JP6672905B2 - Liquid chromatograph equipped with temperature control means - Google Patents

Description

  The present invention relates to a temperature controller for controlling the temperature of a mobile phase supply unit, a sample introduction unit, a separation column, a detection unit, and the like provided in a liquid chromatograph apparatus. In particular, the present invention relates to a temperature controller characterized by a temperature measuring unit.

  The liquid chromatograph device includes a mobile phase (eluent) supply means, a sample introduction means, a separation column, a detection means, and a flow path connecting them. When the sample is introduced into the upstream of the separation column by the sample introduction means in order to analyze the components contained in the sample, the sample is introduced into the separation column by the eluent supplied from the eluent supply means. Liquid chromatographs separate components contained in a sample by utilizing the fact that the components of a sample pass through a separation column at different times, and a detection means provided downstream of the separation column with components eluted from the separation column. After detection, discard or collect the eluate.

  In liquid chromatographic analysis, the temperature of the sample introduction means and the temperature of the separation column are increased in order to improve the ability of the separation column to separate components in the sample and to improve the solubility of the components in the sample. It is. Further, the stability of the eluent supplied by the eluent supply means, the peak retention time by the separation column, the baseline of the signal by the detection means, and the like depend on the temperature, and are adjusted as necessary.

  Temperature controllers used in liquid chromatographs are broadly classified into two systems: a hot air circulation system (for example, Patent Document 1) and a block temperature control system (for example, Patent Document 2). In the first hot air circulation system, objects to be temperature controlled, such as an eluent supply unit, a sample introduction unit, a separation column, and a detection unit, are stored individually or collectively in a plurality of units in a constant temperature bath, and air in the bath is supplied. Is heated by a heater or the like, and the air in the tank is stirred and circulated by a fan or the like. The temperature of the air in the tank is measured by a temperature measuring means, and the temperature is controlled to a constant temperature by a temperature control circuit. In the second block temperature control method, a housing of a temperature control target means or a block in close contact with the housing is directly heated by a heater or the like, and the temperature is measured by temperature measurement means installed on the housing or the block. The temperature is controlled to a constant temperature by a temperature control circuit.

  A temperature sensor is used as a temperature measuring means. Examples of usable temperature sensors include a platinum resistance thermometer, a thermocouple, a thermistor, and a semiconductor temperature sensor, which are appropriately selected according to a temperature range to be used. Is done. As the temperature sensor, a small sensor having good time response is generally used.

JP 2014-163731 A JP-A-2000-039428

  In the case of performing a precise analysis in a liquid chromatograph, a high-precision temperature control is required. As one of the methods for achieving high-precision temperature control, a method of increasing the sensitivity of a temperature sensor can be considered.

  Comparing a thermistor and a platinum resistance temperature detector as a temperature sensor, the thermistor is about 10 times more sensitive than a platinum resistance temperature detector, and has the advantages of being small and inexpensive. In addition, there is a large variation in individual differences in temperature-sensitive characteristics, and there is a surface lacking stability. That is, it can be said that the thermistor is superior in temperature precision and inferior in temperature accuracy as compared with a platinum resistance temperature detector. In order to make up for the drawback that the temperature accuracy is inferior, when using a thermistor, it is general to separately perform temperature correction using a separately calibrated thermometer. For example, when temperature control is performed sequentially at multiple temperature control temperatures, the temperature of the temperature control target is measured using a separately calibrated thermometer, and the correlation between the thermistor and the indicated value of the calibrated thermometer is measured. Is used to correct variations in the characteristics of the thermistor element. In this correction, it is necessary to attach / remove a calibrated reference thermometer to / from the temperature control object. For example, in the case of block temperature control, in order to attach / remove the reference thermometer to / from the block to be temperature-controlled. However, there is a problem that it takes time to disassemble / reassemble the cover and the heat insulating material.

  It is also conceivable to provide a small window for attaching / removing the thermometer to the cover or the heat insulating material in advance to make it easier to attach / remove the calibrated reference thermometer. Therefore, there is a possibility that a temperature distribution may occur in the temperature control target, and in an application requiring high-precision temperature control, it may be unacceptable to install a small window.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid chromatograph apparatus having a temperature control means with excellent precision and accuracy. Another object of the present invention is to provide a liquid chromatograph apparatus which does not require attachment / detachment of a reference thermometer when calibrating a temperature sensor used for temperature control means and has high workability.

