A method for determining hydrocarbon compounds in jet fuel by GCxGC-FID-TOFMS

Abstract

The application provides a method for determining hydrocarbon compounds in jet fuel by GCxGC-FID-TOFMS, which comprises the following steps: after a jet fuel sample sequentially passes through a one-dimensional column, a modulator and a two-dimensional column, the sample enters a hydrogen flame ionization detector and a mass spectrometer through a micro-flow path shunt three-way joint at the same time, and double-channel detector data software is used for test analysis; the acquisition frequency of the mass spectrometer is 20-100 Hz. According to the application, the retention time of components on the detectors of two different pressure outlets is basically consistent, the double-channel detector data software is used for test analysis, the difficulty of data processing is greatly reduced, and the determination efficiency and accuracy of hydrocarbon compounds in jet fuel are improved.

Description

Technical Field

[0001] This invention relates to the field of two-dimensional gas chromatography analysis technology, and in particular to a method for determining hydrocarbon compounds in jet fuel using GC×GC-FID-TOFMS. Background Technology

[0002] Jet fuel is a complex mixture composed of thousands of hydrocarbon compounds (alkanes, cycloalkanes, aromatics, etc.), and its performance (such as combustion efficiency, low-temperature performance, and stability) is closely related to the composition and proportion of these components. Hydrocarbon composition data for jet fuel is of significant practical importance for understanding and evaluating its production process and catalysts.

[0003] However, conventional GC / GCMS methods often produce numerous overlapping peaks due to co-eluenting, sometimes even forming bulges, making accurate qualitative and quantitative analysis impossible. Existing methods require sample pretreatment, followed by separate mass spectrometry analysis of the separated saturated and aromatic hydrocarbon components. The concentration of each hydrocarbon is determined by summing characteristic mass fragments. The average carbon number of the hydrocarbons is estimated from the mass spectrometry data, and calculations are performed based on correction data determined from the average carbon number of each hydrocarbon. The results for each component are then normalized according to the separated mass fractions. This method involves cumbersome pretreatment, complex and error-prone calculations, and cannot eliminate the interference of some cycloalkanes on aromatic hydrocarbon determination, leading to inflated aromatic hydrocarbon results.

[0004] Comprehensive two-dimensional gas chromatography (GC×GC) utilizes two columns with different separation mechanisms. A modulator periodically and continuously captures substances eluting from the first-dimensional column and rapidly injects them into the second column for separation. This technique offers higher separation efficiency, larger peak capacity, and better sensitivity. Furthermore, after separation by two columns with different properties, the final data is presented as a two-dimensional planar plot (contour plot). On this plot, compounds exhibit a regular distribution. For example, in a first-order gradient temperature method, homologues (such as alkanes) will arrange themselves in a straight line. This allows for the approximate classification of unknown compounds even without standard samples, greatly simplifying qualitative analysis.

[0005] Existing methods also include using a two-dimensional gas chromatography (GC×GC-FID) system to determine the composition of benzene and naphthalene hydrocarbons in jet fuel. This method eliminates the need for sample pretreatment and provides spectra showing complete separation of most alkanes and aromatics, greatly simplifying the calculation process and eliminating interference from some cycloalkanes in aromatics determination. However, this method only targets benzene and naphthalene aromatics and cannot obtain complete hydrocarbon composition data for jet fuel samples.

[0006] CN117929613A discloses a method and system for quantitative detection of trace gases during the isothermal rapid conversion of hydrocarbon fuels. The method includes: introducing a quantitative tracer gas, uniformly mixing the tracer gas with the generated gas, and then discharging the mixture; dividing the discharged gas into two parts, collecting one part after quantitative analysis and analyzing the concentration of each gas component using gas chromatography; and measuring the signal intensity of each gas component over time using rapid process mass spectrometry to determine the starting and ending points of gas component generation, obtaining real-time generation curves of the volume and mass of each gas component in the total gaseous products; calculating the absolute conversion rate of hydrocarbon fuel to each gas component and the total gaseous products, and performing reaction rate and kinetic parameter calculations. This method provides quantitative detection of the generation characteristics of multi-component trace gaseous products during the rapid thermal conversion of hydrocarbon fuels under isothermal conditions, and easily obtains the absolute conversion rate and kinetic parameters based on the mass evolution of gaseous product components.

