JP3846013B2 - Liquid chromatograph - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a liquid chromatograph apparatus.
[0002]
[Prior art]
A liquid chromatograph basically has a liquid feed pump that pressurizes and feeds a carrier liquid, a sample injection valve for injecting a sample, a column that separates the sample into its components, and the concentration of the separated components as electrical. It consists of a detector that converts it into a signal and a data processor that processes and records the signal.
[0003]
The column may be used at room temperature, that is, exposed to the indoor space, but recently, in order to improve analytical accuracy or to realize optimal separation conditions, the column is stored in a thermostatic bath and kept at a constant temperature. Often used. There are an air bath type and a liquid bath type as the thermostatic bath, but the air bath type is generally used for ease of handling.
[0004]
In many cases, the thermostatic chamber contains not only the column but also a sample injection valve. This is because when only the column is placed in a thermostatic bath, the temperature at the top of the column changes depending on the sample liquid injected at room temperature, and as a result, the analysis conditions change and the reproducibility of the analysis decreases. This is because a sample injection valve is installed in the thermostat and the temperature of the injected sample is made as close as possible to that of the column by using the heat.
[0005]
[Problems to be solved by the invention]
As described above, the sample injection valve with which the sample liquid comes into contact and the surrounding piping receive heat from the surrounding medium (air in the thermostatic chamber) and transfer it to the sample liquid, and the temperature before the sample reaches the column. Is required to quickly equilibrate to the temperature in the tank, that is, a function as a heat exchanger is also required. For example, when the temperature of the thermostatic chamber is higher than room temperature, when a sample at room temperature is injected into the sample injection valve, the sample is warmed by receiving heat from the sample injection valve, but the sample injection valve is reversed. Chilled. As a result, when the temperature in the thermostat decreases and a sensor for temperature control of the thermostat is provided near the sample injection valve, the sensor senses a local temperature drop around the sample injection valve, The entire thermostat may be heated excessively to disturb the thermostat temperature.
[0006]
Thus, if the sample injection valve is placed in the thermostat together with the column in order to eliminate the adverse effect on the column due to the introduction of the room temperature sample into the thermostat, the effect of the sample introduction will disturb the temperature of the thermostat. It does appear that the problem is not solved.
[0007]
An object of the present invention is to solve such problems, that is, to prevent temperature fluctuations in the thermostatic chamber accompanying the introduction of the sample that occur when the sample injection valve is housed in the thermostatic chamber together with the column. It is.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a liquid chromatograph apparatus in which a sample injection valve is installed together with a column in an air bath type thermostat equipped with a temperature control device , and the column and the valve are disposed between the column and the valve. A partition wall for buffering heat transfer is provided , and a temperature sensor of the temperature control device is provided in a column side section, and the temperature of only the column side section is directly controlled. With such a configuration, the temperature disturbance caused by the introduction of the sample at room temperature is prevented from reaching the entire thermostat, and the temperature of the introduced sample is equilibrated to the temperature in the bath before reaching the column. This ensures that the problem of worsening the reproducibility of the analysis is eliminated.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows an embodiment of the present invention.
[0010]
In the figure, a carrier liquid is sucked from a reservoir 1 by a liquid feed pump 2, pressurized and sent out, and flows out through a detector 5 through a sample injection valve 3 and a column 4. On the other hand, the sample is manually injected into the sample injection valve 3 using the syringe 11, and then, when the valve is operated, the sample is introduced into the flow path of the carrier liquid and passes through the column 4 along the flow of the carrier liquid. Each component is separated and its concentration is converted into an electric signal when passing through the detector 5. The data processing unit 6 processes and records the signal.
[0011]
Reference numeral 7 denotes an air bath type thermostat, the temperature of which is adjusted by a temperature control device (not shown), and the sample injection valve 3 and the column 4 accommodated therein are kept at a set temperature. 8 is a preheater. This functions as a heat exchanger that equilibrates the room temperature carrier liquid fed into the thermostatic chamber to the temperature in the bath, and is a thin metal tube with good heat conduction formed into a coil shape. In many cases, it is sufficient to make the portion in the thermostatic chamber of the connection pipe from the liquid pump 2 to the sample injection valve 3 slightly longer. Reference numeral 9 is a connecting pipe that also serves as a preheater, and in order to supplement the heat exchange function of the sample injection valve 3, the temperature of the sample liquid is balanced with the temperature in the tank while flowing toward the column 4. It is.
[0012]
When the liquid chromatograph having such a configuration is operated, the surface temperature of the preheater 8 through which the carrier liquid fed at room temperature flows is lower than the temperature in the tank, but the carrier liquid is in a steady flow. It does not disturb the temperature control. On the other hand, when the sample liquid is introduced, first, heat exchange is performed between the sample injection valve 3 and the sample liquid, and the temperature of the sample injection valve 3 is lowered. Next, when the sample liquid moves in the direction of the column 4 along the flow of the carrier liquid, heat is exchanged with the surrounding medium (air) by the pre-heater 9 (actually a simple connection pipe), and these heats are transferred. As a result of the replacement, the temperature of the air, that is, the temperature in the tank is lowered, and in the case of the conventional apparatus, the constant temperature state is disturbed as described above.
