JPS5946335B2 - flow cell - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a flow cell used for measuring components in a flowing liquid.

When irradiating light across the flow in a flow path system for measuring the concentration or turbidity of a solution, for example, a flow path system used for liquid chromatography or a flow path system used for monitoring culture fluid, the normal optical path length is When only transmitted light, which is extremely weak compared to light, can be obtained, simply shortening the optical path length increases the amount of transmitted light, which solves the problem to some extent. However, when the optical path length is shortened, the cross-sectional area of the flow path decreases, which usually increases the liquid pressure. Therefore, when the flow rate of the fluid is high, the pressure increase is significant, so from the viewpoint of pressure resistance of the flow cell, the optical path length must be set sufficiently. Therefore, the range in which the optical path length can be adjusted is naturally limited, and it is not possible to measure a sufficient increase in the amount of transmitted light. In addition, conventional liquid chromatography has been improved in sensitivity due to the need for analysis, and as its popularity and speed have increased, it has become widely used for the purpose of adjustment. Because the liquid is flowing, conventional monitoring systems may scale out the recorder and make it impossible to track the separation. This is due to the fact that in highly concentrated solutions, the transmittance is significantly weaker than that of the incident light.Even in such cases, shortening the optical path length increases the amount of transmitted light and enables stable measurement recording. is possible. As a means to cope with this concentration change, for example, Japanese Patent Laid-Open No. 109882/1982 discloses a flow cell in which portions with different channel widths are formed in the flow direction of the liquid, and the flow cell absorbs light with various optical path lengths. However, because only one channel with a specific channel width is formed in one cross section that crosses the liquid flow, all liquid passes sequentially through all sections with different channel widths. Must. Therefore, the pressure increase cannot be avoided in the narrow part of the channel, so the optical path width cannot be made too short, and the cross-direction width of the optical path must be increased by the amount that the optical path length is shortened. Although it is possible to widen the cross-sectional area of the passage, the disadvantage is that the flow of liquid becomes non-uniform. The present invention is characterized in that a plurality of portions with different channel widths are formed in one cross section parallel to the optical path direction that crosses the liquid flow at right angles, and the optical path has a sufficient optical path length without significantly increasing the channel width in the cross direction. It is designed to form a short section of j, and to allow stable measurement records to be performed by flowing fluid at a high flow rate or high concentration without causing problems such as increased pressure or non-uniform flow.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Two plate-shaped window plates 1 and 2 made of quartz glass or other transparent material having pressure resistance and chemical resistance are arranged parallel to each other and at an appropriate distance. The inner ends of the cell bodies 3, 3 are packed 4, 4 between the front and rear ends when viewed from the liquid flow direction A.
The inner ends of the restraining members 5, which form the left and right walls of the channel 10 between the left and right ends, are inserted in a liquid-tight manner with the packing 4 in between, and the incident light is Packing 8, 8 is provided between the suppressing member 5, which has a passage 6 and a transmitted light passage 7 perpendicular to the liquid flow direction A, and the window plates 1, 2 and the cell bodies 3, 3, surrounding these passages 6, 7. Insert it to make it liquid-tight.

The front and rear cell bodies 3, 3 are screwed and fixed with joints 9, 9 that are connected to a pipe through which liquid flows, and are provided with liquid passages 11, 11 that communicate the flow path 10 and the joints 9, 9.
Further, the restraining member 5 and the cell bodies 3, 3 are fastened and fixed to each other by screws 12. The front and rear portions of the flow path 10 are widened and have a wide cross-sectional area, and in the embodiment shown in FIGS. A small width portion 10a and large portions 10b, 10b on both sides thereof are formed.

All the incident surfaces and exit surfaces of the two window plates 1 and 2 through which light passes are parallel to each other, and the light is irradiated perpendicularly to these surfaces. In the embodiment shown in FIG. 3, a portion 10a with a small width, a portion 10b with a large width, and a portion 10c with an intermediate size are formed in order in the central portion of the flow path in a direction perpendicular to the flow direction. In the two embodiments described above, the two window plates 1 and 2 are made in a symmetrical shape, each having a portion with a different wall thickness, and portions with the same thickness facing each other to form portions with different channel widths. ing.

