Analysis method and infrared spectrophotometer

Abstract

Provided is an analysis method, said method comprising a step for dripping a sample onto a sample plate, a step for drying the sample (S') on the sample plate, a step for causing infrared light to be incident on the dried sample (S) and detecting reflected light with a photodetector, and a step for identifying the ingredients of the sample (S) on the basis of the received light signal from the photodetector. The sample plate includes at least one well (W) that the sample is dripped into. The periphery of the well (W) of the sample plate has undergone processing for retaining the dripped sample in the well (W).

Description

Analysis method and infrared spectrophotometer

[0001] The present disclosure relates to analytical methods and infrared spectrophotometers.

[0002] Infrared spectroscopy is an analytical method that analyzes the components in a sample by irradiating the sample with infrared light and detecting the transmitted or reflected light. Infrared spectroscopy is performed using an infrared spectrophotometer.

[0003] For example, Japanese Patent Publication No. 2000-505551 (Patent Document 1) discloses a configuration for analyzing the structure of lymphocytes in blood using a Fourier transform infrared spectrophotometer.

[0004] Analysis of proteins, lipids, organic substances such as DNA and RNA, and microorganisms such as bacteria in a liquid sample is performed, for example, as follows: First, a drop of the liquid sample is placed on the prism of an infrared spectrophotometer and allowed to dry. Next, infrared light is incident on the prism and the spectrum of the light reflected from the prism is obtained. Information such as the structure, physical properties, and bacterial species is then obtained based on the spectrum.

[0005] Special table 2000-505551 publication

[0006] However, the prisms generally used in infrared spectrophotometers are expensive, and in order to reuse the prisms, users must clean the surface of the prism after each analysis.

[0007] Therefore, there was a need for an infrared spectrophotometer that could easily analyze the components in liquid samples without using a prism, which requires time-consuming cleaning.

[0008] The present disclosure has been made to solve such problems, and its purpose is to provide an infrared spectroscopy method that can easily analyze components contained in a liquid sample.

[0009] A first aspect of the present invention is an analytical method comprising the steps of: dropping a sample onto a sample plate; drying the sample on the sample plate; irradiating the dried sample with infrared light and detecting reflected light with a photodetector; and identifying components of the sample based on a light reception signal from the photodetector. The sample plate includes one or more wells into which the sample is dropped. The periphery of each well of the sample plate is treated to retain the dropped sample in the well.

[0010] Another aspect of the present invention is an infrared spectrophotometer. The infrared spectrophotometer includes a sample plate, an infrared light source, a photodetector, and a control device. The sample plate includes one or more wells into which samples are each dropped. The infrared light source emits infrared light that is incident on the sample dried on the sample plate. The photodetector detects reflected light in response to the incident infrared light. The control device identifies the components of the sample based on the light reception signal of the photodetector. The wells of the sample plate are surrounded by a processing for retaining the dropped sample in the well.

[0011] According to the present disclosure, it is possible to provide an infrared spectroscopy method that can easily analyze components contained in a liquid sample.

[0012] FIG. 1 is a schematic diagram showing the configuration of an infrared spectrophotometer according to an embodiment; FIG. 2 is a diagram for explaining the configuration of an infrared spectrophotometer according to a comparative example; FIG. 3 is a schematic diagram showing the configuration inside a sample chamber according to an embodiment; FIG. 4 is a diagram showing an example of a sample plate according to an embodiment as viewed from above; FIG. 5 is a diagram for explaining an example of processing the periphery of a well; FIG. 6 is a diagram for explaining an example of processing the periphery of a well; and FIG. 7 is a flowchart of an analysis method according to an embodiment.

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals and description thereof will not be repeated.

[0014] 1. Configuration of Infrared Spectrophotometer Fig. 1 is a schematic diagram showing the configuration of an infrared spectrophotometer according to an embodiment. In one embodiment, the infrared spectrophotometer 100 is a Fourier transform infrared spectrophotometer. The infrared spectrophotometer 100 includes an interferometer 10, a light source unit 20, a circuit unit 30, a sample chamber 40, and a detection unit 50.

[0015] Interferometer 10 includes beam splitter 11, fixed mirror 12, movable mirror 13, etc., and light source unit 20 includes infrared light source 21, focusing mirror 22, collimator mirror 23, etc. Interferometer 10 and light source unit 20 generate coherent infrared light for spectrum measurement. That is, infrared light emitted from infrared light source 21 is irradiated onto beam splitter 11 via focusing mirror 22 and collimator mirror 23, where it is split into two directions, toward fixed mirror 12 and movable mirror 13.

