JP3414079B2 - Liquid chromatograph - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid chromatograph, and more particularly, to a liquid chromatograph for measuring fluorescence of a liquid sample flowing through a flow cell. 2. Description of the Related Art FIG. 2 is a diagram showing a general configuration of a liquid chromatograph for measuring a liquid sample flowing through a flow cell using a fluorescence detector. In the figure, reference numeral 10 denotes a flow cell, the inlet side of which is connected to the mobile phase tank 1, the liquid feed pump 2, the injection device 3, the column 4, and the external pipe 5 on the inlet side, and the outlet side of the flow cell 10 The flow path is connected to the external pipe 6 and the drain 7 on the outlet side. The liquid sample injected from the injection device 3 is sent to the column 4 by the mobile phase, separated into components in the column 4, flows through the flow cell 10, and reaches the drain 7. On the other hand, an excitation light 22 radiated from a light source 21 such as a xenon lamp or a mercury lamp emits
The sample 24 is irradiated with a sample, which is separated into components and flows through the flow cell 10, and the fluorescence 24 excited and emitted by the excitation light irradiation is separated by the fluorescence spectroscope 25, and then the light is detected by a photomultiplier tube or the like. Is detected by the detector 26. In a liquid chromatograph for measuring the fluorescence of a liquid sample flowing through a flow cell, it is necessary to connect an external pipe serving as a flow path from a column to the flow cell. In order to prevent the liquid from leaking, the connection portion is connected via a gasket. By the way, the cross-sectional area of the flow cell in the flow cell and the cross-sectional area of the external pipe generally have a larger cross-sectional area on the flow cell side in order to increase a region (lateral width of the flow cell) for optical detection in the flow cell. Is larger. Therefore, the inner wall of the flow path at the connection between the external pipe and the flow cell has a stepped structure in which the flow cell side is widened (a hole having different diameters is connected to form a stepped boundary), or the flow cell side is widened. It has a tapered inner wall. As a gasket for preventing liquid leakage, a gasket having a hole having a sectional area equal to or larger than the inner diameter of the connection portion on the flow cell side is attached. However, in a flow path for guiding a liquid from a column to a flow cell, in a place where the cross-sectional area of the flow path changes abruptly, such as at a connection portion, depending on the viscosity and flow rate of the liquid to be used, the flow path may be located at a central portion of the flow path cross-section. The flow velocity difference from the peripheral portion of the flow channel cross section is greatly increased. In other words, the sample flowing into the flow cell through the connection portion has a high flow velocity of the sample flowing from the central portion of the flow channel cross section, while the liquid flowing from the periphery of the flow channel cross section has a low flow speed, so the sample is delayed. Since the sample flows into the flow cell, the sample does not flow at a uniform flow rate in the flow cell, and the time required for the sample of a specific component to completely pass through the flow cell becomes longer, which causes a problem that the sample exchange is delayed. The peak of the chromatogram measured in such a state was broad and caused a decrease in resolution. SUMMARY OF THE INVENTION It is an object of the present invention to provide a liquid chromatograph which solves the above-mentioned problems and in which a liquid is uniformly introduced into a flow cell so as to improve the separation ability. A liquid chromatograph of the present invention made to solve the above-mentioned problem is a liquid chromatograph which measures a sample to be measured flowing in a flow cell using a fluorescence detector. The liquid inlet side and the liquid outlet side of the flow cell are each connected to an external pipe through a pipe connection part, and a tapered or stepped flow path having an increased inner diameter on the flow cell side is provided in the pipe connection part. In addition, a distributor having a plurality of small-diameter holes is provided between the liquid inlet side of the flow cell and the inlet-side pipe connection part. DESCRIPTION OF THE PREFERRED EMBODIMENTS In a liquid chromatograph of the present invention, a distributor having a plurality of small-diameter holes is provided between a liquid inlet side of a flow cell and a pipe connection portion. Due to the resistance, the flow velocity distribution in the flow direction of the liquid at the inflow portion into the flow cell decreases, and the liquid flows more uniformly through the flow cell. Therefore, the delay of the replacement of the liquid such as stagnation is reduced, and a decrease in the resolution of the chromatogram peak can be avoided in a wider flow rate range and various liquids. