WO2021213559A1

WO2021213559A1 - A spacer for a cuvette, use thereof and a method of analysing a sample

Info

Publication number: WO2021213559A1
Application number: PCT/CZ2020/050024
Authority: WO
Inventors: Alessandra PICCHIOTTI
Original assignee: Fyzikalni Ustav Av Cr, V.V.I.
Priority date: 2020-04-22
Filing date: 2020-04-22
Publication date: 2021-10-28
Also published as: EP4139658A1

Abstract

The present invention relates to a spacer suitable for micro cell cuvette. The spacer the spacer (1) comprises a base (3) and at least two frame supports (41, 42); wherein the frame supports (41, 42) comprise holes (51, 52) therein allowing to pass a beam (61) into the cuvette (2) on a first side (71) and detect a signal beam (62) on a second side (72) of the spacer (1), when used; and wherein the frame supports (41, 42) are permanently connected via the base (3) only; the frame supports (41, 42) being plane symmetrical in respect to a plane (8) passing through a centre (9) of the spacer (1); and wherein the plane (8) being perpendicular to an edge (30) of the support (3) not connected with the frame supports (41, 42).

Description

A spacer for a cuvette, use thereof and a method of analysing a sample Technical field

[001] The present invention relates to a carrier for holding a sample cuvette, in particular to a cuvette spacer wherein the cuvette is a micro cell cuvette. In another aspect, the present invention relates to use of a spacer and a method of optical analysing a sample having volume less than 200 mI.

Prior art

[002] A cuvette is a small tube-like container with straight sides and a circular or square cross section. There exist several types of the cuvettes, in term of volume, which are suitable for optical spectroscopy such as absorption, emission, dynamic light scattering or any other spectroscopy experiments performed on liquid samples, or experiments employing energy beams (neutrons, electrons, etc.). Typical prior art cuvette is shown in Fig. 1. Fig. 1a shows a typical cuvette while Fig. 1 b shows a micro cell cuvette defined below. The figures are shown in relative scale to show differences.

[003] The micro cell cuvette is species cuvette having a container with significantly smaller volume than the cuvette as shown in Fig. 1 a. The volume of the microcell cuvette is herewith defined as a cuvette up to 200 mI. The micro cell cuvettes are especially suitable for all the spectroscopy techniques where the sample is in liquid form and it is not available in big quantities, as an example biological, radioactive, or specialized samples.

[004] In laser optical spectroscopy, it is essential to focus a laser beam in a cell, in particular into the inner volume of the cell where a liquid sample is contained. More preferably, it is desired to focus a laser beam into the centre of the cuvette. Furthermore, it is an advantage to use the micro cell cuvette because since a laser beam incident onto the sample and a signal coming from the sample are both attenuated by the volume of the sample itself and/or material of the cuvette, the signal and/or laser beam is more intensive in the microcell cuvette rather than in the normal cuvette. It is even more desired in a non-linear spectroscopy where signal is much weaker. Therefore, it is highly desired to provide a cuvette as thin as possible.

[005] The state of the art spectroscopy machine provides a holder designed to fit with the cuvette. For micro cell cuvette, a spacer must be used to make the micro cell compatible with bigger cells. The spacer detachable holds the micro cell cuvette inside the holder. [006] State of the art spacer, as for example shown in Fig. 2, provides a solution which is not sufficient for holding the micro cell cuvette. In particular a liquid sample contained in the micro cell cuvette, is not situated in the centre of the holder. As a result, the laser beam is focused to a wall of the cuvette but not to the sample as such, which is highly undesirable for a laser beam spectroscopy. When providing experiment with the laser beam, the beam is usually focused into the part very close to a wall of the cuvette, sometimes into the wall of the cuvette itself, thus further adjustment is needed. Due to the very delicate nature of the laser optical spectroscopy, any further adjustments are not desirable, as the focus can be difficult to find, the movements given to the cuvette can lead to a rotation of their sides in respect of the axes of the light beam, hence decreasing the signal-to-noise ratio.

[007] The main disadvantage with such a cuvette holder or spacer is connected with replenishment thereof and providing the new micro-cell cuvette. For an ordinary practitioner, the holder and or spacer must be removed as whole from a spectrometer before storing of new sample since a top part is covered by material which prevents easy removal of the micro-cell cuvette. [008] Moreover, in traditional commercial spectrometers, the position of the sample is usually fixed and set to be at the focus of the beam. Offsetting the position of the cuvette increases scattering in the beam which is measurable and degrading the quality of the measured spectrum, especially for very sensitive measurements. [009] It is an object of the present invention to provide a spacer capable to hold a micro cell cuvette whereas a laser beam is focused on the fluid sample contained therein.

