JP2008241640A - Method for automatically determining crystal polymorphism by raman scattering spectroscopy, and device thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain Raman spectrum, such as of a needle crystal, while reducing a determination time of a crystal form. <P>SOLUTION: A well-plate is placed on an XYZ moving stage of a micro Raman spectrometer; XY locations of each well are recognized by a computer; and a height (Z) is set based on the ground surface of a well. The vicinity of the center of the well's ground surface is observed by a charge-coupled device under halogen lighting. Based on the coordinate location that has been recorded by a low-power lens, the well plate is moved so that a crystal comes to the center of an observation region; the focus of a high power lens is auto-focused on the crystal surface; and a crystal image is picked up. Based on the detailed location that has been recorded by the high power object lens, the well plate is moved so that the crystal comes to the center of the conservation region; Raman scattering light is spectroscopically analyzed by irradiating excitation laser and the result is analyzed by analysis software; and the crystal form is automatically determined. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a screening method and apparatus for crystal polymorphism of a target compound.

Crystal polymorphism is caused by crystallization in a state of different energy state at the stage of crystal precipitation from solution, and is generally observed in solid material chemistry, but in medicine, quality, safety, and effectiveness Very important in terms of sex.
Crystal polymorphs have different physical and chemical properties such as solubility, dissolution rate, melting temperature, heat of fusion, lattice energy, and acid-base dissociation constant, affecting bioavailability, usefulness in vivo, and stability. To do.

Therefore, management of crystal polymorphism is extremely important in pharmaceuticals, and screening methods for crystallizing automatically have been proposed (Patent Document 1 and Patent Document 2). reference).
Examples of the method for examining the morphology and molecular state of the crystal polymorph include X-ray diffraction, thermal analysis, IR spectrum, Raman spectroscopy, NMR, water vapor adsorption measurement using microbalance, and microscopy.

Among these, Raman spectroscopy, which is one of spectroscopic methods, is useful for understanding the molecular state. However, when the screening is automated, the amount and shape of the target crystal differ from sample to sample, so that the excitation laser cannot be accurately irradiated to the crystal and a spectrum may not be obtained.
In addition, organic compounds such as pharmaceuticals may generate fluorescence, and the spectrum of the target crystal is hidden behind the fluorescence and cannot be discriminated, or the baseline becomes high, making it difficult to provide analysis.
Further, since it takes a long time to obtain a Raman spectrum of crystals in each well and to analyze a large amount of obtained spectrum data, automation and simplification of operations for the measurement and analysis are required.

JP-T-2004-504596 JP 2005-502861 gazette

An object of the present invention is to perform accurate Raman spectroscopic analysis by automatically determining the position (XYZ coordinates) of the deposited crystal by image processing of the center of the well or mapping and image processing in the well, and the acquired Raman spectrum is subjected to fluorescence. Is included, the re-measurement is performed under the condition that the fluorescence is excluded or reduced by laser pre-irradiation or laser wavelength switching, and the obtained crystal is analyzed to accurately determine the crystal form. To provide an automatic shape determination method and apparatus.

In the crystal polymorphic automatic determination method and apparatus therefor according to the Raman spectroscopy of the present invention, a target compound is precipitated on each well of a multi-well plate under arbitrary conditions to obtain crystals. At this time, [1] the compound is stirred and reacted with a circular and flat magnetic stirrer chip in each well, and the magnetic stirrer chip is also present on the magnetic stirrer chip even after the reaction is completed. There are cases where crystals are precipitated, and [2] there are cases where crystals are precipitated on the bottom of the well without containing foreign substances such as magnetic stirrer chips in the reaction product.

Place the crystal-deposited multiwell plate on the XYZ moving stage of the microscopic Raman spectroscope, let the computer recognize the horizontal (XY) position of each well on the multiwell plate, and make the height relative to the bottom of the well ( Z) is set. Subsequently, it automatically moves to any set well.
The multiwell plate is irradiated with halogen illumination light. At this time, when [1] the magnetic stirrer chip is included in the well and when the crystal is opaque, epi-illumination is performed, and [2] when the crystal is transparent, transmission illumination is performed. Under this irradiation, the vicinity of the center of the well bottom is observed with a charge coupled device connected to an optical microscope provided with a low-magnification objective lens.
The crystal position height (Z) is determined by the autofocus function, and an image of the enlarged crystal is captured by the charge coupled device. The captured image is processed by a computer. The position (coordinates) and area of the crystal are specified by image processing and recorded in a computer.

