Method for synchronously extracting and detecting n-alkanes and polycyclic aromatic hydrocarbons in soil and / or marine sediments

Abstract

The invention discloses a method for synchronously extracting and detecting n-alkanes and polycyclic aromatic hydrocarbons in soil and / or marine sediments, and belongs to the field of analysis and testing of materials, and the method comprises the following steps: removing impurities from the soil and the marine sediments, carrying out pretreatment, carrying out one-step extraction by optimizing a mixed solvent, and purifying to obtain a concentrated extracting solution; and mixing the extracting solution with an internal standard solution to obtain a to-be-detected solution. The mixed standard solution and the to-be-detected solution are subjected to one-step detection through a gas chromatograph-mass spectrometer under optimized detection conditions, and n-alkane components and polycyclic aromatic hydrocarbon components in the soil and / or the marine sediments are detected. The extraction solvent is optimized, impurity interference is reduced, and the application range is wide; the detection method has the advantages of good separation effect, high sensitivity and good repeatability, can simultaneously meet the analysis requirements on the components of n-alkanes and polycyclic aromatic hydrocarbons in soil and / or marine sediments, and greatly shortens the time efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of material analysis and testing, and in particular relates to a method for synchronously extracting and detecting normal alkanes and polycyclic aromatic hydrocarbons in soil and / or marine sediments. Background Art

[0002] Hydrocarbon organic matter in soil and marine sediments mainly includes n-alkanes, polycyclic aromatic hydrocarbons, fatty acids, alcohols, etc. Their main sources include biosynthesis, diagenetic transformation, petroleum pollution and high-temperature synthesis. Among them, the composition and distribution characteristics of n-alkanes can effectively indicate the source of organic matter and reflect the marine environment and petroleum pollution. Polycyclic aromatic hydrocarbons are persistent pollutants and are widely distributed in the air, soil, water and sediments. Ecological risk assessment of polycyclic aromatic hydrocarbons is conducive to understanding the impact of economic development activities on the marine sedimentary environment.

[0003] The existing standard methods and literature all analyze and detect n-alkanes and PAHs separately, which requires sample pretreatment and analysis and detection separately, uses a large amount of organic solvents, and has low efficiency. In practical applications, a one-step method is required to analyze and detect n-alkanes and PAHs. Therefore, the development of an analytical detection method for one-step extraction and detection of n-alkanes and PAHs will greatly improve the detection efficiency and be environmentally friendly. Summary of the invention

[0004] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0005] In view of the above problems and / or the problems existing in the prior art, the present invention is proposed.

[0006] Therefore, the purpose of the present invention is to overcome the shortcomings of the prior art of step-by-step extraction and provide a method for simultaneously extracting normal alkanes and polycyclic aromatic hydrocarbons from soil and / or marine sediments.

[0007] In order to solve the above technical problems, the present invention provides the following technical solutions: The soil and / or marine sediments are freeze-dried, ground, sieved, and collected to obtain samples after removing impurities; The sample is mixed with diatomaceous earth, and an extract is obtained by solvent extraction. A copper sheet is added to the extract to remove sulfur, and a concentrated solution I is obtained by concentration. The solvent used for the solvent extraction is obtained by mixing n-hexane and acetone, and the volume ratio of n-hexane to acetone is 4-9:1; The concentrated solution I is subjected to a sample treatment in an extractor subjected to a pre-activation treatment, and the obtained cleaning solution is purified and concentrated by a solvent to obtain a concentrated extract containing normal alkanes and polycyclic aromatic hydrocarbons; The solvent used for the solvent purification is obtained by mixing n-hexane and dichloromethane, and the volume ratio of n-hexane to dichloromethane is 10-9:1.

[0008] As a preferred embodiment of the method for simultaneously extracting normal alkanes and polycyclic aromatic hydrocarbons from soil and / or marine sediments of the present invention, the mass ratio of the sample to diatomaceous earth is 10:1-3; the mass ratio of the copper sheet to the extract is 15-35:1.

[0009] As a preferred embodiment of the method for simultaneously extracting normal alkanes and polycyclic aromatic hydrocarbons from soil and / or marine sediments according to the present invention, the solvent extraction comprises the following steps: the extraction pressure is 10-11 MPa, the extraction temperature is 70-100° C., and the extraction time is 5-10 min.