Summary of the Invention

[010] The above mentioned problem is solved by a spacer suitable for holding a micro cell cuvette in a centre of a holder, - the spacer comprises a base and at least two frame supports; wherein the frame supports comprise holes therein allowing to pass a beam into the cuvette on a first side and detect a signal beam on a second side of the spacer, when used; and wherein the frame supports are permanently connected via the base only; - the frame supports being plane symmetrical in respect to a plane passing through a centre of the spacer; and wherein the plane being perpendicular to an edge of the support not connected with the frame supports.

[011] The spacer according to the present invention provides a stable position of a micro cell cuvette in a holder originally configured to hold a cuvette of bigger volume, resp. size. Furthermore, due to plane symmetry of the spacer, a focus point of the beam is in the centre of the micro cell cuvette thus, it actually measures the sample. The spacer is thus align with a holder and a centre of the micro cell cuvette is coincident with the centre of the holder. [012] The beam can be any radiation beam suitable for particular spectroscopy, such as beam of electrons or photons. The photon beam can be visible beam such as a laser beam or THz, IR, UV, X-ray and any suitable beam known for particular industrial application. [013] In preferred embodiments, defined in claims 2 and 3, the components are made of thermoplastics which bring additional advantage in respect to manufacturing. The thermoplastics, such as currently used for 3D printers, allow cheap and fast manufacturing. Furthermore, the plastic in general does not scratch the micro cell cuvette as such and thus, it provides also sparing effect thereon. [014] In another embodiment, the frame support can be made of metal, preferably aluminium. In some embodiment, the material of base is metal, preferably aluminium.

[015] In another embodiment, defined by claim 6 and 7, the tape layers serves for holding the micro cell cuvette in more stable position while, at the same time, it also absorbs an undesired diffracted beam from a signal beam or a probe beam.

[016] In another embodiment defined by claim 8, the spacer mounted on a holder provides particular advantage for carrying out an experiment on a laser table top set up. This embodiment is further advantageous in combination with the embodiment defined by claims 6 or 7 in terms, the stability of the sample is crucial due to mechanical vibration of an optical table and it removes a scattered undesired optical signal which may potentially influence experimental measurement.

[017] Adjustable high, as defined in claim 9, is particular advantage in case where spectroscopic devices are not following uniform norm. Adjustable high of the base can be used to further improve position of the micro-cell cuvette so that a probe beam is focused in the sample. [018] In yet another embodiment, the spacer is a part of spectrometric device or used for spectroscopic method as defined by claims 10 or 14.

Brief description of the drawings

[019] Fig. 1a shows a typical prior art cuvette used for optical spectroscopy.

[020] Fig. 1b shows a micro cell cuvette compared to a cuvette.

[021] Fig. 2 shows a state of the art spacer for a micro cell cuvette.

[022] Fig. 3a illustrates a first embodiment of the present invention in axiomatic view.

[023] Fig. 3b illustrates a first embodiment of the present invention in cross section views.

[024] Fig. 4 illustrates an embodiment of the present invention, the spacer for micro cell cuvette is provided with a tape surrounding two sides of the frame of the spacer.

[025] Fig. 5 illustrates another embodiment of the present invention, wherein the spacer is mounted on a holder suitable to be mounted on an optical table.

Detailed description

[026] Fig. 3a and 3b are schematic figures of the spacer 1 according to a first embodiment of the present invention. The spacer 1 is especially suitable for a micro cell cuvette 2 having a container of volume up to 200 mI of a fluid sample. The fluid sample can be liquid or gas. Samples are analysed via optical spectrometry for instance in research, in diagnostics and in quality control. They are analysed for instance by way of absorption-, reflection-, emission-, fluorescence-, Raman- or luminescence spectroscopy in the UV-VIS or IR wavelength range. Examples for analytes to be measured are biomolecules like nucleic acids, proteins, lipids as well as inorganic or organic materials, compounds or biological samples like bacteria or viruses, or in general whole cells. These analytes can be measured directly or after a chemical reaction that serves for facilitating the spectrometric or photometric analysis.

