JP2013044647A - Gas chromatography apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas chromatography apparatus capable of inexpensively protecting a column in a standby state.SOLUTION: The gas chromatography apparatus having a column for temporally separating respective components included in a gas sample introduced with a carrier gas and capable of switching and executing an analysis mode and a standby mode includes: a carrier gas passage 1; a column protection gas passage 2; a passage switching part 3 arranged among the carrier gas passage 1, the column protection gas passage 2 and a column 6 to introduce only either one of the carrier gas and column protection gas to the column 6; and a passage control part 21 for controlling the passage switching part 3 to introduce the carrier gas into the column 6 in the analysis mode and introduce the column protection gas into the column 6 in the standby mode.

Description

  The present invention relates to a gas chromatograph apparatus. In more detail, it is related with the control technique of a gas chromatograph apparatus.

  The gas chromatograph device is a device in which a gas sample is placed on a carrier gas and sent to a column, each component in the sample is temporally separated inside the column, and detected by a detector provided at the column outlet. Since the speed at which each component moves inside the column varies depending on the strength of the interaction between each component in the sample and the stationary phase inside the column, each component is separated in time. At this time, the flow rate of the carrier gas is set to a speed within an optimum flow rate range where components in the sample can be sufficiently separated and a sharp peak can be obtained. In many gas chromatograph apparatuses, helium gas having a wide optimum flow rate range and high safety is used as a carrier gas. Although it is inferior to helium gas in terms of safety, hydrogen gas having a wide optimum flow rate region may be used as the carrier gas, as is the case with helium gas.

  The speed at which the carrier gas and each component in the sample move inside the column varies depending on the temperature inside the column. Therefore, accurate analysis can only be performed after these have been stabilized. However, it takes a long time for the temperature inside the column to stabilize at a predetermined value after the apparatus is turned on. Therefore, even if there is time before the next analysis is completed after a certain analysis is completed, the temperature inside the column, etc. should be maintained in a standby state in which the temperature inside the column is stabilized at a predetermined value as in the analysis. Is common. Even in the standby state, the carrier gas is circulated through the column. This prevents the stationary phase in the column from being deteriorated by moisture or oxygen entering from the outside, or conversely, when the outlet side of the column is in a vacuum state, for example in the case of GC / MS, the stationary phase is This is to prevent outflow from the outlet.

  Thus, in the gas chromatograph apparatus, the carrier gas is circulated in the column even in the standby state to protect the column. However, if the same amount of carrier gas as in the measurement is circulated in the standby state, the running cost becomes high. In order to alleviate such a problem, for example, Patent Literature 1 proposes a gas chromatograph apparatus that reduces the flow rate of the carrier gas in a standby state.

JP 2000-304751 A

  If the gas chromatograph apparatus described in Patent Document 1 is used, the flow rate of the carrier gas in the standby state can be suppressed. However, even if the flow rate is suppressed, if the standby state continues for a long time, the consumption amount of the carrier gas increases. In particular, helium gas used as a carrier gas for many gas chromatograph apparatuses has been increasing in price in recent years, and there is a need for a device that suppresses the running cost of the apparatus.

  The problem to be solved by the present invention is to provide a gas chromatograph apparatus and a gas chromatograph mass spectrometer capable of protecting a column at a low cost in a standby state.

In order to solve the above-mentioned problems, the present invention has an analysis mode in which a column for temporally separating components contained in a gas sample introduced on a carrier gas is separated and the analysis of the gas sample is performed. And a gas chromatograph device that can be executed by switching between a standby mode in which analysis is not performed,
a) a carrier gas flow path for introducing the carrier gas into the column;
b) a column protection gas flow path for introducing a column protection gas different from the carrier gas into the column;
c) Channel switching provided between the carrier gas channel and the column protective gas channel and the column so that only one of the carrier gas and the column protective gas is introduced into the column. And
d) a flow path control unit that controls the flow path switching unit so as to introduce the carrier gas into the column in the analysis mode and to introduce the column protective gas into the column in the standby mode. And

In the gas chromatograph apparatus according to the present invention, a gas that is less expensive than the gas used as the carrier gas can be used as the column protective gas. For example, when the carrier gas is helium gas, nitrogen gas, argon gas, hydrogen gas, or the like may be used as the column protective gas to protect the column in the standby mode (standby state). As a result, the column can be protected at a lower cost than the conventional chromatographic apparatus in which the column is protected using helium gas in the standby state. Further, when the carrier gas is hydrogen gas, nitrogen gas, argon gas, or the like may be used as the column protective gas.
Furthermore, the column protective gas may be the same type of gas as the carrier gas and has a low purity.