[0016] The light reflected by the fixed mirror 12 and the movable mirror 13 is combined again by the beam splitter 11 and sent to the optical path toward the parabolic mirror 42. At this time, the movable mirror 13 is reciprocating back and forth (in the direction of the arrow in FIG. 1 ), so the combined light becomes interference light (interferogram) whose amplitude varies over time. The light collected by the parabolic mirror 42 is irradiated into the sample chamber 40, and the light that passes through the sample S placed in the sample chamber 40 is incident on the detection unit 50. In this specification, when the term "sample S" is simply used, it refers to the sample that has been dropped onto the sample plate P and dried. The dried sample is a solid that may be referred to as a "crystal" or "sample crystal" by those skilled in the art. On the other hand, in this specification, the term "liquid sample" refers to a liquid sample before it becomes a solid by drying. The configuration for measuring the sample S in the sample chamber 40 will be described later with reference to FIG. 3. Light incident on the detection unit 50 is focused onto the photodetector 52 by the ellipsoidal mirror 51.

[0017] The infrared spectrophotometer 100 includes a main interferometer for obtaining an interferogram and a control interferometer for controlling the sliding speed of the movable mirror 13 and generating timing signals for sampling the signal obtained by the detector of the main interferometer. The control interferometer is composed of a laser light source 24, a mirror 14, a beam splitter 11, a fixed mirror 12, a movable mirror 13, etc., and generates laser interference light for obtaining an interference fringe signal. That is, the light emitted from the laser light source 24 is irradiated onto the beam splitter 11 via the mirror 14, and is sent as interference light, similar to the infrared light, toward the parabolic mirror 42. Because this laser interference light travels as a beam of light with an extremely small diameter, it is reflected by a mirror 15 inserted in the optical path and introduced into the photodetector 16.

[0018] The optical components, including the interferometer 10, are placed in a humidity-controlled airtight chamber, primarily to protect the optical components, such as the beam splitter 11, which has a substrate made of deliquescent KBr.

[0019] The light-receiving signal from the photodetector 16, i.e., the laser light interference fringe signal, is input to the signal generator 32, which generates a pulse signal for sampling the light-receiving signal corresponding to the infrared interference light. The light-receiving signal obtained by the photodetector 52 is amplified by the amplifier 33, sampled by the sample-and-hold circuit (S / H) 34 at the timing determined by the pulse signal, and then converted into digital data by the A / D converter (A / D) 35. The data processor 36 performs a Fourier transform on this data to create an absorption spectrum, and further creates a transmittance spectrum using background data. The series of measurement operations is performed under the control of the controller 31. The controller 31, signal generator 32, amplifier 33, sample-and-hold circuit (S / H) 34, A / D converter (A / D) 35, and data processor 36 are included in the circuit unit 30.

[0020] 2. Comparison with an Infrared Spectrophotometer According to a Comparative Example] Fig. 2 is a diagram for explaining the configuration of an infrared spectrophotometer according to a comparative example around a sample S. Specifically, the diagram shows a part of a prism unit 9 for holding a sample in a sample chamber in the infrared spectrophotometer according to the comparative example.

[0021] The prism unit 9 includes a prism 90 and a holder 99 surrounding the prism 90. The prism 90 is formed integrally with the holder 99. Therefore, the prism 90 is always handled as part of the prism unit 9. For example, when the prism 90 is removed from or attached to an infrared spectrophotometer, the prism unit 9 is removed from or attached to the infrared spectrophotometer. Furthermore, when the surface of the prism 90 is cleaned, the prism 90 is cleaned while still adhered to the holder 99.

[0022] The prism 90 has an upper surface 900 on which a sample is placed when measuring the sample. The prism 90 is made of, for example, diamond. When the measurement target is a liquid sample, the liquid sample is dropped onto the upper surface 900 in advance, and the dried sample Sc is measured.

[0023] The holder 99 is a member that supports the prism. The holder 99 includes a first member 91, a second member 92, and a third member 93. The first member 91, the second member 92, the prism 90, and the third member 93 are adhered in this order.

