Supercritical fluid device and pressure control method of supercritical fluid device

Abstract

The present invention provides a supercritical fluid device and a pressure control method for a supercritical fluid device, which can suppress sudden changes in pressure in a flow path in a supercritical fluid device. The supercritical fluid device includes: a solvent supply unit that supplies a solvent; a pressure control device that is arranged in the flow path of the solvent supplied by the solvent supply unit; and a control unit that controls the pressure control device. The control unit may include: a first control unit that controls the pressure control device to increase the pressure of the flow path and make the solvent a supercritical fluid so as to maintain the execution environment of a specified process; and a second control unit that sets an intermediate target value for the pressure of the flow path when the execution environment of the specified process ends, and controls the pressure of the flow path toward the intermediate target value.

Description

Technical Field

[0001] The invention relates to a supercritical fluid device and a pressure control method implemented in the supercritical fluid device. Background Art

[0002] As the analytical method of sample, there is supercritical fluid chromatography (Supercritical Fluid Chromatography, SFC) using supercritical fluid as mobile phase.Supercritical fluid has the property of liquid and gas, has the feature of high diffusivity and low viscosity compared to liquid.By using the supercritical fluid of this property as solvent, can carry out the analysis of sample with high speed, high separation or high sensitivity.In addition, as the extraction method of sample, there is supercritical fluid extraction (Supercritical Fluid Extraction, SFE) using supercritical fluid as extraction medium.

[0003] In order to maintain the solvent in a supercritical state, for example, the flow rate of the solvent is set to a micro-flow rate below 3 ml / min, and the pressure in the flow path is set to more than 10 MPa. Therefore, in a supercritical fluid device for supercritical fluid chromatography or supercritical fluid extraction, a pressure control device is provided in order to adjust the pressure of the flow path of the solvent.

[0004] Patent Document 1 below relates to the structure of a pressure control valve provided in a supercritical fluid chromatograph. In the pressure control valve of Patent Document 1, a stepping motor and a piezoelectric element are used as an actuator for driving a valve body.

[0005] Patent Document 1: International Publication No. 2015-029253 Summary of the invention

[0006] [Problems to be solved by the invention]

[0007] In a supercritical fluid chromatograph, after the analysis and processing is completed, the pressure control device is controlled to perform a decompression process of the flow path. Moreover, the pressure in the separation column included in the supercritical fluid chromatograph also drops from a high pressure of more than 10MPa to about atmospheric pressure. At this time, due to the sudden pressure drop, sometimes deviations will occur in the stationary phase in the separation column, or the path based on the mobile phase will be generated in the stationary phase. In this way, if the uniformity of the stationary phase in the separation column decreases, it will become a cause of deterioration of the separation performance in the next analysis and processing. In addition, if the uniformity of the stationary phase of the separation column decreases, the life of the separation column will also be shortened.

[0008] In a device for supercritical fluid extraction, sometimes useless components are extracted from an extraction container, and the remaining material in the extraction container is collected as a target sample. In such an extraction process, the sample in the extraction container may be disturbed due to a sudden change in the pressure in the flow path.

[0009] An object of the present invention is to suppress a sudden change in pressure within a flow path in a supercritical fluid device.

[0010] [Technical means to solve the problem]

[0011] A supercritical fluid device according to one aspect of the present invention includes: a solvent supply unit for supplying a solvent; a pressure control device provided in a flow path of the solvent supplied by the solvent supply unit; and a control unit for controlling the pressure control device. The control unit includes: a first control unit for controlling the pressure control device to increase the pressure of the flow path so that the solvent is in a state of a supercritical fluid, thereby maintaining an execution environment for a prescribed process; and a second control unit for setting an intermediate target value for the pressure of the flow path when the execution environment for the prescribed process is terminated, and controlling the pressure of the flow path toward the intermediate target value.

[0012] [Effects of the Invention]

[0013] According to the present invention, in a supercritical fluid device, it is possible to suppress a sudden change in pressure within a flow path. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is an overall diagram of the supercritical fluid chromatograph according to the present embodiment.

[0015] Figure 2 : is a flowchart showing the pressure control method according to the present embodiment.

[0016] Figure 3 It is a graph showing the experimental results using the pressure control method according to the present embodiment. DETAILED DESCRIPTION

[0017] Next, the structure of a supercritical fluid chromatograph according to an embodiment of the present invention will be described with reference to the accompanying drawings.