The gas chromatograph apparatus according to the present invention further includes
e) a flow controller having at least one control mode among a constant linear velocity mode, a constant flow rate mode, and a constant pressure mode as a mode for controlling the flow state of the gas introduced into the column;
f) At the time of transition from the analysis mode to the standby mode, the gas introduced into the column is changed from the carrier gas to the column protective gas without changing the control mode by the flow controller and the parameters related to the mode. A determination unit that estimates at least one value of the linear velocity, the flow rate of the column protective gas, and the pressure of the column protective gas, and determines whether the estimated value is within a preset range;
g) When the determination unit determines that the estimated value is not within the range, a change instruction unit that prompts the user to change a control mode of the flow controller and / or a parameter related to the mode by a predetermined method. It is desirable to provide.

When the type of gas is different, characteristics such as viscosity change. Therefore, even if the control mode by the flow controller is continued as it is after the gas is switched and the parameters related to the mode remain the same, the carrier gas is introduced into the column and the column protective gas is introduced into the column. Then, the values of parameters (gas flow rate, gas pressure, etc.) controlled by the gas introduction device are different. For example, when the gas flow state is controlled in the constant linear velocity mode, when switching the gas to be introduced into the column from a highly viscous gas to a less viscous gas, it is necessary to reduce the flow rate of the gas flowing through the column. There is. In such a case, there is a possibility that the lower limit value of the flow rate that can be controlled by the device of the gas introduction unit will fall below and the gas flow state cannot be controlled.
In the gas chromatograph apparatus according to the present invention, by providing the above configuration, it is possible to prevent the flow rate and pressure of the gas from being uncontrollable when shifting from the analysis mode to the standby mode.

The gas chromatograph apparatus according to the present invention further includes
h) Upon transition from the standby mode to the analysis mode, after a predetermined time has elapsed since the switching of the flow path switching unit, the replacement of the column protective gas with the carrier gas has been completed by a predetermined method. It is desirable to provide a notification unit that notifies the user.

When the flow path control unit switches the flow path switching unit when shifting from the standby mode to the analysis mode, it takes a certain time until the gas flowing in the column is replaced with the carrier gas from the column protective gas. . If the analysis is started before the replacement of the gas flowing through the column is completed, the measurement accuracy is lowered. On the other hand, waiting for gas replacement completion for a longer time than necessary results in time loss and increased running costs.
By providing the above configuration, it is possible to wait for the start of analysis for a necessary and sufficient time related to gas replacement. The length of the predetermined time can be determined by measuring in advance the time required until the gas flowing in the column is replaced with the carrier gas.

The gas chromatograph apparatus according to the present invention, or
i) a mass spectrometer capable of introducing a standard substance for mass spectrometry into the interior thereof;
j) When shifting from the standby mode to the analysis mode, mass analysis of the standard material and the column protective gas is performed, and the intensity of mass peaks of ions generated from the standard material and the ions generated from the column protective gas are analyzed. You may make it provide the peak comparison part which compares the intensity | strength of a mass peak.

  In the above configuration, after the flow path control unit switches the flow path switching unit, a certain amount of standard substance is continuously introduced into the mass spectrometer until the transition from the standby mode to the analysis mode is completed. The intensity of the mass peak of ions generated from the standard substance is always constant, whereas the intensity of the mass peak of ions generated from the column protective gas decreases as the replacement of the gas flowing inside the column proceeds. Therefore, by comparing the intensity of the mass peak of the standard substance and the intensity of the mass peak of the column protective gas, it can be confirmed that the gas flowing inside the column is replaced with the carrier gas.

  In order to prevent the column from deteriorating during the standby mode, the gas chromatograph apparatus according to the present invention also protects the gas by flowing through the column as in the conventional case. However, in the gas chromatograph apparatus according to the present invention, a gas that is less expensive than the carrier gas can be used as the protective gas that flows through the column in the standby mode. For example, when the carrier gas is helium gas, nitrogen gas, argon gas, hydrogen gas, or the like is used as the column protective gas to protect the column in the standby state. As a result, the column can be protected at a lower cost than the conventional chromatographic apparatus in which the column is protected using helium gas in the standby state.

The figure explaining the principal part structure of one Example of the gas chromatograph apparatus which concerns on this invention. The figure explaining an example of the transfer procedure from analysis mode to standby mode. The figure explaining an example of the return procedure from standby mode to analysis mode. The figure explaining the principal part structure of another Example of the gas chromatograph apparatus which concerns on this invention. The figure explaining another example of the return procedure from standby mode to analysis mode. The figure which shows the calculation result of the gas flow volume in the case of controlling a flow state in pressure constant mode.