[027] The spacer 1 comprises a base 3 and at least two frame supports 41 , 42. The frame supports 41 , 42 comprises holes 51 , 52. Through the first hole 51 , an optical beam 61 , preferably a laser beam is incident to the sample contained in the container of the micro cell cuvette 2. Thus, the first hole 51 allows the optical beam 61 to pass through a first side 71 of the frame support 41. The optical beam 61 , preferably the laser beam interacts with the sample, such as biomolecules like nucleic acids, proteins, lipids as well as inorganic or organic materials, etc., and emits a signal beam 62. The signal beam must pass through via a second side 72 of the frame support 42. Thus, the frame support 42 is provided with the second hole 52 through which the signal beam 62 comes to a detector. It is not needed to provide both holes symmetrical as shown in Fig. 3. In some embodiments, the first hole 51 may be provided near the bottom of the spacer 1 while the second hole 52 may be provided on the top of the spacer 1 .

[028] The frame supports 41 , 42 are permanently connected to the base 3 only. The top of the frames nor its sides 411 , 412 are not connected via any of connection bridge or nor permanently connected via metal layer mounted on the frames. However, the frame support may be, in preferred embodiment, provided with tape layers 410, 420 absorbing a scattered beam 62.

[029] The advantage of the permanent connection of the frame supports 41 , 42 to the base is its flexibility and easy removal of the micro cell cuvette 2 from the spacer 1.

[030] The frame supports 41 , 42 are plane symmetrical in respect to a plane 8. The plane 8 is a geometrical plane which passes through a centre 9 of the spacer 1 and due to its geometry; it also passes through the centre of micro cell cuvette 2 and holder as well. This is the main advantage of the present invention is respect to the optical beam 61 probing the sample. The plane is perpendicular to an edge 30 of the support 3 which is not the edge of the connection between frame supports 41 , 42 and the base. Thus, the geometry allows coincidence of the centres spacer 1 , micro cell cuvette 2, the holder for standardized cuvette and focus point of the optical beam

61.

[031] Suitable materials of the frame supports 41 , 42 or the base 3 are for example thermoplastics, such as polystyrene, PVC, polypropylene, polyethylene. The advantage of the thermoplastics is cheap and fast in term of manufacturing on the state of the art 3D printer. In another embodiment, the material of the spacer or frame support is metal, such as aluminium or stainless steel.

[032] The spacer was particularly designed to fit into a holder. The holder allows to fit a cuvette of standard size which includes external dimensions 1 to 10 mm, including the glass walls. However, in time-resolved optical spectroscopy we needed to use a micro cell cuvette of size 0.1 to 10 mm (usually), thus the size of the spacer was adjusted accordingly to fit the external dimensions.

[033] In an embodiment, the base is thick just to support the cuvette and hold it in the particular place. Such embodiment is schematically shown in the second embodiment shown in Fig. 4. However, it should be noted that the high of the base 3 is not inextricably linked to the tape layers 410, 420.

[034] In a preferred embodiment (not shown), the spacer 1 is provided with a base 3, wherein height of the base is adjustable. The adjustable height is preferred for embodiments where micro cell cuvette 2 is too short.

[035] Fig. 4 is a schematic view of a spacer 1 according to a second embodiment of the present invention. The spacer 1 of the second embodiment comprises frame supports 41 , 42. [036] The embodiment shown in Fig. 4 further includes tape layers 410, 420 removable attached to sides 411 , 421 of the spacer 1 according to the first embodiment. Tape layers 410, 420 cover sides 411 , 421 of the frame supports 41 , 42 through which the beam 61 does not pass into the cuvette 2 and the signal beam 62 is not passing out, when the spacer is used, for example in an optical spectroscopy inside a spectrometer.

[037] The tape layers 411 , 421 are not permanently fixed but is removable when the micro cell cuvette 2 is needed to be plug or unplug from the spacer 1 . The removable tape layers can be fastened and unfasted by, for example, a velcro. [038] The material of the tape layers 411 , 421 is chosen in respect to the material of the cuvette 2 so that when the cuvette is plug/unplug, the material of the cuvette 2 is not scratched. Furthermore, the material of the tape layers 411 , 421 can be chosen to absorb a scattered light 61 from the sample contained in the container of the cuvette 2. Since the tape layers 411 , 421 absorbs the scattered light 61 , a detection noise caused by the scatter is removed. This is particularly advantageous in table top experiment when several detectors or optical components are on the same optical table.

