A backflush system, backflush method and its application for GC / MS

Abstract

This invention provides a backflushing system, a backflushing method, and its application for GC / MS. The GC / MS backflushing system includes a backflushing gas path (13) and a backflushing three-way connector (10). The carrier gas outlet of the GC column (9), the gas inlet of the MS, and the backflushing gas path (13) are respectively connected to the backflushing three-way connector (10). The backflushing system and method for GC / MS provided by this invention can not only backflush the entire chromatographic column, greatly reducing the contamination of the GC column by high-boiling-point components, significantly improving the stability of detection results, and greatly extending the life of the GC column, but also avoid the influence of air infiltration on the MSD detector. The operation of replacing the GC column is simple and quick, and there is no need to de-vacuum the MS in advance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of gas chromatography analysis, in particular to a backflush system for GC / MS, a backflush method and application thereof. BACKGROUND

[0002] When GC / MS is used to analyze complex samples such as natural extracts, the chromatographic system is easily contaminated by high-boiling components (oils, waxes, pigments, etc.) of natural products, resulting in rapid decline of the separation capacity of the chromatographic column, change of the selectivity of the stationary phase, and serious impact on the quantitative results. After each chromatographic analysis, timely and effective backflush of the chromatographic column is an effective means to reduce the pollution of heavy components of the chromatographic column. For the backflush technology of the GC / MS chromatographic column, it is also necessary to avoid the influence of air penetration in the backflush carrier gas on the mass spectrometry system.

[0003] Based on the above reasons, commercial instruments and existing invention technologies generally adopt middle-point backflush of the chromatographic column, such as the invention patent 202010857577X “Gas chromatography mass spectrometry detection system and method”, which has the advantages of less influence of air diffusion on mass spectrometry detection and simple installation of the chromatographic column. However, this technology cannot backflush the latter half of the chromatographic column, and has almost no effect on the pollution of the latter half of the chromatographic column. With the increase of the number of injections, heavy components gradually accumulate in the latter half of the chromatographic column, and the chromatographic separation effect gradually deteriorates, so this technology cannot fundamentally solve the problem of pollution of the chromatographic column by heavy components. SUMMARY

[0004] In view of the above-mentioned shortcomings of the prior art, the purpose of the present application is to provide a backflush system for GC / MS, a backflush method and application thereof, which can solve the technical problem that the backflush of the GC / MS chromatographic column cannot completely solve the pollution of the chromatographic column.

[0005] To achieve the above-mentioned purposes and other related purposes, the present application is obtained by the following technical solutions.

[0006] One of the purposes of the present application is to provide a backflush system for GC / MS, which comprises a backflush gas path and a backflush tee joint, and the carrier gas outlet end of the GC chromatographic column, the gas inlet end of the MS and the gas inlet path of the backflush gas are respectively connected with the backflush tee joint.

[0007] Preferably, a flow limiting component is arranged on the backflush gas path; the flow limiting component comprises a switch valve and flow limiting branches; the switch valve is arranged on the backflush gas inlet gas pipeline; the flow limiting branches comprise a first flow limiting branch, a second flow limiting branch and a third flow limiting branch; the first flow limiting branch and the second flow limiting branch are arranged in parallel, and the tail end of the first flow limiting branch and the tail end of the second flow limiting branch are both communicated with the third flow limiting branch; the head end of the first flow limiting branch and the head end of the second flow limiting branch are respectively communicated with the backflush gas path, and the head end of the first flow limiting branch and the head end of the second flow limiting branch are respectively located upstream and downstream of the airflow of the switch valve.

[0008] More preferably, a pressure stabilizing valve and a flow stabilizing valve are further arranged on the backflush gas path.

[0009] More preferably, the switch mode of the switch valve can be selected from one of manual, pneumatic, electric control and program control. More preferably, the switch mode is program control, such as gas chromatography program control.

[0010] Preferably, the inner diameter of the first flow limiting branch, the second flow limiting branch and the third flow limiting branch is 0.05-0.25mm, and the length is 0.3-20m; the inner diameter of the third flow limiting branch is greater than the inner diameter of the first flow limiting branch and the second flow limiting branch.

[0011] More preferably, the inner diameter of the first flow limiting branch and the second flow limiting branch is 0.125mm, and the length is 0.5m; the inner diameter of the third flow limiting branch is 0.25mm, and the length is 1m.

[0012] Preferably, the backflush tee joint is a specially customized device or is combined by a tee joint and a two-way joint.

[0013] Preferably, the interface end of the backflush tee joint connected with the carrier gas outlet end of the GC chromatographic column is provided with a glass lining layer; the MS further comprises an MS flow limiting inlet gas pipe, the backflush tee joint is connected with the MS through the MS flow limiting inlet gas pipe; the inlet end of the MS flow limiting inlet gas pipe is arranged in the backflush tee joint provided with the glass lining layer or in the GC chromatographic column.

[0014] More preferably, when the inner diameter of the GC chromatographic column 9 is 0.1-0.25mm and the outer diameter is 0.38mm, the MS flow limiting inlet gas pipe 12 adopts a capillary chromatographic column with an outer diameter of 0.38mm, and the inlet end of the MS flow limiting inlet gas pipe and the carrier gas outlet end of the GC chromatographic column are both arranged in the glass lining layer.

[0015] More preferably, when the inner diameter of the GC column is 0.32 mm and the outer diameter of the GC column is 0.45 mm, the MS flow-limiting inlet tube is a fused quartz hollow column with an outer diameter of 0.17 mm, and the gas inlet end of the MS flow-limiting inlet tube is arranged in the GC column.

[0016] Preferably, the outer diameter of the GC column matches the inner diameter of the glass lining layer.

[0017] More preferably, when the outer diameter of the GC column is 0.38 mm, the inner diameter of the glass lining layer is 0.4 mm.

[0018] More preferably, when the outer diameter of the GC column is 0.45 mm, the inner diameter of the glass lining layer is 0.5 mm.

[0019] Preferably, the outer diameter of the MS flow-limiting inlet tube is 0.38 mm or 0.17 mm.

[0020] Preferably, the inner diameter of the MS flow-limiting inlet tube is 0.10-0.15 mm, and the length is 0.2 m.

[0021] More preferably, the inner diameter of the MS flow-limiting inlet tube is 0.10-0.11 mm.

[0022] Preferably, a transmission line is arranged between the backflush tee joint and the MS, and a graphite gasket is used to seal the connection between the transmission line and the backflush tee joint.

[0023] The second object of the present application is to provide a backflush method for a backflush system. Before and / or after GC / MS detection, the on-off valve (3) is opened, and backflush gas enters the backflush tee joint to perform backflush operation on the GC column. During backflush operation, the gas pressure at the backflush tee joint is greater than the gas pressure at the GC inlet.

[0024] Preferably, the gas flow of the backflush gas entering the backflush tee joint is adjusted by the flow-limiting assembly.