  An embodiment of a gas chromatograph apparatus according to the present invention will be described below with reference to FIG. The gas chromatograph apparatus according to the present embodiment is a GC / MS including a mass spectrometer as a detection unit.

The GC / MS according to the present embodiment includes a carrier gas flow channel 1, a column protective gas flow channel 2, a flow channel switching unit 3 that allows only one of the two flow channels to communicate with a subsequent flow channel, and flow channel switching. A flow controller (AFC) 4 that is positioned downstream of the unit 3 to control the gas flow state, a sample injection unit 5 that injects a gas sample, a capillary column 6, and a mass spectrometer disposed at the outlet end of the capillary column 6 11 is provided. The capillary column 6 is arranged in a column oven 7 provided with a heater 8.
The GC / MS according to the present embodiment further includes a device control unit 10 that operates each of the above-described components, and a computer 20 that gives an instruction to the device control unit 10. The computer 20 equipped with a required program includes a mode switching unit 21, a data processing unit 22, a determination unit 23, a change instruction unit 24, a mode information storage unit 25, and a transition time storage unit 26. Details of each part of the computer 20 will be described later. An input unit 30 and a display unit 31 are connected to the computer 20.

  First, the operation in the analysis mode will be described. In the GC / MS of the present embodiment, helium gas is used as a carrier gas, and nitrogen gas is used as a column protective gas. The instrument control unit 10 controls the flow path switching unit 3 to introduce helium gas into the capillary column 6 in accordance with an instruction from the mode switching unit 21 and injects a gas sample from the sample injection unit 5 at a predetermined timing. Further, the flow controller 4 controls in a constant pressure mode so that the injection pressure of helium gas at the inlet end of the capillary column 6 is maintained at 100 kPa.

  Each component in the sample introduced into the capillary column 6 in the column oven 7 on the helium gas is temporally separated inside the capillary column 6 and sequentially reaches the outlet end. Each component that has reached the outlet end is ionized by the ionization unit 111 of the mass spectrometer 11, passes through the mass separation unit 112, and is then detected by the ion detector 113. A detection signal obtained by the ion detector 113 is digitally converted by an A / D converter (ADC) 15 and then sent to a data processing unit 22 in the computer 20.

Next, the transition from the analysis mode to the standby mode will be described with reference to FIG. When the user instructs the transition from the analysis mode to the standby mode through the input unit 30, the mode switching unit 21 sets the device control parameters (the type of carrier gas, the control mode and control parameters by the flow controller 4, etc.) in the analysis mode. The information is stored in the information storage unit 25 (step S1).
In addition, the determination unit 23 determines the control mode (pressure constant mode) and control parameters (injection) of the flow controller 4 based on preset conditions (gas viscosity, capillary column inner diameter and length, column oven temperature, etc.). Without changing the pressure (100 kPa), the gas flow rate and linear velocity when the gas introduced into the column is changed from helium gas to nitrogen gas are estimated (step S2). Then, it is determined whether the estimated value is within a preset value range (a flow rate range that can be controlled by a gas supply device, a linear velocity range that can protect the column, or a flow rate range that is acceptable by the mass spectrometer 11). (Step S3). When the estimated value is outside the set value range, the determination unit 23 displays a screen on the display unit 31 that prompts the user to change the control mode and / or control parameter of the flow controller 4. In response to this, when the user changes the control mode and / or the control parameter (step S31), the determination unit 23 calculates the estimated value again and performs the determination. This is repeated until the estimated value by the determination unit 23 falls within a preset value range. Since the present embodiment is GC / MS, one of the preset value ranges includes the “flow range allowable in the mass spectrometer 11”, but this varies depending on the type of detector used.

  When the setting of the control mode and control parameters of the flow controller 4 is completed, the mode switching unit 21 operates the flow channel switching unit 3 through the device control unit 10, and the flow channel communicating with the capillary column 6 is changed from the carrier gas flow channel 1 to the column. Change to the protective gas channel 2 (step S4). Thereby, the gas introduced into the capillary column 6 is changed from helium gas to nitrogen gas, and the transition to the standby mode is completed. When the standby mode is entered, the gas flowing through the capillary column is gradually replaced by nitrogen gas from helium gas.

  In the GC / MS of the present embodiment, the capillary column can be protected by nitrogen gas during the standby mode, so that it is lower than the conventional gas chromatograph apparatus in which helium gas is circulated even in the standby mode as in the prior art. The column can be protected at a cost.