[0007] CN111999409A discloses a fingerprint identification method for marine heavy fuel oil and crude oil. The method includes: extracting the oil sample to be identified using n-hexane / dichloromethane to obtain an oil sample extract; analyzing the oil sample extract using gas chromatography-mass spectrometry (GC-MS) for qualitative analysis of polycyclic aromatic hydrocarbons (PAHs), including methylphenanthrene (MP) and methylanthracene (MA); and determining the oil sample category based on the diagnostic ratio parameters of PAHs in the oil sample extract. Marine oil spills mainly consist of marine fuel oil and crude oil extracted during oil exploration and development. This method uses the ratio of methylphenanthrene to methylanthracene to establish diagnostic indicators for identifying heavy fuel oil and crude oil. The 2-MA / 2-MP, 2-MA / 3-MP, 2-MA / 9-MP, and 2-MA / MP ratios can effectively distinguish between heavy fuel oil and crude oil, providing technical support for oil spill investigations.

[0008] CN120801554A discloses a method and system for calculating volatile organic compounds (VOCs) in exhaust gas from stationary pollution sources. The method includes determining the sampling locations and points for exhaust gas emissions from stationary pollution sources; collecting data on the main product outputs and main raw material or fuel consumption of a pre-defined enterprise and establishing a database; collecting exhaust gas using an exhaust gas sampling device; obtaining exhaust gas chromatography using a mass spectrometer; obtaining low molecular weight components using a flame ionization detector (FID) to obtain VOC components; dividing the low molecular weight components into different concentration series and performing gas chromatography analysis to plot working curves; calculating the correlation coefficients between the low molecular weight components and the response area for different concentration series; analyzing other compounds using a mass spectrometer; calculating the correlation coefficients between other compounds and the response area; calculating the concentration of VOCs; establishing pollution source data based on the database; and performing regression analysis using the database and the VOC concentrations to output the results.

[0009] However, none of the above detection methods are suitable for the accurate quantitative determination of hydrocarbon compounds in jet fuel. Summary of the Invention

[0010] In view of the problems existing in the prior art, the present invention provides a method for determining hydrocarbon compounds in jet fuel by GC×GC-FID-TOFMS. The jet fuel sample is passed sequentially through a one-dimensional column, a modulator, and a two-dimensional column, and then simultaneously enters the hydrogen flame ionization detector and the time-of-flight mass spectrometer through a microflow path split tee. This ensures that the retention times of the components on the detectors at the two different pressure outlets of the hydrogen flame ionization detector and the time-of-flight mass spectrometer are basically consistent. Subsequently, dual-channel detector data software is used for testing and analysis, which greatly reduces the difficulty of data processing and improves the efficiency and accuracy of hydrocarbon compound determination in jet fuel.

[0011] To achieve this objective, the present invention adopts the following technical solution: This invention provides a method for determining hydrocarbon compounds in jet fuel using GC×GC-FID-TOFMS. The method includes: The jet fuel sample passed sequentially through a one-dimensional column, a modulator, and a two-dimensional column, and then simultaneously entered the hydrogen flame ionization detector and the mass spectrometer detector through a microflow path shunting three-way valve. The dual-channel detector data software was used for testing and analysis. The mass spectrometer detector has a sampling frequency of 20~100Hz.

[0012] The method for determining hydrocarbon compounds in jet fuel using GC×GC-FID-TOFMS described in this invention employs a two-dimensional gas chromatography (GC×GC), a flame ionization detector (FID), and a time-of-flight mass spectrometer (TOFMS). This invention couples two-dimensional gas chromatography with both FID and TOFMS to analyze jet fuel samples. Throughout the analysis, the difference in retention times between the two detectors is minimal, and the responses of each hydrocarbon compound on the FID detector are essentially consistent. The mass fraction of each hydrocarbon component can be determined using peak area normalization, eliminating the need for cumbersome calculations. The results are simple, intuitive, and accurate. This method eliminates the need for sample pretreatment for alkane and aromatic hydrocarbon separation; a single direct injection provides chromatographic and mass spectrometric information showing complete separation of most components in the jet fuel sample. It offers excellent separation, high sensitivity, and more accurate and reliable qualitative and quantitative analysis. Two-dimensional separation effectively eliminates interference from certain cycloalkanes in aromatic hydrocarbon determination, preventing overestimation of aromatic hydrocarbon levels.

[0013] The mass spectrometer detector described in this invention has an acquisition frequency of 20~100Hz, which can obtain the precise mass numbers of different compound molecules. By matching the precise mass numbers with those in the database, the range of candidate compounds can be significantly narrowed down. Furthermore, this invention employs dual-channel detector data software for testing and analysis, simultaneously opening chromatographic mass spectrometry data to assist in aligning compound peaks, synchronously labeling identified compounds on the chromatogram, and simultaneously establishing family groups on the chromatogram according to the mass spectrometry family template, etc., reducing the difficulty of data processing and improving efficiency and accuracy.