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a flow cell portion which is a main part of a liquid chromatograph showing one embodiment of the present invention. In FIG. 1, reference numeral 10 denotes a flow cell made of quartz glass or the like, 5 denotes an external pipe on the inlet side which is a flow path from a column, and 6 denotes an outlet side connected to a drain for discharging a liquid. External piping. The external pipe 5 is connected to an inlet-side pipe connection 11, and the external pipe 6 is connected to an outlet-side pipe connection 12. The configuration on the upstream side of the external pipe 5 and the configuration on the downstream side of the external pipe 6 are the same as in FIG. 2, and the excitation light optical system and the fluorescent optical system for the flow cell are also the same as in FIG. Therefore, the description of these parts is omitted. Each of the inlet-side pipe connecting portion 11 and the outlet-side pipe connecting portion 12 has an internal flow passage section which is tapered so that the expanded side comes to the flow cell side. is there. An inlet gasket 13 is mounted between the pipe connection 11 and the flow cell 10, and an outlet gasket 14 is mounted between the pipe connection 12 and the flow cell 10. These gaskets are
It is provided to prevent breakage of the quartz glass and liquid leakage. In this embodiment, a distributor is constructed by using the gasket 13 on the inlet side. In other words, the gasket 13 is not of a structure having a single hole as large as the wide opening cross-sectional area of the flow cell inlet, but a gasket 13 having a plurality of small-diameter holes is attached. The small diameter serves as a resistance to the flow of the liquid, and functions as a distributor. If the sum of the cross-sectional areas of the plurality of small-diameter holes is equal to or larger than the cross-sectional area of the inner diameter of the external pipe 5 on the inlet side, the flow velocity does not decrease. In addition, if there is no distributor, the flow velocity in the central part of the flow path becomes larger than the flow velocity in the peripheral part. Therefore, as shown in FIG. It is more desirable to provide a plurality of small diameters at positions slightly closer to the periphery (four small diameters are provided at positions slightly deviated from the center in FIG. 1). On the other hand, in the gasket 14 on the outlet side, a gasket having one large hole having a cross-sectional area equal to or larger than the inner diameter on the outlet side of the flow cell is used in the same manner as in the prior art to prevent stagnation at this portion. Try to prevent it. By attaching the gasket 13 having the structure as in the present embodiment to the inlet side of the flow cell, the liquid sent from the column is distributed by the gasket 13 so that the flow velocity distribution in the flow cell becomes small. Flows into. In this embodiment, the gasket 13 is made to have a function as a distributor. However, the gasket itself has a conventional large hole, and a gasket 13 having a plurality of small diameters is used separately. A vessel may be provided and attached in the order of flow cell, gasket, distributor, gasket, and pipe connection. Further, as shown in FIG. 3, a sintered body filter such as a stainless steel particle or a fluororesin particle is installed at a pipe connecting portion having a stepped channel, and the flow rate distribution is controlled by the sintered body. The size may be reduced (even in the case of a tapered flow path, the sintered body may be adjusted to the tapered shape). As described above, the liquid chromatograph of the present invention has the above-described structure, so that the sample flowing through the pipe connection into the flow cell is flow-rate-distributed by the distributor. Can flow through the flow cell in a small state, and the problem of slow sample exchange in the flow cell can be resolved.The peak of the measured chromatogram can be sharpened, and the resolution can be improved. it can.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram of a flow cell part which is a main part of a liquid chromatograph according to one embodiment of the present invention. FIG. 2 is an overall configuration diagram of a liquid chromatograph according to one embodiment of the present invention. FIG. 3 is a configuration diagram of a flow cell part which is a main part of a liquid chromatograph according to another embodiment of the present invention. [Description of Signs] 10: Flow cell 11: Piping connection (inlet side) 12: Piping connection (outlet side) 13: Gasket (also used as distributor) 14: Gasket

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01N 30/74 G01N 21/05

Claims (1)

(57) [Claim 1] In a liquid chromatograph for measuring a sample to be measured flowing in a flow cell using a fluorescence detector,
The liquid inlet side and the liquid outlet side of the flow cell are each connected to an external pipe through a pipe connection part, and a tapered or stepped flow path having an increased inner diameter on the flow cell side is provided in the pipe connection part. A liquid chromatograph characterized in that a distributor having a plurality of small-diameter holes is provided between the liquid inlet side of the flow cell and the inlet-side pipe connection part.