  Next, the return from the standby mode to the analysis mode will be described with reference to FIG. At the time when the standby mode is to be ended, nitrogen gas is flowing through the capillary column 6. Therefore, before starting the analysis of the gas sample, it is necessary to replace the nitrogen gas flowing through the capillary column 6 with helium gas as the carrier gas.

  First, the mode switching unit 21 reads out device control parameters for the analysis mode from the mode information storage unit 25 (step S5). The mode switching unit 21 sets parameters for each device such as the flow controller 4 through the device control unit 10 based on the read device control parameters for the analysis mode. Further, the flow path switching unit 3 is operated to return the flow path communicating with the capillary column 6 from the column protective gas flow path 2 to the carrier gas flow path 1 (step S6).

  Subsequently, the mode switching unit 21 reads out the gas replacement time required to replace the gas in the capillary column 6 from nitrogen gas to helium gas from the transition time storage unit 26, and waits for that time (step S7). In the transition time storage unit 26, the gas replacement time is measured by a preliminary experiment and stored in advance.

  After the gas replacement time has elapsed, the mode switching unit 21 displays on the screen of the display unit 31 that the gas flowing through the capillary column 6 has been replaced with helium gas and the sample can be analyzed. And notify the user. Thus, the return to the analysis mode is completed.

  The above example is a GC / MS using a mass spectrometer as a detector, but even when using a detector such as a flame ionization detector (FID), the transition from the analysis mode to the standby mode is performed by the same procedure, and It is possible to return from the standby mode to the analysis mode. The mode switching unit 21 according to the present embodiment functions as a flow path control unit and a notification unit while performing mode switching and the like.

  Next, when returning from the standby mode to the analysis mode, another embodiment is used to confirm that the gas in the capillary column has been replaced with nitrogen gas from helium gas and to complete the return to the analysis mode. Will be described with reference to FIGS. 4 and 5. FIG.

  The apparatus configuration in this case is shown in FIG. The GC / MS includes a standard material injection unit 9 for injecting PFTBA, which is a standard material used for mass spectrometry, at a position before the ionization unit 111. In addition, the computer 20 includes a peak comparison unit 27 that performs operations described later. Since the configuration other than these is the same as that of the GC / MS shown in FIG. 1, the same reference numerals are given and description thereof is omitted. Further, the standby mode transition step (step S1 to step S4) and a part of the analysis mode return step (step S5 and step S6) in this embodiment are the same as those in the above embodiment, and thus description thereof is omitted. .

In the configuration shown in FIG. 4, after performing step S6 described above, the standard substance injection unit 9 continues to inject a constant amount of PFTBA according to the instruction of the mode switching unit 21 (step S71). Thereby, in addition to nitrogen gas and helium gas, PFTBA is introduce | transduced into the ionization part 111 of a mass spectrometer, and each is ionized. These ions are detected by the ion detector 113 after passing through the mass separator 112. The detection signal obtained by the ion detector 113 is A / D converted by the A / D converter 15, then spectralized by the data processing unit 22 and displayed on the display unit 31 (step S 72).
At this time, the peak comparison unit 27 compares the intensities of ions generated from the nitrogen gas and PFTBA (step S73). When the ratio of these peak intensities becomes equal to or less than a preset value, it is determined that the gas flowing in the capillary column 6 has been replaced with nitrogen gas from helium gas.
In response to this, the mode switching unit 21 displays on the screen of the display unit 31 that the sample can be analyzed and notifies the user. In addition, PFTBA in this Example is given as an example of a standard substance used for mass spectrometry, and naturally, the type of standard substance is not limited to this.

The above-described embodiments are merely examples, and can be appropriately changed or modified in accordance with the spirit of the present invention.
For example, in the above embodiment, the case where the carrier gas is helium gas and the column protective gas is nitrogen gas has been described as an example. However, the present invention is not limited to this combination, and the column protective gas is less expensive than the carrier gas. Any combination may be used. At this time, the column protective gas does not necessarily need to be a different type of gas from the carrier gas, and may be the same type of gas having a lower purity than the carrier gas.
Even if the gas is relatively expensive, depending on the characteristics of the column used and the viscosity of the gas, the flow rate of the gas flowing through the column may be suppressed, and the column may be protected at low cost. An example is shown in FIG.