[0014] The mass spectrometer detector described in this invention has a sampling frequency of 20~100Hz, such as 20Hz, 25Hz, 28Hz, 32Hz, 40Hz, 50Hz, 80Hz or 100Hz, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0015] Preferably, the material of the microflow path shunt tee includes quartz glass or metal, and it is an inert microflow path tee connector. Then, by using specific FID shunt gas barrier column and TOF shunt gas barrier column specifications in terms of length and flow range, it can be ensured that the retention time of the components on the detectors with different pressure outlets, namely the hydrogen flame ionization detector and the time-of-flight mass spectrometer detector, is basically the same.

[0016] Preferably, the one-dimensional column comprises a (5%-phenyl)-methylpolysiloxane stationary phase weakly polar column.

[0017] Preferably, the two-dimensional column comprises a 100% polyethylene glycol stationary phase polar column or a (50% phenyl)-methylpolysiloxane stationary phase polar column.

[0018] Preferably, the modulator is provided with modulation columns HV (C5-C30) or SV (C7-C40).

[0019] The modulation column HV (C5-C30) mentioned in this invention refers to a modulation column of model HV for the analysis of C5-C30 compounds; SV (C7-C40) refers to a modulation column of model SV for the analysis of C7-C40 compounds.

[0020] Preferably, the transmission line length of the mass spectrometer detector is 15~50cm, for example, it can be 15cm, 20cm, 25cm, 30cm, 40cm or 50cm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0021] Furthermore, when the two-dimensional column is a 100% polyethylene glycol stationary phase polar column, the FID split gas barrier column has a length of 0.35~1.0m, for example, it can be 0.35m, 0.5m, 0.65m, 0.8m, 0.9m or 1.0m, etc., but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0022] Inert hollow columns with a diameter of 0.1 to 0.25 mm, such as 0.1 mm, 0.13 mm, 0.16 mm, 0.19 mm, 0.22 mm or 0.25 mm, etc., but not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0023] The TOF splitter column has a length of 0.3~1.0m, for example, it can be 0.3m, 0.5m, 0.6m, 0.7m, 0.8m or 1.0m, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0024] Inert hollow columns with a diameter of 0.1 to 0.25 mm, such as 0.1 mm, 0.13 mm, 0.16 mm, 0.19 mm, 0.22 mm or 0.25 mm, etc., but not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0025] Preferably, the transmission line length of the mass spectrometer detector is 15~50cm, for example, it can be 15cm, 20cm, 25cm, 30cm, 40cm or 50cm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0026] Furthermore, when the two-dimensional column is a polar column in the (50%-phenyl)-methylpolysiloxane stationary phase, the FID split gas barrier column has a length of 0.35~1.0m, for example, it can be 0.35m, 0.5m, 0.65m, 0.8m, 0.9m or 1.0m, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0027] Inert hollow columns with a diameter of 0.1 to 0.25 mm, such as 0.1 mm, 0.13 mm, 0.16 mm, 0.19 mm, 0.22 mm or 0.25 mm, etc., but not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0028] The TOF splitter column has a length of 0.3~1.0m, for example, it can be 0.3m, 0.5m, 0.6m, 0.7m, 0.8m or 1.0m, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0029] Inert hollow columns with a diameter of 0.1 to 0.25 mm, such as 0.1 mm, 0.13 mm, 0.16 mm, 0.19 mm, 0.22 mm or 0.25 mm, etc., but not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0030] The FID split gas barrier column described in this invention is placed before the flame ionization detector (FID) and the TOF split gas barrier column is placed before the mass spectrometer (TOF) detector. Different FID split gas barrier columns and different TOF split gas barrier columns are matched according to different two-dimensional columns, which has the advantages of high separation, high sensitivity, good consistency of retention time of the two detectors during programmed temperature rise, and good repeatability.

[0031] Preferably, the all-two-dimensional gas chromatograph includes a column oven, wherein the one-dimensional column, the two-dimensional column and the microflow path splitter are disposed inside the column oven, and the modulator is disposed outside the column oven.

[0032] Preferably, the injection port temperature of the two-dimensional gas chromatograph is 230~320℃, for example, it can be 230℃, 250℃, 270℃, 290℃, 310℃ or 320℃, etc., but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0033] Preferably, the full two-dimensional gas chromatograph uses split injection with a split ratio of 50:1 to 200:1, such as 50:1, 70:1, 100:1, 130:1, 170:1 or 200:1, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0034] Preferably, the temperature program of the column oven of the two-dimensional gas chromatograph is 40℃~50℃, for example, it can be 40℃, 42℃, 44℃, 46℃, 48℃ or 50℃, etc., but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable. Maintain for 1 to 2 minutes, for example, 1 minute, 1.2 minutes, 1.4 minutes, 1.6 minutes, 1.8 minutes, or 2 minutes, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable. The speed is 1.5~3℃ / min, for example, it can be 1.5℃ / min, 1.8℃ / min, 2.0℃ / min, 2.3℃ / min, 2.6℃ / min or 3.0℃ / min, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable. Raise the temperature to 230°C and hold for 0 to 5 minutes, for example, 0 minutes, 1 minute, 2 minutes, 3 minutes, 4 minutes, or 5 minutes, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0035] Preferably, the mass spectrometer detector uses helium as the carrier gas, and the flow rate is 1.0~1.8 mL / min, for example, it can be 1.0 mL / min, 1.2 mL / min, 1.3 mL / min, 1.5 mL / min, 1.6 mL / min or 1.8 mL / min, etc., but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0036] Preferably, the modulation period of the modulator is 6 to 12 seconds, for example, it can be 6 seconds, 7 seconds, 8 seconds, 9 seconds, 10 seconds or 12 seconds, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0037] Preferably, the inlet hot zone temperature of the modulator is the same as the column oven temperature of the full two-dimensional gas chromatograph.