[0025] Preferably, during backflush, in order to ensure that the backflush gas has sufficient gas flow to sufficiently backflush the GC column, when the inner diameter of the GC column is 0.25 μm, the gas flow of the GC column is 0.3-3 ml / min; and when the inner diameter of the GC column is 0.32 μm, the gas flow of the GC column is 0.3-5 ml / min.

[0026] Preferably, the temperature of the inlet and the column oven is higher than the temperature during analysis and detection.

[0027] Preferably, the pipeline of the flow-limiting branch is one or both of a stainless steel pipe and an elastic quartz capillary. More preferably, the pipeline of the flow-limiting branch is a stainless steel pipe.

[0028] Preferably, the pipe of the MS flow-limiting inlet pipe is a quartz capillary.

[0029] The third object of the present application is to provide a method for avoiding air penetration into the MS, when the GC / MS performs an analysis operation, the switch valve is closed, and the backflush gas is introduced into the backflush tee joint through the first flow-limiting branch and the second flow-limiting branch for purging; the gas flow rate at which the backflush gas enters the backflush tee joint is 0.1-1 mL / min.

[0030] The fourth object of the present application is to provide a method for detecting aroma components in flue-cured tobacco leaves, which adopts the backflush system as described above.

[0031] The specific steps of detecting aroma components in flue-cured tobacco leaves are as follows:

[0032] (1) Sample pretreatment

[0033] The tobacco leaf sample is weighed, solvent extraction is performed, centrifugation is carried out, and the supernatant is taken as the sample solution.

[0034] Preferably, the solvent is a mixed solution of n-hexane and methyl tert-butyl ether, and more preferably, the volume ratio of the n-hexane to the methyl tert-butyl ether is 1:1.

[0035] Preferably, the internal standard solution is an α-ionone solution.

[0036] More preferably, the concentration of the α-ionone solution is 0.1-10 mg / ml.

[0037] Preferably, the tobacco leaf sample needs to be ground into powder.

[0038] Preferably, the solvent extraction is vortex oscillation after the tobacco sample is added to the extraction solvent and the internal standard solution.

[0039] Preferably, the mass of the tobacco sample to the volume of the solvent and the internal standard solution is 1-10:80-98:1-10 (g / ml / ml).

[0040] (2) GC / MS detection

[0041] The sample solution is injected into the GC column 9 and the pre-column 8 through the injection port 7, and then GC / MS analysis and detection are performed, the internal standard method is used for qualitative analysis, and the aroma components in the sample solution are determined.

[0042] Preferably, the sample injection port 7 and GC column 9, pre-column 8 cooperate with the sample injection conditions as follows: the injection port 7 is an MMI injection port; the injection mode is cold splitless injection; the injection volume is 0.5-20 uL; the injection port 7 temperature is 40-60℃ for 0.1 min, then raised to 250℃ at a rate of 500℃ / min for 3-10 min, then lowered to 40-60℃ at a rate of 500℃ / min for 30-70 min, and then raised to 320-350℃ at a rate of 500℃ / min for 10-30 min; the split valve opening time is 1 min, and the split flow is 15-50 mL / min; the carrier gas and backflush gas is high-purity helium with a purity of ≥99.999%; and the carrier gas is set to a gradient pressure mode: 20-30 psig at 0 min, and directly lowered from 20-30 psig to 2-10 psig at 35-75 min.

[0043] Preferably, the GC / MS analysis detection conditions are as follows:

[0044] Gas chromatography conditions: GC column: DB-5MS, deactivated flexible quartz capillary column; pre-column 8: deactivated flexible quartz capillary; temperature rising program: initial temperature 35-60℃ for 1-5 min, then raised to 80-120℃ at a rate of 5-20℃ / min, then raised to 230-280℃ at a rate of 2-10℃ / min for 0-5 min, and then raised to 290-310℃ at a rate of 10-40℃ / min for 10-30 min.

[0045] Mass spectrometry conditions: transfer line temperature: 280-320℃; MS ion source temperature: 230℃, quadrupole temperature: 150℃; mass scan range 29-600 amu.

[0046] More preferably, the lower limit of the mass scan range is 29-45 amu, and the upper limit is 300-600 amu.

[0047] A fourth object of the present application is to provide a method for detecting silanized components in the mainstream smoke of cigarettes from flue-cured tobacco, which uses the backflush system as described above.

[0048] The specific steps for detecting silanized components in the mainstream smoke of cigarettes from flue-cured tobacco are as follows:

[0049] (1) Sample pretreatment

[0050] Smoke the cigarette, collect the total particulate matter, add the internal standard solution after extraction, and use it as the test solution.

[0051] Preferably, the internal standard solution is one or more of cinnamyl alcohol, hexadecanol, or nonadecanol solution.

[0052] More preferably, the internal standard solution is cinnamyl alcohol, and further preferably, the concentration of the cinnamyl alcohol is 0.1-10 mg / ml.

[0053] Preferably, the extraction solution is dichloromethane.

[0054] (2) GC / MS detection

[0055] The sample is injected into the injection port 7 and GC column 9, pre-column 8, and then analyzed and detected by GC / MS, and the silanized components in the sample are determined by internal standard method.

[0056] Preferably, the injection conditions of the injection port 7 and GC column 9, pre-column 8 are as follows: the injection port 7 is an MMI injection port; the injection mode is cold splitless injection; the injection volume is 0.5-20 uL; the temperature of the injection port 7 is 50-70℃ for 0.1 min, then increased to 260-290℃ at a rate of 500℃ / min for 5 min, then decreased to 50-70℃ at a rate of 500℃ / min for 50-70 min, and then increased to 300-330℃ at a rate of 500℃ / min for 5-30 min; the split valve opening time is 1 min, and the split flow is 20-50 mL / min; the carrier gas and backflush gas are high-purity helium with a purity of ≥99.999%; and the carrier gas is set to a gradient flow mode: 1.0-3.0 ml / min at 0 min, and directly decreased to 0.1-0.8 mL / min at 55-75 min.

[0057] Preferably, the GC / MS analysis and detection conditions are as follows:

[0058] Gas chromatography conditions: GC column 9: DB-5MS, deactivated elastic quartz capillary column; pre-column 8: deactivated elastic quartz capillary; temperature rising program: initial temperature 35-60℃ for 0-5 min, then increased to 90-120℃ at a rate of 5-20℃ / min, then increased to 240-280℃ at a rate of 1-10℃ / min, and then increased to 290-320℃ at a rate of 10-40℃ / min for 5-30 min.

[0059] Mass spectrometry conditions: transmission line temperature: 280-320℃; MS ion source temperature: 230℃, quadrupole temperature: 150℃; mass scan range: 29-700 amu.

[0060] More preferably, the lower limit of the mass scan range is 29-45 amu, and the upper limit is 400-700 amu.

