Sample introduction method and sample introduction device

Abstract

One aspect of the sample introduction method according to the present invention is a sample introduction method for collecting and injecting a sample by an SPME method using an SPME Arrow, the sample introduction method comprising: an adsorption step (S3) for adsorbing a target component in the sample to an adsorption unit of the SPME Arrow; an exposure step (S4) for exposing the adsorption part of the SPME Arrow after the adsorption step to a dry inert gas atmosphere for a predetermined time; and an injection step (S5) for heating the adsorption part of the SPME Arrow after the exposure step, thereby separating the target component from the adsorption part and introducing the target component into an analysis device.

Description

Technical Field

[0001] This invention relates to a sample introduction method and apparatus for introducing samples into analytical apparatus, primarily gas chromatography apparatus, and more specifically, to a sample introduction method and apparatus using solid-phase microextraction. Background Technology

[0002] When analyzing low-concentration components in a sample using a gas chromatography apparatus (GC apparatus) that includes a gas chromatography-mass spectrometry system (hereinafter referred to as a "GC apparatus"), the target component needs to be concentrated before being introduced into the GC apparatus. Solid phase microextraction (SPME) is one of the widely used sample introduction methods primarily for this purpose.

[0003] In conventional SPME methods, firstly, a thin, elongated fiber made of fused silica is inserted into a container containing a sample (liquid or solid). An adsorbent (liquid phase) coated on the fiber surface adsorbs the target component in the gaseous phase that evaporates from the sample. Then, the fiber is inserted into the vaporization chamber of a GC apparatus and heated, causing the target component to desorb from the adsorbent and be carried on a carrier gas and introduced into the chromatographic column for analysis (see Patent Document 1). However, conventional SPME fibers of this type have difficulty increasing the amount of components that can be adsorbed by the adsorbent, posing a challenge in detection sensitivity. Furthermore, the fiber itself suffers from low mechanical durability.

[0004] In response, devices known as SPME Arrows (arrow-shaped solid-phase microextraction) have been developed in recent years (see Non-Patent Literature 1). SPME Arrows utilize a stainless steel rod with a larger outer diameter than conventional fibers, and the surface of this rod retains a large amount of adsorbent. Therefore, in SPME methods using SPME Arrows, compared to methods using conventional SPME fibers, the adsorption of target components can be increased, resulting in higher concentrations and enabling highly sensitive analysis.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2007-47156

[0008] Non-patent literature

[0009] Non-Patent Literature 1: Kawamura, “Analysis of Aroma Component Distribution Map Using SPME Arrow-GC-MS Analysis”, Journal of the Society for Odor and Fragrance Environment, Vol. 52, No. 4, 2021 Summary of the Invention

[0010] The problem the invention aims to solve

[0011] As disclosed in Non-Patent Document 1, the inventors are advancing research on using SPME Arrow for GC analysis of odor components and other substances in samples. To accurately analyze odors, it is often necessary to detect trace amounts of components in samples with high quantification; SPME Arrow, capable of concentrating high concentrations of components, is a very useful device. However, it has been found that during repeated experiments, depending on the type of sample, the type of component, and the GC analysis conditions, problems may arise such as peak shape collapse leading to reduced quantitative accuracy, or peak retention time shifts leading to inaccurate identification.

[0012] This invention was made to solve such problems, and its main objective is to provide a sample introduction method and apparatus that can improve the quantitative and identification performance of target components in analysis using the SPME method with SPME Arrow.

[0013] Solution for solving the problem

[0014] One embodiment of the sample introduction method involved in this invention is a sample introduction method for collecting and injecting samples using a SPME Arrow via solid-phase microextraction, which has the following characteristics:

[0015] The adsorption process causes the target component in the sample to be adsorbed onto the adsorption section of the SPME Arrow.

[0016] The exposure process involves exposing the adsorption section of the SPME Arrow after the adsorption process to a dry, inert gas atmosphere for a specified time; and

[0017] In the injection process, the target component is detached from the adsorption section of the SPME Arrow after the exposure process by heating the adsorption section and introduced into the analytical device.