[0038] Preferably, the inlet hot zone temperature of the modulator is ≥50℃, for example, it can be 50℃, 80℃, 110℃, 140℃, 170℃ or 200℃, etc., but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0039] Preferably, the outlet hot zone temperature of the modulator is 30-40°C higher than the column oven temperature of the two-dimensional gas chromatograph, for example, it can be 30°C, 32°C, 34°C, 36°C, 38°C or 40°C, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0040] Preferably, the outlet hot zone temperature of the modulator is 50~320℃, for example, it can be 50℃, 70℃, 100℃, 200℃, 290℃, 310℃ or 320℃, etc., but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0041] Preferably, the cold zone temperature of the modulator is -51 to -40°C, for example, it can be -51°C, -48°C, -46°C, -44°C, -42°C or -40°C, etc., but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0042] Preferably, the mass spectrometer detector includes a time-of-flight mass spectrometer or a single quadrupole mass spectrometer.

[0043] Preferably, the mass acquisition range of the time-of-flight mass spectrometer is 35~450 amu, for example, it can be 35~350 amu or 45~450 amu, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0044] Preferably, the transmission line temperature of the time-of-flight mass spectrometer detector is 230~250℃, for example, it can be 230℃, 232℃, 235℃, 238℃, 245℃ or 250℃, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0045] Preferably, the ion source temperature of the time-of-flight mass spectrometer detector is 200~230℃, for example, it can be 200℃, 205℃, 210℃, 215℃, 220℃ or 230℃, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0046] Preferably, the voltage of the time-of-flight mass spectrometer detector is 1250~1500V, for example, it can be 1250V, 1300V, 1350V, 1400V, 1450V or 1500V, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0047] Preferably, the mass acquisition range of the single quadrupole mass spectrometer detector is 35~350 amu, for example, it can be 35~350 amu or 45~350 amu, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0048] Preferably, the transmission line temperature of the single quadrupole mass spectrometer detector is 230~280℃, for example, it can be 230℃, 240℃, 250℃, 260℃, 270℃ or 280℃, etc., but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0049] Preferably, the acquisition frequency of the single quadrupole mass spectrometer detector is 20~50Hz, for example, it can be 20Hz, 25Hz, 30Hz, 35Hz, 45Hz or 50Hz, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0050] Preferably, the ion source temperature of the single quadrupole mass spectrometer detector is 200~230℃, for example, it can be 200℃, 205℃, 210℃, 215℃, 220℃ or 230℃, etc., but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0051] Preferably, the detector voltage of the single quadrupole mass spectrometer detector is 1250~1500V, for example, it can be 1250V, 1300V, 1350V, 1400V, 1450V or 1500V, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0052] Preferably, the method further includes classifying hydrocarbon compounds in the jet fuel sample into alkanes, monocyclic alkanes, bicyclic and higher alkanes, monocyclic aromatics, and bicyclic aromatics.

[0053] This invention combines the qualitative results given by the mass spectrometer detector to segment different compound groups according to the carbon number of n-alkanes, and obtains the relative content or mass fraction of compounds corresponding to different carbon number fractions of n-alkanes.

