GC-IMS correction composition for tobacco flavors and fragrances and application of GC-IMS correction composition

Abstract

The invention discloses a GC-IMS correction composition for tobacco flavors and fragrances and application of the GC-IMS correction composition. The correction composition comprises a siloxane compound composition and an organic solvent, the siloxane compound composition is formed by combining at least two different siloxane compounds, and the concentration of each siloxane compound is 10 ppb to 10 ppm. The method comprises the following steps: adding the correction composition into a to-be-detected sample, uniformly mixing, introducing the sample into GC-IMS to obtain two-dimensional spectrogram data of the sample, calculating the reduced mobility and retention index of each peak according to the spectrogram data, and comparing the reduced mobility and retention index with a database to obtain the product. The collision cross-sectional area of the correction composition and migration gas molecules is large, the boiling point is very low compared with the molecular weight of the correction composition, the migration time in the analysis process is not overlapped with the migration time of each compound in a sample, and analysis of normal compounds is not interfered; and the reduced mobility and retention index of each peak can be accurately calculated according to the corrected two-dimensional spectrogram.

Description

Technical Field

[0001] This invention relates to a GC-IMS correction composition, specifically to a GC-IMS correction composition for tobacco flavorings and fragrances and its application, belonging to the field of analytical chemistry. Background Technology

[0002] Ion mobility spectrometry (IMS) is a rapid detection and analysis technique that separates gaseous ions at ambient pressure by colliding with counter-current neutral gas molecules under an electric field, resulting in different migration rates. IMS shares similarities with time-of-flight mass spectrometry (TOF-MS), but it analyzes gaseous ions at ambient pressure, eliminating the need for the high vacuum conditions required for mass spectrometry. Furthermore, IMS offers advantages such as high stability, high sensitivity, fast response, low cost, and portability. Therefore, IMS plays a crucial role in the detection of explosives and pharmaceuticals. Coupling gas chromatography (GC) with ion mobility spectrometry (IMS), which utilizes two different separation mechanisms, organically combines the high separation capability of GC with the high resolution and high sensitivity of IMS. This technique has been reported to be applied to the detection of trace organic components volatile from liquid or solid samples, offering advantages such as simple operation, rapid and non-destructive testing, and high sensitivity. It is used for food identification, food quality and stability assessment, and the detection of volatile organic compounds in solids and liquids. GC-IMS combines the high resolution of GC with the high sensitivity of IMS. Solid / liquid samples can be analyzed directly via headspace injection without solid-phase microextraction, achieving detection limits down to the ppbv level. Typical analysis times are generally within half an hour. Results are presented as a visual fingerprint, revealing differences in flavor compounds within the sample. It allows for qualitative and quantitative analysis of single markers, as well as non-targeted analysis of all volatile organic compounds in a sample.

[0003] Because the analytical results of gas chromatography-ion mobility spectrometry (GC-IMS) are affected by multiple factors such as atmospheric pressure, water content in the migration gas, water content in the sample, voltage stability, migration tube temperature stability, as well as the repeatability of the GC temperature program, column aging, and carrier gas flow rate and pressure stability, the migration and retention times always fluctuate to some extent. Qualitative analysis of GC-IMS mainly relies on retention and migration times. To accurately identify the chromatographic peaks generated by two-dimensional analysis of GC-IMS, and considering that different ion mobility spectrometers have different migration tubes and voltages, using the reduced mobility rate, which is corrected for gas pressure, voltage, and length, is more comparable. However, even in a single analysis, analytical conditions may fluctuate. Therefore, it is necessary to use standard substances to correct and measure the reduced mobility and retention index.

