Method for detecting content of polycyclic aromatic hydrocarbon and application

Abstract

The invention discloses a method for detecting the content of polycyclic aromatic hydrocarbon and application. The method comprises the following steps: S1, pretreatment; s2, extracting; s3, reverse extraction; s4, activating; s5, purifying; s6, detecting; and S7, analyzing. The method is applied to polycyclic aromatic hydrocarbon detection of rubber filling oil, polycyclic aromatic hydrocarbon detection of smokeless tobacco products, nitro polycyclic aromatic hydrocarbon detection of rice and soil or polycyclic aromatic hydrocarbon detection of milk. Aiming at the problem that in the prior art, rubber filling oil and other oil products cannot be subjected to two-phase layering in the extraction process, hexamethylbenzene is adopted as an internal standard substance, and after absolute ethyl alcohol is selected to be added, the two phases can be layered to break the emulsification phenomenon; meanwhile, a comprehensive solid-phase extraction column combining a silica gel reverse-phase solid-phase extraction column and an aluminum oxide column is adopted, the separation effect is good, losses caused in the separation process are reduced, and errors are reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of polycyclic aromatic hydrocarbon detection, and specifically relates to a method for detecting the content of polycyclic aromatic hydrocarbons and its applications. Background Art

[0002] Polycyclic Aromatic Hydrocarbons (PAHs) refer to compounds containing two or more benzene rings linked together, and are widely present in substances such as coal, petroleum, wood, and tobacco. To date, many PAHs and their derivatives have been discovered. PAHs can be produced when fuels such as petroleum and coal, as well as wood and combustible gases, are incompletely burned or under high-temperature treatment conditions. Among them, a considerable number of PAHs have strong carcinogenicity, teratogenicity, and mutagenicity, posing a serious threat to human health and the ecological environment. Therefore, the detection of PAHs in the environment is particularly important.

[0003] Eight substances in polycyclic aromatic hydrocarbons are highly carcinogenic substances. Among them, benzo[a]pyrene is the first environmental chemical carcinogen discovered and has strong carcinogenicity. Therefore, benzo[a]pyrene is usually used as the representative of polycyclic aromatic hydrocarbons. According to the existing regulations, the maximum allowable limit for the total amount of PAHs is 10 μg / g, and the maximum allowable limit for benzo[a]pyrene is 1 μg / g.

[0004] PAHs are not highly volatile and belong to semi-volatile organic compounds. The analysis of PAHs usually includes steps such as sample extraction, purification and enrichment, and determination. The literature "Verfahren zur bestimmung desgehaltes an polycyclischenaromatischen kohlenwasserstoffen in mais mit hilfederkapillargaschromatographie" proposed a method for analyzing polycyclic aromatic hydrocarbons in corn, including steps such as Soxhlet extraction, saponification, silica gel chromatography, Sephadex LH20 gel chromatography purification, and HPLC determination. The literature "Extractionand determination of selected polycyclic a romatic hydrocarbons in planttissues" proposed a method for analyzing 16 polycyclic aromatic hydrocarbons in plant samples. First, the polycyclic aromatic hydrocarbons in the plant samples were extracted into acetonitrile by ultrasonic waves, then partitioned with pentane, purified through a silica gel column, and analyzed by gas chromatography. However, due to the high initial equipment cost and great operation difficulty, multiple analyses are required for the determination of a large number of PAH components. Moreover, for oil products such as rubber filling oil, the two phases cannot be separated during the extraction and separation process, resulting in a large loss of oil products and a large error. Most of these methods are not suitable for daily detection. Summary of the Invention

[0005] In view of the above problems, the present invention provides a method and application for detecting the content of polycyclic aromatic hydrocarbons.