When the image processing cannot be performed and the crystal position cannot be specified, the XYZ moving stage is automatically operated in the XY direction according to the arbitrarily set conditions (number of moving points in the X and Y directions and the distance between the points). The inside of the well is mapped, and the crystal position height (Z) is determined, photographed, and image processing is repeated to detect crystals.
Subsequently, the low magnification objective lens is automatically replaced with a high magnification objective lens. Based on the coordinate position recorded using the low-magnification objective lens, the multiwell plate is moved by the XYZ moving stage so that the crystal is arranged at the center of the observation region of the optical microscope. The focus of the high-magnification objective lens is autofocused on the crystal surface, and an image of the enlarged crystal is captured by the charge coupled device. The captured image is processed by a computer, and the detailed position of the crystal is measured and recorded in the computer.

Based on the detailed coordinate position of the crystal recorded using the high magnification objective lens, the multiwell plate is moved by the XYZ moving stage so that the crystal is arranged at the center of the observation region of the optical microscope. The shutter for halogen illumination light is automatically closed and the shutter for excitation laser light for Raman measurement is automatically opened to irradiate the crystal with laser light. The Raman scattered light generated by the laser irradiation light is detected by a Raman light detection unit, and the Raman scattered light is spectrally analyzed by a spectroscope.
The obtained Raman spectrum is determined. When compared with Raman spectra other than crystals such as wells and magnetic stirrer chips obtained in advance, if it is determined that the spectra are equivalent to spectra other than these crystals, the position of the crystal is specified again.

When it is recognized that the fluorescence is generated with a high baseline, the crystal is irradiated with an excitation laser for a certain period of time (pre-irradiation), and the Raman spectroscopic measurement is performed after the fluorescence disappears. Alternatively, generation of fluorescence is avoided by changing the excitation laser wavelength by an automatic wavelength switching device (for example, four wavelength switching) mounted on the Raman spectroscopic device. At this time, generation of fluorescence can generally be avoided by using a near infrared laser.

The XYZ moving stage is moved so that the center of the bottom surface of the well other than the above comes to the observation region of the optical microscope, and the same operation is repeated to screen crystals precipitated in the well on the well plate.
The obtained spectra are classified by multivariate analysis. The spectrogram taken into the computer is analyzed using analysis software (a commercially available computer program for multivariate analysis is Pirouette manufactured by InfoMetrix, USA), and the crystal form is automatically determined.

For example, analysis results are displayed in dendrograms by principal component analysis (PCA), which is one of the multivariate analysis methods, and crystal forms are grouped by visualization.
When the crystal form is known, a Raman spectrum is acquired in advance and a prediction model is created by the SIMCA method. The principal component analysis is performed for each class of the prediction model, and the spectrum of the unknown sample is compared with each class and assigned to the most suitable class.
Furthermore, substance identification can be performed by comparing the obtained spectrum with a Raman spectrum database or the spectrum of an already obtained substance.
Measurement results such as crystal determination conditions, Raman spectroscopic analysis conditions, Raman spectra, and crystal polymorph determination results by multivariate analysis are compiled in a report format.

By using the above-described method and apparatus for automatically determining crystal polymorphism by Raman spectroscopy according to the present invention, the accurate sample crystal position (XYZ) can be detected by image determination. It becomes possible to obtain a Raman spectrum of a crystal that was difficult to achieve.
When a spectrum cannot be obtained due to the generation of fluorescence, it is possible to avoid the fluorescence by laser pre-irradiation or a wavelength switching function and re-acquire the spectrum.
Further, by automating the entire measurement process and automatically determining the obtained spectrum data, it is possible to simplify the measurement operation and reduce the time required for crystal determination.

The sulfanilamide having the structural formula of FIG. 1 is stable in the β-type crystal form, but depending on the crystallization conditions, the metastable α-type is precipitated. Moreover, it transforms to a γ-type that is stable at high temperatures by melting with heating. Thus, it is necessary to confirm that a substance having a crystalline polymorph does not undergo polymorphic transition in the preparation process.
Therefore, after the sulfanilamide was reacted in a 96-well plate with a flat magnetic stirrer chip made of polytetrafluoroethylene in each well, sulfanilamide crystals were deposited on each well and the above screening was performed. It was.

