Patent Description:
A supercritical fluid chromatograph (SFC) that uses a supercritical fluid as a mobile phase has been known. In an analysis device described in <CIT>, an analysis column is provided in a first flow path, and a first back pressure regulating valve is provided at a downstream of the analysis column. Further, a second flow path into which the first flow path branches is provided, and a second back pressure regulating valve is provided at the second flow path. Parts of a sample and a mobile phase introduced into a supercritical fluid chromatograph are introduced into the analysis column of the first flow path, and the remaining sample and mobile phase are discharged through the second flow path. <CIT> discloses a supercritical fluid device such as a supercritical fluid chromatograph (SFC) and an online supercritical fluid extraction (SFE)-SFC system.

In the analysis device described in <CIT>, it is possible to adjust the ratio (hereinafter referred to as a sample introduction ratio) of the amount of the sample supplied to the first flow path to the amount of the sample discharged from the second flow path by adjusting set values of the pressure in the first back pressure regulating valve and the second back pressure regulating valve. Thus, the amount of the sample to be introduced into the analysis column can be adjusted.

However, even when the set values of the pressure in the first back pressure regulating valve and the second back pressure regulating valve are respectively constant, the sample introduction ratio changes due to a pressure loss caused by pipes and the analysis column used in the analysis device. Because the change in sample introduction ratio influences detection sensitivity and analysis accuracy, it is necessary to adjust the sample introduction ratio to the value prescribed in the analysis method indicating the analysis condition by adjusting the set value of the pressure in the first back pressure regulating valve. In this case, after it is confirmed that the sensitivity of the detector of the analysis device is constant, analysis for adjustment of the sample introduction ratio must be carried out, and the set value of the pressure in the first back pressure regulating value must be adjusted by trial and error with a peak intensity acquired by the detector used as an index. Thus, it takes time and effort to make settings for analysis.

An object of the present invention is to provide an analysis assistance method, an analysis assistance device, an analysis assistance program and an analysis system that enable a sample introduction ratio to be easily and reliably adjusted. Further aspects are defined in the dependent claims.

An analysis assistance method according to one aspect of the present invention of assisting determination of an analysis condition of a supercritical fluid chromatograph including a liquid sender that supplies a mobile phase including a supercritical fluid to a supply flow path, first and second back pressure regulators respectively provided in first and second flow paths into which the supply flow path branches and an analysis column provided at an upstream of the first back pressure regulator in the first flow path, includes setting pressure in the first back pressure regulator to a value higher than a prescribed second set value with pressure in the second back pressure regulator set to the second set value, instructing the supercritical fluid chromatograph to supply the mobile phase to the supply flow path at a flow rate of the mobile phase that is to be theoretically supplied to the first flow path when the mobile phase is supplied to the supply flow path at a prescribed total flow rate and a prescribed sample introduction ratio, and then instructing the supercritical fluid chromatograph to gradually decrease a set value of the pressure in the first back pressure regulator, and detecting a set value of the pressure in the first back pressure regulator at the time when supply of the mobile phase to the second flow path is stopped due to a decrease in set value of the pressure in the first back pressure regulator, as a first set value.

According to the analysis assistance method, the set value of the pressure in the first back pressure regulator at the time when the supply of the mobile phase to the second flow path is stopped is equivalent to the first set value at which the predetermined flow rate of the mobile phase is supplied to the first flow path at the prescribed sample introduction ratio. Therefore, it is possible to determine the set value of the pressure in the first back pressure regulator in a short time, which is to be set in order that a desired sample introduction ratio is acquired, without carrying out the analysis. Further, it is possible to determine the set value of the pressure in the first back pressure regulator without the influence by another factor such as sensitivity of the detector. Therefore, the sample introduction ratio can be easily and reliably adjusted.

The analysis assistance method may further include setting the pressure in the first back pressure regulator to the detected first set value. In this case, the pressure in the first back pressure regulator is automatically set such that the prescribed sample introduction ratio is acquired.

The analysis assistance method may further include storing the analysis condition including the prescribed sample introduction ratio, the prescribed total flow rate of the mobile phase and the prescribed second set value, and determining or updating the detected first set value as part of the analysis condition. In this case, the analysis method defining analysis condition of the sample can be easily created and updated.