[0006] The technical solution of the present invention is as follows:

[0007] A method for detecting the content of polycyclic aromatic hydrocarbons, comprising the following steps:

[0008] S1. Pretreatment: Heating the rubber filling sample to be detected to complete pretreatment;

[0009] S2. Extraction: Taking the pretreated rubber filling sample, adding hexamethylbenzene and cyclohexane, obtaining a polycyclic aromatic hydrocarbon internal standard after preliminary stirring, adding n-hexane and accelerating stirring to dissolve, adding the extraction solvent dimethyl sulfoxide for oscillating extraction, and then adding absolute ethanol to break the emulsification phenomenon to obtain a mixed solution;

[0010] Among them, the mass ratio of the rubber-filled sample to hexamethylbenzene is 100:1.2 - 1.5, the mass-volume ratio w:v of the rubber-filled sample to cyclohexane is 1g:1 - 1.5ml, the volume ratio of cyclohexane to n-hexane is 40 - 60:1 - 2, the volume ratio of the extraction solvent dimethyl sulfoxide to n-hexane is 2 - 3:1, and the volume ratio of absolute ethanol to the extraction solvent dimethyl sulfoxide is 1 - 1.5:1 - 1.5;

[0011] S3. Back extraction: Continuously add sodium chloride solution to the mixed solution for oscillating back extraction, keep the temperature at 70 - 90°C, then add a funnel with a desiccant to filter out water, collect the filtered filtrate and concentrate it by nitrogen blowing in a nitrogen evaporator to obtain a concentrated solution;

[0012] Among them, the volume ratio of the mixed solution to the sodium chloride solution is 5 - 10:1 - 2;

[0013] S4. Activation: Connect a silica gel reversed-phase solid-phase extraction column in series at the upper end of an alumina column to obtain a comprehensive solid-phase extraction column, successively add dichloromethane and cyclohexane to activate the comprehensive solid-phase extraction column, and start the vacuum pump to dry it;

[0014] S5. Purification: Pass the concentrated solution obtained in S3 through the comprehensive solid-phase extraction column in S4, then rinse and purify it with an eluent to remove impurities. The eluent is a mixture of dichloromethane and cyclohexane in a volume ratio of 1 - 1.5:2 - 2.5 to obtain a purified solution;

[0015] S6. Detection: Use a gas chromatography - mass spectrometry (GC - MS) instrument to detect the purified solution obtained in S5 to obtain the polycyclic aromatic hydrocarbon detection data in the sample;

[0016] S7. Analysis: Use chromatography - mass spectrometry data processing software to perform integration, calibration, and quantitative calculation on the detection data, then establish a standard curve for polycyclic aromatic hydrocarbons, and calculate the accurate content of polycyclic aromatic hydrocarbons in the sample according to the ratio of the peak area of the target compound in the sample to the peak area of the internal standard.

[0017] Furthermore, the heating temperature in S1 is 90 - 100°C, and the heating time is 15 - 30 min.

[0018] Note: The rubber-filled sample to be detected is kept in good fluidity by pre-treatment heating.

[0019] Furthermore, the stirring speed of the preliminary stirring in S2 is 100 - 200 rpm, the time of the preliminary stirring is 5 - 6 min, the stirring speed of the accelerated stirring is 300 - 400 rpm, and the time of the accelerated stirring is 1 - 2 min.

[0020] Note: The rubber-filled sample to be detected is completely dissolved by controlling and adjusting the stirring speed.

[0021] Further, in step S2, the oscillation extraction time is 1 - 2 min, and the amplitude range of the oscillation extraction is 0 - 60 mm.

[0022] Note: By controlling and adjusting the parameters of the oscillation extraction, the extraction can be ensured to be complete.

[0023] Further, in step S3, the oscillation back - extraction time is 1 - 2 min, and the amplitude range of the oscillation back - extraction is 0 - 60 mm.

[0024] Note: By controlling and adjusting the parameters of the oscillation back - extraction, the back - extraction can be ensured to be complete.

[0025] Further, in step S3, the mass concentration of the sodium chloride solution is 4%, the desiccant is anhydrous sodium sulfate, 1 - 2 g of absorbent cotton extracted with dichloromethane for 72 h is stuffed in the funnel, the addition amount of the desiccant and the mass - volume ratio w:v of the mixed solution is 1 - 2 g:300 - 350 ml, the water - filtering time is 10 - 20 min, the nitrogen - blowing concentration time is 15 - 30 min, and the mixed solution is concentrated to 1 - 2 mL.

[0026] Note: By controlling and adjusting the parameters of the nitrogen - blowing concentration, the efficiency in subsequent purification can be improved.