[0061] The present application provides a backflush system and method for GC / MS and its application, which has the following advantages:

[0062] (1) can be back flushing the whole chromatographic column, the chromatographic column aging is more effective, thorough, greatly reduces the pollution of high boiling point components to GC chromatographic column, significantly improves the stability and repeatability of detection results, greatly prolongs the service life of GC chromatographic column;

[0063] (2) effectively reduces the dead volume and interface activity of back flushing tee joint, improves the stability, accuracy and repeatability of detection, and is suitable for GC chromatographic column with different inner diameters;

[0064] (3) avoid the influence of air permeation on MSD detector;

[0065] (4) according to the gas flow of the third flow limiting branch, the real-time flow of each gas path in the back flushing system can be calculated, the flow direction of the gas in each gas path is monitored in real time, so as to judge whether the parameter setting is correct and the instrument state is normal; when analyzing, the gas flow of back flushing gas entering the back flushing tee joint and the gas flow entering the MS are monitored, so that the gas flow entering the MS is not too large, so as to affect the vacuum degree, and then ensure the analysis effect; when back flushing, the gas flow of back flushing gas entering the back flushing tee joint is monitored, so as to ensure that the back flushing gas has sufficient gas flow to fully back flush the GC chromatographic column;

[0066] (5) the components are simple, easy to install, simple and easy to operate, and low in cost;

[0067] (6) the operation of replacing GC chromatographic column is simple and fast, and the MS does not need to be evacuated in advance. BRIEF DESCRIPTION OF DRAWINGS

[0068] Figure 1 It is a structure diagram of back flushing gas path and flow limiting component of the application.

[0069] Figure 2 It is one of the schematic diagrams of GC chromatographic column connection method at back flushing tee joint.

[0070] Figure 3 It is the second schematic diagram of GC chromatographic column connection method at back flushing tee joint.

[0071] Figure 4 It is a schematic diagram of analysis state of back flushing system.

[0072] Figure 5 It is a schematic diagram of back flushing state of back flushing system.

[0073] Figure 6 It is the GC / MS total ion flow chromatogram of example 1.

[0074] Figure 7 It is the GC / MS total ion flow chromatogram of example 2.

[0075] Figure 4Explanation of reference numerals in the attached figures

[0076] 1. Pressure regulating valve

[0077] 2. Flow control valve

[0078] 3. Switch valve

[0079] 4 First flow-limiting branch

[0080] 5 Second flow-limiting branch

[0081] 6 Third flow-limiting branch

[0082] 7. Inlet

[0083] 8 GC pre-columns

[0084] 9 GC column

[0085] 10 Backflush T-junction

[0086] 11 Transmission Line

[0087] 12 MS flow-limiting intake manifold

[0088] 13 Backflush air path Detailed Implementation

[0089] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0090] It should be noted that the process equipment or apparatus not specifically mentioned in the following embodiments are all conventional equipment or apparatus in the art.

[0091] Furthermore, it should be understood that the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps, does not preclude the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps, unless otherwise stated. It should also be understood that the combined connection relationship between one or more devices / apparatus mentioned in this invention does not preclude the existence of other devices / apparatus before or after the combined devices / apparatus, or the insertion of other devices / apparatus between these explicitly mentioned devices / apparatus, unless otherwise stated. Moreover, unless otherwise stated, the numbering of each method step is merely a convenient tool for identifying each method step, and not for limiting the order of the method steps or limiting the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0092] In one specific embodiment as shown in the accompanying drawings, Figures 4-5 In one specific embodiment as shown in the accompanying drawings,

[0093] In the above technical solution of the present application, the backflushing system can backflush the entire GC chromatographic column 9, effectively and completely clean the heavy component pollution in the GC chromatographic column 9, improve the stability and repeatability of detection, and greatly prolong the service life of the GC chromatographic column 9. Moreover, the operation of replacing the GC chromatographic column 9 is simple and convenient, and the MS does not need to be pre-evacuated.

[0094] In one specific embodiment as shown in the accompanying drawings, Figure 1 、 4 In one specific embodiment as shown in the accompanying drawings,

[0095] In the above technical solution of the present application, the switch valve 3 and the flow limiting branch play the role of adjusting the gas flow and pressure of the backflushing gas entering the backflushing tee joint. When the GC / MS is in the analysis mode, the switch valve 3 is closed, most of the backflushing gas is discharged through the first flow limiting branch 4 and the third flow limiting branch 6, and a small amount of backflushing gas enters the second flow limiting branch 5 through the first flow limiting branch 4, so as to enter the backflushing tee joint (10) for purging. When the GC / MS is in the backflushing mode, the switch valve 3 is opened, part of the backflushing gas enters the backflushing tee joint 10 through the switch valve 3 to backflush the GC chromatographic column, and the other part of the backflushing gas is discharged through the first flow limiting branch 4, the second flow limiting branch 5 and the third flow limiting branch 6.

[0096] In one specific embodiment as shown in the accompanying drawings, Figure 1 In one specific embodiment as shown in the accompanying drawings,

[0097] In a more specific embodiment, the switching method of the switching valve can be selected as one of manual, pneumatic, electric control or program control.

[0098] In a further specific embodiment, the switching method of the switching valve can be selected as program control, such as gas chromatograph control.

[0099] In one specific embodiment, the inner diameters of the first current-limiting branch 4, the second current-limiting branch 5, and the third current-limiting branch 6 are 0.05 to 0.25 mm; the inner diameter of the third current-limiting branch 6 is larger than the inner diameters of the first current-limiting branch 4 and the second current-limiting branch 5.

[0100] In the above technical solution of this application, the inner diameter of the third flow-limiting branch 6 is larger than the inner diameter of the first flow-limiting branch 4 and the second flow-limiting branch 5. This is to increase the gas flow rate of the backflush gas through the third flow-limiting branch 6. When GC / MS is in analysis mode, it can encourage more backflush gas to be discharged from the third flow-limiting branch 6, reduce the gas flow rate entering the second flow-limiting branch 5, and prevent the impact on MS and GC detection.

[0101] In a more specific embodiment, the inner diameter of the first current-limiting branch 4 and the second current-limiting branch 5 is 0.125 mm and the length is 0.5 m; the inner diameter of the third current-limiting branch 6 is 0.25 mm and the length is 1 m.

[0102] In one specific embodiment, the backflush tee interface is a tee interface or a combination of a tee and a two-way connector.

[0103] In a like Figures 2-5 In the specific embodiment shown, the interface end of the backflush tee port 10 connected to the carrier gas outlet end of the GC column 9 is provided with a glass inner liner; the MS also includes an MS flow-limiting inlet pipe 12, and the backflush tee port 10 is connected to the MS through the MS flow-limiting inlet pipe 12; the inlet end of the MS flow-limiting inlet pipe 12 is located in the backflush tee port 10 provided with the glass inner liner or in the GC column 9.

[0104] In the above technical solution of this application, the function of the glass liner is to reduce the interface activity at the interface between the carrier gas outlet end of the GC column 9 and the MS flow-limiting inlet pipe 12, reduce the adsorption of carrier gas on the inner wall of the backflush tee interface, thereby improving the stability, accuracy and repeatability of the detection.

[0105] The way the MS flow-limiting inlet tube 12 is set greatly reduces the dead volume and interface activity at the interface between the GC column 9 and the MS flow-limiting inlet tube 12, thereby improving the accuracy, stability and repeatability of the detection.