FIG. 2 shows a schematic diagram of an automatic crystal polymorph determination device based on the Raman spectroscopy described above. In FIG. 2, a quartz glass 96-well plate 36 on which sulfanilamide crystals are deposited is fixed on an XYZ stage 37 of an optical microscope, and crystals are deposited in each well on the 96-well plate. Above the 96-well plate, an auto-switchable low-magnification objective lens 33 and high-magnification objective lens 34 mounted on the turret 35 are arranged.
Also, below the 96-well plate 36, the halogen-transmitted illumination light 38 necessary as an irradiation means when measuring the [2] transparent crystal is disposed.

In the optical microscope, epi-illumination light 32 is arranged as means for irradiating the sample on the stage, and a charge coupled device image sensor 39 and a Raman optical system 27 are installed via a half mirror 31. Also, the excitation laser irradiation unit 1,
2, 3, 4 (4 wavelengths, 3 and 4 are tunable) and the spectroscope 29 are connected to the Raman optical system 27 by optical fibers 5, 6, 7 and 28, respectively. Microscope section and excitation laser irradiation section 1,
2, 3, 4, and the spectroscope 29 can be installed at any location within the fiber length range.

A cooled charge coupled device detector 30 is connected to the spectrometer 29. A computer 47 for control comprising a Raman spectrum acquisition unit 40, an automatic wavelength switching unit 41, a sample image acquisition unit 42, a microscope control unit 43, and an XYZ movement stage control unit 44 includes a spectroscope 29, a cooling charge coupled device detector 30, a charge Coupling element 39, microscope objective lens 33,
34 and XYZ moving stage 37 are connected. Further, the computer includes multivariate analysis software 45 and a Raman spectrum database 46.

FIG. 3 shows the operation of the crystal polymorphic automatic determination apparatus based on Raman spectroscopy constructed as described above.
First, a 96-well plate 36 made of quartz glass on which sulfanilamide crystals are deposited is placed on the XYZ moving stage 37.
In response to a command from the XYZ movement stage control unit 44 of the control computer 47, the XYZ movement stage 37 is driven to automatically move the 96 well plate 96 so that the center of the well enters the observation region. For the crystals in the well irradiated with halogen illumination light 32 (or 38) and magnified by the low magnification objective lens 33, the height (Z) of the crystal position is determined by the autofocus function, and the magnified image is charge coupled. An image is picked up by the element 39 and binarized by the computer 47. The approximate position and area of the crystal are calculated by binarization processing and recorded in the computer 47. A crystal image and a binarized image are shown in FIG.

If binarization processing cannot be performed and crystals cannot be identified, the computer 47 controls the XY direction of the XYZ moving stage 37 to map the inside of the well according to preset conditions, and the height (Z position) by focusing ) Confirmation, image capture, and binarization are performed. If the crystal can be detected, the mapping ends.

Next, the microscope control unit 43 automatically replaces the low magnification objective lens 33 with the high magnification objective lens 34. Based on the coordinate position recorded using the low-magnification objective lens 33, the XYZ moving stage 37 is moved so that the crystal is arranged at the center of the observation region of the optical microscope. The focus of the high-magnification objective lens 34 is autofocused on the crystal surface, and an image of the enlarged crystal is picked up by the charge coupled device 39. The captured image is binarized by the computer 47, and the detailed position and area of the crystal are measured and recorded in the computer 47. A crystal image and a binarized image are shown in FIG.

Subsequently, based on the detailed coordinate position of the crystal recorded using the high-magnification objective lens 34, the multiwell plate 36 is moved by the XYZ moving stage 37 so that the crystal is arranged at the center of the observation region of the optical microscope. . In order to perform the Raman spectroscopic measurement, the shutter of the halogen illumination light 32 (or 38) is automatically closed. The laser spot is adjusted in advance so that the center of the observation area is irradiated. Therefore, the laser is always irradiated to the crystal detected by the image processing.