[0024] The arrow AR indicates the optical path of the infrared light incident on the prism unit 9. The position of the prism unit 9 is precisely adjusted to correspond to the position of the optical system that inputs infrared light into the sample chamber and receives infrared light exiting the sample chamber. Specifically, the position of the prism unit 9 is strictly set based on the position of the parabolic mirror 42 that inputs infrared light into the sample chamber and the position of the ellipsoidal mirror 51 that receives infrared light from the sample chamber. The infrared light reflected from the parabolic mirror 42 is incident on a predetermined position on the third member 93 at a predetermined angle, and then on a predetermined position on the prism 90 at a predetermined angle. The infrared light then reflects a predetermined number of times within the prism 90 (eight times in the example shown in Figure 2). The predetermined number of reflections is designed in advance based on the material of the prism 90. During the predetermined number of reflections, each time the infrared light reaches the interface between the upper surface 900 of the prism 90 and the sample Sc, the infrared light leaks into the sample Sc (an evanescent wave). The evanescent waves are then absorbed by the sample Sc, resulting in absorption of infrared components of a predetermined wavelength corresponding to the components of the sample Sc. The infrared light is then reflected a predetermined number of times within the prism 90, and then incident on a predetermined position on the third member 93 at a predetermined angle, and then incident on the ellipsoidal mirror 51 at a predetermined angle.

[0025] However, the prism 90 is generally expensive, and disposable prisms 90 are not practical from a cost perspective. Therefore, users clean the upper surface 900 of the prism 90 every time they replace the sample Sc and reuse the same prism 90. Infrared spectrophotometers generally have high sensitivity, and even a small amount of sample Sc remaining from a previous analysis can cause noise in the next analysis and affect the analysis results. Therefore, users have had to completely remove all sample S from the upper surface 900 every time they perform an analysis.

[0026] Specifically, users have removed the sample Sc on the upper surface 900 by absorbing it with paper (Kimwipes, cotton swabs), rubbing it off, or wiping it off with paper soaked in alcohol. However, as described above, the prism 90 is integrated with the surrounding holder 99, making cleaning difficult. Cleaning the end face of the prism 90 (for example, near the second member 92) is particularly difficult. Furthermore, as described above, the prism 90 is an expensive component, so care must be taken when handling it during cleaning. For these reasons, cleaning the prism 90 every time the sample Sc is replaced places a burden on the analysis.

[0027] Therefore, in the infrared spectrophotometer 100 according to this embodiment, a sample plate P that has been subjected to a predetermined process is used instead of the prism 90. Specifically, in the sample plate P, the periphery of the well into which the liquid sample is dropped is processed so that the liquid sample remains in the well during drying. This allows the formation of a sample S in the well with a predetermined thickness sufficient for analysis. Therefore, by irradiating infrared light onto the sample S and detecting the reflected light, a spectrum is obtained in which infrared components corresponding to the components in the sample are absorbed according to the thickness of the sample S. This makes it possible to perform infrared spectroscopic analysis with high sensitivity without using the prism 90.

[0028] 3. Configuration of the Sample Chamber FIG. 3 is a schematic diagram showing the configuration of the sample chamber 40 according to the embodiment. Referring to FIG. 3, mirrors 43 and 46, ellipsoidal mirrors 44 and 45, a sample plate P, and a stage 41 are installed in the sample chamber 40. In FIG. 3, a line 700 located at the center of the infrared light incident on the sample S and the infrared light reflected by the stage 41 is defined as the Z-axis direction, and a plane perpendicular to the Z-axis is defined as the XY plane. In one embodiment, the infrared spectrophotometer 100 is used in a state where it is installed so that the negative direction of the Z-axis roughly coincides with the direction of gravity. In other words, the stage 41 and the sample plate P are used in a state where they are installed roughly horizontally.

[0029] The light collected by the parabolic mirror 42 is reflected by a mirror 43 and enters an ellipsoidal mirror 44 in the sample chamber 40. The light collected by the ellipsoidal mirror 44 enters the sample S, passes through the interior of the sample S, and is reflected by the upper surface P0 of the sample plate P. The reflected infrared light (reflected light) passes through the sample S again and enters the ellipsoidal mirror 45. The light collected by the ellipsoidal mirror 45 is reflected by a mirror 46 and enters an ellipsoidal mirror 51 of the detection unit 50. Note that in the example of FIG. 3 , the point at which the infrared light enters the sample S is indicated as an incident point 71, the point at which the infrared light is reflected on the sample plate P is indicated as a reflection point 70, and the point at which the infrared light exits the sample S is indicated as an exit point 72. The example of FIG. 3 also shows a first optical path 710 connecting the incident point 71 and the reflection point 70, and a second optical path 720 connecting the reflection point 70 and the exit point 72 from the sample S.

[0030] With this configuration, infrared light that has passed through the sample S is emitted from the sample chamber 40. The optical path length of the infrared light within the sample S is the sum of the length of the first optical path 710 and the length of the second optical path 720. As the infrared light passes through the first optical path 710 and the second optical path 720, infrared components of wavelengths corresponding to the components of the sample are absorbed. This allows a spectrum reflecting this absorption to be created. The lengths of the first optical path 710 and the second optical path 720 are proportional to the thickness T of the sample S in a dried state.