[039] Fig. 5 is a schematic view of another preferred embodiment, the third preferred embodiment of the present invention, when the spacer 1 according to the first or the second embodiment of the present invention serves directly as a holder of a micro cell cuvette 2. The both previously mentioned embodiments can be mounted directly to a stick serving as another holder 21 which can be mounted on an optical table. Preferably the spacer 1 is pilotable or rotatable mounted on the stick so that the sample hold by a spacer 1 is capable to move around a rotational axis. The base thickness of the spacer according to the third embodiment is chosen such that a screw provides sufficiently stable position of the spacer on top of the stick. [040] According to another embodiment, as an alternative of the screw as mentioned above, there are means for detachably locking the stick part to the spacer. These may be incorporated magnets, in the stick and base of the spacer. Elastic catching hooks that co-operate with catching edges may exist in stick. The catching hooks and catching edges can be made in one piece with the stick and base of the spacer.

It is understood that the means for detachably locking is provided on rare part of the spacer, not on part adjacent to the sample.

[041] In yet another embodiment, the all of the above-mentioned embodiments can be, directly or with ordinary workshop skills of a skilled person in the art, mounted to a spectrometer or on an optical table.

[042] In a preferred embodiment, the spectrophotometer comprises the micro cell cuvette hold by a holder comprises the spacer according to any of the previously described embodiment. The micro cell cuvette thus may contain small volume of the sample, such as 2 mI or 20 mI or 200 mI or any value in between, wherein the samples is for instance protein containing solution. In yet further preferred embodiment, the spectrophotometer comprises a laser providing a laser beam. The laser beam is directed to the sample.

[043] In a preferred embodiment, the spectrophotometer comprises a measuring unit and a PC to process and evaluate data obtained from the measurement.

Claims

1 . A spacer (1 ) suitable for holding a micro cell cuvette (2) in a centre of a holder,

- the spacer (1) comprises a base (3) and at least two frame supports (41 , 42); wherein - the frame supports (41 , 42) comprise holes (51 , 52) therein allowing to pass a beam (61) into the cuvette (2) on a first side (71) and detect a signal beam (62) on a second side (72) of the spacer (1), when used; and wherein

- the frame supports (41 , 42) are permanently connected via the base (3) only; characterized in that, - the frame supports (41 , 42) being plane symmetrical in respect to a plane (8) passing through a centre (9) of the spacer (1); and wherein the plane (8) being perpendicular to an edge (30) of the support (3) not connected with the frame supports (41 , 42).

2. The spacer (1 ) according to the claim 1 , wherein material of the frame supports (41 , 42) is plastic, preferably thermoplastic.

3. The spacer (1) according to any of the preceding claims, wherein material of the base (3) is plastic, preferably thermoplastic.

4. The spacer according to claim 1 or 3, wherein the material of the frame supports (41 , 42) is metal, preferably aluminium.

5. The spacer (1 ) according to any of the preceding claims but not in combination with claim 3, wherein material of the base (3) is metal, preferably aluminium.

6. The spacer (1) according to any of the preceding claims further comprises tape layers (410, 420) removable attached to the frame supports (41 , 42); the tape layers (410, 420) are configured to cover sides (411 , 421) of the frame supports (41 , 42) through which the beam (61) does not pass into the cuvette (2) and the signal beam (62) is not passing out, when the spacer is used.

7. The spacer (1) according to the claim 6, wherein material of the tape layers (410, 420) absorbs a scattered beam (63).

8. The spacer (1) according to any of the preceding claims, wherein the spacer (1) is mounted on a holder (21).

9. The spacer (1) according to any of the preceding claims, wherein high of the base (3) is adjustable.

10. A spectrometer comprising the spacer (1) according to anyone of the preceding claims.

11 . The spectrometer according to claim 7, wherein the beam (61 ) is a laser beam.

12. Use of the spacer (1) according to anyone of the claims 1 - 5 in dynamical optical spectroscopy.

13. Use of the spacer (1) according to anyone of the claim 6 for spectroscopy carried out on an optical table.

14. A method of analysing a sample by means of optical spectroscopy, wherein the sample having volume less than 200 mI, the method comprises steps of: providing a fluid sample, preferably a liquid sample; - introducing the sample into a micro-cell cuvette (2); inserting the micro-cell cuvette (2) into the spacer (1) according to anyone of the claim 1 - 9; use of the optical spectroscopic method to analyse the sample.