The analysis assistance method may further include presenting warning when the gradually decreasing set value of the pressure in the first back pressure regulator decreases to a value lower than a predetermined threshold value. In this case, the user can be informed of an occurrence of a problem such as clogging in the first or second flow path.

An analysis assistance device according to another aspect of the present invention that assists determination of an analysis condition of a supercritical fluid chromatograph including a liquid sender that supplies a mobile phase including a supercritical fluid to a supply flow path, first and second back pressure regulators respectively provided in first and second flow paths into which the supply flow path branches and an analysis column provided at an upstream of the first back pressure regulator in the first flow path, includes a setter that sets pressure in the first back pressure regulator to a value higher than a prescribed second set value with pressure in the second back pressure regulator set to the second set value, an instructor that instructs the supercritical fluid chromatograph to supply the mobile phase to the supply flow path at a flow rate of the mobile phase that is to be theoretically supplied to the first flow path when the mobile phase is supplied to the supply flow path at a prescribed total flow rate and a prescribed sample introduction ratio, and then instructs the supercritical fluid chromatograph to gradually decrease a set value of the pressure in the first back pressure regulator, and a detector that detects a set value of the pressure in the first back pressure regulator at the time when supply of the mobile phase to the second flow path is stopped due to a decrease in set value of the pressure in the first back pressure regulator, as a first set value.

The analysis assistance device enables the sample introduction ratio to be automatically, easily and reliably adjusted.

The setter may set the pressure in the first back pressure regulator to the detected first set value. In this case, the pressure in the first back pressure regulator is automatically set such that the prescribed sample introduction ratio is acquired.

The analysis assistance device may further include a storage that stores the analysis condition including the prescribed sample introduction ratio, the prescribed total flow rate of the mobile phase and the prescribed second set value, and a determination updater that determines or updates the detected first set value as part of the analysis condition. In this case, the analysis method defining the analysis condition of the sample can be easily created and updated.

The analysis assistance device may further include a presenter that presents warning when the gradually decreasing set value of the pressure in the first back pressure regulator based on an instruction given by the instructor decreases to a value lower than a predetermined threshold value. In this case, the user can be informed of an occurrence of a problem such as clogging in the first or second flow path.

An analysis assistance program according to yet another aspect of the present invention for assisting determination of an analysis condition of a supercritical fluid chromatograph that includes a liquid sender that supplies a mobile phase including a supercritical fluid to a supply flow path, first and second back pressure regulators respectively provided in first and second flow paths into which the supply flow path branches and an analysis column provided at an upstream of the first back pressure regulator in the first flow path, allows a computer to execute a process of setting pressure in the first back pressure regulator to a value higher than a prescribed second set value with pressure in the second back pressure regulator set to the second set value, a process of instructing the supercritical fluid chromatograph to supply the mobile phase to the supply flow path at a flow rate of the mobile phase that is to be theoretically supplied to the first flow path when the mobile phase is supplied to the supply flow path at a prescribed total flow rate and a prescribed sample introduction ratio, and then instructing the supercritical fluid chromatograph to gradually decrease a set value of the pressure in the first back pressure regulator, and a process of detecting a set value of the pressure in the first back pressure regulator at the time when supply of the mobile phase to the second flow path is stopped due to a decrease in set value of the pressure in the first back pressure regulator, as a first set value.

The analysis assistance program enables the sample introduction ratio to be easily and reliably adjusted.

An analysis system according to yet another aspect of the present invention includes a supercritical fluid chromatograph including a liquid sender that supplies a mobile phase including a supercritical fluid, first and second back pressure regulators respectively provided in first and second flow paths into which the supply flow path branches and an analysis column provided at an upstream of the first back pressure regulator in the first flow path, and the above-mentioned analysis assistance device that assists determination of an analysis condition of the supercritical fluid chromatograph.

This analysis system enables the sample introduction ratio to be easily and reliably adjusted.

Other features, elements, characteristics, and advantages of the present invention will become more apparent from the following description of preferred embodiments of the present invention with reference to the attached drawings.

An analysis assistance method, an analysis assistance device, an analysis assistance program and an analysis system according to embodiments of the present invention will be described below in detail with reference to drawings.

<FIG> is a block diagram showing the configuration of the analysis system including the analysis assistance device according to one embodiment of the present invention. <FIG> is a schematic diagram showing the configuration of a supercritical fluid chromatograph included in the analysis system of <FIG>.