[0031] In the example of Figure 3, the reflection point 70 corresponds to the intersection (focal point) of the central axis of the infrared light incident on the sample (dotted line 73 in Figure 3) and the central axis of the infrared light exiting the sample (dotted line 74 in Figure 3). In another example, the infrared spectrophotometer 100 may be configured so that the focus is adjusted to the upper surface S0 of the sample S or to the interior of the sample S. Even with this configuration, infrared spectroscopy can be performed more easily than in the comparative example in which the prism 90 is used.

[0032] A sample plate P is placed on the stage 41. In one embodiment, the stage 41 is a two-axis (XY axis) stage, and the position of the sample plate P in the X and Y directions can be moved by moving the stage 41 in the X and Y directions. This allows the position of the sample S desired to be analyzed to be moved to the position to be analyzed (the position where the infrared light from the ellipsoidal mirror 44 is incident).

[0033] In one embodiment, the sample S is obtained by dropping and drying an aqueous solution containing protein. The components of the sample S are not limited to proteins, but may include, for example, DNA, RNA, lipids, microorganisms such as bacteria, or other chemical substances. The solvent for the components of the sample S is not limited to water, but may be, for example, oil or an organic solvent.

[0034] The sample plate P is made of a material that does not transmit infrared light. More specifically, the sample plate P is made so that at least the portion of the top surface P0 within the well W does not transmit infrared light. With this configuration, it is possible to obtain the spectrum of infrared light that has passed through the sample S, is reflected on the sample plate P, and then passes through the sample S again. In other words, the optical path length in the sample S of the infrared light reflected in the spectrum is doubled compared to when the infrared light passes through the sample S only once. Therefore, the sample S can be analyzed with twice the sensitivity compared to the spectrum of infrared light that has passed through the sample S only once.

[0035] As a specific example, the sample plate P includes a metal that does not transmit infrared light. A first example of the sample plate P is a plate-shaped member made of gold. Since gold has a high reflectivity for infrared light, this configuration can increase the reflectivity of the sample plate P for infrared light. A second example of the sample plate P is a plate-shaped member made of a relatively inexpensive material, the surface of which is coated with gold. Examples of such relatively inexpensive materials include stainless steel, aluminum, or silicon. A third example is a plate-shaped member made of the above-mentioned relatively inexpensive material, which is coated with silver. Silver has a high reflectivity, although not as high as gold, and is cheaper than gold.

[0036] In the second or third example, the upper surface P0 of the sample plate P has a high infrared light reflectance. On the other hand, in the second or third example, the sample plate P can be manufactured more inexpensively than in the first example, so disposing of the sample plate P does not incur excessive costs and does not pose a cost problem. In other words, even when considering costs, disposable sample plates P are easy to use. Disposable sample plates P eliminate the need to clean the sample plate P after each measurement, reducing the burden on the user. Furthermore, it is preferable that the sample plate P be stored before use in a state where no substances adhere to the surface (upper surface P0) onto which the liquid sample is dripped. For example, the sample plate P is sealed in a plastic bag immediately after production. Storing the sample plate P before use in this manner reduces the possibility that substances adhering to the sample plate P before use will cause measurement noise. From a similar perspective, if the sample plate P is not disposable but is to be used repeatedly, it is preferable that the upper surface P0 of the sample plate P be cleaned with alcohol or the like after and / or before use.

[0037] Strictly speaking, reflected light includes specularly reflected light directed toward the ellipsoidal mirror 45 and scattered light directed in all directions, but since both pass through the sample S and reflect the components of the sample S, they are collectively referred to as "reflected light" in this specification.

[0038] 4. Sample Plate Next, the structure of the sample plate P will be described with reference to FIGS.

[0039] FIG. 4 is a top view of an example of a sample plate according to an embodiment. The sample plate P includes one or more wells W into which a liquid sample is dropped. In the example of FIG. 4, 8 x 8 = 64 wells W are formed in the sample plate P. By including multiple wells W in the sample plate P, multiple samples can be measured at once. The wells W of the sample plate P are surrounded by processing (see 8A and 8B in FIGS. 5 and 6) to retain the liquid sample in the well W during drying. FIG. 4 shows that samples S, each with a substantially uniform thickness T in the Z-axis direction and a substantially flat top surface S0, are formed on several wells W.

[0040] In one embodiment, the processing of the periphery of the well W includes forming a groove 8A around the periphery of the well W. FIG. 5 shows the state of a liquid sample being dried after being dropped into a well W with a groove 8A formed around its periphery. Referring to FIG. 5, by providing the groove 8A around the periphery of the well W, the liquid sample being dried is retained in the well W in a predetermined shape (see S' in FIG. 5) due to surface tension. Then, by drying the liquid sample retained in the predetermined shape in the well W, a sample S spread to a substantially uniform thickness T on the well W can be obtained. The liquid sample dropped into the well W can be dried either outside or inside the sample chamber 40. According to one embodiment, after the liquid sample is dropped into the well W and the dried sample S is obtained, the sample plate P is placed in the sample chamber 40.