In the embodiment shown in FIG. 4, the window plate 1 on the entrance side has a uniform thickness toward the flow path, and the window plate 2 on the exit side has portions with different thicknesses, so that the window plate 1 can be directed in the direction perpendicular to the flow direction. A portion 10c having an intermediate size, a small portion 10a, and a large portion 10b are formed in this order.

In the embodiment shown in FIG. 5, the entrance side window plate 1 toward the flow path is provided with portions with different wall thicknesses, and the exit side window plate 2 is made to have a uniform thickness, so that the window plate 1 facing the flow path is directed in the direction perpendicular to the flow direction. A portion 10b having a large passage width, a portion 10C having an intermediate size, and a portion 10a having a small passage width are formed in this order.

It goes without saying that the portions having different channel widths in the direction perpendicular to the flow direction, that is, the optical path direction, are not limited to the arrangement shown in the drawings, but can be formed in any number and in any arrangement.
The light is appropriately irradiated onto portions having different channel widths as indicated by arrows Ba, Bb, and Bc.

According to the present invention configured as described above, the liquid to be measured does not flow through each of the portions formed in the flow path where the width of the flow path in the direction across the flow of the liquid differs, and the cross-sectional area of the flow path is Since the liquid is not greatly reduced as a whole and the liquid that passes through the narrow part of the channel is only a portion of the total liquid, it does not cause uneven flow, and even if a large amount of liquid is flowed at a high flow rate, it will not cause a significant pressure increase. Therefore, it is possible to measure the increase in the amount of transmitted light by making the small part of the flow path sufficiently small without considering pressure resistance in particular, and therefore the measurement records of high concentration solutions are also stable. It can be done.

In addition, since liquid exchange occurs quickly between the narrow and wide channel width sections, the light transmittance in the narrow channel width sections can be monitored without delay in determining the concentration of the total solution. It can be tracked. That is, according to the present invention, even if the flow rate of the liquid is increased, it does not cause a large pressure increase, so it is possible to monitor a large amount of liquid, and at the same time, it is possible to monitor a large amount of liquid. In addition to being able to measure and record the state of separation without worrying about scale-out, it is also possible to adjust the size ratio between the small and large channel widths arbitrarily as long as the concentration difference between the measurement location and other locations does not interfere with the measurement purpose. The same flow cell can be used for measuring liquids with large volumes and high flow rates.It has multiple sections with different channel widths, so it is possible to select and measure the channel width section with the desired optical path length. By combining a plurality of measuring devices, the measurable concentration range can be greatly increased.

Next, test results of the present invention will be described.

Heptanoic acid and pelargonic acid were used as samples, and the mobile phase used for elution was a solution of caustic soda dissolved in 75% methanol at a concentration of 0.2 mol.
I drained it at a rate of l.

For comparison, measurement was performed using a carboxylic acid analyzer manufactured by Seishin Pharmaceutical Co., Ltd., and as shown in FIG. 6A, the area near the peak was scaled out on the recording paper, and the separation of that portion was unclear. On the other hand, when the product of the present invention shown in Figs. 1 and 2 (the optical path length of the narrow channel width portion 10a was set to 1 mm) was used, the separation near the peak was recorded as shown in Fig. 6. is clear.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional view showing an embodiment of the present invention, and FIG.
FIG. 3, FIG. 4, and FIG. 5 are sectional views similar to FIG. 2 showing different embodiments of the present invention, and FIG. 6 shows the test results. This is a graph showing. 1, 2...Window plate, 3...Cell body, 5
... Suppressing member, 6 ... Incident light path, 7
...Transmitted light path, 10...Flow path, 10
a... Part where the passage width is small, 10b...
・Parts with large aisle widths.

Claims (1)

[Claims] 1. A flow cell characterized in that a plurality of portions having different channel widths are formed in one cross section parallel to the optical path direction that crosses the flow of liquid at right angles.