JPH083483B2 - Array spectrophotometer detector - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a spectrophotometer detector used as a detector for a liquid chromatograph or a clinical automatic analyzer, and in particular, a spectroscope is a polychromator and is provided at the exit of the spectroscope. The present invention relates to an array type spectrophotometer detector including an array type light receiving element.

(Prior Art) An example of an array type spectrophotometer detector of a liquid chromatograph is shown in FIG.

Reference numeral 2 is a flow cell of a liquid chromatograph, which has a cylindrical optical path and through which the effluent from the column flows. One end surface of the cylindrical optical path is a light incident surface and the other end surface is a light transmitting surface. Reference numeral 4 denotes a light source and 6 denotes a lens. Light from the light source 4 is collected by the lens 6 and enters the flow cell 2. A splitter 8 is provided in front of the flow cell 2, and part of the light from the light source 4 is reflected by the splitter 8 and enters the photocell 10.

Reference numeral 12 is a concave diffraction grating of the spectroscope, and the light passing through the flow cell 2 enters the diffraction grating 12 through the slit 14. A photodiode array element 16 as an array type light receiving element is provided on the exit surface of the spectroscope of the diffraction grating 12. This spectroscope constitutes a polychromator that simultaneously detects light of a plurality of wavelengths.

An image of the slit 14 formed by the light passing through the flow cell 2 is formed on the photodiode array element 16 by the diffraction grating 12. On the photodiode array element 16, the light that has passed through the flow cell 2 is separated by the diffraction grating 12 and condensed to form a spectrum.

The detection signal of the photocell 10 is used as a reference signal for the sample signal detected by the photodiode array element 16 to cancel fluctuations in the light amount of the light source 4.

FIG. 6 shows a spectrophotometer detector using a monochromator.

The flow cell 2a is installed after the spectroscope. The entrance slit 14, the diffraction grating 12 and the exit slit 20 constitute a spectroscope, and in this case, the wavelength is scanned and extracted from the exit slit 20 by rotating the diffraction grating 12. The light transmitted through the flow cell 2a is received and detected by the silicon photocell 26, which is a light receiving element.

The flow cell 2a has a plano-convex lens 22 on its light incident surface. In this figure, the light transmitting surface is also composed of a plano-convex lens 24. The reason why the plano-convex lens 22 is used on the light incident surface is that all the incident light is incident on the light receiving element 26 without hitting the inner wall of the flow cell 2a even when the refractive index of the solution flowing through the flow cell 2a changes. Yes (Japanese Patent Laid-Open No. 61-1054
(See Japanese Patent No. 45).

(Problems to be Solved by the Invention) When gradient analysis in which the composition of the mobile phase is changed by an array type spectrophotometer detector using a polychromator as shown in FIG. The refractive index of the solution is changed and the amount of light incident on the light receiving element 16 is changed. Therefore, the gradient curve is disturbed,
A large solvent front appears. this is,
In the array type spectrophotometer detector of FIG. 5, since the entrance slit 14 of the polychromator is installed immediately after the flow cell 2 and functions as a diaphragm, only a part of the light incident on the flow cell 2 is received. This is because the light amount does not reach the element 16 and changes with the change in the refractive index of the solution flowing through the flow cell 2.

Even if the flow cell 2 is replaced with the flow cell 2a shown in FIG. 6, the problem that the amount of light reaching the light receiving element 16 changes due to the change in the refractive index still remains unsolved. If the flow cell 2a is used, the light incident on the flow cell 2a can be transmitted through the light transmitting surface without hitting the inner wall of the flow cell 2a, but the light spot on the slit 14 slightly changes and passes through the slit 14. This is because the amount of light changes.

It is an object of the present invention to eliminate the disturbance and distortion of the gradient curve and the solvent front peak in the array type spectrophotometer detector.

(Means for Solving Problems) In the present invention, light transmitted through a flow cell having an elongated cylindrical optical path extending along an optical axis is made incident on a spectroscope to disperse the light, and an array provided at the exit of the spectroscope. In an array type spectrophotometer detector for detecting with a type light receiving element, a condenser lens is provided on the light incident surface of the flow cell, and an entrance slit of the spectrometer is installed on the light incident side of the flow cell.

(Function) By installing the entrance slit of the polychromator on the incident surface side of the flow cell, even if the optical axis changes due to the change of the refractive index of the solution flowing through the flow cell, it is installed before the incident surface of the flow cell. There is no effect on the amount of light passing through the entrance slit. Then, by the means provided in the flow cell, all the light that has passed through the entrance slit and entered the flow cell enters the light receiving element.

(Embodiment) FIG. 1 shows an embodiment.

Reference numeral 4 is a light source, and 6 is a lens that collects light from the light source 4. Reference numeral 12 is a concave diffraction grating which is a dispersive element of the polychromator, and 14 is an entrance slit of the polychromator. 2a
Is a flow cell, and the light incident surface 22 is provided between the slit 14 and the diffraction grating 12 so as to approach the slit 14. A photodiode array detection element 16 as an array type light receiving element is arranged at the position of the exit of the polychromator.