[0018] Furthermore, one embodiment of the sample introduction device involved in this invention is a sample introduction device that uses an SPME Arrow to collect and inject samples into an analytical apparatus via solid-phase microextraction, comprising:

[0019] The adsorption treatment section inserts the adsorption section of the SPME Arrow into a container containing the sample, so that the target component in the sample is adsorbed onto the adsorption section.

[0020] The SPME Arrow's adsorption section, after the adsorption of components in the adsorption treatment section is completed, is exposed to a dry, inert gas atmosphere for a predetermined time; and

[0021] The moving part moves the SPME Arrow between the adsorption treatment section and the exposure treatment section, and between the exposure treatment section and the component introduction position where the target component adsorbed on the adsorption section is introduced into the analytical device.

[0022] Invention Effects

[0023] The inventors repeatedly analyzed various samples and components under various analytical conditions and discovered that the main reason for the aforementioned peak shape collapse and retention time shift is that a large amount of solvent (aqueous or organic solvent) contained in the sample is adsorbed onto the adsorption section of the SPME Arrow and introduced into the analytical apparatus (GC apparatus). In response, the sample introduction method and apparatus of the present invention, as described above, can remove at least a portion of the solvent that was simultaneously adsorbed onto the adsorption section of the SPME Arrow when the target component in the sample was adsorbed, from the adsorption section before performing analysis.

[0024] Therefore, according to the above-described scheme of the sample introduction method and apparatus of the present invention, for example, during GC analysis, the influence of solvents such as water or organic solvents originating from the sample can be reduced, and the collapse of the chromatographic peak shape and the shift in retention time of the target component can be suppressed. Thus, the quantitative and identification performance of the target component can be improved. Attached Figure Description

[0025] Figure 1 This is a flowchart illustrating an example of the operation / processing procedure of the SPME method as an embodiment of the present invention.

[0026] Figure 2 This is a schematic structural diagram of an example of a sample introduction device for implementing the SPME method of this embodiment.

[0027] Figure 3 yes Figure 2 A schematic diagram of the aging / solvent purging unit in the diagram.

[0028] Figure 4 This is an example of a chromatogram obtained by GC analysis using the conventional SPME method. Detailed Implementation

[0029] [The reasons for the problems that arose in previous SPME methods]

[0030] As described above, the SPME Arrow retains a large amount of adsorbent (liquid phase) on its surface. Therefore, in SPME methods using the SPME Arrow, not only the target component contained in the sample, but also the solvent contained in the sample is largely adsorbed onto the adsorbent. Then, if the adsorption section of the SPME Arrow is heated in the vaporization chamber of the GC apparatus, a large amount of solvent is introduced into the chromatographic column along with a high concentration of the target component. For example, if the SPME Arrow is used to collect components from an aqueous sample, a large amount of water contained in the sample as a solvent will also be captured by the adsorbent.

[0031] Figure 4 This is an example of a total ion chromatogram (TIC) obtained by GC / MS analysis of an aqueous sample using the conventional SPME method. Additionally, in Figure 4 For reference, the extracted ion chromatogram at m / z 18 is also shown in the figure.

[0032] In mass spectrometry, the water-derived peak mainly appears at m / z 18. In typical GC / MS analysis, the lower limit of m / z (mass-to-charge ratio) is usually set around 35, therefore the water-derived peak is not observable on the chromatogram. However, if the lower limit of m / z is set to 17 for analysis, then... Figure 4 As shown, a large peak originating from water is observed on the chromatogram (total ion chromatogram: TIC). This water-originating peak is observed over a wide time range, and peaks of components with retention times within this range overlap with the water-originating peak, inevitably causing peak waveform collapse. Furthermore, peaks of other components appearing immediately after the large water-originating peak are prone to retention time shifts due to the large amount of water retained in the column.

[0033] The influence of solvent on the adsorbent that is heavily adsorbed onto the SPME Arrow in GC analysis has generally been unknown, and no countermeasures have been taken to mitigate this influence. In response, the inventors devised a method to mitigate the influence of solvent by performing a process of removing the solvent from the time the component is collected using the SPME Arrow until it is introduced into the GC apparatus, in a way that minimizes the impact on the component adsorbed onto the adsorbent. This invention thus completes the present invention.