[0018] (1) Overall structure of supercritical fluid chromatograph

[0019] Figure 1 1 is an overall structural diagram of a supercritical fluid chromatograph 10 according to the present embodiment. The supercritical fluid chromatograph 10 includes: a carbon dioxide gas cylinder 1, a modifier tank 2, a first pump 3, a second pump 4, a mixer 5, an automatic sampler 6, a separation column 7, a detector 8, and a back pressure control valve (back pressure regulator (BPR)) 9.

[0020] Liquefied carbon dioxide is stored in the carbon dioxide cylinder 1. The liquefied carbon dioxide in the carbon dioxide cylinder 1 is transported to the carbon dioxide flow path R1 by driving the first pump 3. An organic solvent as a modifier is stored in the modifier tank 2. The modifier in the modifier tank 2 is transported to the modifier flow path R2 by driving the second pump 4. In this embodiment, methanol is used as the modifier.

[0021] The liquefied carbon dioxide transported in the carbon dioxide flow path R1 and the methanol transported in the modifier flow path R2 are mixed in the mixer 5. Thus, in the supercritical fluid chromatograph 10 of the present embodiment, liquefied carbon dioxide and methanol are used as mobile phases. Carbon dioxide obtains a supercritical state at a relatively low temperature and low pressure. The modifier is used to improve the solubility of the sample as the measurement object. As the modifier, other organic solvents such as ethanol can be used.

[0022] The liquefied carbon dioxide and methanol mixed by the mixer 5 are supplied to the analysis flow path AR as a mobile phase. During the analysis process, the internal pressure of the analysis flow path AR is adjusted to 10 MPa or more by the back pressure control valve 9 provided downstream of the detector 8. In addition, in order to make the carbon dioxide a supercritical fluid, the temperature of the analysis flow path AR is adjusted to an appropriate temperature (31.1 degrees or more). Thus, the mobile phase supplied to the analysis flow path AR becomes a supercritical fluid.

[0023] The mobile phase supplied to the analysis flow path AR is sent to the autosampler 6. In the autosampler 6, the sample is dropped into the mobile phase in the analysis flow path AR by the injector 61. The mobile phase, which is a supercritical fluid to which the sample is dropped in the autosampler 6, is sent to the separation column 7.

[0024] The mobile phase into which the sample is injected is supplied to the separation column 7. In the separation column 7, the sample is separated while the mobile phase passes through the stationary phase in the separation column 7. The mobile phase in which the sample is dissolved and flows out from the separation column 7 is sent to the detector 8.

[0025] The mobile phase in which the sample is separated in the separation column 7 is supplied to the detector 8. The sample is detected in the detector 8. As the detector 8, for example, an ultraviolet detector, a visible light detector, or a fluorescence detector is used.

[0026] In addition, if Figure 1As shown, the supercritical fluid chromatograph 10 includes a pressure sensor 11 and a control unit 12. The pressure sensor 11 is provided in an analysis flow path AR in which a mobile phase as a supercritical fluid flows. The pressure sensor 11 is provided in the analysis flow path AR from the detector 8 to the back pressure control valve 9. The control unit 12 detects the pressure of the supercritical fluid, i.e., the mobile phase, detected by the pressure sensor 11. The control unit 12 inputs the detection value of the pressure sensor 11. The control unit 12 controls the back pressure control valve 9 based on the detection value of the pressure sensor 11 and the like.

[0027] (2) Structure of the control unit

[0028] The control unit 12 includes a first control unit 121 and a second control unit 122. The first control unit 121 controls the pressure of the mobile phase in the analysis flow path AR during the analysis process performed by the supercritical fluid chromatograph 10. The first control unit 121 controls the back pressure control valve 9 to increase the pressure of the analysis flow path AR and make the mobile phase a supercritical fluid to maintain the execution environment of the analysis process. The first control unit 121 controls the back pressure control valve 9 to maintain the pressure in the analysis flow path AR above 10 MPa. The first control unit 121 controls the back pressure control valve 9 based on the detection value of the pressure sensor 11.

[0029] The second control unit 122 performs pressure reduction control of the analysis flow path AR after the supercritical fluid chromatograph 10 completes the analysis process. The second control unit 122 controls the back pressure control valve 9 to reduce the pressure in the analysis flow path AR to about atmospheric pressure. The second control unit 122 controls the back pressure control valve 9 based on the detection value of the pressure sensor 11.