[0106] In a likeFigure 2 In a more specific embodiment, the MS flow restrictor inlet end is configured as shown:

[0107] When the GC column 9 has an inner diameter of 0.1-0.25 mm and an outer diameter of 0.38 mm, the MS flow restrictor 12 is a capillary column with an outer diameter of 0.38 mm, and the MS flow restrictor inlet end and the GC column outlet end are both in the glass lining, the dead volume and interface activity at the interface between the GC column 9 and the MS flow restrictor 12 are greatly reduced.

[0108] In one specific embodiment, the GC column 9 has an outer diameter matching the glass lining. Figure 3 In a more specific embodiment, the MS flow restrictor inlet end is configured as shown:

[0109] When the GC column has an inner diameter of 0.32 mm and an outer diameter of 0.45 mm, the MS flow restrictor is a fused silica hollow column with an outer diameter of 0.17 mm, and the MS flow restrictor inlet end is in the GC column 9, and the GC column outlet end is in the glass lining or not in the glass lining, the dead volume and interface activity at the interface between the GC column 9 and the MS flow restrictor 12 are greatly reduced.

[0110] In one specific embodiment, the GC column 9 has an outer diameter matching the glass lining.

[0111] In the above technical solution of the present application, the outer diameter of the GC column 9 matches the glass lining, which can reduce the dead volume and interface activity at the interface between the GC column 9 and the MS flow restrictor 12, and improve the accuracy, stability and repeatability of detection.

[0112] In a more specific embodiment, when the outer diameter of the GC column is 0.38 mm, the inner diameter of the glass lining is 0.4 mm.

[0113] In a more specific embodiment, when the outer diameter of the GC column is 0.45 mm, the inner diameter of the glass lining is 0.5 mm.

[0114] In one specific embodiment, the MS flow restrictor 12 has an inner diameter of 0.10-0.15 mm, an outer diameter of 0.15-0.38 mm, and a length of 0.2 m.

[0115] In a more specific embodiment, the MS flow restrictor 12 has an inner diameter of 0.10-0.11 mm and an outer diameter of 0.17 mm.

[0116] In one specific embodiment, the GC column 9 has an outer diameter matching the glass lining. Figures 2-5In the specific embodiment shown, a transmission line 11 is provided between the backflush tee interface 10 and the MS, and the connection between the transmission line 11 and the backflush tee interface 10 is sealed with a graphite gasket.

[0117] In one specific embodiment, the injection port 7 is an MMI injection port.

[0118] In a like Figures 4-5 In the specific embodiment shown, a pre-column 8 is used in GC / MS, and the two ends of the pre-column 8 are connected to the GC column and the injection port, respectively.

[0119] In a more specific embodiment, the pre-column 8 is a quartz capillary tube with an inner diameter of 0.25-0.53 mm and a length of 1-30 m.

[0120] In one specific embodiment, the pre-column 8 and the GC column 9 are connected by a two-way connector.

[0121] In a more specific embodiment, the two-way connector is made of one or more of metal, glass, or quartz.

[0122] In a more specific embodiment, the pre-column 8 and the GC column 9 are connected using a universal glass compression connector.

[0123] like Figure 5 As shown, the present invention provides a backflushing method for a backflushing system. When the switch valve 3 is opened, backflushing gas enters the backflushing three-way interface 10 to perform a backflushing operation on the GC column. During the backflushing operation, the gas pressure at the backflushing three-way interface 10 is greater than the gas pressure at the GC inlet.

[0124] During the backflushing operation, the carrier gas from the injection port 7 is discharged from the split outlet and does not enter the GC column 9.

[0125] The specific procedure for the backflush method is as follows:

[0126] After the analyte elutes from the GC column, a backflush operation is immediately initiated. Switch valve 3 is opened, and the pressure at injection port 7 is reduced to 0-10 psig (gauge pressure). Backflush gas is introduced into backflush gas path 13. A portion of the backflush gas flows out from the first flow-limiting branch 4, the second flow-limiting branch 5, and the third flow-limiting branch 6; the other portion enters backflush tee connector 10 through switch valve 3. Part of the backflush gas entering backflush tee connector 10 backflushes the GC column 9, while the other portion flows into the MS flow-limiting inlet pipe 12.

[0127] Because the pressure at injection port 7 is lower than the pressure at the backflush tee connector 10, residual high-boiling-point components in the GC column 9 are discharged through the split outlet at injection port 7 via backflush, resulting in a more thorough cleaning of the GC column. This significantly reduces contamination of the GC column 9 by high-boiling-point components, improves the stability and repeatability of results, and greatly extends the lifespan of the GC column. In one specific embodiment, during the backflush operation, the temperature of injection port 7 and the column oven is higher than the temperature during analysis and detection. The higher temperature of injection port 7 and the column oven promotes the complete removal of residual high-boiling-point components from the GC column 9 and injection port 7, improving the cleanliness of the GC column 9 and injection port 7.

[0128] In one specific implementation, the flow rate of the backflush gas entering the backflush tee port 10 is adjusted by the flow limiting component.

[0129] In one specific embodiment, to ensure that the backflush gas has a sufficient flow rate to fully backflush the GC column 9, when the inner diameter of the GC column 9 is 0.25 μm, the gas flow rate of the GC column 9 is 0.3 to 3 ml / min; when the inner diameter of the GC column is 0.32 μm, the gas flow rate of the GC column is 0.3 to 5 ml / min.

[0130] In one specific embodiment, the conduit of the flow-limiting branch is selected from one or both of stainless steel pipes and elastic quartz capillary tubes.

[0131] In a more specific embodiment, the conduit for the flow-limiting branch is a stainless steel pipe.

[0132] In one specific embodiment, the MS flow-limiting intake pipe 12 is a quartz capillary tube.

[0133] like Figure 4 As shown, the present invention also provides a method to prevent air from penetrating into the MS. When the GC / MS is performing analysis, the switch valve 3 is closed, and the backflush gas is introduced into the backflush tee port 10 through the first flow-limiting branch 4 and the second flow-limiting branch 5 for purging. The gas flow rate of the backflush gas entering the backflush tee port 10 is 0.1 to 1 mL / min.

[0134] A small amount of backflush gas ensures that gas is used to purge the backflush tee port 10, preventing air infiltration; it also prevents backflush gas from entering the GC column and interfering with detection; in addition, it ensures that the gas flow rate entering the MS is not too large, thus affecting the vacuum level and the analytical results.

[0135] The method for avoiding air penetration into the MS provided by the application has a backflush gas flow at the backflush tee joint 10 all the time, air penetration into the backflush tee joint 10 is avoided, and thus air penetration into the MS is avoided; and backflush of the backflush tee joint 10 by the backflush gas can reduce the dead volume of the backflush tee joint 10, thereby improving the stability, accuracy and repeatability of detection.

