JP5206504B2 - Gas chromatograph - Google Patents

Description

  The present invention relates to a gas chromatograph apparatus, and more particularly to a gas chromatograph apparatus capable of back flash analysis.

  In gas chromatographic analysis, a method called backflushing is known. Backflushing refers to unnecessary components (typically high-boiling points) from the column or sample vaporization chamber by backflowing the carrier gas immediately after the target component (generally low-boiling point components) previously eluted from the column has passed through the detector. This is a method of expelling components) (see, for example, Patent Document 1). As a result, the analysis time can be shortened and the next analysis can be started quickly, and it is effective in reducing the contamination of the column.

  FIG. 6 is a schematic flow path configuration diagram of a gas chromatograph apparatus capable of backflushing described in Patent Document 2 and the like. In this configuration, the sample vaporizing chamber 1 is connected to the inlet of the column 8, and the detector 10 is connected to the outlet of the column 8 via the backflush element 9.

During normal analysis, the pressure in the sample vaporizing chamber 1, that is, the column inlet pressure PA is set higher than the column outlet pressure PB (PA> PB). Therefore, as shown in FIG. 6A, the sample introduced into the sample vaporizing chamber 1 rides on a carrier gas (in this example, helium) flow, passes through the column 8, passes through the backflash element 9, and goes to the detector 10. be introduced.
On the other hand, at the time of backflushing, the column inlet pressure PA is made smaller than the column outlet pressure PB (PA <PB). Therefore, as shown in FIG. 6 (b), the carrier gas advances from the outlet of the column 8 toward the inlet, contrary to the above-described normal analysis, and finally from the outlet provided in the sample vaporizing chamber 1 to the outside. Is discharged. As a result, the sample component remaining in the column 8 is quickly discharged from the discharge port.

  Thus, at the time of backflushing, it is necessary to change the column inlet pressure PA and the column outlet pressure PB from those during normal analysis. Therefore, in general, a general analysis is first performed on the target sample to obtain a chromatogram, and an analyst confirms this chromatogram to determine unnecessary components, and controls column inlet pressure and column outlet pressure. Create a pressure control program for For example, it is assumed that a chromatogram as shown in FIG. 7 is obtained by normal analysis. Assuming that the A part is the target component and the B part is an unnecessary component for the analyst, the analyst determines an appropriate time between the A part and the B part as the backflush start time (in this example, 5 minutes). ), It is necessary to create a pressure control program for the column inlet pressure and the column outlet pressure as shown in FIG. Such operations are complicated and time consuming, and input errors are likely to occur.

  Also, when creating the pressure control program as described above, it is necessary to pay attention to restrictions on the column outlet pressure. This is because if the column outlet pressure, that is, the detector inlet pressure is too high, the detector may be adversely affected. For example, when the detector is a flame ionization detector, if the detector inlet pressure is high and the flow rate of gas flowing into the detector is too high (for example, 30 mL / min or more), the hydrogen flame may disappear. In addition, when the detector is a mass spectrometer, if the flow rate of gas flowing into the detector is too high (for example, 20 mL / min or more), the vacuum pump that evacuates the vacuum chamber of the mass spectrometer may be damaged. There is also. For this reason, it is necessary to create a pressure control program in consideration of the restrictions according to the detector to be used, and the creation of the pressure control program is more troublesome.

JP-A-11-218527 JP-A-5-126814

  The present invention has been made to solve the above-mentioned problems, and the object of the present invention is to reduce the trouble of creating a pressure control program at the time of backflush analysis and to prevent adverse effects on the detector. An object of the present invention is to provide a gas chromatograph apparatus capable of creating a pressure control program that does not exert an effect.