The present invention made in view of the above problems includes the following aspects.
[1] The liquid chromatograph apparatus of the present invention is a temperature controller for controlling the temperature of at least one of a mobile phase supply unit, a sample introduction unit, a separation unit, a detection unit, and each of the units. Means, and a liquid chromatograph apparatus comprising:
The temperature control means,
Heating / cooling means for heating or cooling the temperature control target;
A first temperature sensor for indicating a temperature of a temperature control object,
A second temperature sensor thermally coupled to the first temperature sensor, wherein the second temperature is different from the first temperature sensor in at least one of a type, a shape, a characteristic, and a temperature measurement method. Sensors and
A temperature control circuit for controlling the temperature control target to a predetermined temperature using the heating / cooling means and the first temperature sensor;
Temperature calibration means for correcting the temperature indicated by the first temperature sensor based on the temperature indicated by the second temperature sensor;
It is characterized by having.

  If the error in the measured temperature due to the variation in the characteristics of the element itself of the second temperature sensor is smaller than the systematic error allowed in the temperature control, the second temperature sensor is used as a reference thermometer and its indicated value (indicated temperature) is set. ), The indicated temperature of the first temperature sensor can be corrected or calibrated.

[2] The temperature control means may have a heat conductive block in contact with the temperature control target, and if both the first temperature sensor and the second temperature sensor are fixed to the heat conductive block, the temperature control means The temperature of the temperature control target can be efficiently controlled, the heat insulation structure for the temperature control target is strengthened, and the workability is improved by eliminating the need for attaching / detaching the second temperature sensor (reference thermometer) during calibration. be able to.
[3] The temperature calibrating means sets the temperature control target to a temperature range including at least the target temperature, correlates the temperature indication value between the first temperature sensor and the second temperature sensor, and obtains a linear function It is preferable to obtain the above correction formula. That is, the value indicated by the first temperature sensor is substituted into the correction formula to obtain a value converted into the temperature indication value of the second temperature sensor (reference thermometer). The conversion of the temperature indication value may be applied to the circuit constant of the temperature conversion circuit that outputs the indication value of the temperature sensor, or may be applied to digital data after A / D conversion of the output of the temperature conversion circuit. May be.

[4] In the present invention, when the difference between the temperature indicated by the first temperature sensor and the temperature indicated by the second temperature sensor exceeds a predetermined threshold, the temperature adjustment means outputs error information relating to temperature adjustment. It can also be configured. The present invention has two temperature sensors independent of each other in the temperature control section, so that almost the same measured temperature value can be obtained after temperature correction, so that one of the temperature sensors, the temperature conversion circuit, the A / D converter, etc. When an error occurs, an abnormality can be detected early by comparing the measured values of the two temperature sensors. When an error is detected, an error signal is output or a flag is added to the chromatogram data being measured to alert the user that the measurement is in a state where the temperature control is abnormal. Can be.
[5] A resistance thermometer (thermistor, platinum resistance thermometer, semiconductor temperature sensor, etc.) utilizing a change in resistance value is used as the first temperature sensor and the second temperature sensor, and the sign of the resistance temperature coefficient is used. If different sensors are used, when two sensors are covered by some kind of device abnormality and the electrical conduction state changes, the behavior of the two sensors will be different, so it is possible to detect the trouble of the solution early. Become.

[6] As a first and a second temperature sensor, a temperature sensor having different temperature detection principles from each other, for example, a resistance thermometer, and a phenomenon in which a thermoelectromotive force is generated due to a temperature difference between two contacts of different metals (Seebeck effect) is used. When a thermocouple is used, the behavior of the sensor when the electrical conduction state changes due to some device abnormality is different due to a difference in detection principle, so that the abnormality can be detected early. In that case, a resistance thermometer may be used for the first temperature sensor and a thermocouple may be used for the second temperature sensor, or conversely, a resistance thermometer may be used for the second temperature sensor using a thermocouple for the first temperature sensor. A meter can also be used. Which combination to use may be appropriately selected according to the accuracy, accuracy, operating temperature, and the like required for temperature control.
[7] As the first temperature sensor of the present invention, it is preferable to use a thermistor or the like which is a highly sensitive temperature sensor in order to realize more precise temperature control. As the second temperature sensor, it is preferable to use, as a reference thermometer, a platinum resistance temperature detector having less variation in the characteristics of the element itself than the first temperature sensor.

  The temperature control means used in the liquid chromatograph device according to the present invention includes a second temperature sensor for correcting a temperature measured by the first temperature sensor, in addition to the first temperature sensor used for temperature control. Therefore, the calibration of the first temperature sensor can be directly performed in the temperature state of the temperature control target in use. In addition, since the thermometer is attached / detached, the labor for disassembling / reassembling the cover or the heat insulating material for accommodating the temperature control target can be omitted. As a result, it is possible to shorten and simplify the adjustment process at the time of manufacturing and maintenance of the liquid chromatograph.

  In addition, the present invention has two independent temperature sensors as temperature control means, and can obtain almost the same measured temperature value after temperature correction, so that one temperature sensor, a temperature conversion circuit, an A / D converter, etc. When an abnormality occurs, the abnormality can be detected early by comparing the measured values of the two temperature sensors. When an error is detected, an error signal is output or a flag is added to the chromatogram data being measured to alert the user that the measurement is in a state where the temperature control is abnormal. Can be.