[0034] The SPME method and the apparatus for carrying out the method, which are embodiments of the sample introduction method involved in this invention, will be described with reference to the accompanying drawings.

[0035] [Structure of the apparatus for implementing the SPME method of the present invention]

[0036] Figure 1 This is a flowchart illustrating an example of the operation / processing procedure in the SPME method of this embodiment. Figure 2This is a schematic diagram of an example of a sample introduction device for performing the SPME method. Figure 3 yes Figure 2 A schematic diagram of the aging / solvent purging unit in the diagram.

[0037] Figure 2 The sample introduction device shown is similar to, for example, the "AOC-6000Plus" automated sample introduction system manufactured by Shimadzu Corporation, which selectively collects multiple pre-prepared samples and automatically injects them into the GC device. This sample introduction device includes an SPME Arrow 1, an SPME Arrow drive unit 2, an aging / solvent purging unit 3, and a sample acquisition unit 4. Figure 2 The GC device 5 includes a vaporization chamber 50, a chromatographic column 51, and a detection unit 52. The GC device 5 itself is not included in the sample introduction device, but the vaporization chamber 50 has the function of introducing the target component into the chromatographic column 51 together with the sample introduction device.

[0038] SPME Arrow 1 is a commercially available product, such as that described in Non-Patent Document 1, which includes a retainer 10, a plunger 11, a cylindrical needle 12, a rod 13 with an arrowhead-shaped tip, and an adsorption portion 14 formed on a part of the surface of the rod 13. Figure 2 This diagram shows the rod 13 protruding from the needle 12, which can be retracted into the needle 12 via the plunger 11. Regarding the dimensions of the SPME Arrow 1 and the type of adsorbent (liquid phase) held in the adsorption section 14, appropriate dimensions and types can be used depending on the type of sample being analyzed.

[0039] The SPME Arrow drive unit 2 includes a main body moving part 20 and a plunger drive part 21. The main body moving part 20 is used to move the SPME Arrow 1 between the aging / solvent purging unit 3, the sample collection unit 4, and the vaporization chamber 50. The plunger drive part 21 is used to push or pull the plunger 11 of the SPME Arrow 1 to extend or retract the rod 13 from the needle 12.

[0040] like Figure 3 As shown, the aging / solvent purging unit 3 includes: a housing 30 having a recess 33 with space sufficient to accommodate the rod 13 of the SPME Arrow 1, and a heating / cooling section 34 for heating / cooling the housing 30. The housing 30 has a gas supply opening 31 and a gas discharge opening 32. Although not shown, dry inert gas (He, N2, etc.) is supplied to the recess 33 through a pipe connected to the gas supply opening 31, and the inert gas, after flowing within the recess 33, is discharged to the outside through a pipe connected to the gas discharge opening 32.

[0041] [An example of the operation / processing procedure of the SPME method of the present invention]

[0042] according to Figure 1 This describes the steps from sample collection to analysis. Additionally, the following instructions will use... Figure 2 The sample introduction device shown is designed to operate automatically, but it goes without saying that some of its operations can be replaced by manual operations by the operator.

[0043] Before analysis, the operator prepares an SPME Arrow suitable for the type (size and adsorbent) of analysis and installs it in the designated position on the sample introduction device (step S1). Alternatively, if the SPME Arrow used in the previously performed analysis is still used, step S1 is omitted.

[0044] Next, if the analysis is initiated via an operation unit (not shown), the aging / solvent purging unit 3 conditions the SPME Arrow 1 (step S2). Specifically, the main body moving unit 20 moves the SPME Arrow 1 into the recess 33 of the aging / solvent purging unit 3, and the plunger driving unit 21 pushes the plunger 11 in, exposing the rod 13 (adsorption section 14). The heating and cooling unit 34 heats the adsorption section 14 to a predetermined temperature (e.g., 200°C or higher) via the housing 30 and maintains this temperature for a certain period of time. As a result, the heated adsorption section 14 is exposed to a dry, inert gas atmosphere, and the various components adsorbed in the adsorption section 14 evaporate and are removed. That is, the adsorption section 14 is purified. The components removed at this time are mainly those adsorbed in the adsorption section 14 during the last analysis and which did not detach by thermal desorption, or impurities that adhered to the adsorption section 14 during the storage of the SPME Arrow 1.