[0054] As a preferred technical solution of the present invention, the method includes: The jet fuel sample passed sequentially through a one-dimensional column, a modulator, and a two-dimensional column, and then simultaneously entered the hydrogen flame ionization detector and the mass spectrometer detector through a microflow path shunting three-way valve. The dual-channel detector data software was used for testing and analysis. The microflow path shunt tee is made of quartz glass or metal; the one-dimensional column is a (5% phenyl)-methylpolysiloxane stationary phase weakly polar column; the two-dimensional column is a 100% polyethylene glycol stationary phase polar column or a (50% phenyl)-methylpolysiloxane stationary phase medium polar column; the modulator is equipped with a modulation column HV (C5-C30) or SV (C7-C40); When the transmission line length of the mass spectrometer detector is 15~50cm and the two-dimensional column is a polar column, the FID split gas barrier column is an inert empty column with a length of 0.35~1.0m and a diameter of 0.1~0.25mm; the TOF split gas barrier column is an inert empty column with a length of 0.3~1.0m and a diameter of 0.1~0.25mm. When the transmission line length of the mass spectrometer detector is 15~50cm and the two-dimensional column is a neutral polarity column, the FID shunt gas barrier column is an inert empty column with a length of 0.35~1.0m and a diameter of 0.1~0.25mm; the TOF shunt gas barrier column is an inert empty column with a length of 0.3~1.0m and a diameter of 0.1~0.25mm. The all-two-dimensional gas chromatograph includes a column oven, with the one-dimensional column, two-dimensional column, and microflow path split tee disposed inside the column oven, and the modulator disposed outside the column oven; the injection port temperature of the all-two-dimensional gas chromatograph is 230~320℃; the all-two-dimensional gas chromatograph uses split injection with a split ratio of 50:1~200:1; the temperature program of the column oven of the all-two-dimensional gas chromatograph is to hold at 40℃~50℃ for 1~2 min, then increase to 230℃ at a rate of 1.5~3℃ / min and hold for 0~5 min; helium is used as the carrier gas at a flow rate of 1.0~1.8 mL / min; The modulation cycle of the modulator is 6~12s; the inlet hot zone temperature of the modulator is the same as the column oven temperature of the two-dimensional gas chromatograph, and the inlet hot zone temperature is ≥50℃; the outlet hot zone temperature of the modulator is 30~40℃ higher than the column oven temperature of the two-dimensional gas chromatograph, and the outlet hot zone temperature is 50~320℃; the cold zone temperature of the modulator is -51~-40℃. The mass spectrometer detector includes a time-of-flight mass spectrometer (TOF-MS) or a single quadrupole mass spectrometer (SQMS). The TOF-MS has a mass acquisition range of 35–450 amu, a transfer line temperature of 230–250 °C, an ion source temperature of 200–230 °C, and a voltage of 1250–1500 V. The acquisition frequency of the TOF-MS is 20–100 Hz. The SQMS has a mass acquisition range of 35–350 amu, a transfer line temperature of 230–280 °C, an acquisition frequency of 20–50 Hz, an ion source temperature of 200–230 °C, and a detector voltage of 1250–1500 V. The method also includes classifying hydrocarbon compounds in jet fuel samples into alkanes, monocyclic alkanes, bicyclic and higher alkanes, monocyclic aromatics, and bicyclic aromatics.

[0055] Compared with the prior art, the present invention has at least the following beneficial effects: The method for determining hydrocarbon compounds in jet fuel using GC×GC-FID-TOFMS provided by this invention combines two-dimensional gas chromatography, a flame ionization detector (FID), and a time-of-flight mass spectrometry (TOFMS) detector. A specific split-flow gas barrier column ensures consistent retention times for compounds in both detectors, resulting in largely consistent responses from each hydrocarbon compound to the FID. The peak area normalization method can be used to determine the mass fraction of each hydrocarbon component, eliminating the need for cumbersome calculations. The results are simple, intuitive, and accurate, making it suitable for widespread application. Attached Figure Description

[0056] Figure 1This is a schematic diagram of the apparatus for determining hydrocarbon compounds in jet fuel using GC×GC-FID-TOFMS in Example 1 of the present invention.

[0057] Figure 2 This is the spectrum obtained from the hydrogen flame ionization detector in Embodiment 1 of the present invention.

[0058] Figure 3 This is the spectrum obtained from the time-of-flight mass spectrometer in Embodiment 1 of the present invention.

[0059] Figure 4 This is a spectrum of compound family distribution of the jet fuel sample in Example 1 of the present invention.

[0060] Figure 5 This is a spectrum of the jet fuel sample in Example 1 of the present invention, segmented by group according to the number of carbon atoms in n-alkanes.

[0061] Figure 6 This is a statistical result diagram of the carbon number distribution of different groups of compounds in the jet fuel sample in Example 1 of the present invention.

[0062] Figure 7 This is a spectrum of the jet fuel sample in Example 2 of the present invention, segmented by group according to the number of carbon atoms in n-alkanes.

[0063] Figure 8 This is a statistical result diagram of the carbon number distribution of different groups of compounds in the jet fuel sample in Example 2 of the present invention.

[0064] In the figure: 1-One-dimensional column; 2-Modulator; 3-Two-dimensional column; 4-Microflow path splitter tee; 5-Flame ionization detector; 6-Mass spectrometer detector; 7-Injector. Detailed Implementation

[0065] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0066] The present invention will now be described in further detail. However, the examples described below are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims.