[0013]
In this invention, in order to prevent such a situation, the partition 10 is provided in the thermostat. The partition wall 10 divides the space in the tank into a column side and a sample injection valve side, and a specific example is a metal box-like structure surrounding the sample injection valve 3. Although the preheater 8 is in the valve side compartment in FIG. 1, the preheater 8 may be placed in the column side compartment and connected to the sample injection valve 3 through the gap of the partition wall 10. The preheater 9 is provided across both sections because of its function. Since there is essentially no temperature difference between the two sides of the partition, heat insulation is not required for the partition material. Rather, since appropriate heat transfer is required as described later, a metal thin plate is suitable as the material. Further, the partition wall 10 does not completely seal the sample injection valve 3, but it is preferable to provide an appropriate gap or hole so that air as a heat medium can flow between both compartments by diffusion. By adopting such a structure, the temperature change generated in the sample injection valve 3 and the preheater 9 causes a time delay while being transmitted to the column side section by heat conduction through the partition wall 10 or by diffusion inflow of the heat medium, As a result, the rapid change is alleviated, so that the temperature of the column side section is not greatly disturbed. That is, it is possible to suppress the temperature of the sample injection valve 3 or the like that has received a thermal disturbance (room temperature sample introduction) from disturbing the temperature control of the entire thermostatic chamber. In addition, since there is a heat exchange between the column side section and the valve side section through the partition wall, the temperature of the sample injection valve 3 and the preheater 9 can be restored to the equilibrium state relatively quickly after being subjected to disturbance. .
[0014]
Of the two compartments separated by the partition walls, only the compartment on the column side is directly controlled in temperature. That is, the temperature sensor for temperature control must be provided in the compartment on the column side. The compartment on the valve side is indirectly maintained by the inflow of heat from the temperature controlled column side, and it is inevitable that the temperature will temporarily change due to disturbance such as sample injection. Should. If it is necessary to accurately control the temperature of the valve side section, it is necessary to control the temperature of each section separately using two temperature controllers, but for the purpose of the present invention, That is not necessary.
[0015]
In addition to the above, as a simpler embodiment, there is an embodiment in which the sample injection valve 3 and the surrounding piping (such as the preheater 9) are surrounded by a mild heat insulating material. Specifically, a thin glass wool with an aluminum foil on one side is suitable as a material, and the sample injection valve 3 is loosened so that the surface of the aluminum foil faces outward and an air layer is left appropriately. Wrap. In this case, the aluminum foil functions as the partition wall 10, and the air layer contained in the glass wool inside the aluminum foil corresponds to the valve side section. The heat insulation of thin glass wool is not so great, so proper heat transfer is maintained through the aluminum foil. Since this embodiment does not have a structure, it can be easily implemented and has an effect sufficient to achieve the object.
[0016]
The above is a description of the case of a thermostatic chamber set to a temperature higher than room temperature, but the present invention can be applied as it is even when the temperature is controlled to be lower than room temperature.
[0017]
【The invention's effect】
As described in detail above, the present invention provides a liquid chromatograph apparatus in which a sample injection valve and a column are both housed in the same air bath type thermostatic chamber, and a heat is interposed between the sample injection valve and the column. By providing a partition wall for buffering transmission, it is possible to prevent the disturbance of the temperature in the tank caused by introducing a sample at room temperature from adversely affecting the temperature around the column. As a result, the column temperature is stabilized, so that the reproducibility of the measurement results is improved, and the stability of the baseline is improved particularly when a detector sensitive to temperature change (for example, an electrical conductivity detector) is used. .
[0018]
In addition, by not disturbing the temperature equilibrium state of the column, the repeatability of retention time and resolution is improved, and the interaction between the mobile phase and the stationary phase is less disturbed by the influence of temperature. This also has the effect of improving the baseline stability during high sensitivity analysis.
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment of the present invention.
DESCRIPTION OF SYMBOLS 1 ... Reservoir 2 ... Liquid feed pump 3 ... Sample injection valve 4 ... Column 5 ... Detector 6 ... Data processing part 7 ... Constant temperature bath 8, 9 ... Preheater 10 ... Septum 11 ... Syringe

Claims (1)

A valve for sample injection is installed together with a column in an air bath type thermostat equipped with a temperature control device, a partition for buffering heat transfer is provided between the column and the valve, and the temperature sensor of the temperature control device is a column. A liquid chromatograph that is provided in the side compartment and directly controls the temperature of only the column side compartment.

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