[0010] As a preferred embodiment of the method for simultaneously extracting normal alkanes and polycyclic aromatic hydrocarbons from soil and / or marine sediments according to the present invention, the pre-activated extractor comprises three activation treatments of the extractor by different solvents, wherein: The first activation was performed with dichloromethane; The second and third activations were performed with n-hexane; The flow rate of each activation was 1~3 mL / min, and the volume of the solvent used was 3~5 mL.

[0011] As a preferred embodiment of the method for simultaneously extracting normal alkanes and polycyclic aromatic hydrocarbons from soil and / or marine sediments of the present invention, the flow rate of the sample loading treatment is 1-2 mL / min and the volume is 1-2 mL.

[0012] Another object of the present invention is to overcome the shortcomings of the prior art in the step-by-step detection and provide a method for the simultaneous detection of normal alkanes and polycyclic aromatic hydrocarbons in soil and / or marine sediments.

[0013] In order to solve the above technical problems, the present invention provides the following technical solutions: The method for simultaneously extracting normal alkanes and polycyclic aromatic hydrocarbons from soil and / or marine sediments is used to extract and obtain a concentrated extract containing normal alkanes and polycyclic aromatic hydrocarbons; The concentrated extract containing normal alkanes and polycyclic aromatic hydrocarbons is mixed with an internal standard solution to obtain a test solution; The mixed standard solution and the test solution are detected by gas chromatography-mass spectrometry respectively; wherein, The mixed standard solution was scanned in full scan mode, and the components of n-alkanes and polycyclic aromatic hydrocarbons in the mixed standard solution were qualitatively analyzed by library search and retention time; The ion scanning method was used to scan the test solution, using deuterated tetracosane, anthracene-D 10 , Perylene-D 12 The relative response factors (RRFs) of n-alkane components and polycyclic aromatic hydrocarbon components to the internal standard were calculated, so as to quantitatively analyze the contents of n-alkane components and polycyclic aromatic hydrocarbon components in the concentrated extract containing n-alkane and polycyclic aromatic hydrocarbons.

[0014] As a preferred embodiment of the method for synchronously detecting normal alkanes and polycyclic aromatic hydrocarbons in soil and / or marine sediments of the present invention, the volume ratio of the concentrated extract to the internal standard solution is 10:1-2; the internal standard solution is 3 internal standard substances: deuterated n-tetracosane, anthracene-D 10 , Perylene-D 12 The total concentration of the internal standard solution is 10~40μg / mL.

[0015] As a preferred embodiment of the method for synchronously detecting normal alkanes and polycyclic aromatic hydrocarbons in soil and / or marine sediments of the present invention, wherein: in the detection by gas chromatography-mass spectrometry, The injection conditions of the gas chromatography were as follows: injection port temperature of 200-250°C, injection volume of 1 μL, splitless mode, carrier gas helium purity >99.9995%, and flow rate of 1-1.5 mL / min; The temperature program of the gas chromatography column oven is as follows: in the initial stage, the temperature is kept at 40-50℃ for 2-3 min; in the second stage, the temperature is increased to 70-170℃ at a rate of 5-10℃ / min; in the third stage, the temperature is increased to 100-220℃ at a rate of 5-10℃ / min and kept for 0-3min; in the fourth stage, the temperature is increased to 150-260℃ at a rate of 3-10℃ / min and kept for 3-5 min; in the fifth stage, the temperature is increased to 200-280℃ at a rate of 5-10℃ / min and kept for 2-5min; in the sixth stage, the temperature is increased to 250-320℃ at a rate of 3-10℃ / min and kept for 5-10min; in the seventh stage, the temperature is increased to 280-320℃ at a rate of 5-10℃ / min and kept for 5-10min; in the eighth stage, the temperature is increased to 300-320℃ at a rate of 5-10℃ / min and kept for 10-15min; The detection conditions of mass spectrometry were as follows: electron bombardment ion source, electron energy of 70 eV, ion source temperature of 200-220°C, interface temperature of 250-280°C, and solvent delay of 2-5 min.