[0041] In another embodiment, processing the periphery of the well W includes applying a hydrophobic material 8B to the periphery of the well W. FIG. 6 is a top view of a well W with a hydrophobic material 8B applied to its periphery. Applying the hydrophobic material 8B can be achieved, for example, by applying a hydrophobic substance (e.g., fluorine). Alternatively, it can be achieved, for example, by attaching a hydrophobic sheet. In this case, as in the example of FIG. 5, the liquid sample being dried can be retained in the well W in a predetermined shape by surface tension. Then, by drying the liquid sample retained in the predetermined shape in the well W, a sample S spread to a substantially uniform thickness T on the well W can be obtained.

[0042] As described above, by processing the periphery of the well W, the sample S spreads over the well W with a substantially constant thickness T. As a result, no matter what position (position on the XY plane, the same applies below) on the sample S at which infrared light is incident, the optical path length in the sample S will be substantially the same, and the resulting absorption spectrum will also be substantially the same.

[0043] On the other hand, if no processing is performed around the well W, the position and shape of the liquid sample dropped at the position of the well W are not limited by the processing. Therefore, the thickness of the well W may also vary greatly depending on the position. Furthermore, for example, a portion of the liquid sample may extend beyond the well W. Therefore, the spectrum obtained may vary depending on the position on the sample S where the infrared light is incident.

[0044] As described above, the sample plate P according to this embodiment is effective in preventing uneven sensitivity caused by the position on the sample S where infrared light is incident.

[0045] Furthermore, by processing the periphery of the well W, the liquid sample dropped into the well W is less likely to spread outside the well W. As a result, when the liquid sample is a predetermined amount or more, when the periphery of the well W is processed, the liquid sample can be arranged on the sample plate P in a mounded shape compared to when the processing is not performed (for example, when the liquid sample is dropped onto the prism 90). In other words, when the periphery of the well W is processed, the height in the Z-axis direction of the droplet of the liquid sample dropped onto the sample plate P is higher than when the processing is not performed. This also allows the thickness of the sample S formed by drying the liquid sample to be made thicker.

[0046] In the infrared spectrophotometer according to the comparative example, the penetration depth of the evanescent wave into the sample is approximately the same as the wavelength (e.g., several μm). On the other hand, in the infrared spectrophotometer according to the embodiment, the penetration depth of the infrared light through the sample is approximately the same as the thickness of the sample (e.g., several hundred μm). As described above, the infrared spectrophotometer 100 according to the embodiment can ensure an optical path length of the infrared light in the sample that is equal to or longer than that of the infrared spectrophotometer according to the comparative example, without using the prism 90 to irradiate the sample with infrared light multiple times, as in the infrared spectrophotometer according to the comparative example. This enables the infrared spectrophotometer 100 according to the embodiment to perform highly sensitive component analysis.

[0047] As described above, the infrared spectrophotometer 100 according to this embodiment can perform sensitive analysis without repeatedly penetrating infrared light into a large sample surface, as in the infrared spectrophotometer using the prism 90 according to the comparative example. More specifically, the first area of ​​the sample S formed on the sample plate P according to this embodiment may be smaller than the second area of ​​the sample Sc formed on the prism 90 according to the comparative example. Note that, in this specification, the term "area" refers simply to the area on the XY plane. More specifically, the first area refers to the area of ​​the portion of the sample plate P that contacts the sample S. The second area refers to the area of ​​the portion of the prism 90 that contacts the sample Sc. Therefore, the area of ​​the wells W in the sample plate P can also be smaller than the area of ​​the prism 90. While not limited thereto, the diameter of the wells W is, for example, 2 mm or more and 3 mm or less. Therefore, even if the sample plate P is designed to include multiple wells W, the area of ​​the sample plate P does not become too large. This facilitates handling of the sample plate P during analysis or in preparation for analysis.

[0048] As described above, the sample S on the sample plate P according to the embodiment can have a smaller area and a larger thickness than the sample Sc on the prism 90 according to the comparative example. This has the advantage that the amount of liquid sample required for analysis can be reduced compared to when the prism 90 is used. While not limited to this, for example, the comparative example requires 60 μl of liquid sample, whereas the amount of liquid sample dropped into the well W on the sample plate P according to the present embodiment is sufficient to be 3 μl or more and 10 μl or less.