[0004] The composition of tobacco flavorings and fragrances is complex, and variations in the content of characteristic components make it difficult to maintain a consistent aroma. Therefore, qualitative and quantitative analysis is crucial. GC-IMS two-dimensional analysis offers unique advantages for characterizing tobacco flavorings and fragrances, but the identification of compounds relies on precise retention and migration time measurements. Existing migration time correction methods primarily rely on reacted ion peaks (RIP peaks) and standard substances. In gas chromatography-ion mobility spectrometry (GC-IMS), compounds such as DMMP, 2,6-DTBP, or a series of volatile aldehydes and ketones are often used as internal standards for migration time correction and retention index calculation. The chromatographic retention indices of these compounds have been reported in the literature, and their reduced migration rates or relative migration rates to RIP peaks have also been reported. However, their application in reduced migration rate correction and retention index calculation has several drawbacks. First, the peaks of these compounds overlap with those of many other compounds in the sample, making complete separation difficult. Therefore, adding these compounds to the sample can affect the qualitative and quantitative analysis of characteristic peaks. Secondly, RIP peaks are greatly affected by temperature and humidity, resulting in poor repeatability of relative migration times. Thirdly, many internal standard compounds are themselves affected by humidity, leading to poor repeatability of their migration times. Finally, most of these compounds exhibit multiple migration peaks in ion migration spectra, including monomeric, dimer, and polymeric ion peaks, causing additional difficulties in quantitative calibration. Internal standard compounds in chromatographic analysis must meet certain basic requirements. First, the physicochemical properties of the internal standard and the analyte, such as boiling point, polarity, and elution time, should be similar. Second, the internal standard should be a pure substance not present in the sample or a substance present in large quantities with a stable concentration. The internal standard must be soluble in the analyte (or solvent) and not react chemically with it. It should be completely separated from the chromatographic peaks of each component in the sample. The amount of the internal standard should be close to the amount of the analyte, and the position of its chromatographic peak should be close to that of the analyte peak, or between several analyte peaks, without co-elution. According to the above standards, the internal standard compounds currently used in practice often exhibit a high probability of peak identification bias, which seriously affects the accuracy of qualitative analysis. Using the above compounds for quantitative correction will also introduce many errors. Summary of the Invention

[0005] To address the problems existing in the prior art, the first objective of this invention is to provide a GC-IMS correction composition for tobacco flavorings and fragrances. This correction composition has a large collision cross-sectional area with migrating gas molecules and a very low boiling point compared to its molecular weight. During the analysis process, the migration time does not overlap with the migration time of each compound in the sample, thus not interfering with the analysis of normal compounds. Due to the large steric hindrance, the correction compounds in this correction composition cannot form dimers or polymers, and therefore only show a single peak in the ion mobility spectrum, making them easy to identify and quantify.

[0006] The second objective of this invention is to provide an application of a GC-IMS correction composition for tobacco flavorings and fragrances, used for the complete identification of tobacco flavoring and fragrance components. Based on the unique physicochemical effects of the correction composition provided by this invention, the chromatographic retention time is uniformly and regularly distributed in the sample, with good peak shape, low residue, good stability, low price, and high sensitivity. It produces only a single peak in the ion mobility spectrometry, and its migration time is unaffected by humidity in the migrating gas. Furthermore, it can accurately correct the two-dimensional spectra of tobacco flavorings and fragrances throughout the entire time period and accurately calculate the retention index.

[0007] To achieve the above-mentioned technical objectives, the present invention provides a GC-IMS correction composition for tobacco flavorings, comprising a siloxane compound composition and an organic solvent, wherein the siloxane compound composition is obtained by combining at least two different siloxane compounds, and the concentration of each siloxane compound is 10 ppb to 10 ppm.

[0008] The correction composition provided by this invention has a large collision cross-sectional area with migrating gas molecules and a very low boiling point compared to its molecular weight. During the analysis process, the migration time does not overlap with the migration time of each compound in the sample, and does not interfere with the analysis of normal compounds.

[0009] As a preferred embodiment, the siloxane compound is at least two of the following: hexamethyldisiloxane, octamethyltrisiloxane, decamethyltetrasiloxane, dodecylpentasiloxane, tetradecylhexasiloxane, hexadecylheptasiloxane, octadecyloctasiloxane, 1,2-bis(triethoxysilyl)ethane, hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecylcyclohexylsiloxane, tetradecylcycloheptane, hexamethylcyclooctylsiloxane, and octadecylcyclononylsiloxane.

[0010] As a preferred embodiment, the organic solvent is at least one selected from dichloromethane, dichloroethane, chloroform, methanol, ethanol, acetone, diethyl ether, acetonitrile, n-hexane, benzene, and toluene.

[0011] The present invention also provides an application of a GC-IMS correction composition for tobacco flavorings and fragrances for complete identification of tobacco flavoring and fragrance components.

[0012] As a preferred embodiment, the process of fully identifying the flavor and fragrance components is as follows: the calibration composition is added to the sample to be tested and mixed evenly, then injected into GC-IMS to obtain two-dimensional spectral data of the sample, and then the reduced mobility and retention index of each peak are calculated based on the spectral data and compared with the database to obtain the result.

[0013] As a preferred option, the sample to be tested is an extract of tobacco flavoring and fragrance.