Excitation laser irradiation unit 1 (or 2,
Laser light is introduced into the Raman optical system 27 through the optical fiber 5 (or 6, 7) from 3, 4). The bandpass filter 12 automatically selected by the automatic wavelength switching unit 41 so that the laser light is reflected by the automatic wavelength switching unit 41 by moving the prism through the same optical path for all four wavelengths, so that the center wavelength matches the laser beam. (Or 13,
14, 15), and is reflected by the flat mirror 17 and the beam splitter 18 (or 20, 23, 25) automatically selected by the automatic wavelength switching unit 41 and introduced into the optical microscope. The laser light is condensed by the high-magnification objective lens 34 and irradiates the crystal. The Raman scattered light generated from the crystal by the laser light is collected by the high-magnification objective lens 34 and returns to the Raman optical system 27.

Subsequently, the Raman scattered light travels straight through the beam splitter 18 (or 20, 23, 25) and the notch filter 19 (or 21, 22, 24) automatically selected by the automatic wavelength switching unit 41, and passes through the optical fiber 28. Are introduced into the spectroscope 29 and detected by the cooled charge coupled device detector 30. By analyzing the detected Raman scattered light data by the Raman spectrum acquisition unit 40 of the control computer 47, a Raman spectrum of the crystal can be obtained. The Raman spectrum is shown in FIG.
The obtained Raman spectrum is compared with the Raman spectra of a 96-well plate 36 made of quartz and a flat magnetic stirrer chip made of polytetrafluoroethylene obtained in advance. If it is determined that the spectrum is equivalent to that of the well plate or magnetic stirrer chip, the crystal position is specified again.

In addition, fluorescence may be generated from sulfanilamide. If it is not possible to obtain a spectrum, or if it is recognized that fluorescence has occurred due to a high baseline, etc., the crystal is irradiated with an excitation laser for several seconds (pre-irradiation), and the fluorescence decreases and a spectrum of sulfanilamide is obtained. After confirming this, the spectrum of the Raman scattered light is recorded in the computer 47.
If fluorescence does not decrease even after pre-irradiation, the wavelength automatic switching unit 41 changes the excitation laser 1 (or 2, 3) to laser 2 (or 3, 4) to avoid the generation of fluorescence. FIG. 6 shows a Raman spectrum when fluorescence is generated and measurement is performed by changing the wavelength to a near infrared laser.
The XYZ moving stage 37 is moved so that the center of the well bottom other than the above comes to the observation region of the optical microscope, and the above operation is repeated to screen the crystals deposited in the wells on the well plate.

After obtaining spectra for all the crystals in the set wells, the polymorphism is determined by multivariate analysis. The spectrogram taken into the computer 47 automatically determines the crystal form using the analysis software 45.
For example, when analyzing by the HCA method, the crystal form candidates displayed in a dendrogram as shown in FIG. 7 and divided into groups can be visually grasped.
In addition, if the Raman spectra of crystal forms α, β, and γ are acquired in advance and a prediction model is created by the SIMCA method, the crystal spectrum is assigned to the most suitable class compared to each class of the prediction model. It is done. The analysis result can be visually grasped like the three-dimensional diagram of FIG. These analysis results can also be shown in a table display as shown in FIG.
With the above-mentioned measurement and analysis conditions, measurement results such as Raman spectra obtained, and crystal polymorphism determination results by multivariate analysis in a report format, reports can be made easily and quickly in a 96-well plate. A determination can be made.

1 is a structural diagram of sulfanilamide used in Examples of the present invention. 1 is a schematic configuration diagram of an embodiment of the present invention. It is an operation | movement flowchart in the Example of this invention. It is the binarization determination image (20-times objective lens magnification) of the crystal | crystallization by the Example of this invention. It is the binarization determination image (objective lens magnification 50 times) of the crystal | crystallization by the Example of this invention. The Raman spectrum before and behind wavelength switching by the Example of this invention is shown. The spectrum determination example (1) (HCA method) by the Example of this invention is shown. The Raman spectrum ((alpha), (beta), (gamma)) of the crystal polymorph acquired previously is shown. The spectrum determination example (2) (SIMCA method) by the Example of this invention is shown. The spectrum determination example (3) (SIMCA method and classification table) by the Example of this invention is shown.

