JPH08122246A - Spectral analyzer - Google Patents

Abstract

PURPOSE: To reduce a drift by influence of a temperature change by arranging a temperature sensor to measure the temperature of a photodiode array and a correcting means to correct the quantity of measuring light by using the signal from the temperature sensor. CONSTITUTION: A temperature sensor 22 is connected to a photodiode array 21, and the temperature of the photodiode array 21 is measured, and a temperature signal is sent to the computer 32 of an analyzing part 30. First of all, a shutter 12 is opened, and the quantity of light in a sample nonexistent condition is measured, and is taken in the analyzing part 30. The shutter 12 is opened as it is, and a sample is introduced, and the quantity of light is measured, and at the same time, the temperature of the photodiode array 21 at measuring time is measured, and is taken in the analyzing part 30. A dark current is corrcted by the analyzing part 30 by performing operation based on a calculating expression.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an analyzer using a spectrometer such as a spectrophotometer or a detector for high performance liquid chromatograph, and more particularly to a spectrometer using a semiconductor photodiode array for the detector. .

[0002]

2. Description of the Related Art FIG. 2 is a block diagram of a conventional spectroscopic analyzer using a semiconductor photodiode array detector.
This includes a light source 11, a shutter 12, and a condenser mirror 1.
3, a spectroscopic optical system 10 including a grating 14, a detection system 20 including a photodiode array 21, and an analyzing unit 30.

In the spectroscopic optical system 10, a sample cell 15 is attached between a condenser mirror 13 and a grating 14, and white light from a light source 11 is incident on a sample in the sample cell via the condenser mirror 13. It is like this. The transmitted light that has passed through the sample cell 15 is configured to be separated by the grating 14.

When the apparatus is a high-performance liquid chromatograph apparatus, a sample cell 15 (also called a flow cell for a liquid sample) is introduced with a sample eluted from a column of the high-performance liquid chromatograph apparatus (not shown). There is. If the device is a spectrophotometer, the sample to be measured is mounted at the sample cell position. In any case, the spectrum of the transmitted light transmitted through the sample can be obtained.

A photodiode array 21 is used in the detection system 20 so that the spectrum from the grating 14 can be simultaneously detected for each wavelength. That is, the respective elements of the photodiode array 21 are arranged so as to detect one wavelength component dispersed by the grating 14, for example, wavelengths 500 to 510n.
The wavelength of 510 nm to 520 nm is emitted by the element with the element number λ
Is detected by the element having the element number λ + 1.

The analysis unit 30 comprises a signal processing unit 31 having an amplifier and an A / D converter, and a computer 32. The detection signal for each wavelength from the photodiode array 21 is transmitted through the signal processing unit 31 to the intensity for each wavelength. It is converted into data and sent to the computer 33, where it is converted into an absorbance spectrum.

The measurement by this device is performed by following the steps (1) to (4) below.

(1) The value D of the dark current of the photodiode array when the shutter 12 is closed and no light is emitted.
Measure (λ). (2) Next, the shutter 12 is opened, and the output value R (λ) of the photodiode without the sample is measured. (3) With the shutter still open, the output value S (λ) in the state where the sample is introduced into the sample cell 15 is measured. (4) The absorbance A (λ) is calculated by the following formula 1.
Here, λ is the element number of the photodiode array.

A (λ) = − log ₁₀ {(S (λ) −D (λ)) / (R (λ) −D (λ))} ... (Equation 1)

[0010]

When measuring the absorbance with the above-mentioned apparatus, if the temperature of the measurement environment near the photodiode changes, the dark current of the photodiode array changes greatly due to the temperature change. When performing continuous measurement for a long time without measuring the dark current, the dark current changes due to the influence of temperature change during measurement (D
(Λ changed), and drift of the measurement data occurred. Also, the obtained absorbance data has poor linearity. It is an object of the present invention to solve the above problems and provide a spectroscopic analysis device that reduces drift due to the influence of temperature changes.