[0014] As a preferred embodiment, the volume ratio of the test sample to the calibration composition is 3–7 mg / uL.

[0015] As a preferred embodiment, the calculation process for the reduced mobility of each peak is as follows:

[0016] 1) The reduced mobility of compounds in the sample whose retention time is less than that of the first siloxane compound S1 in the corrected compound composition is calculated as follows:

[0017] Formula 1:

[0018] 2) The reduced mobility of compounds whose retention times are within the retention times of the i-th siloxane compound Si and the (Si+1)-th siloxane compound in the corrected compound composition is calculated as follows:

[0019] Formula 2:

[0020] In equations 1 and 2: K 0(U) The reduced mobility of compound U is given in cm. 2· V -1 ·s -1 ;t d(S1) The migration time of the first siloxane compound S1 is given in milliseconds (ms); t d(U) K represents the migration time of compound U, in milliseconds (ms). 0(S1) The reduced mobility of the first siloxane compound S1 is given in cm⁻¹. 2· V -1 ·s -1 ; For the i-th siloxane compound S i The migration time is in milliseconds (ms). For the Sth i+1 A siloxane compound S i+1 The migration time is in milliseconds (ms); t d(U) The migration time of compound U is expressed in milliseconds (ms). To correct compound S i Reduced mobility, in cm 2· V -1 ·s -1 ; For the Sth i+1 A siloxane compound S i+1 Reduced mobility, in cm 2· V -1 ·s -1 .

[0021] As a preferred embodiment, the calculation process for the retention index of each peak is as follows:

[0022] 1) The retention index of compounds in the sample whose retention time is less than that of the first siloxane compound S1 in the corrected compound composition is calculated as follows:

[0023] Formula 3:

[0024] 2) The retention time of the sample is at the level of the i-th siloxane compound S in the corrected compound composition. i and the Sth i+1 The retention index of a siloxane compound is calculated as follows:

[0025] Formula 4:

[0026] In equations 3 and 4: RI (U) RI is the retention index of compound U, dimensionless. (S1) The retention index of the first corrected compound (S1), dimensionless; t' r(U) To adjust the retention time of compound U, t' r(S1) The adjusted retention time for compound (S1) is adjusted in minutes.

[0027] As a preferred embodiment, the GC-IMS detection conditions are: injection volume of 1–2 μL, carrier gas of nitrogen, carrier gas flow rate of 1–2 mL / min, injection port temperature of 50–70 °C, and ion source of… 63 Ni radioactive ionization source.

[0028] Compared with the prior art, the beneficial technical effects of the technical solution of the present invention are as follows:

[0029] 1) The correction composition provided by this invention has a large collision cross-sectional area with the migrating gas molecules and a very low boiling point compared with its molecular weight. During the analysis process, the migration time does not overlap with the migration time of each compound in the sample and does not interfere with the analysis of normal compounds. Due to the large steric hindrance, each correction compound in this correction composition cannot form dimer or polymer ions. Therefore, it only shows a single peak in the ion mobility spectrum, which is easy to identify and quantify.

[0030] 2) The technical solution provided by this invention is based on the special chemical structure of the correction composition. The chromatographic retention time is uniformly and regularly distributed in the sample, with good peak shape, low residue, good stability, low price, and high sensitivity. It only produces a single peak in the ion mobility spectrum, and its migration time is not affected by the humidity in the migrating gas. Furthermore, it can accurately correct the two-dimensional spectrum in the gas chromatography-ion mobility spectrum of tobacco flavorings and fragrances for the entire duration and accurately calculate the retention index.

[0031] 3) The technical solution and correction composition provided by this invention can compensate for various fluctuations during the analysis process, such as air pressure fluctuations and temperature fluctuations. In actual work, it corrects migration time and retention index segment by segment, which is more accurate than the single-point correction method. Compared with other types of compounds, fragrances and flavorings do not contain such compounds, have large structural differences, and will not interfere with the sample analysis process. Attached Figure Description

[0032] Figure 1 This is a flowchart of the retention index and reduced mobility in Embodiment 1 of the present invention;

[0033] Figure 2 This is the gas chromatography-ion migration spectrum of the corrective composition added in Example 1 of the present invention;

[0034] Figure 3 This is a two-dimensional gas chromatography-ion migration spectrum of the fragrance formulation in Example 1 of the present invention. Detailed Implementation

[0035] The present invention will be further described below with reference to the accompanying drawings and embodiments. It should be noted that the following detailed description is exemplary and intended to provide further explanation of this disclosure. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. Embodiments will now be described in detail with reference to the accompanying drawings.