[0027] Further, in step S4, the height ratio of the silica gel reversed - phase solid - phase extraction column to the alumina column is 3 - 5:0.5 - 1. When activating, 6 - 8 mL of dichloromethane is added, the dichloromethane activation time is 30 - 60 min, 12 - 14 mL of cyclohexane is added, and the cyclohexane activation time is 30 - 60 min.

[0028] Note: By optimizing the height ratio of the silica gel reversed - phase solid - phase extraction column to the alumina column, impurities can be removed more thoroughly.

[0029] Further, in step S5, the eluent flushing and purification time is 60 - 90 min, and the volume ratio of the concentrated solution to the eluent is 1 - 2:10 - 12.

[0030] Note: By optimizing and adjusting the eluent flushing and purification time and the eluent amount, the complete elution of the concentrated solution can be ensured.

[0031] Further, in step S6, the chromatographic column is Rtx - 5MS, HP - 5MS UI or DB - 5MS, the ion source temperature is 250 °C, the injection port temperature is 300 °C, the chromatographic column temperature is 60 °C, the interface temperature is 280 °C, and the injection volume is 1 μL.

[0032] The present invention also provides an application of the above method for detecting the content of polycyclic aromatic hydrocarbons, which is applied to the detection of polycyclic aromatic hydrocarbons in rubber filling oil, the detection of polycyclic aromatic hydrocarbons in smokeless tobacco products, the detection of nitro-polycyclic aromatic hydrocarbons in paddy rice and soil, or the detection of polycyclic aromatic hydrocarbons in milk.

[0033] The beneficial effects of the present invention are as follows:

[0034] 1. The method for detecting the content of polycyclic aromatic hydrocarbons according to the present invention aims at the problem that in the prior art, two-phase stratification cannot be achieved during the extraction process for oils such as rubber filling oil. By using hexamethylbenzene as an internal standard, adding anhydrous ethanol can break the emulsification phenomenon and achieve two-phase stratification. At the same time, the combined solid-phase extraction column combining a silica gel reversed-phase solid-phase extraction column and an alumina column has good separation effect, reducing the loss caused during the separation process and minimizing errors.

[0035] 2. In the method for detecting the content of polycyclic aromatic hydrocarbons according to the present invention, the selected hexamethylbenzene is synthetic rather than natural. Moreover, hexamethylbenzene has a benzene ring, and its peak emergence time is in the middle position, without participating in the reaction and not interfering with the determination. Finally, hexamethylbenzene has a lower cost compared to deuterated compounds and good economy.

[0036] 3. The application of the method for detecting the content of polycyclic aromatic hydrocarbons according to the present invention, in addition to being mainly applied to the detection of polycyclic aromatic hydrocarbons in rubber filling oil, also gives various different application scenarios, which also demonstrates the broad application prospects of the method of the present invention in various fields. Description of the Drawings

[0037] Figure 1 is the standard curve plotted based on the benzo[a]anthracene data measured in the experimental examples of the present invention;

[0038] Figure 2 is the data measured in the experimental examples of the present invention and the plotted standard curve;

[0039] Figure 3 is the standard curve plotted based on the benzo[b]fluoranthene and benzo[j]fluoranthene data measured in the experimental examples of the present invention;

[0040] Figure 4 is the standard curve plotted based on the benzo[k]fluoranthene data measured in the experimental examples of the present invention;

[0041] Figure 5 is the standard curve plotted based on the benzo[a]pyrene standard data measured in the experimental examples of the present invention;

[0042] Figure 6 is the standard curve plotted based on the benzo[e]pyrene standard data measured in the experimental examples of the present invention;

[0043] Figure 7It is the standard curve measured for dibenzo[a,h]anthracene data in the experimental examples of the present invention and plotted;

[0044] Figure 8 It is the chromatogram of 8 PAHs standard solutions measured in the experimental examples of the present invention;

[0045] Figure 9 It is the chromatogram of polycyclic aromatic hydrocarbons in the rubber filling oil measured in the experimental examples of the present invention; Detailed implementation manners

[0046] Example 1

[0047] A method for detecting the content of polycyclic aromatic hydrocarbons, comprising the following steps:

[0048] S1. Pretreatment: Heat the sample to be detected to complete pretreatment, with a heating temperature of 95 °C and a heating time of 20 min;