[0045] After aging, the sample is collected in the sample collection unit 4 (step S3). Specifically, the rod 13 of SPMEArrow 1 is temporarily housed inside the needle 12, and the main body moving part 20 moves the SPME Arrow 1 to a predetermined position in the sample collection unit 4. Then, the plunger drive part 21 pushes the plunger 11 in, inserting the front end of the rod 13 (adsorption part 14) into the upper space of a prepared sample vial. The sample vial contains a liquid or solid sample. The sample vial is heated to an appropriate temperature (e.g., 60°C) and stirred at a predetermined rotation speed for a predetermined time. This promotes the evaporation of components from the sample, and the upper space of the sample vial is filled with the target component in a gaseous state. The target component in the gaseous state is adsorbed into the adsorption part 14.

[0046] In step S3, the upper space inside the sample vial contains not only a large amount of the target component, but also a large amount of solvent from the sample (in the case of liquid samples). Therefore, this solvent will also be adsorbed onto the adsorption section 14. Therefore, in order to remove this solvent, the adsorption section 14 of the SPME Arrow 1 is exposed to an atmosphere in which dry inert gas flows for a specified time (step S4).

[0047] Specifically, the rod 13 of SPME Arrow 1 is temporarily housed within the needle 12, and the main body moving part 20 moves SPME Arrow 1 into the recess 33 of the aging / solvent purging unit 3. The plunger driving part 21 pushes in the plunger 11 to expose the rod 13 (adsorption part 14). The heating and cooling part 34 maintains the adsorption part 14 at an appropriate temperature (e.g., around 30°C to 40°C) for a certain period of time via the housing 30, ensuring that the target component does not volatilize. Since the adsorption part 14 is exposed to a dry, inert gas atmosphere, the water and organic solvents adsorbed in the adsorption part 14 evaporate and are removed.

[0048] Of course, the temperature at this point is much lower than the aging temperature in step S2, and also sufficiently lower than the temperature used for thermal desorption in step S5 described later. Therefore, it has almost no effect on the target component adsorbed in the adsorption section 14. Furthermore, since the housing 33 of the aging / solvent purging unit 3 is heated to a high temperature during aging, it cannot be cooled to approximately 30°C to 40°C by natural heat dissipation during the processing in step S3. Therefore, the heating-cooling section 34 preferably cools the housing 33, etc., to approximately 30°C to 40°C after aging. Alternatively, cooling can be performed without the heating-cooling section 34, and the temperature can be lowered by natural heat dissipation.

[0049] After the solvent removal process in step S4 is performed for a specified time, thermal desorption is carried out in the vaporization chamber 50 of the GC apparatus 5. The target components adsorbed on the adsorption section 14 of the SPME Arrow 1 are introduced into the chromatographic column 51 by the carrier gas flow. Then, the various target components are separated in the time direction during their passage through the chromatographic column 51 and are detected in the detection section 52 (step S5).

[0050] Specifically, the rod 13 of SPME Arrow 1 is temporarily retracted into the needle 12, and the main moving part 20 moves SPME Arrow 1 to the component introduction position above the vaporization chamber 50 of the GC device 5. The plunger drive part 21 pushes the plunger 11 in, so that the tip of the rod 13 passes through the injection pad at the top of the vaporization chamber 50 and inserts the adsorption part 14 into the vaporization chamber 50. At this time, since the vaporization chamber 50 is heated to a specified temperature (usually above 200°C), if the adsorption part 14 is inserted into the vaporization chamber 50, the various target components adsorbed on the adsorption part 14 will evaporate in a short time. The evaporated target components, carried by the carrier gas, are introduced into the chromatographic column 51 almost simultaneously.

[0051] Because the carrier gas flow rate is low, the concentration of the target component in the gas is higher than that during sample collection in step S3. That is, the target component is concentrated to a high concentration and introduced into the chromatographic column 51. This allows for the detection of the target component with high sensitivity. Furthermore, since the solvent has been removed from the adsorption section 14 in step S4, the amount of solvent introduced into the chromatographic column 51 in step S5 is significantly reduced compared to the amount adsorbed in step S3. Therefore, almost no peaks corresponding to the solvent appear on the chromatogram generated based on the detection signal from the detection section 52. This mitigates the collapse of the peak waveform and the shift in retention time of the target component caused by the large amount of solvent introduced into the chromatographic column 51.

