which is defined by the first detector light deflection being arranged at 90° to the direction of incidence of the excitation light or in alignment with the direction of incidence of the excitation light, and in the beam path after the second detector light deflection (209, 309') a second light exit (206, 306') is provided, the horizontal direction of which is defined by the second detector light deflection being arranged in alignment with the direction of incidence of the excitation light or in contrast to the first light exit (206', 306) at 90° to the direction of incidence of the excitation light. [15] Device according to one of claims 11 to 14, wherein the first light deflection (7, 207, 307) on the one hand and the first and second detector light deflection (9; 209', 309; 209, 309') on the other hand are arranged on the same horizontal level.

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