[0036] Example 1

[0037] In this embodiment, the corrective compound group contains five corrective compounds, namely hexamethyldisiloxane (S1, RI value 645), hexamethylcyclotrisiloxane (S2, RI value 829, Ko value 1.11), octamethylcyclotetrasiloxane (S3, RI value 1004), decamethylcyclopentasiloxane (S4, RI value 1169), and dodecylcyclohexasiloxane (S5, RI value 1342). The concentration of each compound is 50 ppb. The compounds are dissolved in a dichloromethane solution that has been dehydrated and dried using 4A molecular sieves and stored under frozen conditions.

[0038] The samples consisted of a natural extract (A) and a formulated fragrance (B) containing the extract. 10 mg of the extract was added to the sample vial, followed by 2 μL of calibration solution. After incubation at 60 °C for 20 min, the samples were injected using a heated microsyringe. The chromatographic column was an HP-1ms UI (30 m × 0.32 m, 0.25 μm), with an injection volume of 500 μL, nitrogen as the carrier gas at a flow rate of 1.5 mL / min, splitless injection, septum purging at 3 mL / min, and an injection port temperature of 70 °C. The gas chromatographic column was connected to an ion mobility spectrometer via a heated transfer line. The ion source for the ion mobility spectrometer was...63 Ni radioionization source with an activity of 10 mCi. The sample preparation and analysis procedures for formulated fragrances were the same as those for extracts. The gas chromatography temperature program and ion mobility spectrometry operating conditions are shown in Tables 1 and 2, respectively. Formulated fragrance samples were analyzed one day after the analysis of the natural extract.

[0039] Table 1

[0040]

[0041] Table 2

[0042]

[0043] Samples were injected and analyzed at different time intervals of 21 days according to the conditions in Tables 1 and 2. Two-dimensional gas chromatography-ion mobility spectra of the natural extracts were collected. Figure 2 ) and two-dimensional gas chromatography-ion mobility spectra of the formulated fragrance ( Figure 3 ).from Figure 2 The results show that the peaks of the correction composition are regular and evenly distributed throughout the entire retention time range. The sample peaks with migration times longer than the corresponding retention times do not interfere with the sample analysis. Each compound is a single peak, making it an ideal set of correction compounds for calculating retention index and reduced mobility.

[0044] The reduced mobility and retention index of the characteristic compound U1 in the sample were calculated. Since the retention time of U1 is between S3 and S4, its retention index is calculated as follows:

[0045]

[0046] The retention times for S3 were calculated to be 15.634 min, S4 to be 18.018 min, and U1 to be 16.976 min. Based on the retention index and retention time of the corrected compound group, the retention index of U1 was calculated to be 1081.

[0047] The migration time for U1 is 12.776ms, for S3 it is 17.465ms (Ko is 0.889), and for S4 it is 18.658ms (Ko is 0.835).

[0048]

[0049] Calculations show that the reduced mobility of the characteristic compound U1 is 1.220.

[0050] Figure 3The figure shows a two-dimensional spectrum of the formulated fragrance. As can be seen from the figure, even under the same analytical conditions, the migration time of the reaction ion peaks in the ion migration spectrum changes accordingly due to slight variations in atmospheric pressure, desiccant usage time, temperature, and voltage during sample analysis. Therefore, the method of correction using relative migration time carries a significant risk. Figure 3 Without correction using the method proposed in this invention, the retention times of peak UX are 16.976 and 16.850 min, respectively, and their migration times are 12.776 and 12.530 ms, respectively, with a retention time difference of 0.246 ms and an error of 1.9%. Therefore, during compound identification, they would be identified as two different compounds within a 0.5% error range. Using the method of this invention, the retention time and reduced mobility of UX are calculated, yielding retention indices of 1081 and 1.218. Both the reduced mobility and retention indices achieve precise matching, with an error of only 0.16% in the reduced mobility, far less than the 0.5% error range. Therefore, the two peaks are identified as the same compound.

[0051] It should be noted that the terminology used herein is for descriptive purposes only and is not intended to limit the exemplary embodiments according to this disclosure. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof. It should be noted that, without conflict, the various embodiments and features described in this disclosure can be combined with each other.