[0030] Figure 2 is a flowchart showing a pressure control method executed by the second control unit 122. After the second control unit 122 completes the analysis process performed by the supercritical fluid chromatograph 10, Figure 2 Pressure control method shown. Figure 2 The pressure control method shown is a method for decompressing the analysis flow path AR. For example, the second control unit 122 executes the following command to terminate the analysis process or the command to decompress the analysis process: Figure 2 Pressure control method shown.

[0031] At the beginning Figure 2 In the pressure control method shown in FIG. 1 , the second control unit 122 obtains the current pressure in the analysis flow path AR from the pressure sensor 11. That is, the second control unit 122 obtains the pressure in the analysis flow path AR under the execution environment of the analysis process. For example, the second control unit 122 obtains the detection value 10 MPa from the pressure sensor 11 as the current pressure in the analysis flow path AR.

[0032] At the beginning Figure 2 When the pressure control method shown in the figure is used, the second control unit 122 resets the timer 123 to 0 and starts measuring the elapsed time (T1) during the execution of the pressure control method. In step S1, the second control unit 122 obtains the current elapsed time (T1) from the timer 123. In step S1, the second control unit 122 determines whether the current elapsed time (T1) exceeds the decompression setting time (T2).

[0033] Here, the so-called decompression setting time (T2) refers to the time until the pressure in the analysis flow path AR is reduced from the pressure in the execution environment of the analysis process to about atmospheric pressure. That is, the so-called decompression setting time (T2) refers to the time until the pressure in the analysis flow path AR used to make the solvent in a supercritical fluid state is reduced to about atmospheric pressure. For example, it is the time until the pressure in the analysis flow path AR is reduced from the pressure in the analysis process, that is, 10 MPa, to about atmospheric pressure, that is, 0.1 MPa. Here, as an example, the pressure in the analysis flow path AR in the execution environment of the analysis process is set to 10 MPa, and the decompression setting time (T2) is set to 200 seconds.

[0034] When the elapsed time (T1) does not exceed the decompression setting time (T2), the second control unit 122 executes step S2. In step S2, the second control unit 122 calculates an intermediate target value. The intermediate target value is a target value of the pressure in the analysis flow path AR. The second control unit 122 sets an intermediate target value higher than the final target value as the target value of the pressure in the analysis flow path AR, rather than setting the atmospheric pressure as the final target value as the target value of the pressure in the analysis flow path AR.

[0035] In order to calculate the intermediate target value, the second control unit 122 first calculates the decompression rate (V). The decompression rate (V) is obtained by the following formula 1.

[0036] (Formula 1) Decompression speed (V) = set pressure (P) / decompression setting time (T2)

[0037] The set pressure (P) is the pressure set in the execution environment of the analysis process. Here, as mentioned above, the set pressure (P) is set to 10 MPa, and the decompression set time (T2) is set to 200 seconds.

[0038] Decompression rate (V) = 10 (MPa) / 200 (seconds) = 0.05 (MPa / second)

[0039] express.

[0040] Next, the second control unit 122 calculates the intermediate target value using the following formula 2.

[0041] (Formula 2) Intermediate target value = set pressure (P) - (decompression rate (V) × elapsed time (T1))

[0042] If the elapsed time (T1) is 10 seconds, the intermediate target value is as follows.

[0043] Intermediate target value after 10 seconds

[0044] =10(MPa)-(0.05(MPa / second)×10(second))=9.5MPa

[0045] That is, at the point in time when the elapsed time (T1) from the start of the decompression step reaches 10 seconds, the intermediate target value is set to 9.5 MPa.

[0046] When the intermediate target value is calculated, then, the second control unit 122 performs pressure control based on the intermediate target value in step S3. The second control unit 122 obtains the current pressure in the analytical flow path AR from the pressure sensor 11, and performs feedback control based on the difference between the intermediate target value and the obtained pressure. For example, a stepper motor and a piezoelectric element are used as an actuator for driving the valve body of the back pressure control valve 9. When feedback control toward the intermediate target value is performed by the second control unit 122, the stepper motor or piezoelectric element included in the back pressure control valve 9 is controlled. For example, when the control amount is large, the valve body is driven by a stepper motor, and when the control amount is small, the valve body is driven by a piezoelectric element.