[0049] By using the sample plate P according to the embodiment, it is possible to increase the thickness of the sample S on the sample plate P and also to control the thickness to an appropriate value. In infrared spectroscopy, it is useful to be able to control the thickness of the sample S.

[0050] For example, if the sample S is too thick, most of the infrared light incident on the sample S may be absorbed within the sample S, and the sample S may not emit infrared light of sufficient intensity to analyze the sample S. In such cases, it is necessary to reduce the thickness of the sample S. However, if the sample plate does not limit the position of the liquid sample on the XY plane, reducing the amount of liquid sample dispensed will only reduce the radial spread of the liquid sample on the sample plate, and the thickness of the liquid sample will not change. Therefore, the thickness of the sample after drying cannot be reduced. On the other hand, in the sample plate P according to this embodiment, the wells W limit the radial spread of the liquid sample on the sample plate P. Therefore, reducing the amount of liquid sample dispensed reduces the thickness of the liquid sample. Therefore, the thickness of the liquid sample can also be reduced.

[0051] On the other hand, if the sample S on the sample plate P absorbs almost no infrared light, the thickness of the sample S needs to be increased. Even in this case, if there is no restriction on the position of the liquid sample on the XY plane, increasing the amount of liquid sample dispensed increases the radial spread of the liquid sample on the sample plate, and the thickness of the liquid sample remains unchanged. Therefore, it is not possible to increase the thickness of the sample after drying. On the other hand, in the sample plate P according to this embodiment, the well W limits the spread of the liquid sample on the sample plate P. Therefore, increasing the amount of liquid sample dispensed increases the thickness of the liquid sample. Therefore, the thickness of the sample S can also be increased.

[0052] As described above, the thickness of the sample S on the sample plate P can be controlled to an appropriate value. More specifically, in the sample plate P, the liquid sample remains in the well W, so the area of ​​the sample S after drying is constant (equivalent to the area of ​​the well W). This correlates with the amount of liquid sample dispensed and the thickness of the sample S after drying. For example, the thickness of a 10 μl droplet of a given liquid sample is approximately twice as thick as the thickness of a 5 μl droplet. Therefore, for example, a user can estimate the required thickness of the sample S after drying based on information about the liquid sample (components, solutes, concentration, etc.) and thereby calculate the appropriate amount of liquid sample to dispense. In this way, a user can control the thickness of the sample S after drying based on the amount of liquid sample dispensed.

[0053] In addition to processing the periphery of the well W, a hydrophilic member 8C may be applied to the well W (see FIG. 6). Applying the hydrophilic member 8C to the well W means, for example, applying a hydrophilic substance to the surface of the well W. This makes it easier for the sample to remain in the well W during drying.

[0054] In one example, the infrared spectrophotometer 100 according to the embodiment is used to determine the structure of a protein and / or identify the protein, for example, a secondary structure such as an α-helix or a β-sheet.

[0055] In a related aspect, absorption spectra for each type and / or structure of protein may be stored in advance in a memory (not shown) of the infrared spectrophotometer 100. Then, the structure of a protein may be specified and / or the protein may be identified by comparing the shape of the stored absorption spectrum with that of an absorption spectrum created based on the light reception signal of the photodetector 52. Such an infrared spectrophotometer 100 allows for easy specification of the structure of a protein contained in a liquid sample and / or identification of the protein. However, specification of the structure of a protein in the sample S and / or identification of the protein may also be performed by referring to absorption spectra for each type and / or structure of protein stored in an external database or the like.

[0056] 7 is a flowchart of an analysis method according to an embodiment. The process of FIG. 7 is performed by a user using the infrared spectrophotometer 100 and laboratory equipment typically used to prepare an infrared spectrophotometer for measurement.

[0057] In step (hereinafter referred to as "ST") 1, a liquid sample is dropped onto a sample plate P. The sample plate P includes one or more wells W into which the liquid sample is dropped. The periphery of each well W of the sample plate P is processed to retain the dropped sample in the well W.

[0058] In ST2, the liquid sample is dried on the sample plate P. In ST3, infrared light is irradiated onto the dried sample S, and the reflected light is detected by the photodetector 52.