The present invention made to solve the above problems includes a column, a first pressure control unit for controlling the column inlet pressure, a second pressure control unit for controlling the column outlet pressure, and the second pressure control unit. In a gas chromatograph device comprising a detector disposed on the downstream side,
a) display means for displaying a chromatogram obtained by normal analysis of the target sample;
b) instruction means for an analyst to instruct an arbitrary time on the chromatogram displayed on the display means;
c) an inlet pressure detecting means for detecting the column inlet pressure and an outlet pressure detecting means for detecting the column outlet pressure;
d) Based on the time indicated by the indicating means, the chromatogram is divided into a required part in the first half and an unnecessary part in the latter half, where the column inlet pressure exceeds the column outlet pressure and the unnecessary part has the column outlet pressure. Pressure control program creating means for creating and storing both a pressure control program for the first pressure control unit and a pressure control program for the second pressure control unit so as to exceed the column inlet pressure;
It is characterized by having.

  The pointing means is, for example, a pointing device such as a mouse. By operating the pointing device, the cursor superimposed on the chromatogram is moved to an arbitrary time position, and a predetermined operation such as double-clicking is performed. It is convenient to indicate any time on the gram. The instruction of time here does not necessarily indicate a certain position on the time axis, and it may be considered that when an arbitrary position in the chromatogram display frame is specified, the corresponding time is specified. .

  In the gas chromatograph apparatus according to the present invention, the analyst confirms the chromatogram on the screen of the display means, determines the peak due to the necessary component and the peak due to the unnecessary component, and double-clicks an appropriate position between them, for example. By simply operating, a pressure control program for performing backflush analysis can be created. When the backflush analysis is performed by controlling the first pressure control unit and the second pressure control unit in accordance with the pressure control program created by the pressure control program creation unit for the target sample (or another sample of the same type), In the corresponding time range, in normal mode, the components that have passed through the column are introduced into the detector and detected, and when the time range ends, the mode shifts to backflush mode, where the carrier gas flows backward through the column and remains in the column. The remaining components are discharged from the column inlet side. In this way, the backflush analysis intended by the analyst is achieved.

  As one embodiment of the gas chromatograph apparatus according to the present invention, the pressure control program creating means is configured to reduce the immediately preceding column inlet pressure to the first predetermined pressure during the time indicated by the indicating means. The pressure control programs for the first pressure control unit and the second pressure control unit can be created so that the column outlet pressure of the first pressure rises to the second predetermined pressure.

  Here, each of the first predetermined pressure and the second predetermined pressure may be set in advance by an analyst, or may be a default value appropriately determined in advance. However, as described above, depending on the type of detector used, it is necessary to impose restrictions on the column outlet pressure in order to protect the detector.

  Therefore, in the gas chromatograph apparatus according to the present invention, preferably, the pressure control program creation means is configured to limit the second predetermined pressure to an upper limit value or less according to the type of the detector specified in advance. Good. When the second predetermined pressure is the default value as described above, the default value may be determined to be equal to or lower than the upper limit value according to the type of detector, and the second predetermined pressure is set by the analyst. In this case, it is only necessary to prevent the setting exceeding the upper limit value according to the type of detector. This makes it possible to keep the column outlet pressure below the upper limit that can protect the detector without any consideration given by the analyst about restrictions on the column outlet pressure according to the type of detector used.

  Further, for example, when the analyst can rewrite the second predetermined pressure in the created pressure control program, a setting value exceeding the upper limit value corresponding to the type of the detector specified in advance is the second value. A warning message may be displayed when a predetermined pressure is input. Thereby, it is possible to prevent the analyst from inputting an inappropriate setting value.

  According to the gas chromatograph apparatus according to the present invention, an analyst himself / herself can detect an appropriate component, that is, a necessary component reliably without performing complicated operations such as creation / input of a pressure control program, and can quickly detect an unnecessary component. A backflush analysis can be performed such as Therefore, the burden on the analyst regarding the analysis work is reduced, the analysis efficiency is improved, and inappropriate execution of the analysis due to an input error of the analyst can be prevented. In addition, it is possible to avoid setting the column outlet pressure (detector inlet pressure) to an excessive pressure when setting the pressure control program input, thereby reliably protecting the detector.