[0047] After the second control unit 122 performs pressure control based on the intermediate target value in step S3, it returns to step S1. Then, the second control unit 122 obtains the elapsed time (T1) from the timer 123. When the elapsed time (T1) does not exceed the decompression setting time (T2), the second control unit 122 executes step S2 again to calculate a new intermediate target value. Then, the second control unit 122 performs pressure control based on the new intermediate target value in step S3. In this way, the second control unit 122 calculates the new intermediate target value according to the elapsed time (T1) and performs pressure control based on the new intermediate target value. Since the intermediate target value is calculated by the above-mentioned formula 2, the intermediate target value and the elapsed time (T1) become small values ​​together.

[0048] The second control unit 122 repeatedly executes the processing of step S1 to step S3 to gradually reduce the pressure in the analytical flow path AR. Then, in step S1, when the elapsed time (T1) exceeds the decompression setting time (T2), the second control unit 122 ends the decompression. Figure 2 Pressure control method shown.

[0049] Thus, the supercritical fluid chromatograph 10 of the present embodiment includes the second control unit 122, which sets an intermediate target value of the pressure in the analysis flow path AR when the execution environment of the analysis process is terminated, and controls the pressure in the analysis flow path AR toward the intermediate target value. Thus, when the execution environment of the analysis process is terminated, the pressure in the analysis flow path AR can be slowly reduced compared to the control in which the final target value is set as the pressure in the analysis flow path AR.

[0050] In the supercritical fluid chromatograph 10 of the present embodiment, when the execution environment of the analytical process is terminated, a sudden change in the pressure in the analytical flow path AR can be suppressed. Thus, the loss of uniformity of the stationary phase in the separation column 7 can be suppressed. Thus, the separation performance of the separation column 7 can be prevented from being reduced. In addition, the separation column 7 can be prevented from being degraded and the life of the separation column 7 can be prevented from being shortened.

[0051] In the supercritical fluid chromatograph 10 of the present embodiment, after controlling the pressure in the analysis flow path AR toward the intermediate target value, the second control unit 122 sets a new intermediate target value lower than the intermediate target value and controls the pressure in the analysis flow path AR toward the new intermediate target value. Thus, the pressure in the analysis flow path AR can be gradually reduced.

[0052] In the above embodiment, the intermediate target value of the pressure is calculated using equations 1 and 2. Thus, the pressure drop speed can be adjusted according to the decompression setting time (T2). By adjusting the decompression setting time (T2), the pressure fluctuation in the analysis flow path AR can be suppressed, and the degradation of the separation column 7 can be prevented.

[0053] In the embodiment, after the analysis process of the supercritical fluid chromatograph 10 is completed, the decompression setting time (T2) is set to 200 seconds, but this is an example. As long as the optimal decompression setting time (T2) is appropriately determined according to the structure of the supercritical fluid chromatograph 10 or the structure of the separation column 7. For example, it is preferred to set the decompression setting time (T2) in a manner that the time until the pressure (P) is halved is at least 10 seconds or more. By setting the decompression setting time (T2) in a manner that the time until the pressure (P) is halved is more than 10 seconds, the sudden change of the pressure in the analysis flow path AR can be suppressed. It is further preferred that the time until the pressure (P) is halved is more than 1 minute. By setting the decompression setting time (T2) in a manner that the time until the pressure (P) is halved is more than 1 minute, the sudden change of the pressure in the analysis flow path AR can be more effectively suppressed. In the embodiment, since 200 seconds are set as the decompression setting time (T2), the time until the pressure (P) is halved is about 100 seconds.

[0054] (3) Experimental results

[0055] Figure 3 It is a graph showing the experimental results when the pressure control method according to the present embodiment is implemented. Figure 3 The horizontal axis is the elapsed time T1 (minutes), and the vertical axis is the pressure (MPa) on the upstream side of the back pressure control valve 9. Figure 3 In FIG. 1 , the graph G1 indicated by the solid line is a graph showing the detection value of the pressure sensor 11 when the pressure control method of the present embodiment is executed. That is, the graph G1 is a graph showing the pressure change on the upstream side of the back pressure control valve 9 when the pressure control method of the present embodiment is executed. Figure 3 In the figure, the graph G2 indicated by the dotted line is a graph showing the detection value of the pressure sensor 11 when the pressure control method of the present embodiment is not executed. That is, the graph G2 is a graph showing the pressure change when the valve body of the back pressure control valve 9 is fully opened at the end of the analysis process, and the pressure in the analysis flow path AR is suddenly reduced.