[0016] As a preferred embodiment of the method for synchronously detecting normal alkanes and polycyclic aromatic hydrocarbons in soil and / or marine sediments of the present invention, the mixed standard solution is composed of C9~C 40 Standard stock solution, 16 PAH standard stock solutions, internal standard solution and 3 alternatives: naphthalene-D8, acenaphthene-D 10 , p-terphenyl-D 14 The stock solution of standard solution was obtained by dilution with n-hexane solvent.

[0017] As a preferred embodiment of the method for synchronously detecting normal alkanes and polycyclic aromatic hydrocarbons in soil and / or marine sediments of the present invention, the concentration of the mixed standard solution is 10-40 μg / mL; the C9-C 40 The concentration of the standard stock solution is 500-2000 μg / mL; the concentration of the standard stock solution of the 16 PAHs is 500-2000 μg / mL; the three substitutes naphthalene-D8, acenaphthene-D 10 , p-terphenyl-D 14 The concentration of the standard solution stock solution is 500~2000μg / mL.

[0018] Beneficial effects of the present invention: Compared with the prior art, the present invention has the advantages of simple operation, rapidity and efficiency, high sensitivity, good selectivity, ability to simultaneously extract and detect and analyze two types of substances, and environmental friendliness.

[0019] By using accelerated solvent extraction technology, the extraction solvent is optimized to achieve one-step extraction of normal alkanes and polycyclic aromatic hydrocarbons, and the detection conditions are optimized to achieve one-step analysis, which shortens the analysis time and improves the analysis efficiency.

[0020] The method of the present invention can simultaneously extract and detect normal alkanes and polycyclic aromatic hydrocarbons in soil and / or marine sediments, thereby improving analysis efficiency, reducing analysis costs, reducing the use of organic solvents, and being more environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0022] Figure 1 This is a total ion current chromatogram of 32 normal alkanes, pristane and phytane, 16 polycyclic aromatic hydrocarbons, 3 substitutes and 3 internal standards in soil and marine sediments detected in Example 2 of the present invention.

[0023] Figure 2The figure is a comparison chart of the recovery rates of normal alkane components in the solutions extracted in Example 1 and Example 3 of the present invention.

[0024] Figure 3 The figure is a comparison chart of the recovery rates of polycyclic aromatic hydrocarbon components in the solutions extracted in Example 1 and Example 3 of the present invention.

[0025] Figure 4 The figure is a comparison chart of the recovery rates of normal alkane components in the solutions extracted by Example 1 of the present invention and Comparative Example 3.

[0026] Figure 5 The figure is a comparison chart of the recovery rates of polycyclic aromatic hydrocarbon components in the solutions extracted by Example 1 of the present invention and Comparative Example 3.

[0027] Figure 6 The figure is a comparison chart of the recovery rates of normal alkane components in the solutions extracted by Example 1 of the present invention and Comparative Examples 4 to 6.

[0028] Figure 7 The figure is a comparison chart of the recovery rates of polycyclic aromatic hydrocarbon components in the solutions extracted by Example 1 of the present invention and Comparative Examples 4 to 6.

[0029] Figure 8 This is a total ion current chromatogram of 32 normal alkanes, pristane and phytane, 16 polycyclic aromatic hydrocarbons, 3 substitutes and 3 internal standards in soil and marine sediments detected in Comparative Example 7 of the present invention.

[0030] Fig. 9 This is a total ion current chromatogram of 32 normal alkanes, pristane and phytane, 16 polycyclic aromatic hydrocarbons, 3 substitutes and 3 internal standards in soil and marine sediments detected in Comparative Example 8 of the present invention.

[0031] Fig.10 This is a total ion current chromatogram of 32 normal alkanes, pristane and phytane, 16 polycyclic aromatic hydrocarbons, 3 substitutes and 3 internal standards in soil and marine sediments detected in Example 4 of the present invention. DETAILED DESCRIPTION

[0032] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification.

[0033] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0034] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0035] The gas chromatograph-mass spectrometer used in the present invention is a Shimadzu gas chromatograph-mass spectrometer, model GCMS-QP2020NX.

[0036] The C9~C 40 The concentration of the standard stock solution (containing pristane and phytane) is 500 μg / mL.

