A detection method and application of C1~C2-alkyl substituted phenol isomers

Abstract

The present invention discloses a method for detecting and applying C1-C2-alkyl-substituted phenol isomers, which relates to the technical field of environmental detection and includes: selecting a corresponding sample pretreatment process to prepare a test sample according to the petroleum content range in the sample; under a mobile phase of methanol-5.0-6.5 mmol / L ammonia water, using LC-MS to detect the test sample to obtain the concentration of the first component and the standardized concentrations of co-eluted 3,5-dimethylphenol and 2,6-dimethylphenol; under a mobile phase of acetonitrile-4.0-10.0 mmol / L ammonia water, using LC-MS to detect the test sample to obtain the concentration of 3,5-dimethylphenol, or the standardized concentrations of co-eluted 3,5-methylphenol and 3-ethylphenol, or the standardized concentrations of co-eluted 2,6-dimethylphenol and 2,4-dimethylphenol; under a mobile phase of methanol-5.0-6.5 mmol / L ammonia water or acetonitrile-4.0-10.0 mmol / L ammonia water, using LC-MS to separately detect the calibration samples of the co-eluted components, and calculate the conversion factor of the co-eluted components and the concentration of the other component. The present invention realizes the accurate quantification of phenol and 12 C1-C2-alkyl-substituted phenol isomers.

Description

Technical Field

[0001] The present invention relates to the technical field of environmental detection, and in particular to a detection method and application of C1-C2-alkyl substituted phenol isomers. Background Art

[0002] The stripping water discharged from the sulfur-containing and salt-containing wastewater stripping unit of the petroleum refinery belongs to oily wastewater and is the main process wastewater. Volatile phenol is the main contributing component of COD (chemical oxygen demand) of this type of wastewater, with a content as high as 0.2-0.5 kg / m 3 The volatile phenolic components in the stripping water mainly include C0-alkyl substituted phenol (phenol), C1-alkyl substituted phenol (methyl phenol isomers), C2-alkyl substituted phenol (dimethyl / ethyl phenol isomers) and C3-alkyl substituted phenol.

[0003] There are many isomers of volatile phenolic components. When using chromatography-mass spectrometry for quantification, it is necessary to achieve chromatographic separation of isomers, and chromatographic separation of isomers has always been a technical difficulty in this field. Song Lingyong et al. (Song Lingyong, Zhao Qi, Huang Shijie, et al. Simultaneous determination of 15 phenolic components in mainstream cigarette smoke by gas chromatography-mass spectrometry [J]. Physical and Chemical Testing (Chemical Section), 2020, 56(10): 1085-1090) established a GC-MS method for detecting 12 C1-C2-alkyl substituted phenols, among which m-cresol and p-cresol co-eluted. Barnaba et al. (C.Barnaba, E.Dellacassa, G.Nicolini, et al. Identification and quantification of 56 targeted phenols in wines, spirits, and vinegars by online solid-phase extraction-ultrahigh-performance liquid chromatography-quadrupole-orbitrap mass spectrometry. Journal of Chromatography A, 2015, 1423: 124-135) established a UPLC-Orbitrap MS method for 56 phenolic compounds in wines, spirits and vinegar. This method only included 5 C1-C2-alkyl substituted phenols, among which m-cresol and p-cresol co-eluted. In addition, Liu Guihua et al. (Liu Guihua, Su Feng, Li Wei, et al. Determination of the migration amount of 9 phenolic substances in food contact materials and products by high performance liquid chromatography [J]. Journal of Analysis and Testing, 2021, 40(11): 1619-1626) established a HPLC-fluorescence detector method for testing 8 C1~C2-alkyl substituted phenols.

[0004] In the prior art, whether using gas chromatography separation or liquid chromatography separation technology, the problem of accurate quantification of single components of chromatographic co-eluting isomers when simultaneously detecting 12 C1-C2-alkyl substituted phenols has not been completely solved. Summary of the invention

[0005] The present invention aims to provide a detection method and application of C1-C2-alkyl substituted phenol, which uses LC-MS detection technology to quantitatively detect the content of phenol and 12 C1-C2-alkyl substituted phenol isomers in oily wastewater. The present invention is also suitable for quantitative detection of phenol and 12 C1-C2-alkyl substituted phenol isomers in drinking water, surface water and groundwater, as well as oily wastewater and oily solid waste.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] In one aspect, the present invention provides a method for detecting C1-C2-alkyl substituted phenol isomers, the method comprising the following steps:

[0008] According to the petroleum content range in the sample, select the corresponding sample pretreatment process to prepare the sample;

[0009] The sample is detected by LC-MS in a methanol-5.0-6.5 mmol / L ammonia water mobile phase system to obtain the concentration of the first component and the standardized concentrations of the co-eluted 3,5-dimethylphenol and 2,6-dimethylphenol;

[0010] In an acetonitrile-4.0-10.0 mmol / L ammonia water mobile phase system, the sample is detected by LC-MS to obtain the concentration of 3,5-dimethylphenol, or the standardized concentration of co-eluted 3,5-dimethylphenol and 3-ethylphenol, or the standardized concentration of co-eluted 2,6-dimethylphenol and 2,4-dimethylphenol;

[0011] In a methanol-5.0-6.5 mmol / L ammonia mobile phase system or in an acetonitrile-4.0-10.0 mmol / L ammonia mobile phase system, using LC-MS to respectively detect calibration samples of the co-eluting components, and calculate the conversion factors of the co-eluting components;

[0012] The concentration of one of the coeluting components is calculated based on the normalized concentration of the coeluting components, the conversion factor of the coeluting components, and the concentration of the other component of the coeluting components.