[0056] like Figure 3 As shown in the graph G1, when the pressure control method of the present embodiment is executed, the second control unit 122 controls the pressure toward the intermediate target value, so the pressure change becomes slow. In contrast, it can be seen that when the pressure control method of the present embodiment is not executed, the pressure on the upstream side of the back pressure control valve 9 drops sharply. In this way, when the pressure control method of the present embodiment is executed, the reduction rate of the pressure reduced toward the intermediate target value is slower than the reduction rate of the pressure when the pressure is reduced without setting the intermediate target value. As a result, compared with the case where the back pressure control valve 9 is fully opened at once, the pressure change in the flow path can be suppressed.

[0057] (4) Correspondence between the components of the technical solution and the components of the embodiment

[0058] Hereinafter, examples of correspondence between the components of the technical solution and the components of the embodiment are described, but the present invention is not limited to the following examples. In the embodiment, the supercritical fluid chromatograph 10 is an example of a supercritical fluid device. In addition, the carbon dioxide gas cylinder 1, the modifier tank 2, the first pump 3, the second pump 4, the carbon dioxide flow path R1 and the modifier flow path R2 are examples of a solvent supply unit. In addition, in the embodiment, the back pressure control valve 9 is an example of a pressure control device, the analysis flow path AR is an example of a flow path, and the analysis process performed using the supercritical fluid chromatograph 10 is an example of a prescribed process.

[0059] As each constituent member of the claims, various members having the structure or function described in the claims can be used.

[0060] (5) Other Implementation Methods

[0061] As described above, in the present embodiment, as a device using a supercritical fluid, the supercritical fluid chromatograph 10 is cited as an example for explanation. In addition, the present invention can also be applied to a device that performs a method (SFE) of extracting a sample using a supercritical fluid as a supercritical fluid device. Even in the case where the present invention is applied to a device that performs SFE, the pressure in the flow path is suppressed from changing sharply. In SFE, sometimes useless components are extracted from the extraction container, and the residue in the extraction container is collected as a target sample. In the case of such an extraction process, the sample in the extraction container will be disturbed due to the sudden change in the pressure in the flow path. By implementing the pressure control method of the present embodiment, it is possible to suppress the sample in the extraction container from being disturbed due to pressure changes. The sample in the container extracted by SFE is kept neatly.

[0062] In addition, the specific structure of the present invention is not limited to the above-mentioned embodiment, and various changes and modifications can be made within the scope not departing from the gist of the invention.

[0063] (6) Morphology

[0064] Those skilled in the art will understand that the multiple exemplary embodiments are specific examples of the following forms.

[0065] (Item 1) A supercritical fluid device in one form may include: a solvent supply unit for supplying a solvent;

[0066] A solvent supplying unit for supplying a solvent;

[0067] a pressure control device provided in a flow path of the solvent supplied by the solvent supply unit; and

[0068] a control unit, for controlling the pressure control device;

[0069] The control unit may include:

[0070] a first control unit that controls the pressure control device to increase the pressure of the flow path so that the solvent is in a supercritical fluid state, thereby maintaining an execution environment for a predetermined process; and

[0071] The second control unit sets an intermediate target value for the pressure of the flow path when the execution environment of the predetermined process ends, and controls the pressure of the flow path toward the intermediate target value.

[0072] In a supercritical fluid device, sudden changes in pressure in a flow path can be suppressed.

[0073] (Second item) According to the supercritical fluid device described in the first item, it can also be that: after the second control unit controls the pressure of the flow path toward the intermediate target value, it sets a new intermediate target value lower than the intermediate target value, and controls the pressure of the flow path toward the new intermediate target value.

[0074] The pressure in the flow path can be gradually reduced.

[0075] (Item 3) According to the supercritical fluid device described in Item 1, it can also be that: if the pressure of the flow path under the execution environment of the specified process is set to a set pressure (P), the time from the start of decompression of the flow path is set to an elapsed time (T1), and the set time until the decompression of the flow path is completed is set to a decompression set time (T2), then the intermediate target value is obtained by

[0076] Decompression speed (V) = set pressure (P) / decompression setting time (T2)

[0077] Intermediate target value = set pressure (P) - (decompression rate (V) × elapsed time (T1))

[0078] Figure it out.

[0079] The pressure drop speed can be adjusted by the pressure reduction setting time. By adjusting the pressure reduction setting time, the pressure fluctuation in the flow path can be suppressed.

[0080] (Item 4) The supercritical fluid device according to Item 1, wherein a rate of decrease in pressure when decreasing toward the intermediate target value may be slower than a rate of decrease in pressure when the pressure is decreased without setting the intermediate target value.