[0037] The concentration of the 16 PAH standard stock solutions used in the present invention is 1000 μg / mL.

[0038] The internal standard solutions used in the present invention are 3 kinds of internal standard substances: deuterated tetracosane (C 24 D 50 ), anthracene-D 10 , Perylene-D 12 Standard solution, concentration is 10μg / mL.

[0039] The three substitutes used in the present invention are naphthalene-D8, acenaphthene-D 10 , p-terphenyl-D 14 The concentration of the standard solution stock was 1000 μg / mL.

[0040] The mixed standard solution used in the present invention is C9~C 40 Standard stock solutions (including pristane and phytane), 16 PAH standard stock solutions and 3 internal standards deuterated n-tetracosane (C 24 D 50 ), anthracene-D 10 , Perylene-D 12 and three alternatives: naphthalene-D8, acenaphthene-D 10 , p-terphenyl-D 14 The standard solution stock solution was diluted with n-hexane solvent, and the concentration of the mixed standard solution was 10 μg / mL.

[0041] Example 1: This example provides a method for simultaneously extracting normal alkanes and polycyclic aromatic hydrocarbons from soil and marine sediments, specifically: Sample extraction: The soil and marine sediments were discarded of debris, freeze-dried, ground, and sieved through an 80-mesh sieve to collect the samples; Weigh 10.0 g of sample and mix it evenly with 3.0 g of diatomaceous earth, add it to the extraction cell of the rapid solvent extractor (ASE), heat it at 80 °C for 10 min under 10.34 MPa, set the flushing volume to 60%, and the purge time to 90 s. Elute it twice with a mixed solvent of n-hexane and acetone in a volume ratio of 4:1 to obtain an extract, add 2.0 g of copper sheet, extract it with ultrasonic extraction for 10 min to remove sulfur, and concentrate it to 1.0 mL to obtain concentrated solution I.

[0042] Purification and concentration: The sample channel of the solid phase extractor was cleaned with a mixed solvent of n-hexane and dichloromethane, and the waste liquid was discharged; the neutral alumina solid phase extraction column was activated for the first time with dichloromethane, and the second and third activations were performed with n-hexane, and the waste liquid was discharged, wherein the flow rate of each activation was 3 mL / min and the volume was 5 mL; Load the concentrate I into the pre-activated extractor at a flow rate of 1 mL / min, with a loading volume of 1-1.5 mL, and wash the sample bottle 3 times with n-hexane, with a flow rate of 1 mL / min and a volume of 1 mL each time, and collect the washing liquid; The cleaning liquid was eluted twice with a mixed solvent of n-hexane and dichloromethane in a volume ratio of 10:1. The flow rate of each elution was 2 mL / min and the elution volume was 5 mL. The eluate was collected as the purified sample and concentrated to 0.5 mL using a nitrogen blower to obtain a concentrated extract containing n-alkanes and polycyclic aromatic hydrocarbons.

[0043] Example 2: This example provides a method for synchronously detecting normal alkanes and polycyclic aromatic hydrocarbons in soil and marine sediments, specifically: (1) Instrument detection: The concentrated extract containing normal alkanes and polycyclic aromatic hydrocarbons obtained in Example 1 was transferred to a sample injection bottle, 50 μL of the internal standard solution was added, the volume was fixed to 1.0 mL, and mixed to obtain a test solution.

[0044] The automatic sampler draws the mixed standard solution and the test solution, and then detects them through the gas chromatography-mass spectrometer. The injection conditions were set as follows: injection port temperature of 250 °C, injection volume of 1 μL, splitless mode, carrier gas helium purity >99.9995%, flow rate of 1 mL / min; The column oven temperature program was set as follows: the temperature was 50 °C for 2 min in the initial stage, increased to 70 °C at a rate of 5 °C / min in the second stage, increased to 110 °C at a rate of 10 °C / min in the third stage, increased to 160 °C at a rate of 5 °C / min and maintained for 5 min in the fourth stage, increased to 220 °C at a rate of 8 °C / min and maintained for 2 min in the fifth stage, increased to 260 °C at a rate of 3 °C / min and maintained for 10 min in the sixth stage, increased to 280 °C at a rate of 6 °C / min and maintained for 5 min in the seventh stage, increased to 320 °C at a rate of 6 °C / min and maintained for 10 min in the eighth stage; The mass spectrometry conditions were set as follows: electron bombardment ion source, electron energy of 70 eV, ion source temperature of 200 °C, interface temperature of 280 °C, and solvent delay of 5 min.