[0067] Example 1 This embodiment provides a method for determining hydrocarbon compounds in jet fuel using GC×GC-FID-TOFMS. A schematic diagram of the apparatus used in this method is shown below. Figure 1 As shown. The method includes: The jet fuel sample passed sequentially through a one-dimensional column 1, a modulator 2, and a two-dimensional column 3, and then simultaneously entered the hydrogen flame ionization detector 5 and the mass spectrometer detector 6 through a microflow path split tee 4. The data was tested and analyzed using dual-channel detector data software. Figure 1 The number 7 in the middle indicates the sample injector.

[0068] The microfluidic flow divider tee 4 is made of quartz glass; the one-dimensional column 1 is a weakly polar column HP-5MS with a length of 30m × inner diameter of 0.25mm × liquid film thickness of 0.25μm; the two-dimensional column 3 is a polar column DB-HeavyWax with a length of 0.75m × inner diameter of 0.18mm × liquid film thickness of 0.18μm; the modulator 2 contains a modulation column HV (C5-C30). When the transmission line length of the mass spectrometer detector 6 is 20cm and the two-dimensional column 3 is a polar column DB-HeavyWax, the FID shunt gas barrier column is an inert empty column with a length of 0.35m and a diameter of 0.12mm; the TOF shunt gas barrier column is an inert empty column with a length of 0.4m and a diameter of 0.1mm. The all-two-dimensional gas chromatograph includes a column oven, with the one-dimensional column 1, the two-dimensional column 3, and the microflow path split tee 4 disposed inside the column oven, and the modulator 2 disposed outside the column oven; the injection port temperature of the all-two-dimensional gas chromatograph is 250℃; the all-two-dimensional gas chromatograph uses split injection with a split ratio of 100:1; the column oven temperature program of the all-two-dimensional gas chromatograph is to hold at 47℃ for 1.2 min, then increase to 230℃ at a rate of 2℃ / min and hold for 1.5 min; helium is used as the carrier gas at a flow rate of 1.3 mL / min; The modulation period of the modulator 2 is 12s; the inlet hot zone temperature of the modulator 2 is the same as the column box temperature, and the initial temperature of the inlet hot zone is 50℃; the outlet hot zone temperature of the modulator 2 is 30℃ higher than the column box temperature; the inlet hot zone and the outlet hot zone have the same programmed heating rate as the column box; the cold zone temperature of the modulator 2 is -51℃. The mass spectrometer detector 6 is a time-of-flight mass spectrometer; the mass acquisition range of the time-of-flight mass spectrometer is 350 amu, the transmission line temperature is 240°C, the acquisition frequency is 50 Hz, the ion source temperature is 210°C, and the voltage is 1300 V.

[0069] In this embodiment, the spectrum obtained by the jet fuel sample after full two-dimensional gas chromatography and in a hydrogen flame ionization detector is as follows: Figure 2 As shown, the spectrum obtained in the time-of-flight mass spectrometer is as follows: Figure 3 As shown. From Figure 2 and 3 It can be seen that the retention times of the same components in the one-dimensional and two-dimensional dimensions are basically the same.

[0070] Based on their structure, properties, and distribution in a full two-dimensional spectrum, compounds are classified into alkanes, monocyclic alkanes, bicyclic and higher-order alkanes, monocyclic aromatics, and bicyclic aromatics. Full two-dimensional data processing software is used to simultaneously open and align mass spectrometry and chromatographic data. Detected compounds are qualitatively identified, templates for different compound groups are established, and these templates are applied to the chromatographic data for matching and quantification.

[0071] The compound family distribution spectrum of the jet fuel sample in this embodiment is as follows: Figure 4 As shown, Figure 4 Different types of compound family templates established from mass spectrometry data are simultaneously applied to chromatographic data. Since the responses of hydrocarbon compounds in the FID detector are basically consistent, the proportion of different compound families in the sample can be directly obtained.

[0072] Based on the qualitative results provided by the mass spectrometer detector, different compound groups were segmented according to the number of carbon atoms in the n-alkanes. The group segmentation spectra are shown below. Figure 5 As shown, the relative content or mass fraction of compounds corresponding to different carbon number fractions of n-alkanes is then obtained.

[0073] The statistical results of the carbon number distribution of different groups of compounds in the jet fuel sample in this embodiment are as follows: Figure 6 As shown, from Figure 6 The data shows that the compounds in this sample are mainly distributed in the C7-C14 fraction, with the highest content in the C10-C12 fraction. Among these compounds, alkanes (including n-alkanes, isoalkanes, monocyclic alkanes, and bicyclic alkanes) account for the highest proportion, monocyclic aromatics are less common, and bicyclic aromatics are even less common. Moreover, the composition of compounds varies in different carbon number ranges. For example, in the C7 fraction, monocyclic aromatics and alkanes account for about the same proportion, while in the C8 fraction, alkanes are the main component. In the C11 fraction, where the content is the highest, n-alkanes, isoalkanes, and monocyclic alkanes account for about the same proportion, which also accounts for about 80% of all components in this fraction.