The schematic block diagram of the gas chromatograph which is one Example of this invention. The flowchart which shows the execution procedure of the back flash analysis in the gas chromatograph of a present Example. The figure which shows an example of a backflush analysis setting screen. The figure which shows an example of the pressure control program for backflush analysis. The figure which shows an example of the screen of the state by which the pressure control program for backflush analysis was created automatically. The schematic flow-path block diagram for demonstrating backflush analysis. The figure which shows an example of the chromatogram acquired by normal analysis. The figure which shows the pressure control program creation and setting screen for the conventional backflush analysis.

  An embodiment of a gas chromatograph apparatus according to the present invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic configuration diagram of a gas chromatograph according to this embodiment.

  In FIG. 1, a carrier gas such as helium supplied from a cylinder (not shown) is adjusted to a predetermined flow rate by a flow rate control unit (mass flow controller) 3 provided in the carrier gas supply channel 2 and supplied to the sample vaporizing chamber 1. Is done. A part of the carrier gas is discharged to the outside through a split valve 5 provided in the split flow path 4 branched from the sample vaporizing chamber 1. A very small part of the carrier gas is discharged from the purge flow path 6 together with the gas that volatilizes from the septum attached to the upper part of the sample vaporizing chamber 1. Between the flow path resistance on the purge flow path 6 and the sample vaporizing chamber 1, a pressure sensor 7 for monitoring the pressure in the sample vaporizing chamber 1 is installed.

  Carrier gases other than those discharged through the purge flow path 6 and the split flow path 4 flow from the sample vaporization chamber 1 to the column 8 and are sent to the detector 10 via the backflush element 9. The backflush element 9 includes a pressure sensor that monitors the column outlet pressure, a flow rate valve that adjusts the flow rate of makeup gas such as helium, and the like so that the column outlet pressure monitored by the pressure sensor becomes the instructed target value. The flow rate of makeup gas supplied to the flow path connecting the outlet of the column 8 and the detector 10 is adjusted.

  The detection signal from the detector 10 is input to the data processing unit 15, and the data processing unit 15 creates a chromatogram based on the input signal, and performs qualitative analysis and quantitative analysis of each peak on the chromatogram. Or The control unit 11 controls the analysis operation of the entire gas chromatograph, and is connected to an input unit 13 and a display unit 14. The control unit 11 and the data processing unit 15 use a personal computer as a hardware resource, and the functions are realized by executing dedicated control / processing software installed in advance on the personal computer. be able to. In this case, the input unit 13 is a pointing device such as a keyboard or a mouse, and the display unit 14 is a liquid crystal display monitor or the like.

Next, characteristic operations in the gas chromatograph of this embodiment will be described with reference to FIGS. FIG. 2 is a flowchart showing the execution procedure of backflush analysis.
First, in order to create a pressure control program for backflush analysis, the analyst executes normal analysis of the target sample (step S1). During normal analysis, the column inlet pressure, that is, the pressure in the sample vaporizing chamber 1 detected by the pressure sensor 7 is set higher than the column outlet pressure, that is, the pressure detected by the pressure sensor in the backflush element 9. As a result, the carrier gas flows from the sample vaporizing chamber 1 to the column 8 as indicated by the solid line arrow in FIG. At this time, the control unit 11 monitors the pressure in the sample vaporizing chamber 1 with the pressure sensor 7 and controls the opening of the split valve 5 while maintaining the gas flow rate through the flow rate control unit 3 constant. The pressure in the vaporizing chamber 1 is maintained at a target value. That is, the control unit 11 maintains the gas pressure in the sample vaporizing chamber 1 constant by the back pressure control method.

  In this state, when a sample liquid is injected into the sample vaporizing chamber 1 from an injector (not shown), the sample is immediately vaporized and is introduced into the column 8 on the carrier gas flow. In the process of passing through the column 8, each component in the sample gas is separated in the time direction and detected by the detector 10. A detection signal from the detector 10 is processed by the data processing unit 15 to create a chromatogram as shown in FIG. 7, for example. In this example, a sample containing various components from a low boiling point component to a high boiling point component is analyzed. Generally, the low boiling point component passes through the column 8 first, and the high boiling point component is delayed when passing through the column 8. In FIG. 7, if the component required by the analyst is only the A part, the B part is an unnecessary component for the analyst. Therefore, this B part can be removed by backflushing.