[0045] (2) Qualitative analysis: The mixed standard solution was scanned in full scan (SCAN) mode with a scanning range of 50-500 m / z. The components of n-alkanes and polycyclic aromatic hydrocarbons in the mixed standard solution were qualitatively analyzed using library retrieval and retention time to obtain the total ion current chromatogram as shown below: Figure 1 The specific information parameters are shown in Table 1.

[0046] (3) Quantitative analysis: The ion scanning (SIM) method was used to scan the test solution, with deuterated n-tetracosane (C 24 D 50 ), anthracene-D 10 , Perylene-D 12 As an internal standard, the normal alkane components (C9~C 40 ), the relative response factor (RRF) of the PAH components and the internal standard, thereby calculating the contents of n-alkanes and PAH components in the test solution.

[0047] 500 μL of the mixed standard solution was transferred and diluted stepwise with n-hexane to prepare a standard series of solutions at 12 concentration levels, so that the mass concentration of each compound was 10 ng / mL, 20 ng / mL, 40 ng / mL, 80 ng / mL, 156 ng / mL, 312.5 ng / mL, 625 ng / mL, 1.25 μg / mL, 2.5 μg / mL, 5 μg / mL, 10.0 μg / mL, and 20 μg / mL, and the mass concentration of the internal standard was 500.0 ng / mL.

[0048] Under the same conditions as step (3) in Example 2, the SIM mode was used for acquisition, and the mass concentration ratio of the target compound to the internal standard was used as the horizontal axis, and the response value (peak area) ratio of the target compound to the internal standard was used as the vertical axis to draw a standard curve. The specific information is shown in Tables 1-2.

[0049] Table 1 Spectral information of n-alkanes, polycyclic aromatic hydrocarbons and their substitutes

[0050] Table 2 Standard curves and linear correlation coefficients of n-alkanes, polycyclic aromatic hydrocarbons and their substitutes

[0051] from Figure 1 It can be seen from the total ion current chromatogram and the spectrum information in Table 1 that the components can be well separated under the conditions of this scheme, and the simultaneous analysis and detection of n-alkanes and polycyclic aromatic hydrocarbons can be achieved.

[0052] It can be seen from Table 2 that the correlation coefficients are all greater than 0.999, indicating that the method of the present invention has a good linear relationship and high sensitivity.

[0053] Comparative Example 1: This comparative example adopts the normal alkane extraction scheme in the standard method GB / T 30739-2014, and uses normal hexane solvent as the extraction solvent. This analytical detection method is limited to the extraction and detection of normal hexane, and fails to achieve effective extraction and detection of polycyclic aromatic hydrocarbons.

[0054] Comparative Example 2: This comparative example adopts the polycyclic aromatic hydrocarbons extraction scheme in the standard method DZ / T 0423.3-2022, and uses a mixed solvent of dichloromethane and acetone as the extraction solvent. This analytical detection method is limited to the extraction and detection of polycyclic aromatic hydrocarbons, and fails to achieve effective extraction and detection of normal alkanes. In addition, the solvent extraction method has more impurities and serious interference.

[0055] Compared with Comparative Examples 1 and 2, the present invention uses a mixed solvent of n-hexane and acetone for extraction first, and then uses a mixed solvent of n-hexane and dichloromethane for purification, which can efficiently extract n-alkanes and polycyclic aromatic hydrocarbons in soil and marine sediments, and the impurity interference is low under the solvent system. Through the optimized detection method, the effective separation of n-alkanes and polycyclic aromatic hydrocarbons components can be achieved simultaneously.

[0056] Example 3: This example differs from Example 1 in that the volume ratio of n-hexane to acetone in step (1) of Example 1 is adjusted to 9:1, and the rest of the method is the same as that of Example 1.