The analysis system <NUM> of <FIG> includes the supercritical fluid chromatograph <NUM> and the analysis assistance device <NUM>. First, the supercritical fluid chromatograph <NUM> shown in <FIG> will be described. In the present embodiment, CO<NUM> (carbon dioxide) is used as a supercritical fluid.

The supercritical fluid chromatograph <NUM> includes a liquid sender <NUM>, a supercritical fluid extractor <NUM>, an autosampler <NUM>, a column oven <NUM>, a detector <NUM>, a first back pressure regulator (hereinafter referred to as a BPR) <NUM>, a second back pressure regulator (hereinafter referred to as a BPR) <NUM> and a makeup pump <NUM>. In the present embodiment, the supercritical fluid extractor <NUM> and the autosampler <NUM> constitute a sample introducer <NUM>.

The liquid sender <NUM> includes a CO<NUM> pump <NUM>, a modifier pump <NUM> and a mixer <NUM>. The CO<NUM> pump <NUM> extracts CO<NUM> from a cylinder <NUM> while pressurizing CO<NUM>. The CO<NUM> pump <NUM> has a pressure meter for detecting a discharge pressure and a monitor for displaying a pressure value. The modifier pump <NUM> extracts a modifier, which is a polar solvent, from a modifier container <NUM>. As the modifier, methanol or ethanol is used, for example.

The mixer <NUM> mixes the CO<NUM> extracted by the CO<NUM> pump <NUM> with the modifier extracted by the modifier pump <NUM>, and supplies a liquid mixture to a supply flow path PA as a mobile phase. In the present embodiment, the mixer <NUM> is a gradient mixer that mixes CO<NUM> with the modifier at a set ratio.

The supply flow path PA is provided with the supercritical fluid extractor <NUM>. The supercritical fluid extractor <NUM> includes an extraction container <NUM> that stores a sample. During the analysis of the sample, the supercritical fluid extractor <NUM> extracts a component to be analyzed from the sample as a sample component using a supercritical fluid (CO<NUM> in the present embodiment) included in the mobile phase. The extracted sample component and the mobile phase are supplied to the supply flow path PA.

The autosampler <NUM> includes a needle <NUM>, an injection port <NUM>, a switching valve <NUM> and a sample loop <NUM>. The needle <NUM> sucks a reference sample and discharges the reference sample to the injection port <NUM>. The sample loop <NUM> temporarily retains the reference sample that has been injected to the injection port <NUM>. The supply flow path PA, the supply flow path PB, the injection port <NUM> and the sample loop <NUM> are connected to the switching valve <NUM>. The switching valve <NUM> can switch between a first state and a second state, the first state being the state where the supply flow path PA is connected to the supply flow path PB and the injection port <NUM> is connected to the sample loop <NUM>, and the second state being the state where the supply flow path PA, the sample loop <NUM> and the supply flow path PB are connected to one another.

The supply flow path PB branches into a first flow path P1 and a second flow path P2 at a branch portion N1. The column oven <NUM> stores an analysis column <NUM> and keeps the temperature in the analysis column <NUM> at a set temperature. In the first flow path P1, the analysis column <NUM>, the detector <NUM> and the first BPR <NUM> are provided in order. The sample component and the mobile phase are introduced into the analysis column <NUM>. The analysis column <NUM> separates the sample component into further specific components. The separated components are detected by the detector <NUM>. The detector <NUM> is an ultraviolet detector, for example.

The first BPR <NUM> operates to keep the suction pressure (the pressure in the downstream of the detector <NUM> in the present embodiment) at a set value. The pressure in the downstream of the first BPR <NUM> is an air pressure. The makeup pump <NUM> extracts a makeup liquid from the makeup container <NUM> and supplies the makeup liquid to a junction N2 with the first flow path P1.

The second flow path P2 is provided with the second BPR <NUM>. The second BPR <NUM> operates to keep the suction pressure (the pressure in the second flow path P2 in the present embodiment) at a set value. A flow rate sensor <NUM> is provided in a drain of the second BPR <NUM>. The flow rate sensor <NUM> is used to detect the stop of discharge of the mobile phase from the drain of the second BPR <NUM> (the flow rate of the mobile phase has become <NUM>). The flow rate sensor <NUM> does not have to be provided. In that case, a user visually detects the stop of the discharge of the mobile phase from the drain, or the second BPR <NUM> being put into a closed state.