It is a figure showing an example of a liquid chromatograph device. FIG. 9 is a diagram illustrating an example of a temperature control unit of a conventional liquid chromatograph device. FIG. 9 is a diagram showing an example of a configuration for correcting a temperature sensor in a temperature control unit of a conventional liquid chromatograph device. It is a figure showing an example of the temperature control means of the liquid chromatograph device of the present invention. FIG. 3 is a cross-sectional view of the temperature-controlled differential refractometer of the example when viewed from above. It is sectional drawing when the temperature-controlled differential refractometer of an Example is seen from the side surface. It is a figure showing a result of an example.

  FIG. 1 shows an example of a liquid chromatograph apparatus. The eluent contained in the eluent container 36 is sent by the mobile phase supply means 38 connected by the pipe 25. The sample is introduced into the flow channel by the sample introducing means 39, and the sample is separated by the separating means 40. After the separated sample is detected by the detecting means 41, the eluate is discarded into the waste liquid container 37.

  FIG. 2 shows an example of a temperature control means used in a conventional liquid chromatograph apparatus. Temperature control is performed on at least one of the mobile phase supply means, the sample introduction means, the separation means, and the detection means. The temperature control target block 1 is covered with a heat insulating material 4, and a cover 5 is provided outside the heat control material 4. The temperature control target block 1 is insulated and kept warm so that the temperature control target block 1 is hardly affected by ambient environmental temperature fluctuation. The temperature control target block 1 is heated by the heater 2, the temperature is measured by the temperature sensor 3, and the temperature is controlled.

  The temperature conversion circuit 6 is connected to the temperature sensor 3 and outputs a temperature signal 10 indicating the temperature of the temperature control target block. A temperature control temperature is set by the temperature setting / display 9, and a target temperature control temperature set value signal 11 is output. The temperature control circuit 7 outputs the heat generation amount instruction signal 13 using the temperature signal 10 as a control amount, the temperature control temperature set value signal 11 as a set value, and the heat generation amount of the heater 2 as an operation amount. Further, the temperature signal 10 is A / D converted and a current temperature display signal 12 is output, and the temperature setting / display 9 displays the current temperature. The power supply circuit 8 supplies power to the heater 2 based on the heat generation amount instruction signal 13.

  FIG. 3 shows an example of correction of the temperature sensor of the temperature control means used in the conventional liquid chromatograph device. In order to make a correction, the calibrated temperature sensor 14 is separately disassembled from the heat insulating material 4 and the cover 5, installed near the temperature sensor 3 of the temperature control target block, and then the heat insulating material 4 and the cover 5 are assembled. The correction coefficient is multiplied by the temperature measurement value from the temperature sensor 3 so that the temperature measurement value from the temperature sensor 3 matches the measurement value from the calibrated temperature measurement device 15. After the correction work is completed, the heat insulating material 4 and the cover 5 are disassembled again, the calibrated temperature sensor 14 is removed, and the heat insulating material 4 and the cover 5 are assembled.

  FIG. 4 shows an example of the temperature control means used in the liquid chromatograph device of the present invention. The first temperature sensor 16 is used for controlling the temperature similarly to the conventional temperature sensor 3. A second temperature sensor 17 is provided near the first temperature sensor 16, and the first and second temperature sensors measure the same temperature of the block whose temperature is to be adjusted. The temperature measured by the second temperature sensor is used to correct the variation in the characteristics of the element itself of the first temperature sensor. When temperature control is performed at two or more temperature control set temperatures, the measured temperatures of the first temperature sensor and the second temperature sensor are compared, and the measured temperature of the first temperature sensor is measured by the second temperature sensor. A first-order or higher-order correction formula is created so as to be equal to the temperature, and the measured temperature of the first temperature sensor is substituted into the formula to obtain a value converted into a temperature indication value of the second temperature sensor (reference thermometer). .

  In the present invention, a differential refractometer is used as a detecting means, and the apparatus configuration when the differential refractometer is targeted for temperature control is shown in FIGS. FIG. 5 is a cross-sectional view as viewed from above, and FIG. 6 is a cross-sectional view as viewed from the side. The optical elements of the flow cell 23, the mirror 26, the lens 28, the LED 30, the collimating lens 31, and the photodiode 32 are held by a cell holder 24, a mirror holder 27, a lens holder 29, and a light emitting / receiving element holder 33, respectively. The optical block 22 is fixed to the optical block 22 with screws. A heat insulating material 4 is provided around the optical block 22, and a cover 5 is further provided outside the optical block 22, and the optical block 22 and the optical block support 34 are connected and fixed. The mobile phase flowing in the pipe 25 flows into the flow cell 23, and a beam is deflected by a difference in refractive index between the sample injected into the mobile phase and the mobile phase, thereby obtaining a chromatogram.