[0136] The specific process for avoiding air penetration into the MS is as follows:

[0137] The GC / MS is in an analysis mode, the switch valve 3 is closed, and the sample inlet 7 maintains normal pressure. The carrier gas enters the mass spectrometer through the sample inlet 7, the GC column 9, the backflush tee joint 10 and the MS flow-limiting gas inlet pipe 12. The backflush gas enters the backflush gas path 13 and the flow-limiting branch through the pressure stabilizing valve 1 and the flow stabilizing valve 2, most of the backflush gas is discharged through the first flow-limiting branch 4 and the third flow-limiting branch 6, and a small amount of backflush gas enters the backflush gas path 13 through the second flow-limiting branch 5 from the first flow-limiting branch 4, thereby sweeping the backflush tee joint 10.

[0138] The fourth object of the application is to provide a method for detecting aroma components in flue-cured tobacco leaves, and the specific steps are as follows:

[0139] (1) Sample pretreatment

[0140] The tobacco leaf sample is weighed, solvent extraction is performed, centrifugation is performed, and the supernatant is taken as the test solution.

[0141] (2) GC / MS detection

[0142] The test solution is injected into the sample inlet 7 and the GC column 9 in combination with the pre-column 8, and then GC / MS analysis and detection are performed, qualitative determination is performed by using an internal standard method, and the aroma components in the test solution are determined.

[0143] In a specific embodiment, the solvent is a mixed solution of n-hexane and methyl tert-butyl ether, and more preferably, the volume ratio of the n-hexane to the methyl tert-butyl ether is 1:1.

[0144] In a specific embodiment, the internal standard solution is an alpha-ionone solution.

[0145] In a more specific embodiment, the concentration of the alpha-ionone solution is 0.1-10 mg / ml.

[0146] In a specific embodiment, the tobacco leaf sample needs to be ground into powder.

[0147] In a specific embodiment, the solvent extraction is vortexing the tobacco sample with the extraction solvent and internal standard solution. In a specific embodiment, the ratio of the mass of the tobacco sample to the volume of solvent and internal standard solution added is 1-10:80-98:1-10 (g / ml / ml).

[0148] In a specific embodiment, the conditions for the injection port 7 and GC column 9, pre-column 8 combination injection are as follows: the injection port 7 is a MMI injection port; the injection mode is cold splitless injection; the injection volume is 0.5-20 uL; the injection port 7 temperature is an initial temperature of 40-60 °C for 0.1 min, a rate of increase of 500 °C / min to 250 °C for 3-10 min, a rate of decrease of 500 °C / min to 40-60 °C for 30-70 min, and a rate of increase of 500 °C / min to 320-350 °C for 10-30 min; the split valve opening time is 1 min, and the split flow is 15-50 mL / min; the carrier gas and backflush gas is high-purity helium with a purity of ≥99.999%; and the carrier gas is set to a gradient pressure mode: 20-30 psig at 0 min, and directly from 20-30 psig to 2-10 psig at 35-75 min.

[0149] In a specific embodiment, the GC / MS analysis detection conditions are as follows:

[0150] The gas chromatography conditions are as follows: the GC column is a DB-5MS deactivated fused silica capillary column; the pre-column 8 is a deactivated fused silica capillary; and the temperature program is an initial temperature of 35-60 °C for 1-5 min, a rate of increase of 5-20 °C / min to 80-120 °C, a rate of increase of 2-10 °C / min to 230-280 °C for 0-5 min, and a rate of increase of 10-40 °C / min to 290-310 °C for 10-30 min.

[0151] The mass spectrometry conditions are as follows: the transfer line temperature is 280-320 °C; the MS ion source temperature is 230 °C; and the quadrupole rod temperature is 150 °C.

[0152] More preferably, the lower limit of the mass scan range is 29-45 amu, and the upper limit is 300-600 amu.

[0153] A fourth object of the present application is to provide a method for detecting silanized components in the mainstream smoke of a cigarette.

[0154] (1) Sample pretreatment

[0155] The cigarette is smoked, the total particulate matter is collected, the internal standard solution is added after extraction, and the resulting solution is used as the test solution.

[0156] (2) GC / MS detection

[0157] The sample solution is injected into the injection port 7 and GC column 9 and pre-column 8, and then analyzed and detected by GC / MS. The internal standard method is used for qualitative analysis to determine the silylated components in the sample solution.

[0158] In one specific embodiment, the internal standard solution is one or more of cinnamyl alcohol, hexadecanol or nonadecanol solution.

[0159] In a more specific embodiment, the internal standard solution is cinnamyl alcohol, preferably the concentration of the cinnamyl alcohol is 0.1-10 mg / ml.

[0160] In one specific embodiment, the extraction solution is dichloromethane.

[0161] In one specific embodiment, the injection conditions of the injection port 7 and GC column 9 and pre-column 8 are as follows: the injection port 7 is an MMI injection port; the injection mode is cold splitless injection; the injection volume is 0.5-20 uL; the temperature of the injection port 7 is 50-70 °C for 0.1 min, then increased to 260-290 °C at a rate of 500 °C / min for 5 min, then decreased to 50-70 °C at a rate of 500 °C / min for 50-70 min, and then increased to 300-330 °C at a rate of 500 °C / min for 5-30 min; the split valve opening time is 1 min, and the split flow is 20-50 mL / min; the carrier gas and backflush gas are high-purity helium with a purity of ≥99.999%; the carrier gas is set to a gradient flow mode: 1.0-3.0 ml / min at 0 min, and directly decreased to 0.1-0.8 mL / min at 55-75 min.

[0162] In one specific embodiment, the GC / MS analysis and detection conditions are as follows:

[0163] Gas chromatography conditions: GC column 9: DB-5MS, deactivated fused silica capillary column; pre-column 8: deactivated fused silica capillary; temperature program: initial temperature 35-60 °C for 0-5 min, then increased to 90-120 °C at a rate of 5-20 °C / min, then increased to 240-280 °C at a rate of 1-10 °C / min, and then increased to 290-320 °C at a rate of 10-40 °C / min for 5-30 min.

[0164] Mass spectrometry conditions: transfer line temperature: 280-320 °C; MS ion source temperature: 230 °C, quadrupole rod temperature: 150 °C; mass scan range: 29-700 amu.

[0165] In a more specific embodiment, the lower limit of the mass scan range is 29-45 amu and the upper limit is 400-700 amu.

[0166] Example 1

[0167] This example provides a more specific method for detecting flavor components in Chinese-style roasted tobacco leaves.

[0168] 1. Sample pretreatment

[0169] A 0.2000 g sample of tobacco leaf powder was weighed into a 5 ml extraction solvent (V 正己烷 :V 甲基叔丁基醚 was 1:1) and 200 μl of an α-ionone internal standard solution, vortexed for 1 min, left to stand overnight, vortexed again, and the supernatant was taken for testing after centrifugation.

[0170] 2. GC / MS testing

[0171] The test solution was injected into the sample inlet 7 and GC column 9, pre-column 8, and then analyzed by GC / MS. The internal standard method was used for qualitative analysis to determine the aroma components in the test solution.