The set value of the pressure in the first BPR <NUM> and the set value of the pressure in the second BPR <NUM> are adjusted, whereby CO<NUM> in the supply flow paths PA, PB, the first flow path P1 and the second flow path P2 is put into a supercritical state. Further, the set value of the pressure in the first BPR <NUM> and the set value of the pressure in the second BPR <NUM> are adjusted, whereby the ratio (hereinafter referred to as a sample introduction ratio) of the flow rate of the sample introduced into the first flow path P1 to the flow rate of the sample introduced into the second flow path P2 is changed. The sample introduction ratio is equivalent to the ratio of the flow rate of the mobile phase supplied to the first flow path P1 to the flow rate of the mobile phase supplied to the second flow path P2. The sample introduction ratio is also referred to as a split ratio. For example, it may be preferable that the amount of sample introduced into the supercritical fluid extractor <NUM> is large, and it may be preferable that the amount of sample introduced into the analysis column <NUM> is relatively small. In such a case, it is possible to respectively adjust the flow rates of the samples respectively introduced into the supercritical fluid extractor <NUM> and the analysis column <NUM> to suitable values by adjusting the sample introduction ratio.

As shown in <FIG>, the supercritical fluid chromatograph <NUM> includes a control device <NUM>. The control device <NUM> controls the CO<NUM> pump <NUM>, the modifier pump <NUM>, the mixer <NUM>, the supercritical fluid extractor <NUM> and the autosampler <NUM>. Further, the control device <NUM> controls the column oven <NUM>, the first BPR <NUM>, the second BPR <NUM>, the detector <NUM> and the makeup pump <NUM>. Further, the control device <NUM> acquires a pressure value from the pressure meter of the CO<NUM> pump <NUM> and acquires a value of the flow rate detected by the flow rate sensor <NUM>.

The analysis assistance device <NUM> includes an input output I/F (interface) <NUM>, a CPU (Central Processing Unit) <NUM>, a RAM (Random Access Memory) <NUM>, a ROM (Read Only Memory) <NUM> and a storage device <NUM>, and is constituted by a personal computer or a server, for example. The input output I/F <NUM>, the CPU <NUM>, the RAM <NUM>, the ROM <NUM> and the storage device <NUM> are connected to a bus <NUM>. An operation unit <NUM> and a display <NUM> are connected to the bus <NUM> of the analysis assistance device <NUM>. The operation unit <NUM> includes a keyboard, a pointing device and the like, and is used for input of various values and so on, and various operations. The display <NUM> includes a liquid crystal display, an organic electroluminescence display or the like, and displays various information and images. The operation unit <NUM> and the display <NUM> may be constituted by a touch panel display.

The storage device <NUM> includes a storage medium such as a hard disk, an optical disc, a magnetic disc, a semiconductor memory or a memory card, and stores the analysis assistance program. The RAM <NUM> is used as a work area for the CPU <NUM>. A system program is stored in the ROM <NUM>. The CPU <NUM> executes the analysis assistance program stored in the storage device <NUM> on the RAM <NUM>, whereby the below-mentioned analysis assistance method is performed.

The method of adjusting the sample introduction ratio will be described below. As the method of analyzing a sample, the sample introduction ratio, the type of the analysis column <NUM> (the inner diameter of the analysis column, the length of the analysis column and a filler), the total flow rate of a mobile phase, the type of a modifier, the concentration of a modifier, the type of a makeup liquid, the set value of the pressure in the second BPR <NUM> and so on are prescribed in the analysis method. The supply flow path PA and the supply flow path PB are connected to each other through the switching valve <NUM>.

First, the user installs the analysis column <NUM> prescribed in the analysis method and the modifier container <NUM> in the supercritical fluid chromatograph <NUM>. Next, the user or the analysis assistance device <NUM> sets the pressure in the second BPR <NUM> to a second set value prescribed in the analysis method. Further, the user installs the makeup container <NUM> storing the makeup liquid prescribed in the analysis method in the supercritical fluid chromatograph <NUM> as necessary.