[0057] The solutions extracted in Examples 1 and 3 were tested, and the results were as follows: Figure 2~Figure 3 As shown, Figure 2is the recovery rate of each component of normal alkanes under different solvent ratios, Figure 3 is the recovery rate of each component of PAHs under different solvent ratios. It can be seen that under the conditions of Example 3, the simultaneous extraction of n-alkanes and PAHs in soil and marine sediments can be achieved, and the recovery rate can reach 70% to 130% required by the standard method.

[0058] Comparative Example 3: This comparative example differs from Example 1 in that the volume ratio of n-hexane to acetone in step (1) of Example 1 is adjusted to 1:1, and the rest of the process is the same as that of Example 1.

[0059] The solutions extracted from Example 1 and Comparative Example 3 were tested, and the results were as follows: Figure 4~Figure 5 As shown, Figure 4 is the recovery rate of each component of normal alkanes under different solvent ratios, Figure 5 is the recovery rate of each component of PAHs under different solvent ratios. It can be seen that the recovery rate of PAHs in the concentrated extract of Comparative Example 3 is relatively low, only 60% to 85%.

[0060] Comparative Example 4: This comparative example differs from Example 1 in that the mixed solvent of n-hexane and acetone in step (1) of Example 1 is adjusted to n-hexane, and the rest of the process is the same as that of Example 1.

[0061] Comparative Example 5: This comparative example differs from Example 1 in that the volume ratio of n-hexane to dichloromethane in step (2) of Example 1 is adjusted to 4:1, and the rest of the process is the same as that of Example 1.

[0062] Comparative Example 6: This comparative example differs from Example 1 in that the mixed solvent of n-hexane and dichloromethane in step (2) of Example 1 is adjusted to dichloromethane, and the rest of the process is the same as Example 1.

[0063] The solutions extracted from Example 1 and Comparative Examples 4 to 6 were tested, and the results were as follows: Figure 6~Figure 7 As shown. Among them, Figure 6 is the recovery rate of each component of n-alkanes under different solvent conditions, Figure 7 is the recovery rate of each component of PAHs under different solvent conditions.

[0064] from Figure 7 It can be seen that when the mixed solvent of n-hexane and acetone is adjusted to n-hexane, and the volume ratio of n-hexane to dichloromethane is adjusted to 4:1, the PAHs in the extracted solution cannot be completely extracted. In addition, when the mixed solvent of n-hexane and dichloromethane is adjusted to dichloromethane, both n-hexane and PAHs cannot be completely extracted.

[0065] It can be seen that the types and proportions of extraction solvents in Comparative Examples 3 to 6 are unable to completely extract normal alkanes and polycyclic aromatic hydrocarbons.

[0066] Comparative Example 7. The difference between this comparative example and Example 2 is that the injection condition in step (1) of Example 2 is adjusted to an injection port temperature of 280°C, and the column oven temperature program is set as follows: the initial stage temperature is 50°C and maintained for 2 min, and the second stage is heated to 320°C at a rate of 6°C / min and maintained for 20 min. The rest of the methods are the same as Example 1.

[0067] The test results of Comparative Example 7 are as follows Figure 8 shown.

[0068] Comparative Example 8. The difference between this comparative example and Example 2 is that the column oven temperature heating program in step (1) of Example 2 is adjusted as follows: the temperature in the initial stage is 60°C and maintained for 1 min; in the second stage, the temperature is increased to 195°C at a rate of 15°C / min and maintained for 6 min; in the third stage, the temperature is increased to 240°C at a rate of 15°C / min and maintained for 2 min; in the fourth stage, the temperature is increased to 275°C at a rate of 3°C / min; in the fifth stage, the temperature is increased to 280°C at a rate of 2°C / min and maintained for 2 min; in the sixth stage, the temperature is increased to 300°C at a rate of 20°C / min and maintained for 3 min. The remaining methods are the same as in Example 1.

[0069] The test results of Comparative Example 8 are as follows: Fig. 9 shown.

[0070] from Figure 8~Figure 9 It can be seen that under the detection conditions in Comparative Examples 7 and 8, there is a peak overlap phenomenon, and the normal alkanes and polycyclic aromatic hydrocarbons components cannot be completely detected.