[0049] S2. Extraction: Take the pretreated sample, add hexamethylbenzene and cyclohexane, and obtain a polycyclic aromatic hydrocarbon internal standard after preliminary stirring. The stirring speed of the preliminary stirring is 150 rpm, and the time of the preliminary stirring is 5 min. Add n-hexane and accelerate stirring to dissolve. The stirring speed of the accelerated stirring is 350 rpm, and the time of the accelerated stirring is 2 min. Add the extraction solvent dimethyl sulfoxide for oscillating extraction. The oscillating extraction time is 2 min, and the amplitude range of the oscillating extraction is 40 mm. Then add absolute ethanol to break the emulsification phenomenon to obtain a mixed solution;

[0050] Among them, the mass ratio of the sample to hexamethylbenzene is 100:1.3, the mass-volume ratio w:v of the sample to cyclohexane is 1 g:1.2 ml, the volume ratio of cyclohexane to n-hexane is 50:1.5, the volume ratio of the extraction solvent dimethyl sulfoxide to n-hexane is 2.5:1, and the volume ratio of absolute ethanol to the extraction solvent dimethyl sulfoxide is 1:1;

[0051] S3. Back extraction: Continue to add sodium chloride solution to the mixed solution for oscillating back extraction. The oscillating back extraction time is 1.5 min, and the amplitude range of the oscillating back extraction is 40 mm. Keep the temperature at 80 °C. Then add a funnel with a desiccant to filter out water, collect the filtered filtrate and concentrate it by nitrogen blowing in a nitrogen blowing instrument to obtain a concentrated solution;

[0052] Among them, the volume ratio of the mixed solution to the sodium chloride solution is 6:1, the mass concentration of the sodium chloride solution is 4%, the desiccant is anhydrous sodium sulfate, the funnel is plugged with 1.5 g of degreased cotton extracted with dichloromethane for 72 h, the addition amount of the desiccant to the mass-volume ratio w:v of the mixed solution is 1.5 g:320 ml, the time for filtering out water is 15 min, the time for nitrogen blowing concentration is 20 min, and the mixed solution is concentrated to 1 mL;

[0053] S4, Activation: Connect a silica gel reversed-phase solid-phase extraction column in series at the upper end of an alumina column. The height ratio of the silica gel reversed-phase solid-phase extraction column to the alumina column is 5:1 to obtain a comprehensive solid-phase extraction column. Then, add dichloromethane and cyclohexane successively to activate the comprehensive solid-phase extraction column. When activating, add 7 mL of dichloromethane, and the activation time of dichloromethane is 40 min. Add 13 mL of cyclohexane, and the activation time of cyclohexane is 40 min. Start the vacuum pump to dry it completely;

[0054] Among them, both the silica gel reversed-phase solid-phase extraction column and the alumina column are commercially available products;

[0055] S5, Purification: Pass the concentrated solution obtained in S3 through the comprehensive solid-phase extraction column in S4, and then rinse and purify it with an eluent to remove impurities. The eluent is a mixture of dichloromethane and cyclohexane with a volume ratio of 1.2:2.2. The rinsing and purification time with the eluent is 70 min, and the volume ratio of the concentrated solution to the eluent is 1.5:11 to obtain a purified solution;

[0056] S6, Detection: Use a gas chromatography-mass spectrometry (GC-MS) instrument to detect the purified solution obtained in S5. The chromatographic column is Rtx-5MS, the ion source temperature is 250 °C, the injection port temperature is 300 °C, the chromatographic column temperature is 60 °C, the interface temperature is 280 °C, and the injection volume is 1 μL to obtain the detection data of polycyclic aromatic hydrocarbons in the sample;

[0057] S7, Analysis: Use chromatographic-mass spectrometry data processing software to perform integration, calibration, and quantitative calculation on the detection data, then establish a standard curve for polycyclic aromatic hydrocarbons, and calculate the accurate content of polycyclic aromatic hydrocarbons in the sample according to the ratio of the peak area of the target compound in the sample to the peak area of the internal standard.

[0058] Example 2

[0059] The difference between this example and Example 1 is as follows:

[0060] S1, Pretreatment: Heat the sample to be detected to complete the pretreatment. The heating temperature is 100 °C, and the heating time is 15 min.