A splitter 8 is provided in the optical path between the lens 6 and the slit 14 so that part of the light is extracted and detected by the photocell 10.

A signal processing circuit 18 calculates the absorbance at each wavelength from the detection signal of the photodiode array detection element 16 and the detection signal of the photocell 10 as a reference signal.

 The part of the flow cell 2a is shown enlarged in FIG.

In the flow cell 2a, an elongated cylindrical optical path 30 having a diameter of 1 mm is formed in a stainless block, and a sample inflow tube 26 and a sample outflow tube 28 are connected to the optical path 30. The length of the optical path 30 is, for example, 1 cm.

On the light incident surface side of the flow cell 2a, a plano-convex lens 22 made of quartz is attached via a gasket 32 made of polytetrafluoroethylene having a thickness of 0.2 mm so that the convex surface is on the outside and the flat surface is on the inside. A plano-convex lens 24 is also mounted on the light-transmitting surface side via a polytetrafluoroethylene gasket 34 such that the convex surface is on the outside and the flat surface is on the inside. The radius of curvature of the plano-convex lens 22 is adjusted so that the focal length is substantially the same as the optical path length of the optical path 30.

The material and shape of the flow cell 2a are not limited to those shown in the figure, and known materials can be used. Various materials such as quartz glass and soda glass can be selected as the material of the plano-convex lenses 22 and 24 according to the type of measurement light.

The plano-convex lens 24 on the light transmitting surface side is not always necessary.
However, when the plano-convex lens 24 is also provided on the light transmitting surface as in the embodiment, the transmitted light is condensed at a predetermined position of the photodiode array detecting element 16 set on the transmitting side without being unnecessarily dispersed. To be done.

In this embodiment, the light emitted from the light source 4 is condensed by the lens 6 or becomes a parallel light flux, passes through the slit 14 and enters the flow cell 2a. The image of the slit 14 is obtained by the photodiode array detecting element 16 by the polychromator including the diffraction grating 12.
Formed on top. The slit width of the slit 14 determines the resolution of the polychromator.

Even if the refractive index of the solution flowing through the flow cell 2a changes, for example, in the gradient analysis, the light incident on the flow cell 2a by the plano-convex lens 22 on the light incident surface does not hit the inner wall of the cell and exits from the light transmitting surface. In this way, the amount of light emitted does not change even if the refractive index of the solution of the flow cell 2a changes, and all the light emitted from the flow cell 2a reaches the concave diffraction grating 12, and is condensed and separated into a photodiode array detector. Make a spectrum on 16.

FIG. 3 shows a flow cell in another embodiment.

In this flow cell 2b, the optical path tapers from the entrance surface to the transmission surface. In a flow cell having an optical path of such a shape, even if the refractive index of the solution changes and the optical axis changes, all the light incident on the incident surface can be incident on the light receiving element (JP-A-54-33871). (See the official gazette).

FIG. 4 shows a flow cell in still another embodiment.

In this flow cell 2c, the optical path of the cell is cylindrical, and
There is a step, and the small diameter of the hole on the incident light side acts as a diaphragm so that the inner wall of the cell is not exposed to light.

(Effect of the invention) In the array type spectrophotometer detector of the present invention, since the entrance slit of the spectroscope is installed on the light incident side of the flow cell, and the flow cell is provided with means for preventing incident light from contacting the inner wall, The light incident on the incident surface of the flow cell is all collected on the array type light receiving element regardless of the change in the refractive index of the solution passing through the flow cell. Therefore, the change in the signal of the array type light receiving element corresponds only to the absorption of light by the sample.
As a result, there is no disturbance or distortion in the gradient curve, and there is no solvent front.

[Brief description of drawings]

FIG. 1 is a schematic view showing an embodiment, FIG. 2 is an enlarged sectional view showing a flow cell portion in the embodiment, FIGS. 3 and 4
FIG. 5 is a sectional view showing a flow cell portion in another embodiment, FIG. 5 is a schematic view showing a conventional array type spectrophotometer detector, and FIG. 6 is a schematic view showing a conventional spectrophotometer detector. . 2a ... Flow cell, 12 ... Concave diffraction grating, 14 ... Inlet slit, 16 ... Photodiode array detector, 22 ... Plano-convex lens.

Claims (1)

[Claims] 1. An array type in which light transmitted through a flow cell having an elongated cylindrical optical path extending along an optical axis is made incident on a spectroscope to disperse the light and is detected by an array type light receiving element provided at the exit of the spectroscope. In the spectrophotometer detector, the flow cell is provided with a condenser lens on its light incident surface, and an entrance slit of the spectroscope is installed on the light incident side of the flow cell. Type spectrophotometer detector.