[0059] In ST4, the components of the sample S are identified based on the light reception signal from the photodetector 52. In one embodiment, the infrared spectrophotometer 100 creates an absorption spectrum based on the light reception signal from the photodetector 52 and identifies the protein structure and / or the protein based on the absorption spectrum. For example, the infrared spectrophotometer 100 identifies the protein structure and / or the protein by comparing the shape of the absorption spectrum created based on the light reception signal from the photodetector 52 with pre-stored absorption spectra for each protein type and / or structure. In another embodiment, the infrared spectrophotometer 100 identifies and / or identifies the structure of organic substances such as lipids and sugars based on the light reception signal from the photodetector 52. In yet another embodiment, the infrared spectrophotometer 100 identifies bacteria based on the light reception signal from the photodetector 52. For example, the infrared spectrophotometer 100 obtains a second derivative spectrum of the spectrum for each bacterial strain and classifies the bacteria based on the similarity of the second derivative spectra. In this case, the strain can be identified by pattern matching the entire spectrum without assigning each peak in the absorption spectrum. The assignment of each peak means, for example, determining the structure and / or protein to which each peak corresponds. In this specification, the process of identifying the components of sample S in ST4 also includes the process of determining whether or not a predetermined reaction has occurred based on a change in the absorption spectrum. As described above, the process of identifying the components of sample S in ST4 does not necessarily include comparing the shapes of the absorption spectra.

[0060] 7, the thickness of the dried sample S can be made substantially uniform by processing the periphery of the well W, and can be made thicker than when the periphery of the well W is not processed. By irradiating the sample S with infrared light and analyzing the reflected light, stable infrared spectroscopic analysis can be performed with sufficient sensitivity without using a prism that requires cleaning after each measurement. Therefore, an infrared spectroscopic method can be provided that can easily analyze components in a liquid sample with high sensitivity.

[0061] Aspects It will be understood by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0062] (Item 1) An analytical method according to one aspect includes the steps of dropping a sample onto a sample plate, drying the sample on the sample plate, irradiating the dried sample with infrared light and detecting reflected light with a photodetector, and identifying components of the sample based on a light reception signal from the photodetector. The sample plate includes one or more wells into which the sample is dropped. The periphery of each well of the sample plate is treated to retain the dropped sample in the well.

[0063] According to the analytical method described in paragraph 1, the thickness of the dried sample can be made substantially uniform by processing the periphery of the well, and can be made thicker than when the periphery of the well is not processed. By irradiating the sample with infrared light and analyzing the reflected light, stable infrared spectroscopy can be performed with sufficient sensitivity without using a prism that requires cleaning after each analysis. Therefore, an infrared spectroscopy method that can easily analyze components contained in a liquid sample can be provided.

[0064] (Item 2) In the analytical method described in item 1, the sample plate includes a plurality of wells.

[0065] According to the analytical method described in paragraph 2, multiple samples can be measured at once. (paragraph 3) In the analytical method described in paragraph 1 or 2, the processing includes forming a groove around the well.

[0066] According to the analytical method described in paragraph 3, the liquid sample is held in the well in a predetermined shape due to surface tension during drying, and by drying the liquid sample held in the well in a predetermined shape, a sample spread to a substantially uniform thickness over the well can be obtained.

[0067] (Item 4) In the analytical method according to item 1 or 2, the processing includes providing a hydrophobic material around the well.

[0068] According to the analytical method described in paragraph 4, the liquid sample is held in the well in a predetermined shape due to surface tension during drying, and by drying the liquid sample held in the well in a predetermined shape, a sample spread to a substantially uniform thickness over the well can be obtained.

[0069] (Item 5) In the analytical method according to item 1 or 2, a hydrophilic material is provided in the well.

[0070] According to the analytical method described in item 5, the sample can be more likely to remain in the well during drying.

[0071] (Item 6) In the analytical method according to any one of items 1 to 5, the sample plate is made of a material that does not transmit infrared light.

[0072] According to the analytical method described in paragraph 6, infrared light that has passed through a sample can be reflected on a sample plate, and then passed through the sample again to obtain a spectrum of the infrared light.

[0073] (Item 7) In the analytical method described in item 6, the sample plate contains stainless steel, aluminum, or silicon.

[0074] According to the analytical method described in paragraph 7, it is easy to make the sample plate disposable, even when considering costs. By making the sample plate disposable, it is no longer necessary to wash the sample plate after each measurement, which reduces the burden on the user.

[0075] (Item 8) In the analytical method according to any one of items 1 to 7, the sample plate is stored in a state where no substances are attached to the surface of the sample plate onto which the sample is dropped.

[0076] According to the analytical method described in paragraph 8, it is possible to reduce the possibility that substances adhering to the sample plate P before use will cause noise in the measurement.

[0077] (Item 9) In the analytical method described in any one of items 1 to 8, the step of identifying the components of the sample includes the step of creating an absorption spectrum based on the light received by the photodetector, and specifying the structure of the components of the sample and / or identifying the components of the sample based on the absorption spectrum.

[0078] According to the analytical method described in item 9, the structure of a sample component contained in a liquid sample can be easily specified and / or the sample component can be easily identified.