[0071] Example 4. The difference between this example and Example 2 is that the column oven temperature program in step (1) of Example 2 is adjusted as follows: the temperature in the initial stage is 50°C and maintained for 2 minutes; in the second stage, the temperature is increased to 170°C at a rate of 5°C / min; in the third stage, the temperature is increased to 220°C at a rate of 6°C / min and maintained for 3 minutes; in the fourth stage, the temperature is increased to 260°C at a rate of 3°C / min and maintained for 5 minutes; in the fifth stage, the temperature is increased to 280°C at a rate of 5°C / min and maintained for 5 minutes; in the sixth stage, the temperature is increased to 320°C at a rate of 5°C / min and maintained for 10 minutes; the remaining methods are the same as in Example 2.

[0072] Example 4 Test results are as follows Fig.10 As shown, it can be seen that both Example 4 and Example 2 can simultaneously detect n-alkanes and polycyclic aromatic hydrocarbons in soil and marine sediments.

[0073] In summary, the present invention provides a method for synchronously extracting and detecting n-alkanes and polycyclic aromatic hydrocarbons in soil and / or marine sediments. The present invention extracts n-alkanes and polycyclic aromatic hydrocarbons from soil and / or marine sediments simultaneously, and performs analysis and detection based on a gas chromatography-mass spectrometer, uses a library search to qualitatively characterize a mixed standard solution consisting of 32 n-alkanes, pristane and phytane, 16 polycyclic aromatic hydrocarbons, 3 substitutes, and 3 internal standards, and uses an internal standard quantitative method to determine the content of n-alkanes and polycyclic aromatic hydrocarbons in the sample.

[0074] Among them, the present invention uses accelerated solvent extraction technology to pre-treat the sample, and realizes the simultaneous extraction of normal alkanes and polycyclic aromatic hydrocarbons by optimizing the extraction solvent, shortening the analysis time and reducing the interference of impurities; By optimizing the detection conditions of gas chromatography-mass spectrometry technology, n-alkanes and polycyclic aromatic hydrocarbons in soil and marine sediments can be determined simultaneously, which improves the analysis efficiency and reduces the analysis cost.

[0075] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for simultaneously extracting normal alkanes and polycyclic aromatic hydrocarbons from soil and / or marine sediments, characterized in that: include, The soil and / or marine sediments are freeze-dried, ground, and sieved in sequence after removing impurities, and the samples are collected; The sample is mixed with diatomaceous earth, and an extract is obtained by solvent extraction. A copper sheet is added to the extract to remove sulfur, and a concentrated solution I is obtained by concentration. The solvent used for the solvent extraction is obtained by mixing n-hexane and acetone, and the volume ratio of n-hexane to acetone is 4-9:1; The concentrated solution I is subjected to a sample treatment in an extractor subjected to a pre-activation treatment, and the obtained cleaning solution is purified and concentrated by a solvent to obtain a concentrated extract containing normal alkanes and polycyclic aromatic hydrocarbons; The solvent used for the solvent purification is obtained by mixing n-hexane and dichloromethane, and the volume ratio of n-hexane to dichloromethane is 10-9:

1.

2. The method for synchronously extracting normal alkanes and polycyclic aromatic hydrocarbons from soil and / or marine sediments according to claim 1, characterized in that: The mass ratio of the sample to diatomaceous earth is 10:1-3; the mass ratio of the copper sheet to the extract is 15-35:

1.

3. The method for synchronously extracting normal alkanes and polycyclic aromatic hydrocarbons from soil and / or marine sediments as claimed in claim 1 or 2, characterized in that: The solvent extraction, wherein the extraction pressure is 10-11 MPa, the extraction temperature is 70-100° C., and the extraction time is 5-10 min.

4. The method for synchronously extracting normal alkanes and polycyclic aromatic hydrocarbons from soil and / or marine sediments as claimed in claim 1, characterized in that: The pre-activated extractor comprises three activation treatments of the extractor using different solvents, wherein: The first activation was performed with dichloromethane; The second and third activations were performed with n-hexane; The flow rate of each activation was 1~3mL / min, and the volume of the solvent used was 3~5mL.

