JPH0521179B2 - - Google Patents

Description

[Detailed description of the invention] (a) Industrial application field The present invention is directed to thin layer chromatography (TLC).
The present invention relates to a densitometer applied to, etc., and more specifically relates to a background correction method in a densitometer.

(b) Prior Art Conventionally, light from a light source such as a tungsten lamp or a deuterium lamp has been zigzag (two-dimensionally) directed toward a sample spot B formed on a thin layer plate A, as shown in FIG. In a densitometer that scans and irradiates the thin layer plate A and detects the light from the thin layer plate A with a detector such as a one-dimensional diode array to obtain a photometric signal, background noise due to dirt on the thin layer plate A or impurities in the developing solvent can be detected. In order to correct the absorption, as shown in Fig. 1, the light of the portion C at both ends of the swing around the zigzag scan is detected, and the detected value is subtracted from the photometric signal of the sample spot B portion for correction. There is.

However, in the conventional background correction method, the measurement for correction is only made at one point for one scan in the x-axis direction (left-right direction in FIG. 1) among the zigzag scans. The problem was that noise components were not completely removed and background correction could not be performed sufficiently.

(c) Purpose The present invention has been made in view of the above-mentioned points, and it is an object of the present invention to perform background correction reliably so that a sample can be measured with a high S/N ratio.

(D) Structure In order to achieve the above-mentioned object, in the present invention, the scan in the x-axis direction of the zigzag scan is performed with a width larger than the width corresponding to the sample spot. The part other than the detection area corresponding to the sample spot is set as a correction area for background correction, and the average value of signals detected at a plurality of points in the correction area for one scan in the x-axis direction is calculated as described above. The background is corrected by subtracting it from the photometric signal detected in the detection area corresponding to the sample spot.

(e) Examples Examples of the present invention will be described in detail below with reference to the drawings. FIG. 2 is a configuration diagram of an optical system of a densitometer to which an embodiment of the present invention is applied.
Light from a tungsten lamp 1 or a deuterium lamp 2 as a light source is reflected by a light source switching mirror 3 and enters an entrance slit 4 of a spectrometer, and then is separated into spectra by a diffraction grating 5 and then passed through a mirror 14.
Monochromatic light is reflected from the exit slit 6 and taken out from the exit slit 6. The light from the exit slit 6 is reflected by two mirrors 7, 8 to a thin layer plate 9 in which a sample spot 15 is formed as shown in FIG.
The light is focused on. The light transmitted through the thin layer plate 9 is
It is reflected by mirror 10 and detected by self-scanning one-dimensional diode array detector 11 . The thin layer plate 9 is driven in the x-axis and y-axis directions by two motors (not shown), thereby scanning the thin layer plate 9 two-dimensionally in a zigzag manner as shown in FIG.

Figure 4 shows the diode array detector 11 in Figure 2.
FIG. Diode array detector 11
is composed of a plurality of light receiving elements arranged in an array. In the present invention, the scanning in the x-axis direction of the zigzag scanning is performed with a width larger than the width corresponding to the sample spot 15, so this diode array detector 11 also corresponds to the sample spot 15. a detection area 12 with a width of
a, 13b. The detection area 12 and the correction area 13 are, as shown in FIG. 3, in scanning in the x-axis direction (horizontal direction in FIG. Width 13'a, 1 excluding width 12'
They correspond to the correction areas 3'b, respectively.

In the background correction method for the densitometer of the present invention, the scan in the x-axis direction of the zigzag scan is performed with a width larger than the width corresponding to the sample spot 15, and the part corresponding to the sample spot within this large scanning width is scanned. A correction area 13 for background correction is applied to a portion other than the detection area 12.
a and 13b, and the average value of signals detected at multiple points (12 points in this embodiment) in the correction areas 13a and 13b for one scan in the x-axis direction is determined as the detection area corresponding to the sample spot. The background is corrected by subtracting it from the photometric signal detected.

In this embodiment, for one scan in the x-axis direction, as shown in FIG.
6 points each in 13b 16~21; 22~
27. A total of 12 points are detected, the average value thereof is calculated, and the average value is subtracted from the measured value detected in the detection area 12 corresponding to the sample spot 15 to obtain a correction value. In this example, the corrected output signal is 〓 ⁱ
(Si−1/12 ₁₂ 〓 ^j=0 Soj), and the background noise is 1/√12 times that of the conventional example that uses only one point as a correction point, improving the S/N ratio. I can do it. Note that Si is the signal value detected in the detection area 12, and 1/12 ₁₂ 〓 ^j=0 Soj is the signal value detected in the correction area 13.
This is the average value of the signals detected at a and 13b.

In the embodiment described above, the background was corrected using the average value of 12 points, but in another embodiment of the present invention, the background may be corrected using the average value of 6 points each.

In the above embodiment, the thin layer plate 9 was irradiated with monochromatic light, but in another embodiment of the present invention, the thin layer plate 9 is irradiated with white light and the light from the thin layer plate is detected by spectroscopy. It may be configured to do so.

In the above embodiment, the case of transmission measurement was described, but the present invention may also be applied to reflection measurement as shown in FIG. 5 as another embodiment of the present invention. Note that in FIG. 5, parts corresponding to those in FIG. 2 are given the same reference numerals.

(F) Effect As described above, according to the present invention, the scan in the x-axis direction of the zigzag scan is scanned with a width larger than the width corresponding to the sample spot, and the sample spot is scanned within this large scanning width. The area other than the detection area corresponding to the sample spot is set as a correction area for background correction, and the average value of the signals detected at a plurality of points in the correction area for one scan in the x-axis direction is calculated as the sample spot. Since the background is corrected by subtracting it from the photometric signal detected in the detection area corresponding to the photometric signal, background correction can be performed more reliably than in the prior art.

[Brief explanation of drawings]

FIG. 1 is a plan view of a thin layer plate A for explaining conventional zigzag scanning, FIG. 2 is a configuration diagram of an optical system of a densitometer to which an embodiment of the present invention is applied, and FIG. A plan view of the thin layer plate 9 of
FIG. 4 is a front view of the diode array detector 11 of FIG. 2, and FIG. 5 is a configuration diagram of another embodiment of the present invention. 9... Thin layer plate, 11... Diode array detector, 12... Detection area, 13a, 13b...
...Correction area.

Claims (1)

[Scope of Claims] 1. Backup in a densitometer in which light from a light source is scanned in a zigzag manner against a thin layer plate on which a sample spot is formed, and the light from the thin layer plate is detected by a detector to obtain a photometric signal. A ground correction method, which scans in the x-axis direction of the zigzag scan,
Scanning is performed with a width larger than the width corresponding to the sample spot, and within this large scanning width, a portion other than the detection area corresponding to the sample spot is used as a correction area for background correction, and one area in the x-axis direction is A densitometer characterized in that background correction is performed by subtracting the average value of signals detected at a plurality of points in the correction area for one scan from the photometric signal detected in the detection area corresponding to the sample spot. background correction method. 2. The background correction method in a densitometer according to claim 1, wherein the detector is a one-dimensional diode array detector.