[0172] (1) Model and specifications of the instrument and equipment

[0173] The instrument was an Agilent 7890A / 5975C (Agilent, USA). The first and second flow restrictors 4 and 5 were each 1 / 16 inch stainless steel with a specification of 0.5 m x 0.125 mm i.d. The third flow restrictor 6 was 1 / 16 inch stainless steel with a specification of 1.0 m x 0.25 mm i.d. The MS flow restrictor inlet tube 12 was a deactivated quartz capillary with a specification of 0.2 m x 0.1 mm i.d. The GC column connection method at the backflush tee joint is shown in Figure 2 .

[0174] (2) Injection conditions: MMI injection port; injection mode: cold splitless injection; injection port temperature: 50°C for 0.1 min, then increased to 250°C at a rate of 500°C / min for 5 min, then decreased to 50°C at a rate of 500°C / min for 55 min, then increased to 350°C at a rate of 500°C / min for 21 min; split valve opening time: 1 min; split flow: 20 mL / min; injection volume: 10 uL; carrier gas and backflush gas: high-purity helium; GC column carrier gas set to gradient pressure mode: 25 psig at 0 min, directly decreased from 25 psig to 5 psig at 60 min.

[0175] (3) Chromatographic conditions

[0176] The GC column 9 was a DB-5MS, with dimensions of 30m × 0.25mm id × 0.25μm df; the pre-column 8 was a deactivated elastic quartz capillary, with dimensions of 6m × 0.53mm id; the column oven temperature program was as follows: hold at 40℃ for 3 min, increase to 100℃ at a rate of 10℃ / min, increase to 250℃ at a rate of 3℃ / min and hold for 1 min, and then increase to 300℃ at a rate of 20℃ / min and hold for 20 min.

[0177] (4) Mass spectrometry conditions: GC / MS transfer line temperature 300℃, MS ion source 230℃, quadrupole 150℃, mass scan range 35-550 amu.

[0178] At 60 minutes, key aroma components elute from the GC column, immediately initiating backflushing mode. Backflushing gas backflushes the GC column 9, and valve 3 switches from off to on at 60 minutes. Simultaneously with backflushing the GC column 9, the injection port pressure is reduced to 5 psig to allow high-boiling-point contaminants to drain into the split outlet. GC separation is completed at 250°C, and GC column 9 backflushing aging is performed at 300°C, effectively and promptly removing the accumulation of high-boiling-point components on the GC column 9. Furthermore, the vaporization temperature of the MMI injection port is 250°C, which is increased to 350°C during column backflushing aging, effectively removing the accumulation of high-boiling-point components in the injection liner.

[0179] GC / MS total ion chromatogram as shown Figure 6 As shown, the qualitative analysis results of the chromatographic peaks in the GC / MS total ion chromatogram are as follows: (1) Geraniol acetone, (2) beta-ionone, (3) oxidized ionone, (4) Maximine, (5) dihydroactinol, (6) 3-OH-beta-dihydrodamasone, (7) megastigmatrienone IV, (8) 3-oxo-aphpa-ionol, (9) neophytadiene, (10) farnesylacetone C.

[0180] 3. Gas flow rate calculation

[0181] The real-time gas flow rate and pressure of each gas pipeline are calculated based on the gas flow rate of the third flow-limiting branch 6 and the relationship between gas flow rate, pressure and gas pipeline size in chemical engineering principles.

[0182] When the GC / MS analysis lasted 3 minutes, the gas flow rate of the third flow-limiting branch 6 was 13.6 ml / min. The calculated gas pressure at the backflush tee port 10 was 5.5 psig, the backflush gas flow rate entering the backflush tee port 10 was 0.1 ml / min, the gas flow rate of the MS flow-limiting inlet pipe 12 was 2.5 ml / min, and the gas flow rate of the GC column 9 was 2.4 ml / min.

[0183] In backflush mode, the gas flow rate of the third flow-limiting branch (6) is 10.5 ml / min. According to calculation, the gas pressure of the backflush tee port 10 is 16.7 psig, the backflush gas flow rate entering the backflush tee port 10 is 3.4 ml / min, the gas flow rate of the MS flow-limiting inlet pipe 12 is 2.9 ml / min, and the gas flow rate of the GC column 9 is 0.5 ml / min.

[0184] 4. Method stability

[0185] The stability of the sample detection method was investigated. The investigation items were the daytime repeatability (n=6) of important aroma components in the sample and the change in response after 160 injections compared with the response after the first injection. The detection results are shown in Table 1.

[0186] The most commonly used instrument for analyzing the aroma components of tobacco leaves is GC / MS. Because tobacco leaves contain high levels of fat-soluble, high-boiling-point substances such as oils, waxes, and pigments, pretreatment methods typically include steam distillation and headspace enrichment. However, steam distillation leads to numerous side reactions (such as Maillard reactions, hydrolysis, and oxidation), and the amount of these side reaction products can significantly exceed the intrinsic aroma components of tobacco leaves, severely interfering with the qualitative and quantitative results of GC / MS analysis of these components. Headspace enrichment has generally poor sensitivity and quantitative repeatability for important aroma components in tobacco leaves (C-13 norisoprene semi-volatiles). Solvent extracts have the least side effects on tobacco aroma components, but direct injection of the extract, even with a vaporization injection port, can cause a rapid decrease in column efficiency. Using the technique described in this application, the GC column is immediately backflushed from the carrier gas outlet after the important aroma components have eluted from the column. The results showed that the method can significantly reduce the contamination of the chromatographic column by high-boiling-point components such as tobacco oil and wax, and significantly improve the stability of quantitative results. The inter-day repeatability RSD% of important aroma components of tobacco was less than 5%, and the change in response after 160 injections relative to the first injection was within ±10%. It can also greatly extend the lifespan of the chromatographic column. Moreover, the important aroma components of tobacco showed good separation, with good peak shapes and a consistently stable baseline.

[0187] Table 1

[0188]

[0189]

[0190] Example 2

[0191] This embodiment provides a more specific method for detecting the mainstream cigarette smoke in Chinese flue-cured tobacco.

[0192] 1. Sample pretreatment

[0193] Cigarettes were smoked according to GB / T 19609, and total particulate matter was collected using a glass fiber filter. After extraction with dichloromethane, an internal standard solution was added.

[0194] 2. GC / MS detection

[0195] The test solution was injected into the GC column 9 and the pre-column 8 via injection port 7, and then analyzed by GC / MS. The internal standard method was used for qualitative analysis to determine the silanized components in the test solution.

[0196] (1) Model and specifications of instruments and equipment:

[0197] The instrument is an Agilent 7890A / 5975C (Agilent Technologies, Inc.). The first and second flow-limiting branches (4 and 5) are both 1 / 16-inch stainless steel, 0.5m × 0.125mm id; the third flow-limiting branch (6) is also 1 / 16-inch stainless steel, 1.0m × 0.25mm id; the MS flow-limiting inlet tube 12 is a fused silica hollow column, 0.2m × 0.11mm id × 0.17mm od. The GC column connection method at the backflush tee is as follows... Figure 3 As shown.