[0061] Example 3

[0062] The difference between this example and Example 1 is as follows:

[0063] S1, Pretreatment: Heat the sample to be detected to complete the pretreatment. The heating temperature is 90 °C, and the heating time is 30 min.

[0064] Note: When performing pretreatment heating, the higher the heating temperature, the shorter the required heating time. It can be reasonably adjusted within the range of pretreatment heating parameters given in the present invention.

[0065] Example 4

[0066] The difference between this embodiment and Embodiment 1 is as follows:

[0067] S2. Extraction: Take the pretreated sample, add hexamethylbenzene and cyclohexane, and obtain a polycyclic aromatic hydrocarbon internal standard after preliminary stirring. The stirring speed of the preliminary stirring is 100 rpm, and the time of the preliminary stirring is 5 min. Then add n-hexane and accelerate the stirring for dissolution. The stirring speed of the accelerated stirring is 300 rpm, and the time of the accelerated stirring is 1 min. Add the extraction solvent dimethyl sulfoxide for oscillating extraction. The oscillating extraction time is 1 min, and the amplitude range of the oscillating extraction is 20 mm. Then add anhydrous ethanol to break the emulsification phenomenon to obtain a mixed solution;

[0068] Among them, the mass ratio of the sample to hexamethylbenzene is 100:1.2, the mass-volume ratio w:v of the sample to cyclohexane is 1 g:1 ml, the volume ratio of cyclohexane to n-hexane is 40:1, the volume ratio of the extraction solvent dimethyl sulfoxide to n-hexane is 2:1, and the volume ratio of anhydrous ethanol to the extraction solvent dimethyl sulfoxide is 1.5:1.

[0069] Embodiment 5

[0070] The difference between this embodiment and Embodiment 1 is as follows:

[0071] S2. Extraction: Take the pretreated sample, add hexamethylbenzene and cyclohexane, and obtain a polycyclic aromatic hydrocarbon internal standard after preliminary stirring. The stirring speed of the preliminary stirring is 200 rpm, and the time of the preliminary stirring is 6 min. Then add n-hexane and accelerate the stirring for dissolution. The stirring speed of the accelerated stirring is 400 rpm, and the time of the accelerated stirring is 2 min. Add the extraction solvent dimethyl sulfoxide for oscillating extraction. The oscillating extraction time is 2 min, and the amplitude range of the oscillating extraction is 60 mm. Then add anhydrous ethanol to break the emulsification phenomenon to obtain a mixed solution;

[0072] Among them, the mass ratio of the sample to hexamethylbenzene is 100:1.5, the mass-volume ratio w:v of the sample to cyclohexane is 1 g:1.5 ml, the volume ratio of cyclohexane to n-hexane is 60:2, the volume ratio of the extraction solvent dimethyl sulfoxide to n-hexane is 3:1, and the volume ratio of anhydrous ethanol to the extraction solvent dimethyl sulfoxide is 1:1.5.

[0073] Note: In Embodiment 1, Embodiment 4 and Embodiment 5, examples of the parameter selection of S2 are given. Among them, the parameter that mainly affects the final extraction effect is the mass-volume ratio of the sample to cyclohexane, and the remaining parameters can be reasonably adjusted within the parameter range given in the present invention.

[0074] Embodiment 6

[0075] The difference between this embodiment and Embodiment 1 is as follows:

[0076] S3. Back extraction: Continuously add sodium chloride solution to the mixed solution for oscillating back extraction. The oscillating back extraction time is 1 min, the amplitude range of oscillating back extraction is 20 mm, the temperature is maintained at 70 °C. Then, add a funnel with a desiccant to filter out water, collect the filtered filtrate and put it into a nitrogen evaporator for nitrogen evaporation concentration to obtain a concentrated solution;

[0077] Among them, the volume ratio of the mixed solution to the sodium chloride solution is 5:1, the mass concentration of the sodium chloride solution is 4%, the desiccant is anhydrous sodium sulfate, the funnel is stuffed with 2 g of degreased cotton extracted with dichloromethane for 72 h, the addition amount of the desiccant to the mass volume ratio of the mixed solution w:v = 1 g:300 ml, the water filtering time is 10 min, the nitrogen evaporation concentration time is 15 min, and the mixed solution is concentrated to 1 mL.