In this state, the pressure in the first BPR <NUM> is set to a value higher than the second set value by a user's operation using the operation unit <NUM> or an instruction given by the analysis assistance device <NUM>. Further, the liquid sender <NUM> supplies a mobile phase having a prescribed concentration of modifier to the supply flow paths PA, PB at a predetermined flow rate by a user's operation using the operation unit <NUM> or an instruction given by the analysis assistance device <NUM>. Here, the predetermined flow rate is the flow rate of a mobile phase that is to be theoretically supplied to the first flow path P1 when the mobile phase is supplied to the supply flow paths PA, PB at a prescribed total flow rate and a prescribed sample introduction ratio. For example, when the total flow rate of the mobile phase is <NUM>/min, and the sample introduction ratio is <NUM> %, the mobile phase is to be supplied to the first flow path P1 theoretically at the flow rate of <NUM>/min. Therefore, the liquid sender <NUM> supplies the mobile phase to the supply flow paths PA, PB at the flow rate of <NUM>/min. The mobile phase is supplied to the first flow path P1 and the second flow path P2 at first.

The set value of the pressure in the first BPR <NUM> decreases by a certain value (<NUM> MPa, for example) at a time by a user's operation using the operation unit <NUM> or an instruction given by the analysis assistance device <NUM>. Thus, the flow rate of the mobile phase in the second flow path P2 gradually decreases.

The analysis assistance device <NUM> detects the set value of the pressure in the first BPR <NUM> at the time when the flow rate of the mobile phase detected by the flow rate sensor <NUM> becomes <NUM>, as a first set value. Alternatively, the user inputs the set value of the pressure in the first BPR <NUM> at the time when the discharge of the mobile phase from the drain of the second BPR <NUM> is stopped or when the second BPR <NUM> is put into the closed state, as the first set value. The difference between the first set value of the pressure in the first BPR <NUM> and the second set value of the pressure in the second BPR <NUM> in this case is the difference in pressure acquired when the mobile phase is introduced into the analysis column <NUM> at the predetermined flow rate (the flow rate theoretically calculated from the prescribed total flow rate and the prescribed sample introduction ratio).

In this manner, the first set value of the pressure in the first BPR <NUM>, which is to be set in order that the prescribed total flow rate of the mobile phase is supplied to the first BPR <NUM> and the second BPR <NUM> at the prescribed sample introduction ratio, is determined.

<FIG> is a block diagram showing the functional configuration of the analysis assistance device <NUM> of <FIG>. As shown in <FIG>, the analysis assistance device <NUM> includes a condition acquirer <NUM>, a condition setter <NUM>, a control instructor <NUM>, a set value detector <NUM>, a storage <NUM>, a presenter <NUM> and a determination updater <NUM>. The functions of the above-mentioned constituent elements (<NUM> to <NUM>) are realized by execution of the analysis assistance program, which is a computer program stored in a storage medium (recording medium) such as the storage device <NUM>, by the CPU <NUM> of <FIG>. Part or all of the constituent elements of the analysis assistance device <NUM> may be realized by hardware such as an electronic circuit.

One or a plurality of analysis methods are stored in the storage <NUM>. The condition acquirer <NUM> acquires analysis conditions such as various set values input by the user using the operation unit <NUM> or analysis conditions prescribed by the analysis method stored in the storage <NUM>. The condition setter <NUM> performs settings of each component of the supercritical fluid chromatograph <NUM> through the control device <NUM> of the supercritical fluid chromatograph <NUM> based on the analysis conditions acquired by the condition acquirer <NUM>. The control instructor <NUM> instructs the control device <NUM> to control each component of the supercritical fluid chromatograph <NUM> based on various instructions input by the user using the operation unit <NUM> or the analysis conditions acquired by the condition acquirer <NUM>.

The set value detector <NUM> detects the set value of the pressure in the first BPR <NUM> at the time when the flow of the mobile phase into the drain of the second BPR <NUM> is stopped, as the first set value. Specifically, the set value detector <NUM> detects the set value of the pressure in the first BPR <NUM> at the time when the flow rate of the mobile phase detected by the flow rate sensor <NUM> becomes <NUM>, as the first set value. Alternatively, the user may see the set value of the pressure in the first BPR <NUM> at the time when the discharge of the mobile phase from the drain of the second BPR <NUM> is stopped or when the second BPR <NUM> is closed, and may input the set value as the first set value using the operation unit <NUM>. In this case, the set value detector <NUM> detects the input first set value.