  For this purpose, the analyst performs a predetermined operation on the input unit 13 and opens a backflush setting screen 30 as shown in FIG. The backflush setting screen 30 includes an analysis condition parameter setting area 31 in the upper stage, a chromatogram display area 32 in the middle stage, and a pressure control program setting area 33 in the lower stage. In the analysis condition parameter setting area 31, set values such as column dimensions, gas flow rates and pressures of the respective parts are displayed, and a part thereof can be changed. Among these set values, “branch pressure” 312 corresponds to the column outlet pressure, and “pressure” 311 corresponds to the column inlet pressure. These pressures are all initial pressures at the start of analysis. The pressure control program setting area 33 is provided with a column inlet pressure pressure control program description column 331 on the right side and a column outlet pressure control program description column 332 on the left side. Numerical values of “pressure” 311 and “branch portion pressure” 312 in the analysis condition parameter setting area 31 are set in the first lines of the pressure control program description fields 331 and 332, respectively.

  The controller 11 displays the chromatogram 321 acquired in the previous normal analysis in the chromatogram display area 32 in the backflush setting screen 30 (step S2). In addition, an arrow-shaped cursor 322 is superimposed on the chromatogram 321. The analyzer looks at the displayed chromatogram 321 and determines a necessary part and an unnecessary part. Then, the pointing device of the input unit 13 is operated to move the cursor 322 to a desired position, that is, the time position where component removal is to be started by backflushing, and the time position is designated by a double click operation (step S3). Here, for example, it is assumed that the vicinity of a time position of 5 minutes is instructed.

  In response to the above instruction, the pressure control program creating unit 12 in the control unit 11 first sets the instructed time position as a boundary of transition from the normal mode to the backflush mode, and a time range before that (0 to 5 minutes). Is determined to be an unnecessary portion, and the subsequent time range (after 5 minutes) is determined to be an unnecessary portion. Then, each pressure control program is created so that the column inlet pressure is lowered to a predetermined pressure from the time of 5 minutes, while the column outlet pressure is raised to a predetermined pressure (step S4).

  Here, the rate of change in the column inlet pressure and the column outlet pressure when shifting from the normal mode to the backflush mode is the maximum value of the pressure change allowed in this apparatus (in this example, ± 400 [kPa / s]). To do. The column outlet pressure in the backflush mode is a maximum value of pressure determined in accordance with the type of the detector 10 (in this example, 100 [kPa]). Further, the column inlet pressure in the backflush mode is determined by calculation so that the gas flow velocity (or flow rate) obtained from the column outlet pressure and the column resistance (calculated from the column dimensions) becomes an appropriate value (in this example, 20). [kPa]). As a result, the pressure before and after the backflush start point and the rate of pressure change are determined respectively, so the time required for the pressure change is also obtained, and a pressure control program for defining the pressure change as shown in FIG. 4 is created. Numerical values representing the programs are displayed in the pressure control program description fields 331 and 332 in FIG. In other words, numerical values that had to be manually calculated and input by the analyst themselves are automatically set in the pressure control program description fields 331 and 332.

  Further, as shown in the chromatogram 321 in FIG. 5, the chromatogram of the time range 321a that is backflushed, that is, removed when the backflush analysis is executed according to the pressure control program is distinguished from the previous time range. It is displayed in different colors as possible. The analyst can see the display and immediately know whether or not the intended backflushing is performed.

Note that each value of the pressure control program shown in the pressure control program description fields 331 and 332 in FIG. 5 can be rewritten as appropriate by the analyst. However, even in such a case, rewriting exceeding the upper limit value of the column outlet pressure corresponding to the type of detector as described above should not be performed, or a pop-up display that calls attention when attempting such rewriting ( It is preferable to display a warning message or output a warning sound. Similarly, for rewriting of numerical values that cannot be backflushed, it is preferable that rewriting is disabled or a warning message display or warning sound is output.