[0078] Example 7

[0079] The difference between this example and Example 1 is that:

[0080] S3. Back extraction: Continuously add sodium chloride solution to the mixed solution for oscillating back extraction. The oscillating back extraction time is 2 min, the amplitude range of oscillating back extraction is 60 mm, the temperature is maintained at 90 °C. Then, add a funnel with a desiccant to filter out water, collect the filtered filtrate and put it into a nitrogen evaporator for nitrogen evaporation concentration to obtain a concentrated solution;

[0081] Among them, the volume ratio of the mixed solution to the sodium chloride solution is 10:1.5, the mass concentration of the sodium chloride solution is 4%, the desiccant is anhydrous sodium sulfate, the funnel is stuffed with 2 g of degreased cotton extracted with dichloromethane for 72 h, the addition amount of the desiccant to the mass volume ratio of the mixed solution w:v = 2 g:350 ml, the water filtering time is 20 min, the nitrogen evaporation concentration time is 30 min, and the mixed solution is concentrated to 2 mL.

[0082] Note: In Example 1, Example 6 and Example 7, examples of parameter selection for S3 are given. Among them, the parameter that mainly affects the final extraction effect is the volume ratio of the mixed solution to the sodium chloride solution, and the remaining parameters can be reasonably adjusted within the parameter range given in the present invention.

[0083] Example 8

[0084] The difference between this example and Example 1 is that:

[0085] S4. Activation: Connect a silica gel reversed-phase solid-phase extraction column in series at the upper end of an alumina column. The height ratio of the silica gel reversed-phase solid-phase extraction column to the alumina column is 3.5:1 to obtain a comprehensive solid-phase extraction column. Add dichloromethane and cyclohexane successively to activate the comprehensive solid-phase extraction column. When activating, add 6 mL of dichloromethane, and the activation time of dichloromethane is 30 min. When activating, add 12 mL of cyclohexane, and the activation time of cyclohexane is 30 min. Start the vacuum pump to dry it.

[0086] S5. Purification: Pass the concentrated solution obtained in S3 through the comprehensive solid-phase extraction column in S4, and then rinse and purify it with an eluent to remove impurities. The eluent is a mixture of dichloromethane and cyclohexane in a volume ratio of 1:2. The rinsing and purification time with the eluent is 60 min, and the volume ratio of the concentrated solution to the eluent is 1:10 to obtain a purified solution.

[0087] Example 9

[0088] The difference between this example and Example 1 is as follows:

[0089] S4. Activation: Connect a silica gel reversed-phase solid-phase extraction column in series at the upper end of an alumina column. The height ratio of the silica gel reversed-phase solid-phase extraction column to the alumina column is 3:0.5 to obtain a comprehensive solid-phase extraction column. Add dichloromethane and cyclohexane successively to activate the comprehensive solid-phase extraction column. When activating, add 8 mL of dichloromethane, and the activation time of dichloromethane is 60 min. When activating, add 14 mL of cyclohexane, and the activation time of cyclohexane is 60 min. Start the vacuum pump to dry it.

[0090] S5. Purification: Pass the concentrated solution obtained in S3 through the comprehensive solid-phase extraction column in S4, and then rinse and purify it with an eluent to remove impurities. The eluent is a mixture of dichloromethane and cyclohexane in a volume ratio of 1.5:2.5. The rinsing and purification time with the eluent is 90 min, and the volume ratio of the concentrated solution to the eluent is 2:12 to obtain a purified solution.

[0091] Note: In Examples 1, 8, and 9, examples of parameter selection for S4 and S5 are given. Among them, the parameter that mainly affects the final purification effect is the volume ratio of the concentrated solution to the eluent. The remaining parameters can be reasonably adjusted within the parameter range given in the present invention.

[0092] Example 10

[0093] The difference between this example and Example 1 is as follows:

[0094] S6. Detection: Use a gas chromatography-mass spectrometry (GC-MS) instrument to detect the purified solution obtained in S5. The chromatographic column is Rtx-5MS.

[0095] Example 11

[0096] The difference between this embodiment and Embodiment 1 is as follows:

[0097] S6. Detection: Use a gas chromatography-mass spectrometry (GC-MS) instrument to detect the purified liquid obtained in S5. The chromatographic column is DB-5MS.