The determination updater <NUM> determines the first set value of the pressure in the first BPR <NUM> detected by the set value detector <NUM> as part of the analysis conditions of the analysis method in the storage <NUM>, or updates the set value of the pressure in the first BPR <NUM> prescribed in the analysis method with the first set value. The above-mentioned condition setter <NUM> sets the first set value detected by the set value detector <NUM> in the first BPR <NUM> of the supercritical fluid chromatograph <NUM> through the control device <NUM>.

The presenter <NUM> determines whether the set value of the pressure in the first BPR <NUM> is lower than a predetermined threshold value in the process in which the set value of the pressure in the first BPR <NUM> decreases. When the set value of the pressure in the first BPR <NUM> is lower than the threshold value, the presenter <NUM> presents the warning to indicate an occurrence of a problem such as clogging in the first or second flow path P1, P2 to the user by the display <NUM>. In this case, the control instructor <NUM> stops the operation of the supercritical fluid chromatograph <NUM>.

<FIG> is a flow chart showing the algorithm of the analysis assistance program. The algorithm of the analysis assistance program will be described with reference to <FIG>. The analysis assistance method is performed by execution of the analysis assistance program.

First, the condition setter <NUM> sets the pressure in the second BPR <NUM> to the second set value prescribed in the analysis method (step S1). More specifically, the user may input the second set value of the pressure in the second BPR <NUM> using the operation unit <NUM>. In this case, the condition acquirer <NUM> acquires the input second set value, and the condition setter <NUM> sets the acquired second set value in the second BPR <NUM> through the control device <NUM>. Further, the condition acquirer <NUM> may acquire the set value of the pressure in the second BPR <NUM> prescribed in the analysis method in the storage <NUM> as the second set value, and the condition setter <NUM> may set the acquired second set value in the second BPR <NUM> through the control device <NUM>. Alternatively, the user may directly set the second set value in the second BPR <NUM> of the supercritical fluid chromatograph <NUM>.

Next, the condition setter <NUM> sets the pressure in the first BPR <NUM> to a predetermined value higher than the second set value of the pressure in the second BPR <NUM> through the control device <NUM> (step S2). Further, the condition setter <NUM> sets the concentration of modifier in the liquid sender <NUM> through the control device <NUM> (step S3). Specifically, the user inputs the prescribed concentration of modifier using the operation unit <NUM>. In this case, the condition acquirer <NUM> acquires the input concentration of modifier, and the condition setter <NUM> sets the acquired concentration of modifier in the liquid sender <NUM>. Alternatively, the condition setter <NUM> may set the concentration of modifier in the liquid sender <NUM> based on the analysis method stored in the storage <NUM>.

Next, the control instructor <NUM> instructs the control device <NUM> to supply a mobile phase to the supply flow path PA at a predetermined flow rate that is calculated from the prescribed total flow rate and the prescribed sample introduction ratio (step S4). Thus, the control device <NUM> controls the liquid sender <NUM> such that the mobile phase is supplied to the supply flow path PA at the predetermined flow rate.

Thereafter, the control instructor <NUM> instructs the control device <NUM> to decrease the set value of the pressure in the first BPR <NUM> by a certain value (<NUM> MPa, for example) at a time (step S5). Thus, the control device <NUM> decreases the set value of the pressure in the first BPR <NUM> by the certain value at a time.

The presenter <NUM> determines whether the set value of the pressure in the first BPR <NUM>, which is decreased by an instruction given by the control instructor <NUM>, is equal to or higher than the threshold value (step S6). In this case, the presenter <NUM> may acquire the set value of the pressure in the first BPR <NUM> based on the instruction of decreasing the set value given by the control instructor <NUM>, or may acquire the set value of the pressure in the first BPR <NUM> from the control device <NUM>. Here, the threshold value is a threshold value for determination of whether a problem such as clogging has occurred in the first or second flow path P1, P2 and is <NUM> Mpa, for example.

When the set value of the pressure in the first BPR <NUM> is equal to or higher than the threshold value, the set value detector <NUM> determines whether the flow rate of the mobile phase discharged from the drain of the second BPR <NUM> is <NUM> (step S7). When the flow rate of the mobile phase discharged from the drain of the second BPR <NUM> is not <NUM>, the control instructor <NUM> returns to the step S5 and repeats the process of the steps S5 to S7.