[0074] Example 2 This embodiment provides a method for determining hydrocarbon compounds in jet fuel using GC×GC-FID-TOFMS, the method comprising: The jet fuel sample passed sequentially through a one-dimensional column, a modulator, and a two-dimensional column, and then simultaneously entered the hydrogen flame ionization detector and the mass spectrometer detector through a microflow path shunting three-way valve. The dual-channel detector data software was used for testing and analysis. The microfluidic flow divider tee is made of metal; the one-dimensional column includes a weakly polar column HP-5MS with a length of 30m × inner diameter of 0.25mm × liquid film thickness of 0.25μm; the two-dimensional column is a medium polar column DB-17ms with a length of 0.75m × inner diameter of 0.18mm × liquid film thickness of 0.18μm; the modulator contains modulation columns SV (C7-C40). When the transmission line length of the mass spectrometer detector is 20cm and the two-dimensional column is a medium polarity column DB-17ms, the FID shunt gas barrier column is an inert empty column with a length of 0.5m and a diameter of 0.15mm; the TOF shunt gas barrier column is an inert empty column with a length of 0.4m and a diameter of 0.12mm. The all-two-dimensional gas chromatograph includes a column oven, with the one-dimensional column, two-dimensional column, and microflow path split tee disposed inside the column oven, and the modulator disposed outside the column oven; the injection port temperature of the all-two-dimensional gas chromatograph is 250℃; the all-two-dimensional gas chromatograph uses split injection with a split ratio of 200:1; the temperature program of the column oven of the all-two-dimensional gas chromatograph is to hold at 50℃ for 1 min, then increase to 230℃ at a rate of 1.5℃ / min and hold for 5 min; helium is used as the carrier gas at a flow rate of 1.0 mL / min; The modulation period of the modulator is 6s; the temperature of the inlet hot zone of the modulator is the same as that of the column box, and the initial temperature of the inlet hot zone is 50℃; the temperature of the outlet hot zone of the modulator is 40℃ higher than that of the column box, and the temperature rise rate of the inlet hot zone and the outlet hot zone is the same as that of the column box; the temperature of the cold zone of the modulator is -51℃. The mass spectrometer detector includes a time-of-flight mass spectrometer; the mass acquisition range of the time-of-flight mass spectrometer is 450 amu, the transfer line temperature is 230°C, the acquisition frequency is 100 Hz, the ion source temperature is 230°C, and the voltage is 1500 V. The method also includes classifying hydrocarbon compounds in jet fuel samples into alkanes, monocyclic alkanes, bicyclic and higher alkanes, monocyclic aromatics, and bicyclic aromatics.

[0075] In this embodiment, the jet fuel samples are segmented into groups according to the carbon number of n-alkanes, as shown in the spectrum. Figure 7 As shown, the relative content or mass fraction of compounds corresponding to different carbon number fractions of n-alkanes is then obtained.

[0076] In this embodiment, the two-dimensional column is a medium polarity column DB-17ms, and the modulator contains a modulation column SV (C7-C40). After testing and analysis, the statistical results of the carbon number distribution of different groups of compounds in the jet fuel sample are as follows: Figure 8 As shown, from Figure 8The analysis reveals that the compounds in this sample are mainly distributed in the C8-C16 fraction, with the highest content in the C10-C13 fraction. Among these compounds, alkanes (including n-alkanes, isoalkanes, monocyclic alkanes, and bicyclic alkanes) account for the highest proportion, while monocyclic aromatics are less abundant, and bicyclic aromatics are even less abundant. Furthermore, the composition of compounds varies across different carbon number ranges. For example, the C9 fraction is mainly composed of alkanes, while in the C11 fraction, which has the highest content, n-alkanes, isoalkanes, monocyclic alkanes, and bicyclic alkanes are roughly equal in proportion, accounting for almost 90% or more of all components in this fraction.

[0077] In summary, the GC×GC-FID-TOFMS method for determining hydrocarbon compounds in jet fuel provided by this invention is rationally designed and simple to operate. It combines two-dimensional gas chromatography, a flame ionization detector, and a time-of-flight mass spectrometry detector, eliminating the need for sample pretreatment to separate alkanes and aromatics. A single direct injection provides chromatographic and mass spectrometric information showing complete separation of most components in the jet fuel sample, resulting in good resolution, high sensitivity, and more accurate and reliable qualitative and quantitative analysis. The responses of each hydrocarbon compound on the flame ionization detector are essentially consistent, allowing for the determination of the mass fraction of each hydrocarbon component using peak area normalization, eliminating the need for cumbersome calculations. The results are simple, intuitive, and accurate, making it suitable for widespread application.