[0098] Embodiment 12

[0099] This embodiment is an application of the method for detecting the content of polycyclic aromatic hydrocarbons in Embodiment 1, and it is applied to the detection of polycyclic aromatic hydrocarbons in rubber filling oil.

[0100] Embodiment 13

[0101] This embodiment is an application of the method for detecting the content of polycyclic aromatic hydrocarbons in Embodiment 1, and it is applied to the detection of polycyclic aromatic hydrocarbons in smokeless tobacco products.

[0102] Embodiment 14

[0103] This embodiment is an application of the method for detecting the content of polycyclic aromatic hydrocarbons in Embodiment 1, and it is applied to the detection of nitro-polycyclic aromatic hydrocarbons in paddy rice or the detection of polycyclic aromatic hydrocarbons in milk.

[0104] Embodiment 15

[0105] This embodiment is an application of the method for detecting the content of polycyclic aromatic hydrocarbons in Embodiment 1, and it is applied to the detection of nitro-polycyclic aromatic hydrocarbons in soil or the detection of polycyclic aromatic hydrocarbons in milk.

[0106] Experimental Example

[0107] Next, we test the accuracy of the method of the present invention through specific experiments. First, 8 substances in polycyclic aromatic hydrocarbons are highly carcinogenic substances (see Table 1 for details).

[0108] Table 1 8 PAHs of high concern

[0109]

[0110] Subsequently, 0.2 g of the rubber filling oil to be detected and 0.3 ml of the polycyclic aromatic hydrocarbon internal standard (prepared from 0.0025 g of hexamethylbenzene + 200 mL of cyclohexane) were taken. Under the selected chromatographic conditions, first, the total ion current chromatogram (TIC) was obtained by full scan mode (GC-MSD / SCAN). Then, based on the fragment ions in its mass spectrum, fragment ions with relatively high abundance, larger molecular mass, and less interference were selected as the characteristic target monitoring ions for determination and confirmation. GC-MSD / SIM determination was carried out for 8 polycyclic aromatic hydrocarbons. The characteristic target monitoring ions for qualitative and quantitative determination finally determined are shown in Table 2, and the retention time of each polycyclic aromatic hydrocarbon is also shown in Table 2. During the determination, internal standard method was used for quantification according to the peak areas in the SIM ion current chromatograms of the standard substance and the sample to be detected. During the confirmation, the types of fragment ions in the positive detected substances to be detected can be used as the basis for positive discrimination.

[0111] Table 2 Molecular formulas, molecular weights, qualitative ions, and quantitative selected ions of 8 PAHs

[0112]

[0113] Determine the linear equation

[0114] Under the solid-phase extraction conditions, the linear equations of each component were determined, and the results are shown in Table 3. It can be seen from the data in the table that the method has high sensitivity.

[0115] Table 3 Linear equations

[0116]

[0117]

[0118] The corresponding standard curves are as Figures 1 to 7 shown. The chromatogram of the 8 PAHs standard solution is as Figure 8 shown. The chromatogram of polycyclic aromatic hydrocarbons in the rubber filling oil is as Figure 9 shown. The GC-MS detection results are shown in Table 4.

[0119] Table 4 Detection results of 8 PAHs of high concern

[0120]

