JPS6046445A - Optical scanner for thin layer chromatography - Google Patents

Abstract

PURPOSE:To make the constitution of an optical system simple by storing preliminarily the photometric output when a sample is scanned at a specified wavelength, reading out the stored result in the stage of scanning at the other specified wavelength and calculating the same with the photometric value. CONSTITUTION:Light of a single wavelength is made incident from a light source 1 through a spectroscope 2 to the sample on a scanning stage 3 and the light transmitted through or reflected from a thin film plate is detected with a photodetector 5 and is converted to an electrical signal in the stage of measuring the spectral absorbancy of the thin film plate in a thin film chromatograph. The electrical signal is stored in an RAM 9 after A/D conversion. The wavelength of the spectroscope 2 is then changed by means of a pulse motor 11 and the light of another single wavelength is made incident to the sample to obtain the photometric output. The photometric output is calculated by using the value stored in the RAM 9 and the noise component arising from the unevenness, etc. of the thin layer plate is removed from the measured result. the measurement of a two-wavelength method is thus accomplished by the simple constitution.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical scanning device when a dual wavelength method is used to measure the spectral absorbance of a thin layer plate in a thin layer chromatograph.

When measuring the absorbance of a thin layer plate in a thin layer chromatograph, a dual wavelength method is used to remove noise caused by uneven thickness of the thin layer plate. Two spectrometers set to emit light at different wavelengths are used, and the emitted light from both spectrometers is alternately directed into the sample using a sector mirror.9, therefore, two spectrometers are required. In addition, a sector mirror and its drive mechanism are required, as well as an optical system to guide the light from the two spectrometers onto the same optical path, making the device expensive and complicated.

The present invention aims to provide an optical scanning device using a thin layer plate, which requires only one spectroscope and does not require a sector mirror and its associated parts, as well as an optical system that introduces light beams coming from two places into the same optical path. The purpose is

The present invention scans a thin layer plate with light of a fixed wavelength, stores the photometric output at that time in memory, then scans the thin layer plate with another fixed wavelength, reads out the previously stored result, and then performs two steps. The present invention provides an optical scanning device that obtains the same result as using the two-wavelength method by performing calculations between the photometric values of the second scan and the photometric value of the second scan. The present invention will be explained below with reference to Examples.

FIG. 1 shows an embodiment of the invention. 1 is a light source, 2 is a spectroscope, 3 is a scanning stage, and 4 is a pulse motor that drives the scanning stage. A thin layer plate of a sample is set on the scanning stage 8. The light emitted from the light source 1 enters the spectroscope 2, and only the light having a single wavelength λl is emitted from the spectrometer 2 and is made to enter the sample on the scanning stage 8.

Only one pulse motor, numbered 4, is shown in the figure for driving the scanning stage 8, but specifically, there are two pulse motors that can drive the scanning stage in the X and Y directions. . Reference numeral 5 denotes a photodetector which receives transmitted light or reflected light from the thin layer plate of the sample and converts it into an electrical signal. This electrical signal is amplified by an amplifier 6 and then converted into a digital signal by an A/D converter 18. 7 is a microprocessor.

The pulse motor 4 is driven by pulses supplied from a control circuit 8, and the control circuit 8 applies forward and reverse rotation pulses to the pulse motor 4 according to commands from the microprocessor 7, and also sends the same pulses to the microprocessor.

The microprocessor counts these pulses to obtain a position signal of the scanning stage 3. The A-D converter 18 receives a sampling signal synchronized with the pulse that drives the υ pulse motor 4 from the microprocessor 7, samples the output of the amplifier 6, and converts it into an A-D converter. It is written to random access memory (RAM) 9 via processor 7. At this time, the information specifying the RAM address is sent to the control circuit 8 by the microprocessor 7.
The RAM address corresponds to the location on the thin plate. Reference numeral 10 denotes a read-only memory (ROM) in which the operating program of the microprocessor 7 is stored.

The microprocessor 7 operates as follows.

When the apparatus is started, the sample stage 3 is moved to the starting point of scanning, and the pulse motor 11 is operated to set the diffraction grating G at the position of a predetermined wavelength λ1, and the scanning stage 8 is caused to perform a scanning movement. The wavelength λ1 was selected to give similar absorption to both the thin plate and the sample material spread on the plate, and the photometry results are based on information about the unevenness of the thin plate itself. When one scan stored in the RAMIQ is completed, the scanning stage is returned to the scanning starting point, the pulse motor 11 is controlled, the wavelength of the spectrometer 2 is set to λ2, and scanning is started again. The wavelength λ2 is chosen to be one that is specifically absorbed by the material spread out on the thin plate. The photometric output is sampled by an A-D converter and converted into a digital signal.Each time the photometric output is sampled, the memory of the address corresponding to the position of the stage 3 at that time is read out from the RAM, and calculations are performed along with the above-mentioned digital signal. Removes noise components based on unevenness of layer plates, etc. The correct information from which noise components have been removed is output to the display device 12 and printed, or it is D-A converted and drawn as a curve. The thin layer plate is expanded into multiple channels as shown in Figure 2. The scanning stage 8 is driven in both the x and y directions, and the scanning lanes are switched via a pulse motor in response to commands from the microprocessor 7.
The scanning locus has two shapes as shown by S in the figure, and the part A is rapid feed, and photometry is performed at the mouth part.

The microprocessor 7 executes R according to the given program.
By using the information stored in AM10 and the information currently being measured, it is possible to perform not only noise removal but also various other information processing. For example, if we calculate the difference between the information currently obtained by differential operation and the information obtained a little earlier, for example, during round sampling (stored in RAM), we can obtain differential information, which cannot be clearly separated by recording absorbance alone. By scanning the lane in which the sample is developed and the lane in between, the two peaks can be separated using the same wavelength. When using the long method, which performs an operation to eliminate fluctuations in the baseline of photometry results due to changes, only one spectrometer is required, and the device configuration is therefore inexpensive. Note that the microprocessor.

When used, various operations and data processing other than the two-wavelength method can be performed with automation and depending on how the program is assembled.

The lock diagram, FIG. 2, is a plan view showing the scan lines on the laminar plate.

l...Light source, 2...Spectroscope, 8...Scanning stage, 4...Pulse motor, 12...Display device.

Agent: Patent Attorney Kosuke Agata

Claims (1)

[Claims] A single spectrometer that projects light for sample irradiation onto the scanning stage and a signal synchronized with the drive of the scanning stage create information about the position of the scanning stage), which specifies a memory address and stores the photometry results. An optical scanning device for thin layer chromatography that has this memory or a control circuit that performs calculations using this memory and currently obtained photometric data.