[0079] (Item 10) In the analytical method described in Item 9, the step of specifying the structure of the components of the sample and / or identifying the components of the sample includes a step of specifying the structure of the components of the sample and / or identifying the components of the sample by comparing the shape of the absorption spectrum for each type and / or structure of the components of the sample, which is pre-stored in the infrared spectrophotometer, with the shape of the absorption spectrum created based on the light reception signal of the photodetector.

[0080] According to the analytical method described in item 10, the structure of a sample component contained in a liquid sample and / or the sample component can be easily identified by a simple method of comparing the shapes of absorption spectra.

[0081] (Item 11) An infrared spectrophotometer according to another aspect includes a sample plate, an infrared light source, a photodetector, and a control device. The sample plate includes one or more wells into which samples are each dropped. The infrared light source emits infrared light that is incident on the sample dried on the sample plate. The photodetector detects reflected light in response to the incident infrared light. The control device identifies the components of the sample based on the light reception signal of the photodetector. The wells of the sample plate are surrounded by a processing for retaining the dropped sample in the well.

[0082] According to the infrared spectrophotometer described in paragraph 11, the thickness of the dried sample can be made substantially constant by processing the periphery of the well, and can be made thicker than when the periphery of the well is not processed. By irradiating the sample with infrared light and analyzing the reflected light, stable infrared spectroscopic analysis can be performed with sufficient sensitivity without using a prism that requires cleaning after each analysis. Therefore, an infrared spectroscopy method that can easily analyze components contained in a liquid sample can be provided.

[0083] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0084] 8A Groove, 8B Hydrophobic member, 8C Hydrophilic member, 9 Prism unit, 10 Interferometer, 11 Beam splitter, 12 Fixed mirror, 13 Movable mirror, 14, 15, 43, 46 Mirror, 16, 52 Photodetector, 20 Light source section, 21 Infrared light source, 22 Condenser mirror, 23 Collimator mirror, 24 Laser light source, 30 Circuit section, 31 Control section, 32 Signal generation section, 33 Amplifier, 36 Data processing section, 40 Sample chamber, 41 Stage, 42 Objective mirror, 44, 45, 51 Ellipsoidal mirror, 50 Detection section, 70 Reflection point, 71 Incident point, 72 Exit point, 90 Prism, 91 First member, 92 Second member, 93 Third member, 99 Holder, 100 Infrared spectrophotometer, 710 First optical path, 720 Second optical path, 900, P0, S0 top surface, P sample plate, S, Sc sample, W well.

Claims

1. Dropping a sample onto a sample plate; drying the sample on the sample plate; irradiating the dried sample with infrared light and detecting reflected light with a photodetector; and identifying components of the sample based on the light received by the photodetector; the sample plate includes one or more wells into which the sample is dropped; The sample plate further includes a processed area around the well, the processed area being designed to retain the dropped sample in the well; The analysis method, wherein the processing includes forming a groove in the processed region.

2. The analytical method according to claim 1 , wherein the sample plate includes a plurality of the wells.

3. The analytical method according to claim 1 , wherein the processing includes providing a hydrophobic material around the well.

4. The analytical method according to claim 1 , wherein the well is provided with a hydrophilic material.

5. 2. The analytical method according to claim 1, wherein the sample plate is made of a material that is opaque to infrared light.

6. The analytical method according to claim 5 , wherein the sample plate includes stainless steel, aluminum, or silicon.

7. The analytical method according to claim 1 , wherein the sample plate is stored in a state where no substance adheres to the surface of the sample plate onto which the sample is dropped.

8. The analytical method according to claim 1, wherein the step of identifying the components of the sample includes the step of creating an absorption spectrum based on the light received by the photodetector, and specifying the structure of the components of the sample and / or identifying the components of the sample based on the absorption spectrum.

9. The step of determining the structure of components of the sample and / or identifying components of the sample comprises:

9. The analytical method according to claim 8, further comprising a step of specifying the structure of the component of the sample and / or identifying the component of the sample by comparing the shape of an absorption spectrum for each type and / or structure of the component of the sample, which is stored in advance in an infrared spectrophotometer, with the shape of an absorption spectrum created based on the light reception signal of the photodetector.

10. a sample plate including one or more wells into which samples are respectively dropped; an infrared light source that emits infrared light that is incident on the sample dried on the sample plate; a photodetector that detects reflected light in response to the incident infrared light; a control device that identifies components of the sample based on the light-receiving signal of the light detector; The sample plate further includes a processed area around the well, the processed area being adapted to retain the dropped sample in the well; The processing includes forming a groove in the processing area.