5. The method for simultaneously extracting normal alkanes and polycyclic aromatic hydrocarbons from soil and / or marine sediments as claimed in claim 4, characterized in that: The flow rate of the sample loading process is 1-2 mL / min, and the volume is 1-2 mL.

6. A method for the simultaneous detection of normal alkanes and polycyclic aromatic hydrocarbons in soil and / or marine sediments, characterized in that: The method of claim 1 is used to extract and obtain a concentrated extract containing normal alkanes and polycyclic aromatic hydrocarbons; The concentrated extract containing normal alkanes and polycyclic aromatic hydrocarbons is mixed with an internal standard solution to obtain a test solution; The mixed standard solution and the test solution are detected by gas chromatography-mass spectrometry respectively; wherein, The mixed standard solution was scanned in full scan mode, and the components of n-alkanes and polycyclic aromatic hydrocarbons in the mixed standard solution were qualitatively analyzed by library search and retention time; The ion scanning method was used to scan the test solution, using deuterated tetracosane, anthracene-D 10 , Perylene-D 12 The relative response factors (RRFs) of n-alkane components and polycyclic aromatic hydrocarbon components to the internal standard were calculated, so as to quantitatively analyze the contents of n-alkane components and polycyclic aromatic hydrocarbon components in the concentrated extract containing n-alkane and polycyclic aromatic hydrocarbons.

7. The method for synchronously detecting normal alkanes and polycyclic aromatic hydrocarbons in soil and / or marine sediments according to claim 6, characterized in that: The volume ratio of the concentrated extract to the internal standard solution is 10:1-2; the internal standard solution is 3 internal standard substances: deuterated tetracosane, anthracene-D 10 , Perylene-D 12 The total concentration of the internal standard solution is 10~40μg / mL.

8. The method for synchronously detecting normal alkanes and polycyclic aromatic hydrocarbons in soil and / or marine sediments according to claim 6, characterized in that: In the detection by gas chromatography-mass spectrometry, The injection conditions of the gas chromatography were as follows: injection port temperature of 200-250°C, injection volume of 1 μL, splitless mode, carrier gas helium purity >99.9995%, and flow rate of 1-1.5 mL / min; The temperature program of the gas chromatography column oven is as follows: in the initial stage, the temperature is kept at 40-50℃ for 2-3 min; in the second stage, the temperature is increased to 70-170℃ at a rate of 5-10℃ / min; in the third stage, the temperature is increased to 100-220℃ at a rate of 5-10℃ / min and kept for 0-3min; in the fourth stage, the temperature is increased to 150-260℃ at a rate of 3-10℃ / min and kept for 3-5 min; in the fifth stage, the temperature is increased to 200-280℃ at a rate of 5-10℃ / min and kept for 2-5min; in the sixth stage, the temperature is increased to 250-320℃ at a rate of 3-10℃ / min and kept for 5-10min; in the seventh stage, the temperature is increased to 280-320℃ at a rate of 5-10℃ / min and kept for 5-10min; in the eighth stage, the temperature is increased to 300-320℃ at a rate of 5-10℃ / min and kept for 10-15min; The detection conditions of mass spectrometry were as follows: electron bombardment ion source, electron energy of 70 eV, ion source temperature of 200-220°C, interface temperature of 250-280°C, and solvent delay of 2-5 min.

9. The method for synchronously detecting normal alkanes and polycyclic aromatic hydrocarbons in soil and / or marine sediments according to claim 6, characterized in that: The mixed standard solution is composed of C9~C 40 Standard stock solution, 16 PAH standard stock solutions, internal standard solution and 3 alternatives: naphthalene-D8, acenaphthene-D 10 , p-terphenyl-D 14 The stock solution of standard solution was obtained by dilution with n-hexane solvent.

10. The method for synchronously detecting normal alkanes and polycyclic aromatic hydrocarbons in soil and / or marine sediments according to claim 7, characterized in that: The concentration of the mixed standard solution is 10-40 μg / mL; 40 The concentration of the standard stock solution is 500-2000 μg / mL; the concentration of the standard stock solution of the 16 PAHs is 500-2000 μg / mL; the three substitutes naphthalene-D8, acenaphthene-D 10 , p-terphenyl-D 14 The concentration of the standard solution stock solution is 500~2000μg / mL.

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