  The column inlet pressure control program and the column outlet pressure control program created as described above are respectively stored in the storage device in the control unit 11 (step S6). For example, when the analyst continues to instruct execution of backflush analysis, the control unit 11 opens the split valve 5 so that the pressure value monitored by the pressure sensor 7 becomes the target pressure according to the pressure control program for the column inlet pressure. The degree of opening of the flow rate valve is controlled so that the pressure value monitored by the pressure sensor in the backflush element 9 becomes the target pressure in accordance with the pressure control program for the column outlet pressure. Thereby, as the analyst intended, the analysis is executed in the normal mode until 5 minutes have elapsed from the start of the analysis.

  Then, when 5 minutes have elapsed from the start of analysis, the column outlet pressure becomes higher than the column inlet pressure, so that the makeup gas introduced from the backflush element 9 and the column 8 as shown in FIG. The carrier gas remaining in the column flows back through the column 8. As a result, the sample gas remaining in the column 8 is pushed back to the sample vaporizing chamber 1 and discharged together with the gas remaining in the sample vaporizing chamber 1 through the split flow path 4. Thereby, unnecessary components can be quickly removed from the column 8 or the sample vaporizing chamber 1.

  In the above embodiment, control is performed such that the column inlet pressure is reduced and the column outlet pressure is increased during backflushing. However, the direction of the gas flowing in the column 8 is determined between the column outlet pressure and the column inlet pressure. Since it is determined only by the height, the relationship between the column outlet pressure and the column inlet pressure may be reversed by fixing one of the column inlet pressure or the column outlet pressure and changing only the other.

  Moreover, the said Example is only an example of this invention, and even if it changes suitably, amends, and is added in the range of the meaning of this invention, it is clear that it is included in the claim of this application.

DESCRIPTION OF SYMBOLS 1 ... Sample vaporization chamber 2 ... Carrier gas supply flow path 3 ... Flow control part 4 ... Split flow path 5 ... Split valve 6 ... Purge flow path 7 ... Pressure sensor 8 ... Column 9 ... Back-flush element 10 ... Detector 11 ... Control Section 12 ... Pressure control program creation section 13 ... Input section 14 ... Display section 15 ... Data processing section 30 ... Backflush setting screen 31 ... Analysis condition parameter setting area 32 ... Chromatogram display area 321 ... Chromatogram 321a ... Time range 322 ... Cursor 33 ... Pressure control program setting area 331, 332 ... Pressure control program description column

Claims (4)

A column, a first pressure control unit that controls the column inlet pressure, a second pressure control unit that controls the column outlet pressure, and a detector disposed downstream of the second pressure control unit. In gas chromatograph equipment,
a) display means for displaying a chromatogram obtained by normal analysis of the target sample;
b) instruction means for an analyst to instruct an arbitrary time on the chromatogram displayed on the display means;
c) an inlet pressure detecting means for detecting the column inlet pressure and an outlet pressure detecting means for detecting the column outlet pressure;
d) Based on the time indicated by the indicating means, the chromatogram is divided into a required part in the first half and an unnecessary part in the latter half, where the column inlet pressure exceeds the column outlet pressure and the unnecessary part has the column outlet pressure. Pressure control program creating means for creating and storing both a pressure control program for the first pressure control unit and a pressure control program for the second pressure control unit so as to exceed the column inlet pressure;
A gas chromatograph apparatus comprising:
The gas chromatograph apparatus according to claim 1,
The pressure control program creating means lowers the immediately preceding column inlet pressure to the first predetermined pressure while increasing the immediately preceding column outlet pressure to the second predetermined pressure at the time indicated by the indicating means. Thus, the gas chromatograph apparatus characterized by creating the pressure control program with respect to the 1st pressure control part and the 2nd pressure control part, respectively. A gas chromatograph apparatus according to claim 2,
The gas control apparatus according to claim 1, wherein the pressure control program creating means limits the second predetermined pressure to an upper limit value or less according to a type of the detector designated in advance. A gas chromatograph apparatus according to claim 2,
A gas chromatograph apparatus that displays a warning message when a set value exceeding an upper limit value corresponding to a type of the detector specified in advance is input as the second predetermined pressure.