[0052] [Variation Example]

[0053] In addition, Figure 2 The sample introduction device shown includes a unit 3 for joint aging and solvent removal, but separate units for aging and solvent removal can also be provided. This structure allows for simultaneous and parallel aging and solvent removal, potentially enabling more efficient GC analysis of large numbers of samples.

[0054] Furthermore, the volatility (non-volatileness) of the solvent adsorbed in the adsorption section 14 varies depending on the type of adsorbent and liquid phase held in the adsorption section 14, the size of the SPME Arrow 1 (the surface area of ​​the adsorption section 14), and the type of solvent. Therefore, it is desirable to appropriately change or adjust the heating temperature, inert gas flow rate, and required time during solvent removal in step S4, depending on the type of SPME Arrow 1 used and the type of solvent in the sample. If the configuration is to automatically determine the type of SPME Arrow used, it is also possible to automatically set the heating temperature, inert gas flow rate, and required time during solvent removal based on the determination result.

[0055] Furthermore, the above-described embodiments are one example of the present invention. It is obvious that even if appropriate modifications, alterations, or additions are made without departing from the spirit of the present invention, they are also included within the scope of the claims of this application.

[0056] For example, although SPME is specifically designed for sample introduction in GC analysis, it can also be applied to other analytical methods, such as liquid chromatography (LC). Therefore, the sample introduction method and apparatus of this invention are not necessarily limited to those applicable only to GC analysis. However, in LC analysis, water or organic solvents are generally not obstacles to the analysis of target components. In this respect, the sample introduction method and apparatus of this invention are particularly useful in GC analysis.

[0057] [Various options]

[0058] It will be apparent to those skilled in the art that the above exemplary embodiments are specific examples of the following schemes.

[0059] (Item 1) One aspect of the sample introduction method of the present invention is a sample introduction method for collecting and injecting samples using a SPME Arrow via solid-phase microextraction, comprising:

[0060] The adsorption process causes the target component in the sample to be adsorbed onto the adsorption section of the SPME Arrow.

[0061] The exposure process involves exposing the adsorption section of the SPME Arrow after the adsorption process to a dry, inert gas atmosphere for a specified time; and

[0062] In the injection process, the target component is detached from the adsorption section of the SPME Arrow after the exposure process by heating the adsorption section and introduced into the analytical device.

[0063] (Item 4) One embodiment of the sample introduction device according to the present invention is an apparatus for implementing the sample introduction method described in Item 1, which is a sample introduction device for collecting and injecting samples into an analytical apparatus using a SPME Arrow via solid-phase microextraction, comprising:

[0064] The adsorption treatment section inserts the adsorption section of the SPME Arrow into a container containing the sample, so that the target component in the sample is adsorbed onto the adsorption section.

[0065] The SPME Arrow's adsorption section, after the adsorption of components in the adsorption treatment section is completed, is exposed to a dry, inert gas atmosphere for a predetermined time; and

[0066] The moving part moves the SPME Arrow between the adsorption treatment section and the exposure treatment section, and between the exposure treatment section and the component introduction position where the target component adsorbed on the adsorption section is introduced into the analytical device.

[0067] In the sample introduction method described in claim 1, implemented using the sample introduction device described in claim 4, at least a portion of the solvent in the sample adsorbed in the adsorption section during the adsorption step is removed from the adsorption section by evaporation during the exposure step. Therefore, according to the sample introduction method described in claim 1 and the sample introduction device described in claim 4, for example, during GC analysis, the influence of solvents such as water or organic solvents originating from the sample can be reduced, and the collapse of the chromatographic peak shape and the shift in retention time of the target component can be suppressed. Thus, the quantitative and identification performance of the target component can be improved.

[0068] (Item 2) In the sample introduction method described in Item 1, during the exposure step, the adsorption portion of the SPME Arrow may be heated to a temperature lower than the temperature during heating in the injection step.