[0081] (Item 5) According to the supercritical fluid device described in Item 1, the intermediate target value can also be set in such a way that the time until the pressure of the flow path is reduced to half under the execution environment of the prescribed process is at least 10 seconds.

[0082] Rapid changes in pressure in the flow path can be suppressed.

[0083] (Item 6) According to the supercritical fluid device described in Item 1, the intermediate target value can also be set in such a way that the time until the pressure of the flow path is reduced to half under the execution environment of the prescribed process is at least 1 minute.

[0084] Rapid changes in pressure in the flow path can be suppressed more effectively.

[0085] (Item 7) According to the supercritical fluid device described in Item 1, it may also be that: the supercritical fluid device includes a supercritical fluid chromatograph.

[0086] The pressure fluctuation of the analytical flow path can be suppressed, thereby preventing the degradation of the separation column.

[0087] (Item 8) According to the supercritical fluid device described in Item 1, it may also be that: the supercritical fluid device includes a device for performing supercritical fluid extraction.

[0088] The pressure fluctuation of the flow path can be suppressed, thereby preventing the sample in the extraction container from being disturbed.

[0089] (Item 9) Another method for controlling the pressure of a supercritical fluid device may include the following steps:

[0090] By controlling a pressure control device provided in a flow path of a solvent supplied by a solvent supply unit, the pressure of the flow path is increased to make the solvent a supercritical fluid so as to maintain an execution environment of a predetermined process; and

[0091] When the execution environment of the predetermined process is terminated, an intermediate target value of the pressure of the flow path is set, and the pressure of the flow path is controlled toward the intermediate target value.

Claims

1. A supercritical fluid device, characterized in that: include: A solvent supplying unit for supplying a solvent; a column disposed in a flow path of the solvent supplied by the solvent supply unit; a pressure control device disposed downstream of the column in the flow path; as well as a control unit, for controlling the pressure control device; The control unit includes: a first control unit that controls the pressure control device to increase the pressure of the flow path including the column so that the solvent is in a supercritical fluid state, thereby maintaining an execution environment for a predetermined process; as well as The second control unit sets an intermediate target value for the pressure of the flow path including the column when the execution environment of the predetermined process ends, and reduces the pressure of the flow path toward the intermediate target value to suppress a sudden pressure drop in the column.

2. The supercritical fluid device according to claim 1, characterized in that: After reducing the pressure of the flow path including the column toward the intermediate target value, the second control unit sets a new intermediate target value lower than the intermediate target value and reduces the pressure of the flow path including the column toward the new intermediate target value.

3. The supercritical fluid device according to claim 1, characterized in that: If the pressure of the flow path under the execution environment of the specified processing is set as the set pressure (P), the time from the start of decompression of the flow path is set as the elapsed time (T1), and the set time until the decompression of the flow path is completed is set as the decompression set time (T2), then the intermediate target value is obtained by Decompression speed (V) = set pressure (P) / decompression setting time (T2) Intermediate target value = set pressure (P) - (decompression rate (V) × elapsed time (T1)) Figure it out.

4. The supercritical fluid device according to claim 1, characterized in that: The rate of decrease of the pressure when decreasing toward the intermediate target value is slower than the rate of decrease of the pressure when the pressure is decreased without setting the intermediate target value.

5. The supercritical fluid device according to claim 1, characterized in that: The intermediate target value is set so that the time until the pressure of the flow path is reduced to half under the execution environment of the predetermined process is at least 10 seconds.

6. The supercritical fluid device according to claim 1, characterized in that: The intermediate target value is set so that the time until the pressure of the flow path is reduced to half under the execution environment of the predetermined process is at least one minute.

7. The supercritical fluid device according to claim 1, characterized in that: The supercritical fluid device includes a supercritical fluid chromatograph.

8. The supercritical fluid device according to claim 1, characterized in that: The supercritical fluid device includes a device for performing supercritical fluid extraction.

9. A method for controlling the pressure of a supercritical fluid device, characterized in that: This includes the following processing: By controlling a pressure control device provided in a flow path of a solvent supplied from a solvent supply unit and downstream of a column, the pressure of the flow path including the column is increased to make the solvent a supercritical fluid, thereby maintaining an execution environment of a predetermined process; and When the execution environment of the predetermined process is terminated, an intermediate target value of the pressure of the flow path including the column is set, and the pressure of the flow path is reduced toward the intermediate target value to suppress a sudden pressure drop in the column.

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