Claims

1. A GC-IMS corrected composition for tobacco flavorings and fragrances, characterized in that: It includes a siloxane compound composition and an organic solvent, wherein the siloxane compound composition is obtained by combining at least two different siloxane compounds, and the concentration of each siloxane compound is 10 ppb to 10 ppm.

2. The GC-IMS corrected composition for tobacco flavoring and fragrance according to claim 1, characterized in that: The siloxane compounds are at least two of the following: hexamethyldisiloxane, octamethyltrisiloxane, decamethyltetrasiloxane, dodecylpentasiloxane, tetradecylhexasiloxane, hexadecylheptasiloxane, octadecyloctasiloxane, 1,2-di(triethoxysilyl)ethane, hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecylcyclohexylsiloxane, tetradecylcycloheptylsiloxane, hexamethylcyclooctylsiloxane, and octadecylcyclononylsiloxane.

3. The GC-IMS corrected composition for tobacco flavoring and fragrance according to claim 1, characterized in that: The organic solvent is at least one selected from dichloromethane, dichloroethane, trichloromethane, methanol, ethanol, acetone, diethyl ether, acetonitrile, n-hexane, benzene, and toluene.

4. The application of the GC-IMS corrected composition for tobacco flavoring and fragrance according to any one of claims 1 to 3, characterized in that: Used for complete identification of flavoring and fragrance components in tobacco products.

5. The application of the GC-IMS corrected composition for tobacco flavorings and fragrances according to claim 4, characterized in that: The process of fully identifying the flavor and fragrance components is as follows: the calibration composition is added to the sample to be tested and mixed evenly, and then injected into GC-IMS to obtain two-dimensional spectral data of the sample. The reduced mobility and retention index of each peak are calculated based on the spectral data and compared with the database to obtain the result.

6. The application of the GC-IMS corrected composition for tobacco flavorings and fragrances according to claim 4, characterized in that: The sample to be tested is an extract of tobacco flavoring and fragrance; the volume ratio of the sample to the calibration composition is 3-7 mg / uL.

7. The application of the GC-IMS corrected composition for tobacco flavorings and fragrances according to claim 4, characterized in that: The calculation process for the reduced mobility of each peak is as follows: 1) The reduced mobility of compounds in the sample whose retention time is less than that of the first siloxane compound S1 in the corrected compound composition is calculated as follows: Formula 1: 2) The reduced mobility of compounds whose retention times are within the retention times of the i-th siloxane compound Si and the (Si+1)-th siloxane compound in the corrected compound composition is calculated as follows: Formula 2: In equations 1 and 2: K 0(U) The reduced mobility of compound U is given in cm. 2· V -1 ·s -1 ; t d(S1) The migration time of the first siloxane compound S1 is given in milliseconds (ms). t d(U) K represents the migration time of compound U, in milliseconds (ms). 0(S1) The reduced mobility of the first siloxane compound S1 is given in cm⁻¹. 2 ·V -1 ·s -1 ; For the i-th siloxane compound S i The migration time is in milliseconds (ms). For the Sth i+1 A siloxane compound S i+1 The migration time is in milliseconds (ms). t d(U) The migration time of compound U is expressed in milliseconds (ms). To correct compound S i Reduced mobility, in cm 2 ·V -1 ·s -1 ; For the Sth i+1 A siloxane compound S i+1 Reduced mobility, in cm 2 ·V -1 ·s -1 .

8. The application of the GC-IMS corrected composition for tobacco flavorings and fragrances according to claim 4, characterized in that: The calculation process for the retention index of each peak is as follows: 1) The retention index of compounds in the sample whose retention time is less than that of the first siloxane compound S1 in the corrected compound composition is calculated as follows: Formula 3: 2) The retention time of the sample is at the level of the i-th siloxane compound S in the corrected compound composition. i and the Sth i+1 The retention index of a siloxane compound is calculated as follows: Formula 4: In equations 3 and 4: RI (U) RI is the retention index of compound U, dimensionless. (S1) The retention index of the first corrected compound (S1), dimensionless; t' r(U) The adjusted retention time for compound U, in minutes; t' r(S1) The adjusted retention time for the calibration compound (S1) is given in minutes.

9. The application of the GC-IMS corrected composition for tobacco flavorings and fragrances according to claim 4, characterized in that: The GC-IMS detection conditions were as follows: injection volume 1–2 μL, carrier gas nitrogen, carrier gas flow rate 1–2 mL / min, injection port temperature 50–70 °C, and ion source [missing information]. 63 Ni radioactive ionization source.

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