Explanation of symbols

1 Excitation laser irradiation part (1)
2 Excitation laser irradiation part (2)
3 Excitation laser irradiation section (3)
4 Excitation laser irradiation part (4)
5 Optical fiber
(1)
6 Optical fiber
(1)
7 Optical fiber
(1)
8 Mirror (1)
9 Mirror (2)
10 Mirror (3)
11 Mirror
(Four)
12 Bandpass filter
(1)
13 Bandpass filter
(2)
14 Bandpass filter
(3)
15 Bandpass filter
(Four)
16 Shutter for pump laser
17 Flat mirror
18 Beam splitter (1)
19 Notch filter (1)
20 Beam splitter (2)
21 Notch filter (2)
22 Notch filter (3)
23 Beam splitter (3)
24 notch filter (4)
25 Beam splitter (4)
26 Shutter for Raman scattered light
27 Raman optical system
28 Optical fiber
29 Spectrometer
30 Cooling charge coupled device detector
31 Half mirror
32 Halogen lighting
33 Low-magnification objective lens
34 High magnification objective lens
35 Turret
36 well plate
37 XYZ moving stage
38 Halogen transmitted illumination light
39 Charge coupled devices
40 Raman spectrum acquisition unit
41 Automatic wavelength switching section
42 Image acquisition unit
43 Microscope control unit
44 XYZ moving stage controller
45 Multivariate analysis software
46 Raman spectrum database
47 Control computer

Claims (7)