[0078] It should be noted that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for determining hydrocarbon compounds in jet fuel using GC×GC-FID-TOFMS, characterized in that, The method includes: The jet fuel sample passed sequentially through a one-dimensional column, a modulator, and a two-dimensional column, and then simultaneously entered the hydrogen flame ionization detector and the mass spectrometer detector through a microflow path shunting three-way valve. The dual-channel detector data software was used for testing and analysis. The mass spectrometer detector has a sampling frequency of 20~100Hz.

2. The method according to claim 1, characterized in that, The microflow path shunt tee is made of materials including quartz glass or metal.

3. The method according to claim 1 or 2, characterized in that, The one-dimensional column comprises a (5%-phenyl)-methylpolysiloxane stationary phase weakly polar column; Preferably, the two-dimensional column comprises a 100% polyethylene glycol stationary phase polar column or a (50% phenyl)-methylpolysiloxane stationary phase polar column.

4. The method according to any one of claims 1 to 3, characterized in that, The modulator is equipped with modulation columns HV (C5-C30) or SV (C7-C40).

5. The method according to claim 3, characterized in that, When the transmission line length of the mass spectrometer detector is 15~50cm and the two-dimensional column is a 100% polyethylene glycol stationary phase polar column, the FID split gas barrier column is an inert empty column with a length of 0.35~1.0m and a diameter of 0.1~0.25mm; the TOF split gas barrier column is an inert empty column with a length of 0.3~1.0m and a diameter of 0.1~0.25mm.

6. The method according to claim 3, characterized in that, When the transfer line length of the mass spectrometer detector is 15~50cm and the two-dimensional column is a polar column in the (50%-phenyl)-methylpolysiloxane stationary phase, the FID split gas barrier column is an inert empty column with a length of 0.35~1.0m and a diameter of 0.1~0.25mm; the TOF split gas barrier column is an inert empty column with a length of 0.3~1.0m and a diameter of 0.1~0.25mm.

7. The method according to any one of claims 1 to 6, characterized in that, The all-two-dimensional gas chromatograph includes a column oven, in which the one-dimensional column, the two-dimensional column, and the microflow path splitter are arranged, and the modulator is arranged outside the column oven; Preferably, the injection port temperature of the two-dimensional gas chromatograph is 230~320℃; Preferably, the two-dimensional gas chromatograph uses split injection with a split ratio of 50:1 to 200:1; Preferably, the temperature program of the column oven of the two-dimensional gas chromatograph is to hold at 40℃~50℃ for 1~2 min, and then increase to 230℃ at 1.5~3℃ / min and hold for 0~5 min. Preferably, the mass spectrometer detector uses helium as the carrier gas at a flow rate of 1.0~1.8 mL / min.

8. The method according to any one of claims 1 to 7, characterized in that, The modulation period of the modulator is 6~12s; Preferably, the inlet hot zone temperature of the modulator is the same as the column oven temperature of the two-dimensional gas chromatograph; Preferably, the inlet hot zone temperature of the modulator is ≥50℃; Preferably, the outlet hot zone temperature of the modulator is 30-40°C higher than the column oven temperature of the full two-dimensional gas chromatograph; Preferably, the outlet hot zone temperature of the modulator is 50~320℃; Preferably, the cold zone temperature of the modulator is -51 to -40°C.

9. The method according to any one of claims 1 to 8, characterized in that, The mass spectrometer detector includes a time-of-flight mass spectrometer or a single quadrupole mass spectrometer. Preferably, the mass acquisition range of the time-of-flight mass spectrometer detector is 35~450 amu; Preferably, the transmission line temperature of the time-of-flight mass spectrometer detector is 230~250℃; Preferably, the ion source temperature of the time-of-flight mass spectrometer detector is 200~230℃; Preferably, the voltage of the time-of-flight mass spectrometer detector is 1250~1500V; Preferably, the mass acquisition range of the single quadrupole mass spectrometer detector is 35~350 amu; Preferably, the transmission line temperature of the single quadrupole mass spectrometer detector is 230~280℃; Preferably, the acquisition frequency of the single quadrupole mass spectrometer detector is 20~50Hz; Preferably, the ion source temperature of the single quadrupole mass spectrometer detector is 200~230℃; Preferably, the detector voltage of the single quadrupole mass spectrometer is 1250~1500V.

10. The method according to any one of claims 1 to 9, characterized in that, The method also includes classifying hydrocarbon compounds in jet fuel samples into alkanes, monocyclic alkanes, bicyclic and higher alkanes, monocyclic aromatics, and bicyclic aromatics.

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