When the flow rate of the mobile phase discharged from the drain of the second BPR <NUM> becomes <NUM>, the set value detector <NUM> detects the set value of the pressure in the first BPR <NUM> as the first set value (step S8). The detected first set value is stored in the storage <NUM>. The determination updater <NUM> determines or updates the first set value as part of the analysis conditions of the analysis method (step S9). Specifically, the determination updater <NUM> determines the first set value as part of the analysis conditions of the analysis method stored in the storage <NUM>. Alternatively, when the set value of the pressure in the first BPR <NUM> is prescribed in the analysis method, the determination updater <NUM> updates the prescribed set value with the first set value. The condition setter <NUM> sets the pressure in the first BPR <NUM> to the first set value detected by the set value detector <NUM> (step S10).

When the set value of the pressure in the first BPR <NUM> is lower than the threshold value in the step S6, the presenter <NUM> presents warning to the user by the display <NUM> (step S11). Further, the control instructor <NUM> instructs the control device <NUM> to stop the operation of the supercritical fluid chromatograph <NUM> (step S12).

The present embodiment allows the pressure in the first BPR <NUM> to be set to a value higher than the prescribed second set value with the pressure in the second BPR <NUM> set to the second set value. In this state, the mobile phase is supplied to the supply flow paths PA, PB at the flow rate of the mobile phase that is to be theoretically supplied to the first flow path P1 when the mobile phase is supplied to the supply flow paths PA, PB at the prescribed total flow rate and the prescribed sample introduction ratio. In this case, the mobile phase is supplied at least to the second flow path P2. Thereafter, the set value of the pressure in the first BPR <NUM> gradually decreases. Thus, the flow rate of the mobile phase supplied to the first flow path P1 increases, and the flow rate of the mobile phase supplied to the second flow path P2 decreases. The set value of the pressure in the first BPR <NUM> at the time when the supply of the mobile phase to the second flow path P2 is stopped is detected as the first set value. The first set value is equivalent to the set value of the pressure in the first BPR <NUM> at which the predetermined flow rate of the mobile phase is supplied to the first flow path P1 at the prescribed sample introduction ratio. Therefore, it is possible to determine the set value of the pressure in the first BPR <NUM> to acquire a desired sample introduction ratio in a short period of time without carrying out the analysis. Further, it is possible to determine the set value of the pressure in the first BPR <NUM> without being influenced by another factor such as sensitivity of the detector <NUM>. Therefore, the sample introduction ratio can be easily and reliably adjusted.

Further, for various samples, the analysis method including sample introduction ratios, first set values of the pressure in the first BPR <NUM> and second set values of the pressure in the second BPR <NUM> can be easily created and updated.

Further, the user can easily identify an occurrence of a problem such as clogging in the first or second flow path P1, P2 based on the warning presented by the display <NUM>.

In the following paragraphs, non-limiting examples of correspondences between various elements recited in the claims below and those described above with respect to various preferred embodiments of the present invention are explained.

In the above-mentioned embodiment, the condition setter <NUM> is an example of a setter, the control instructor <NUM> is an example of an instructor and the set value detector <NUM> is an example of a detector.

As each of constituent elements recited in the claims, various other elements having configurations or functions described in the claims can be also used.

Claim 1:
An analysis assistance method of assisting determination of an analysis condition of a supercritical fluid chromatograph (<NUM>) including a liquid sender (<NUM>) that supplies a mobile phase including a supercritical fluid to a supply flow path (PA, PB), first and second back pressure regulators (<NUM>, <NUM>) respectively provided in first and second flow paths into which the supply flow path (PA, PB) branches and an analysis column (<NUM>) provided at an upstream of the first back pressure regulator (<NUM>) in the first flow path, including:
setting pressure in the first back pressure regulator (<NUM>) to a value higher than a prescribed second set value with pressure in the second back pressure regulator (<NUM>) set to the second set value;
instructing the supercritical fluid chromatograph (<NUM>) to supply the mobile phase to the supply flow path (PA, PB) at a flow rate of the mobile phase that is to be theoretically supplied to the first flow path when the mobile phase is supplied to the supply flow path (PA, PB) at a prescribed total flow rate and a prescribed sample introduction ratio, and then instructing the supercritical fluid chromatograph (<NUM>) to gradually decrease a set value of the pressure in the first back pressure regulator (<NUM>); and
detecting a set value of the pressure in the first back pressure regulator (<NUM>) at the time when supply of the mobile phase to the second flow path is stopped due to a decrease in set value of the pressure in the first back pressure regulator (<NUM>), as a first set value.