  FIG. 6 shows various gases (hydrogen) when the flow controller controls the gas flow state in the constant pressure mode (inlet pressure 100 kPa) in the GC / MS apparatus and introduces the gas into a capillary column having an inner diameter of 0.25 mm. It is the result of calculating the flow rates of gas, helium gas, nitrogen gas, and argon gas. 6 (a) shows the results for a capillary column with a length of 30 m, and FIG. 6 (b) shows the results for a capillary column with a length of 10 m. The capillary column temperature is 40 ° C. and 100 ° C. The calculation results for each case are shown. Under these conditions, when argon gas is used, the gas itself is relatively expensive, but the column can be protected at a low cost by reducing the flow rate.

In the above embodiment, the flow controller 4 controls the gas flow state in the constant pressure mode. However, the flow controller 4 controls the gas flow state in the constant flow rate mode or the constant linear velocity mode. Also good. In this case, the determination unit 23 calculates an estimated value for a value other than the parameter controlled at a constant value, and determines whether the value is within the set value range.
In addition, device control parameters (types of carrier gas, control mode and control parameters by the flow controller 4, etc.) for a plurality of analysis modes and device control parameters for a plurality of standby modes are stored as method files in the mode information storage unit 25 in advance. In addition, the user selects a desired mode from these through the input unit 30 and causes the mode switching unit 21 to execute the mode switching (the transition from the analysis mode to the standby mode, and from the standby mode to the analysis mode). May be performed. Thereby, at the time of shifting from the analysis mode to the standby mode, it is not necessary for the determination unit 23 to perform estimation and determination each time, and the efficiency of mode switching can be increased. Further, in this case, when returning from the standby mode to the analysis mode, it is possible to return to the analysis mode of the instrument control parameter different from the previous analysis mode.

  In addition, in the said Example, although all demonstrated the gas chromatograph apparatus which uses a capillary column as an example, this invention is applicable also to the gas chromatograph apparatus which uses a packed column.

DESCRIPTION OF SYMBOLS 1 ... Carrier gas flow path 2 ... Column protection gas flow path 3 ... Flow path switching part 4 ... Flow controller 5 ... Sample injection part 6 ... Capillary column 7 ... Column oven 8 ... Heater 9 ... Standard substance injection part 10 ... Instrument control part DESCRIPTION OF SYMBOLS 11 ... Mass spectrometer 20 ... Computer 21 ... Mode switching part 22 ... Data processing part 23 ... Determination part 24 ... Change instruction | indication part 25 ... Mode information storage part 26 ... Transition time storage part 27 ... Peak comparison part 30 ... Input part 31 ... Display unit 111 ... Ionization unit 112 ... Mass separation unit 113 ... Ion detector

Claims (4)

It has a column that temporally separates each component contained in a gas sample introduced on a carrier gas, and can be executed by switching between an analysis mode for performing the analysis of the gas sample and a standby mode for not performing the analysis A gas chromatograph device comprising:
a) a carrier gas flow path for introducing the carrier gas into the column;
b) a column protection gas flow path for introducing a column protection gas different from the carrier gas into the column;
c) Channel switching provided between the carrier gas channel and the column protective gas channel and the column so that only one of the carrier gas and the column protective gas is introduced into the column. And
d) a flow path control unit that controls the flow path switching unit so as to introduce the carrier gas into the column in the analysis mode and to introduce the column protective gas into the column in the standby mode. Gas chromatograph device. e) a flow controller having at least one control mode among a constant linear velocity mode, a constant flow rate mode, and a constant pressure mode as a mode for controlling the flow state of the gas introduced into the column;
f) At the time of transition from the analysis mode to the standby mode, the gas introduced into the column is changed from the carrier gas to the column protective gas without changing the control mode by the flow controller and the parameters related to the mode. A determination unit that estimates at least one value of the linear velocity, the flow rate of the column protective gas, and the pressure of the column protective gas, and determines whether the estimated value is within a preset range;
g) When the determination unit determines that the estimated value is not within the range, a change instruction unit that prompts the user to change a control mode of the flow controller and / or a parameter related to the mode by a predetermined method. The gas chromatograph apparatus according to claim 1, comprising: h) Upon transition from the standby mode to the analysis mode, after a predetermined time has elapsed since the switching of the flow path switching unit, the replacement of the column protective gas with the carrier gas has been completed by a predetermined method. The gas chromatograph apparatus according to claim 1, further comprising a notification unit that notifies the user of the above. i) a mass spectrometer capable of introducing a standard substance for mass spectrometry into the interior thereof;
j) When shifting from the standby mode to the analysis mode, mass analysis of the standard material and the column protective gas is performed, and the intensity of mass peaks of ions generated from the standard material and the ions generated from the column protective gas are analyzed. The gas chromatograph according to claim 1, further comprising a peak comparison unit that compares the intensity of the mass peak.

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