[0011]

The spectroscopic analysis device of the present invention made to solve the above problems detects measuring light dispersed by a spectroscopic optical system for each wavelength by a photodiode array and performs signal processing, A spectroscopic analyzer that measures the amount of measurement light is characterized by including a temperature sensor that measures the temperature of the photodiode array, and a correction unit that corrects the amount of measurement light using a signal from the temperature sensor. Hereinafter, how the spectroscopic analysis analyzer operates will be described.

[0012]

In the spectroscopic analyzer of the present invention, the temperature of the photodiode array is measured and sent to the analysis section. The analysis unit calculates the change amount of the dark current due to the temperature change and corrects the dark current value using the calculation result. Therefore, the influence of the temperature change is canceled and the drift is reduced.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a spectroscopic analyzer showing an embodiment of the present invention.

In FIG. 1, the same components as those of the conventional device of FIG. In the device of the present invention, the temperature sensor 22 is connected to the photodiode array 21, and the temperature of the photodiode array 21 is measured, and the measured temperature signal is sent to the computer 32 of the analysis unit 30. I am doing it.

The measurement with this apparatus is performed in the following procedure. (1) First, the shutter 12 is closed and the dark current and the temperature of the photodiode array 21 are measured and incorporated into the analysis unit 30. At this time, the measured dark current value is D0 (λ) and the temperature is T
Set to 0. (2) Next, the shutter 12 is opened, the amount of light in the absence of the sample is measured, and the amount of light is taken into the analysis unit 30. The output value at this time is R (λ). (3) Further, with the shutter 12 kept open, a sample is introduced to measure the amount of light, and at the same time, the temperature of the photodiode 21 at the time of measurement is measured and taken into the analysis unit 30. The output value at this time is S (λ), and the temperature is T. (4) Next, the dark current is corrected in the analysis unit 30 by performing an operation based on the following calculation formula.

When the temperature of the photodiode is T0, the dark current value is D0 (λ), and when it is T, the dark current value is D (λ).
Then, D (λ) is represented by the following two equations due to the nature of the semiconductor.

D (λ) = D0 (λ) K ^T-T0 (Equation 2) In this equation, K is a constant determined by the manufacturing process of the element, and values such as 1.10 and 1.13 are given. To take.

Then, by substituting this D (λ) into the equation 1, the following equation 3 is obtained. A (λ) =-log ₁₀ {(S (λ) -D0 (λ) K ^T-T0 / (R (λ) -D0 (λ) K ^T-T0 } (Equation 3) This formula is used. By calculating the dark current, the influence of the dark current due to the temperature change is corrected, and the corrected absorbance data is obtained.

Therefore, even if the temperature of the photodiode sensor changes due to the measurement for a long time, the dark current correction data can be obtained, so that the drift is reduced,
Data with good linearity can be obtained.

[0020]

As described above, according to the present invention,
Since the temperature of the photodiode array is measured and the dark current value is corrected, even if the temperature of the photodiode array changes due to continuous measurement for a long time, drift does not occur and the absorbance with good linearity is obtained. Measurement can be realized.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a spectroscopic analysis apparatus that is an embodiment of the present invention.

FIG. 2 is a block diagram of a conventional spectroscopic analyzer.

[Explanation of symbols]

 10: Spectroscopic optical system 11: Light source 12: Shutter 14: Grating 15: Sample cell 20: Detection system 21: Photodiode array 30: Analysis part 31: Signal processing part 32: Computer

Claims (1)

[Claims] 1. A temperature for measuring a temperature change of a photodiode array in a spectroscopic analyzer for measuring the amount of measuring light by detecting the measuring light dispersed by a spectroscopic optical system for each wavelength by a photodiode array and processing the signal. A spectroscopic analysis apparatus comprising: a sensor; and a correction unit that corrects a measurement light amount using a signal from a temperature sensor.