[0198] (2) Injection conditions:

[0199] Port 7 is the MMI injection port; injection method: cold splitless injection; injection volume: 5 μL;

[0200] Inlet 7 temperature: Initial temperature 60℃ held for 0.1 min, then increased to 280℃ at a rate of 500℃ / min and held for 5 min, then decreased to 60℃ at a rate of 500℃ / min and held for 60 min, then increased to 330℃ at a rate of 500℃ / min and held for 18 min; Split valve opening time 1 min, split flow rate 40 mL / min; Carrier gas and backflush gas: High-purity helium, carrier gas purity ≥99.999%;

[0201] The carrier gas was set to gradient flow mode: the flow rate was 2.0 ml / min at 0 min and dropped directly to 0.5 ml / min at 66 min.

[0202] (3) Chromatographic conditions:

[0203] GC column 9: DB-5MS, 60m × 0.32mm id × 0.25μm df; Pre-column 8: deactivated elastic quartz capillary, 6m × 0.53mm id;

[0204] Column temperature program: Initial temperature 50℃, hold for 1 min, increase to 110℃ at a rate of 10℃ / min, then increase at 2.5℃ intervals.

[0205] The temperature was increased to 260°C at a rate of 20°C / min, and then increased to 310°C at a rate of 20°C / min and held for 15 min.

[0206] (4) Mass spectrometry conditions: transfer line temperature: 300℃; MS ion source temperature: 230℃; quadrupole temperature: 150℃; mass scan range: 33~550amu.

[0207] At 66 minutes, the target component elutes from GC column 9, immediately initiating backflushing mode. Switch valve 3 switches from off to on at 66 minutes. GC separation is completed at 260°C. Simultaneously with backflushing of GC column 9, the column oven temperature rises to 310°C, the injection port temperature rises to 330°C, and the injection port pressure decreases as the column flow rate is reduced, allowing high-boiling-point contaminants to be discharged into the split outlet.

[0208] GC / MS total ion chromatogram as shown Figure 7 As shown, the qualitative analysis of the chromatographic peaks in the GC / MS total ion chromatogram is as follows: (1) Propylene glycol TMS derivatization, (2) Lactic acid TMS derivatization, (3) Glycerol TMS derivatization, (4) 5-hydroxymethylfurfural TMS derivatization, (5) Triacetylglycerol, (6) Glyceryl monoacetate TMS derivatization, (7) Nicotine, (8) Hydroquinone TMS derivatization, (9) Cinnamyl alcohol TMS derivatization (internal standard 1), (10) 2-ethylhydroquinone TMS derivatization, (11) 5-hydroxymaltol TMS derivatization, (12) L-glucan TMS derivatization, (13) Neophytadiene, (14) 1-Hexadecyl alcohol TMS derivatization (internal standard 2), (15) Palmitic acid TMS derivatization, (16) Oleic acid TMS derivatization, (17) Stearic acid TMS derivatization, (18) 1-Ninedecyl alcohol TMS derivatization (internal standard 3).

[0209] 3. Gas flow rate calculation

[0210] The real-time gas flow rate and pressure of each gas pipeline are calculated based on the gas flow rate of the third flow-limiting branch 6 and the relationship between gas flow rate, pressure and gas pipeline size in chemical engineering principles.

[0211] During GC / MS analysis for 1 min, the gas flow rate of the third flow-limiting branch 6 was 15.0 ml / min. Calculations showed that the gas pressure at the backflush tee port 10 was 6.2 psig, the backflush gas flow rate entering the backflush tee port 10 was 0.8 ml / min, the gas flow rate of the MS flow-limiting inlet pipe 12 was 1.9 ml / min, and the gas flow rate of the GC column 9 was 1.1 ml / min.

[0212] In backflush mode, the gas flow rate of the third flow-limiting branch (6) is 12.0 ml / min. According to calculation, the gas pressure of the backflush tee port 10 is 18.4 psig, the backflush gas flow rate entering the backflush tee port 10 is 5.1 ml / min, the gas flow rate of the MS flow-limiting inlet pipe 12 is 4.5 ml / min, and the gas flow rate of the GC column 9 is 0.6 ml / min.

[0213] 4. Method stability

[0214] The stability of the detection method for mainstream smoke from Chinese flue-cured cigarettes was investigated. The investigation items were the daytime repeatability (n=6) of important silanized components in the mainstream smoke from Chinese flue-cured cigarettes and the change in response after 160 injections compared to the response after the first injection. The detection results are shown in Table 2.

[0215] Some highly polar and less volatile compounds, such as alcohols, phenols, and organic acids, in the mainstream cigarette smoke are difficult to separate, detect, or exhibit poor stability when directly injected into GC / MS analysis. Therefore, derivatization with silanizing reagents is generally required to reduce polarity or improve volatility, stability, and sensitivity. Cigarette tar contains a large amount of high-boiling-point heavy components such as oils, pigments, and polyphenols. Even after silanization, it still contains a significant number of high-boiling-point components. Direct injection, even with a high-temperature vaporization injection port, will lead to a gradual decrease in column efficiency. Using the technology described in this application, the GC column is backflushed immediately from the carrier gas outlet after the target component elutes. This significantly reduces the contamination of the GC column by high-boiling-point components, significantly improves the stability of quantitative results, and achieves inter-day repeatability RSD% of less than 3% for important silanized components. After 160 injections, the response variation relative to the first injection is within ±5%, and the lifespan of the GC column is also greatly extended. Moreover, the chromatographic separation of silanized components in the mainstream flue gas is good, and the baseline is always kept at a low level.

[0216] Table 2

[0217]