Claims

1. A method for detecting the content of polycyclic aromatic hydrocarbons, characterized in that: The following steps are involved: S1. Pretreatment: heating the sample to be tested to complete pretreatment; S2, extraction: take the pretreated sample, add hexamethylbenzene and cyclohexane, and obtain the internal standard of polycyclic aromatic hydrocarbons after preliminary stirring, add n-hexane and accelerate stirring to dissolve, add the extraction solvent dimethyl sulfoxide to perform oscillation extraction, and then add anhydrous ethanol to break the emulsification phenomenon to obtain a mixed solution; The mass ratio of the sample to hexamethylbenzene is 100:1.2-1.5, the mass volume ratio of the sample to cyclohexane is w:v=1g:1-1.5ml, the volume ratio of cyclohexane to normal hexane is 40-60:1-2, the volume ratio of the extraction solvent dimethyl sulfoxide to normal hexane is 2-3:1, and the volume ratio of anhydrous ethanol to the extraction solvent dimethyl sulfoxide is 1-1.5:1-1.5; S3, stripping: continue to add sodium chloride solution to the mixed solution for oscillation stripping, keep the temperature at 70-90°C, then add a funnel with a desiccant to filter and remove water, collect the filtered filtrate and put it into a nitrogen blower for nitrogen concentration to obtain a concentrated solution; Wherein, the volume ratio of the mixed solution to the sodium chloride solution is 5-10:1-2; S4, activation: connect the silica gel reverse phase solid phase extraction column in series to the upper end of the alumina column to obtain a comprehensive solid phase extraction column, add dichloromethane and cyclohexane in sequence to activate the comprehensive solid phase extraction column, and start the vacuum pump to drain; S5, purification: the concentrated solution obtained in S3 is passed through the comprehensive solid phase extraction column in S4, and then washed and purified with an eluent to remove impurities, wherein the eluent is a mixture of dichloromethane and cyclohexane in a volume ratio of 1 to 1.5:2 to 2.5 to obtain a purified solution; S6. Detection: Detect the purified liquid obtained in S5 using a gas chromatography-mass spectrometer GC-MS to obtain detection data of polycyclic aromatic hydrocarbons in the sample; S7. Analysis: Use chromatography-mass spectrometry data processing software to integrate, calibrate and quantitatively calculate the detection data, then establish a standard curve for PAHs, and calculate the accurate content of PAHs in the sample based on the ratio of the peak area of ​​the target compound in the sample to the peak area of ​​the internal standard.

2. A method for detecting the content of polycyclic aromatic hydrocarbons according to claim 1, characterized in that: The heating temperature in S1 is 90-100° C., and the heating time is 15-30 minutes.

3. A method for detecting the content of polycyclic aromatic hydrocarbons according to claim 1, characterized in that: The stirring speed of the preliminary stirring in S2 is 100-200 rpm, the time of the preliminary stirring is 5-6 min, the stirring speed of the accelerated stirring is 300-400 rpm, and the time of the accelerated stirring is 1-2 min.

4. A method for detecting the content of polycyclic aromatic hydrocarbons according to claim 1, characterized in that: The oscillation extraction time in S2 is 1 to 2 minutes, and the amplitude range of the oscillation extraction is 0 to 60 mm.

5. The method for detecting the content of polycyclic aromatic hydrocarbons according to claim 1, characterized in that: The oscillation stripping time in S3 is 1 to 2 minutes, and the amplitude range of the oscillation stripping is 0 to 60 mm.

6. The method for detecting the content of polycyclic aromatic hydrocarbons according to claim 1, characterized in that: The mass concentration of the sodium chloride solution in the S3 is 4%, the desiccant is anhydrous sodium sulfate, the funnel is plugged with 1-2g of absorbent cotton extracted with dichloromethane for 72h, the mass volume ratio of the added desiccant to the mixed solution is w:v=1-2g:300-350ml, the filtration and water removal time is 10-20min, the nitrogen blowing and concentration time is 15-30min, and the mixed solution is concentrated to 1-2mL.

7. A method for detecting the content of polycyclic aromatic hydrocarbons according to claim 1, characterized in that: The height ratio of the silica gel reverse solid phase extraction column to the alumina column in S4 is 3-5:0.5-1. During activation, 6-8 mL of dichloromethane is added, and the dichloromethane activation time is 30-60 min. During activation, 12-14 mL of cyclohexane is added, and the cyclohexane activation time is 30-60 min.

8. The method for detecting the content of polycyclic aromatic hydrocarbons according to claim 1, characterized in that: The washing and purification time of the eluent in S5 is 60 to 90 minutes, and the volume ratio of the concentrated solution to the eluent is 1 to 2:10 to 12.

9. The method for detecting the content of polycyclic aromatic hydrocarbons according to claim 1, characterized in that: The chromatographic column in the S6 is Rtx-5MS, HP-5MS UI or DB-5MS, the ion source temperature is 250°C, the injection port temperature is 300°C, the chromatographic column temperature is 60°C, the interface temperature is 280°C, and the injection volume is 1uL.

10. Use of the method for detecting the content of polycyclic aromatic hydrocarbons according to any one of claims 1 to 9, characterized in that: It is used in the detection of PAHs in rubber filler oil, PAHs in smokeless tobacco products, nitro PAHs in rice and soil, or PAHs in milk.

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