[0069] (Item 5) In the sample introduction device described in Item 4, the exposure treatment section may include a heating section that heats the adsorption section of the SPME Arrow to a temperature at which the target component does not detach.

[0070] According to the sample introduction method described in item 2 and the sample introduction device described in item 5, the removal of solvent from the adsorption section is promoted, thereby further reducing the influence of solvent originating from the sample during GC analysis and thus improving the accuracy of the analysis.

[0071] In addition, in SPME methods using SPME fibers or SPME arrows, conditioning is usually performed before sample collection to remove impurities attached to the adsorbent or residual components from the previous analysis.

[0072] (Item 3) Therefore, in the sample introduction method described in Item 2, it can be set up as follows: before the adsorption process, there is an aging process in which the adsorption part of the SPME Arrow is heated in an inert gas atmosphere, and the heating temperature in the exposure process is lower than the heating temperature in the aging process.

[0073] (Item 6) Furthermore, the sample introduction device described in Item 5 may also include an aging section for purifying the adsorption section of the SPME Arrow by heating it in an inert gas atmosphere, and this aging section may also be used as the exposure treatment section.

[0074] According to the sample introduction method described in item 3, impurities or residual components other than the target component can be avoided from being introduced into the GC device, thereby further improving the accuracy of the analysis. Furthermore, according to the sample introduction device described in item 6, solvent removal can be performed using a unit for aging, thus eliminating the need for additional components for solvent removal and suppressing increases in device cost. In addition, it also helps to suppress increases in the size and weight of the device.

[0075] Symbol Explanation

[0076] 1…SPME Arrow

[0077] 10… Holder

[0078] 11…plunger

[0079] 12… needles

[0080] 13… poles

[0081] 14…Adsorption section

[0082] 2…SPME Arrow Drive Unit

[0083] 20…Main moving part

[0084] 21…Plunger Drive Unit

[0085] 3…Aging / Solvent Purging Unit

[0086] 30…shell

[0087] 31…Gas supply opening

[0088] 32…Gas exhaust opening

[0089] 33…concave

[0090] 34… Heating and cooling section

[0091] 4…Sample Acquisition Unit

[0092] 5…GC device

[0093] 50…Gasification Chamber

[0094] 51… chromatographic column

[0095] 52… Testing Department

Claims

1. A sample introduction method for collecting and injecting samples using a SPME Arrow via solid-phase microextraction, the sample introduction method comprising: The adsorption process causes the target component in the sample to be adsorbed onto the adsorption section of the SPME Arrow. The exposure process involves exposing the adsorption section of the SPME Arrow after the adsorption process to a dry, inert gas atmosphere for a specified time. as well as In the injection process, the adsorption section of the SPME Arrow after the exposure process is heated to cause the target component to detach from the adsorption section and introduce the target component into the analytical device.

2. The sample introduction method according to claim 1, wherein, In the exposure process, the adsorption section of the SPME Arrow is heated to a temperature lower than the temperature during the injection process.

3. The sample introduction method according to claim 2, wherein, Prior to the adsorption process, there is an aging process in which the adsorption section of the SPME Arrow is heated in an inert gas atmosphere. The heating temperature in the exposure process is lower than the heating temperature in the aging process.

4. A sample introduction device, using an SPME Arrow to collect and inject samples into an analytical apparatus via solid-phase microextraction, the sample introduction device comprising: The adsorption treatment section inserts the adsorption section of the SPME Arrow into a container containing the sample, so that the target component in the sample is adsorbed onto the adsorption section. The SPME Arrow's adsorption section, after the adsorption of components in the adsorption treatment section is completed, is exposed to a dry, inert gas atmosphere for a specified time. as well as The moving part moves the SPME Arrow between the adsorption treatment section and the exposure treatment section, and between the exposure treatment section and the component introduction position where the target component adsorbed on the adsorption section is introduced into the analytical device.

5. The sample introduction device according to claim 4, wherein, The exposure treatment section includes a heating section that heats the adsorption section of the SPME Arrow to a temperature at which the target component does not detach.

6. The sample introduction device according to claim 5, wherein, It has an aging section that purifies the adsorption section of the SPME Arrow by heating the adsorption section in an inert gas atmosphere. The aging section is also used as the exposure treatment section.

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