[0218] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for detecting aroma components in Chinese-style flue-cured tobacco leaves, characterized by, The back flushing system of GC / MS comprises a back flushing gas path and a back flushing three-way joint; the outlet end of the GC chromatographic column, the gas inlet end of the MS and the back flushing gas path are connected to the back flushing three-way joint; a flow limiting component is arranged on the back flushing gas path; the flow limiting component comprises a switch valve and flow limiting branches; the switch valve is arranged on the back flushing gas path; the flow limiting branches comprise a first flow limiting branch, a second flow limiting branch and a third flow limiting branch; the first flow limiting branch and the second flow limiting branch are arranged in parallel, and the tail end of the first flow limiting branch and the tail end of the second flow limiting branch are connected to the third flow limiting branch; the head end of the first flow limiting branch and the head end of the second flow limiting branch are connected to the back flushing gas path, and the head end of the first flow limiting branch and the head end of the second flow limiting branch are located upstream and downstream of the gas flow of the switch valve respectively; the inner diameters of the first flow limiting branch, the second flow limiting branch and the third flow limiting branch are 0.05-0.25 mm; the inner diameter of the third flow limiting branch is greater than the inner diameters of the first flow limiting branch and the second flow limiting branch; A pressure stabilizing valve and a flow stabilizing valve are further arranged on the back flushing gas path; The method comprises: (1) Sample pretreatment: weigh 0.2000 g of tobacco powder sample, add 5 ml of V 正己烷 : 甲基叔丁基醚 1:1 extraction solvent and 200 μl of α-ionone internal standard solution, vortex for 1 min, stand overnight, vortex again, take the supernatant after centrifugation for testing; (2) GC / MS detection: injection conditions: MMI injection port; injection mode: cold splitless injection; injection port temperature: 50 ℃ for 0.1 min, then increased to 250 ℃ at a rate of 500 ℃ / min for 5 min, then decreased to 50 ℃ at a rate of 500 ℃ / min for 55 min, then increased to 350 ℃ at a rate of 500 ℃ / min for 21 min; split valve opening time: 1 min, split flow: 20 mL / min; injection volume: 10 uL; carrier gas and back flushing gas: high-purity helium; GC chromatographic column carrier gas setting: gradient pressure mode: 25 psig at 0 min, directly decreased to 5 psig from 25 psig at 60 min; Chromatographic conditions: the type of the GC chromatographic column is DB-5MS, and the specification is 30 m*0.25 mm i.d.*0.25 um df; the pre-column is a deactivated elastic quartz capillary, and the specification is 6 m*0.53 mm i.d.; column oven temperature program: 40 ℃ for 3 min, then increased to 100 ℃ at a rate of 10 ℃ / min, then increased to 250 ℃ at a rate of 3 ℃ / min for 1 min, then increased to 300 ℃ at a rate of 20 ℃ / min for 20 min; Mass spectrometric conditions: GC / MS transmission line temperature: 300 ℃, MS ion source: 230 ℃, quadrupole: 150 ℃, mass scan range: 35-550 amu; When the GC / MS performs analysis operation, the switch valve is closed, and the back flushing gas is introduced into the back flushing three-way joint through the first flow limiting branch and the second flow limiting branch to perform flushing; At 60 min, important flavor components flow out of the GC chromatographic column, and immediately enter the back flushing mode; the switch valve is opened, and the back flushing gas enters the back flushing three-way joint to perform back flushing operation on the GC chromatographic column; during the back flushing operation, the gas pressure at the back flushing three-way joint is greater than the gas pressure at the injection port of the GC. (3) The qualitative analysis results of the chromatographic peaks in the total ion current chromatogram of GC / MS include: geranylacetone, beta-ionone, ionone oxide, muscimole, dihydroactinidiolide, 3-OH-beta-dihydrodamascenone, Maesmin, 3-oxo-aphpa-ionol, neophytadiene, farnesylacetone C.

2. A method for detecting silanized components in the mainstream smoke of a cigarette from flue-cured tobacco, characterized by, The backflush system of GC / MS comprises a backflush gas path and a backflush three-way joint; the outlet end of the GC chromatographic column, the gas inlet end of the MS, and the backflush gas path are connected in communication with the backflush three-way joint; a flow limiting component is arranged on the backflush gas path; the flow limiting component comprises a switch valve and flow limiting branches; the switch valve is arranged on the backflush gas path; the flow limiting branches comprise first, second, and third flow limiting branches; the first flow limiting branch is arranged in parallel with the second flow limiting branch, and the tail end of the first flow limiting branch and the tail end of the second flow limiting branch are both connected in communication with the third flow limiting branch; the head end of the first flow limiting branch and the head end of the second flow limiting branch are respectively connected in communication with the backflush gas path, and the head end of the first flow limiting branch and the head end of the second flow limiting branch are respectively located upstream and downstream of the airflow of the switch valve; the inner diameters of the first, second, and third flow limiting branches are 0.05-0.25 mm; the inner diameter of the third flow limiting branch is greater than the inner diameters of the first and second flow limiting branches; A pressure stabilizing valve and a flow stabilizing valve are further arranged on the backflush gas path; The method comprises: (1) Sample pretreatment: cigarettes are drawn, total particulate matter is collected by using a glass fiber filter, dichloromethane is used for extraction, and an internal standard solution is added; (2) GC / MS detection: injection conditions: MMI injection port; injection mode: cold splitless injection; injection volume: 5 uL; injection port temperature: initial temperature 60 DEG C, maintained for 0.1 min, increased to 280 DEG C at a rate of 500 DEG C / min, maintained for 5 min, decreased to 60 DEG C at a rate of 500 DEG C / min, maintained for 60 min, and then increased to 330 DEG C at a rate of 500 DEG C / min, maintained for 18 min; split valve opening time 1 min, split flow 40 mL / min; carrier gas and backflush gas: high-purity helium; the carrier gas is set to a gradient flow mode: flow 2.0 ml / min at 0 min, directly decreased to 0.5 mL / min at 66 min; Chromatographic conditions: GC chromatographic column: DB-5MS, specification 60 m x 0.32 mm i.d. x 0.25 um df; pre-column is a deactivated elastic quartz capillary, specification 6 m x 0.53 mm i.d.; chromatographic column temperature program: initial temperature 50 DEG C, maintained for 1 min, increased to 110 DEG C at a rate of 10 DEG C / min, increased to 260 DEG C at a rate of 2.5 DEG C / min, and then increased to 310 DEG C at a rate of 20 DEG C / min, maintained for 15 min; Mass spectrometric conditions: transmission line temperature: 300 DEG C; MS ion source temperature: 230 DEG C, quadrupole temperature: 150 DEG C; mass scan range 33-550 amu; When the GC / MS is in analysis mode, the switch valve is closed, and the backflush gas is introduced into the backflush tee through the first and second flow limiting branches to purge the GC / MS; At 66 min, the target component flows out of the GC column and enters the backflush mode immediately, the switch valve is opened, and the backflush gas is introduced into the backflush tee to backflush the GC column, wherein the gas pressure at the backflush tee is greater than the gas pressure at the sample inlet of the GC during the backflush operation; (3) The qualitative analysis results of the chromatographic peaks in the total ion current chromatogram of the GC / MS include: TMS derivatization of propylene glycol, lactic acid, glycerol, 5-hydroxymethyl furfural, glycerol monoacetate, hydroquinone, cinnamic alcohol, 2-ethyl hydroquinone, 5-hydroxymaltol, levoglucosan, 1-hexadecanol, palmitic acid, oleic acid, stearic acid, 1-nonadecanol, triacetin, nicotine, and neophytadiene.

3. The method according to claim 1 or 2, characterized in that, Before and / or after the GC / MS detection, the switch valve is opened, and the backflush gas is introduced into the backflush tee to backflush the GC column.

4. The method according to claim 1 or 2, characterized in that, The interface end of the backflush tee connected to the carrier gas outlet end of the GC column is provided with a glass lining layer; The MS further includes an MS flow limiting gas inlet pipe, and the backflush tee is connected to the MS through the MS flow limiting gas inlet pipe. The gas inlet end of the MS flow limiting gas inlet pipe is arranged in the backflush tee provided with the glass lining layer or in the GC column.

5. The method of claim 4, wherein, The outer diameter of the GC column matches the glass lining layer.

6. The method according to claim 1 or 2, characterized in that, The pipeline of the flow limiting branch is one or both of a stainless steel pipe and an elastic quartz capillary.

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