  Two heaters 2 were provided on the side of the optical block 22 and electrically connected in parallel. Both the first temperature sensor 16 and the second temperature sensor 17 were installed on the bottom surface of the optical block 22 made of aluminum at a position close to the thermal coupling. A thermistor (R25 = 10.0 kΩ, tolerance ± 1%, B constant 3435K ± 1%) was used as the first temperature sensor, and a platinum resistance thermometer (Pt1000Ω, JIS A class) was used as the second temperature sensor. . FIG. 7 shows the measured temperatures (indicated values) of the first and second temperature sensors with the temperature of the optical block set at around 29 ° C. (temperature control OFF) and the temperature control temperature at 40 ° C. When the temperature control was OFF, the measured value of the first temperature sensor was 27.374 ° C., and the measured value of the second temperature sensor was 29.051 ° C. At the time of temperature control, the measured value of the first temperature sensor was 40.000 ° C., and the measured value of the second temperature sensor was 41.407 ° C.

  A first-order correction expression y = 0.97863x + 2.26194 representing the correlation between the measured values of the first and second temperature sensors at the two temperatures is obtained. By using this equation, the first temperature sensor can be calibrated based on the second temperature sensor. In the present embodiment, two points of temperature are measured for correction, and a linear correction equation is obtained by a linear expression. However, in consideration of a temperature range in which temperature control is actually performed, the temperature is set to three or more points. Temperature, and the accuracy of the correction can be improved by using a second or higher order correction formula. For example, when correcting the temperature sensor of the temperature control means having a temperature control temperature range of 40 ° C. to 60 ° C., three temperature control temperatures of 60 ° C. at the upper limit of temperature control, 40 ° C. at the lower limit, and 50 ° C. at the middle point are obtained. Recording the indicated values of the first and second temperature sensors respectively to obtain a quadratic function correction equation.

1 Temperature control target block 2 Heater 3 Temperature sensor 4 Insulation material 5 Cover 6 Temperature conversion circuit 7 Temperature control circuit 8 Power supply circuit 9 Temperature setting / display 10 Temperature signal 11 Temperature control temperature setting value signal 12 Current temperature display signal 13 Heat generation Quantity indicating signal 14 calibrated temperature sensor 15 temperature measuring device 16 first temperature sensor 17 second temperature sensor 18 first temperature sensor temperature signal 19 second temperature sensor temperature signal 20 first temperature sensor Current temperature display signal 21 Current temperature display signal 22 of second temperature sensor 22 Optical block 23 Flow cell 24 Cell holder 25 Piping 26 Mirror 27 Mirror holder 28 Lens 29 Lens holder 30 LED
31 Collimating lens 32 Photodiode 33 Light emitting / receiving element holder 34 Optical block support 35 Differential refractometer 36 Eluent container 37 Waste liquid container 38 Mobile phase supply means 39 Sample introduction means 40 Separation means 41 Detection means

Claims (5)

Mobile phase supply means, sample introduction means, separation means, detection means, temperature control means for controlling the temperature of any one or more of the respective means as a temperature control object, in a liquid chromatograph apparatus comprising:
The temperature control means,
Heating / cooling means for heating or cooling the temperature control target;
A first temperature sensor for indicating a temperature of a temperature control object,
A second temperature sensor thermally coupled to the first temperature sensor, the second temperature sensor having a different temperature detection principle from the first temperature sensor;
A temperature control circuit for controlling the temperature control target to a predetermined temperature using the heating / cooling means and the first temperature sensor;
Temperature calibration means for correcting the temperature indicated by the first temperature sensor based on the temperature indicated by the second temperature sensor;
The liquid chromatograph device having:   The liquid chromatograph apparatus according to claim 1, wherein the temperature control means has a heat conductive block in contact with a temperature control target, and a first temperature sensor and a second temperature sensor are fixed to the heat conductive block.   The temperature calibrating means sets a temperature control target to a temperature range including at least a target temperature, correlates a temperature indication value between the first temperature sensor and the second temperature sensor, and sets a linear function or more. The liquid chromatograph device according to claim 1, wherein the liquid chromatograph device acquires a correction formula.   4. The temperature controller according to claim 1, wherein when a difference between the temperature indicated by the first temperature sensor and the temperature indicated by the second temperature sensor exceeds a predetermined threshold, error information related to temperature adjustment is output. 5. A liquid chromatograph device according to item 1. The liquid chromatograph device according to any one of claims 1 to 4, wherein the first temperature sensor is a thermistor, and the second temperature sensor is a platinum resistance thermometer.

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