A step of precipitating a target compound on each well of a multi-well plate under arbitrary conditions to obtain crystals;
The multi-well plate on which the crystals are deposited is placed on the XYZ moving stage of a microscopic Raman spectroscope, and the computer recognizes the horizontal (XY) position of each well on the multi-well plate so Setting (Z);
Automatically moving to arbitrarily set wells on the multi-well plate and irradiating with halogen illumination light; and
The vicinity of the center of the bottom of the well is observed with a charge coupled device connected to an optical microscope provided with a low-magnification objective lens, and the height (Z) of the crystal position is determined by the autofocus function, and an enlarged image of the crystal Imaging with the charge coupled device,
Processing the captured image with a computer, specifying the crystal position (coordinates), area, and the like by image processing and recording the computer;
When the image processing cannot be performed and the crystal position cannot be specified, the XYZ moving stage is automatically operated in the XY direction according to arbitrarily set conditions (number of moving points in the X and Y directions and distance between the points). And mapping the inside of the well, repeatedly detecting the crystal position height (z), photographing, image processing, and detecting crystals,
The low-magnification objective lens of the optical microscope is automatically replaced with a high-magnification objective lens, and the crystal is arranged at the center of the observation region of the optical microscope based on the coordinate position recorded using the low-magnification objective lens. Moving the multi-well plate by the XYZ moving stage;
Autofocusing the focus of the high-magnification objective lens on the crystal surface, and taking an image of the enlarged crystal with the charge coupled device;
Processing the photographed image with a computer, measuring the detailed coordinate position of the crystal and recording it on the computer;
Moving the multiwell plate by the XYZ moving stage so that the crystal is arranged at the center of the observation region of the optical microscope based on the detailed coordinate position of the crystal recorded using the high-magnification objective lens; ,
The shutter of the halogen illumination light is automatically closed and the excitation laser light shutter for Raman measurement is automatically opened to irradiate the crystal with laser light, and the Raman scattered light generated by the laser irradiation light is detected by the Raman light detector. , Spectroscopic analysis of Raman scattered light with a spectroscope,
The obtained Raman spectrum is judged, compared with a Raman spectrum other than a crystal such as a well or a magnetic stirrer chip obtained in advance, and if it is determined that the spectrum is equivalent to the spectrum other than the crystal, the position of the crystal is specified again. Process,
Moving the XYZ moving stage so that the center of the bottom surface of the well other than the above comes to the observation region of the optical microscope, and repeating the same operation to screen crystals precipitated in the well on the well plate; and
In order to classify the obtained spectrum by multivariate analysis, the spectrogram taken in the computer is analyzed by analysis software, and the crystal form is automatically determined,
A method for automatically determining crystal polymorphism by Raman spectroscopy. In the step of precipitating the desired compound on each well of the multiwell plate under arbitrary conditions to obtain crystals,
2. The automatic determination method according to claim 1, wherein crystals are deposited on the bottom of the well in a state where no foreign matter such as a magnetic stirrer chip is present in the reactant. In the step of precipitating the desired compound on each well of the multiwell plate under arbitrary conditions to obtain crystals,
In each well, the compound is stirred and reacted with a circular or flat magnetic stirrer chip, and crystals are also deposited on the magnetic stirrer chip with the magnetic stirrer chip still present in the well after the reaction. The automatic determination method according to claim 1, wherein: In the process of automatically moving to arbitrarily set wells on the multi-well plate and irradiating with halogen illumination light,
3. The automatic determination method according to claim 1, wherein when the crystal in the well is transparent, irradiation with halogen illumination light is transmitted illumination. In the process of automatically moving to arbitrarily set wells on the multi-well plate and irradiating with halogen illumination light,
4. The automatic determination method according to claim 1, wherein when the magnetic stirrer chip is included in the well and the crystal is opaque, the illumination of the halogen illumination light is epi-illumination. . If the baseline is recognized as having fluorescence, change the excitation laser wavelength by using the wavelength automatic switching device installed in the Raman spectrometer to avoid the generation of fluorescence, or apply the excitation laser to the crystal for a certain period of time. 6. The automatic determination method according to claim 1, wherein the Raman spectroscopic measurement is performed after the irradiation (pre-irradiation) and the fluorescence disappears. A multi-well plate for obtaining crystals by precipitating the target compound on each well under arbitrary conditions;
A micro-Raman spectroscopic device in which the multi-well plate on which crystals are deposited is placed on an XYZ moving stage;
A computer that records the horizontal (XY) position and the height (Z) with respect to the well bottom for each well on the multi-well plate placed on the XYZ moving stage;
A halogen irradiation device that automatically moves to arbitrarily set wells on the multi-well plate and irradiates halogen illumination light; and
An optical microscope installed toward the well of the multi-well plate, in which a low-magnification objective lens and a high-magnification objective lens are automatically replaced;
It is connected to the optical microscope to observe the vicinity of the center of the bottom of the well, and the height of the crystal position (Z) is determined by an autofocus function, and a charge-coupled device that captures an image of the enlarged crystal,
The computer specifies and records the crystal position (coordinates), area, etc. by image processing of the captured image,
If the computer cannot perform image processing and the crystal position cannot be specified, the XYZ moving stage is automatically operated in accordance with arbitrarily set conditions to map the inside of the well, and repeats photographing and image processing to form a crystal. Is to detect,
In the optical microscope, the low-magnification objective lens is automatically replaced with a high-magnification objective lens, and the crystal is arranged at the center of the observation region of the optical microscope based on the coordinate position recorded using the low-magnification objective lens. The multiwell plate is moved by the XYZ moving stage,
The charge-coupled device captures an enlarged crystal image by autofocusing the focus of the high-magnification objective lens on the crystal surface,
The computer processes the captured image of the charge coupled device, measures and records the detailed coordinate position of the crystal,
The multi-well plate is moved by the XYZ moving stage so that the crystal is arranged at the center of the observation region of the optical microscope based on the detailed coordinate position of the crystal recorded using the high-power lens. And
When the shutter of the halogen illumination light of the halogen irradiation device is automatically closed, the shutter of the excitation laser light for Raman measurement of the microscopic Raman spectroscopic device is automatically opened and the crystal is irradiated with the laser light. ,
The microscopic Raman spectroscopic device detects Raman scattered light generated by the laser irradiation light with a Raman light detection unit, and spectrally analyzes the Raman scattered light with a spectrometer.
The obtained Raman spectrum is determined and compared with a Raman spectrum other than a crystal such as a well or a stirrer chip acquired in advance. If it is determined that the spectrum is equivalent to the spectrum other than the crystal, the position of the crystal is specified again. Is,
The XYZ moving stage is moved so that the center of the well bottom other than the above comes to the observation region of the optical microscope, and the same operation is repeated to screen the crystals deposited in the wells on the well plate. An automatic crystal polymorph determination device based on Raman spectroscopy, in which the captured spectrogram is subjected to multivariate analysis using analysis software to automatically determine the crystal shape.