[0013] Furthermore, the first component comprises:

[0014] Phenol, 2-methylphenol, 3-methylphenol, 4-methylphenol, 2,3-dimethylphenol, 2,4-dimethylphenol, 2,5-dimethylphenol, 3,4-dimethylphenol, 2-ethylphenol, 3-ethylphenol and 4-ethylphenol.

[0015] Furthermore, the sample preparation process of selecting a corresponding sample pretreatment process according to the petroleum content range in the sample includes:

[0016] When the petroleum content in the sample does not exceed 50 mg / L, the sample is filtered through a 0.22 μm filter membrane before sampling and testing;

[0017] When the petroleum content in the sample exceeds 50 mg / L, the sample is alkalized with NaOH and extracted with dichloromethane and n-hexane, and the organic phase is separated by centrifugation. The aqueous phase is filtered through a 0.22 μm filter membrane, and then neutralized with formic acid before sampling and testing.

[0018] Furthermore, the elution conditions of the methanol-5.0-6.5 mmol / L ammonia water mobile phase system include:

[0019] The column flow rate was 0.20 mL / min;

[0020] Gradient elution: the initial volume ratio of methanol is 10% to 25%, zero gradient elution is maintained for 1 to 10 minutes, and then isocratic elution is performed to increase the volume ratio of methanol to 40% within 30 minutes, and the volume ratio of methanol is maintained at 40% until all components flow out;

[0021] The column temperature is 35-40°C.

[0022] Furthermore, the elution conditions of the acetonitrile-4.0-10.0 mmol / L ammonia water mobile phase system include:

[0023] The column flow rate is 0.20-0.25 mL / min;

[0024] Gradient elution is as follows: the initial volume ratio of acetonitrile is 25% to 30%, after maintaining zero gradient elution for 1 minute, the elution gradient of acetonitrile is maintained in the range of 0.43 to 1.56% / min for isocratic elution until all components flow out.

[0025] The column temperature is 30-45°C.

[0026] Furthermore, the calculation formula for the concentration of 2,6-dimethylphenol is:

[0027] c' 2,s =(m+1)·c' STD,s -m·c' 1,s ;

[0028] Where c' 2,s represents the concentration of 2,6-dimethylphenol; m represents the conversion factor; c' STD,s represents the normalized concentration of co-eluted 3,5-dimethylphenol and 2,6-dimethylphenol; c' 1,s Indicates the concentration of 3,5-dimethylphenol.

[0029] On the other hand, the present invention also provides an application of a method for detecting C1-C2-alkyl substituted phenol isomers, which is mainly used for analyzing volatile phenol components in oily wastewater and oily solid waste.

[0030] Technical effects and advantages of the present invention:

[0031] First, accurate quantification of phenol and 12 C1-C2-alkyl-substituted phenol isomers was achieved.

[0032] Second, the detection limit of phenol and 12 C1-C2-alkyl-substituted phenol isomers is 0.3-1.0 μg / L. Compared with the standard HJ744-2015 (derivative-GC-MS method) for testing phenolic compounds, the sensitivity of this method is 1-2 orders of magnitude higher.

[0033] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a flow chart of a method for detecting C1-C2-alkyl substituted phenol isomers of the present invention;

[0035] Figure 2 [MH] is the chromatographic separation of 9 C2-alkyl substituted phenol isomers under different elution conditions in a methanol-ammonia mobile phase system in the present invention. - Extracted ion map;

[0036] Figure 3 The present invention is a method for preparing 9 C2-alkyl substituted phenols [MH] in a methanol-4.0-8.0 mmol / L ammonia mobile phase system. - Extracted ion map of

[0037] Figure 4 The present invention shows nine C2-alkyl substituted phenols [MH] under different elution conditions in the acetonitrile-6.0mmol / L ammonia mobile phase system. - Extracted ion map of

[0038] Figure 5 The [MH] of chromatographic separation of 9 C2-alkyl substituted phenol isomers in acetonitrile-6.0mmol / L ammonia water mobile phase system at different chromatographic column temperatures in the present invention is shown in FIG. - Extracted ion map;

[0039] Figure 6 The chromatographic separation of 9 C2-alkyl substituted phenol isomers in the mobile phase system of acetonitrile-4.0~10.0mmol / ammonia water in the embodiment of the present invention is [MH] - Extracted ion map;

[0040] Figure 7 The [MH] of phenol and 12 C1-C2-alkyl substituted phenols in the methanol-6.0 mmol / L ammonia mobile phase system according to the present invention is shown in FIG. - Extracted ion map;

[0041] Figure 8 The [MH] of phenol and 12 C1-C2-alkyl substituted phenols in the acetonitrile-6.0 mmol / L ammonia mobile phase system according to the present invention is shown in FIG. - Extracted ion map. DETAILED DESCRIPTION

[0042] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] In order to solve the deficiencies of the prior art, the present invention discloses a method for detecting isomers of C1-C2-alkyl substituted phenols. Figure 1 The flowchart of the detection method of C1-C2-alkyl substituted phenol isomers of the present invention is as follows: Figure 1 As shown, the method comprises the following steps:

[0044] According to the petroleum content range in the sample, select the corresponding sample pretreatment process to prepare the sample;

[0045] The sample is detected by LC-MS in a methanol-5.0-6.5 mmol / L ammonia water mobile phase system to obtain the concentration of the first component and the standardized concentrations of the co-eluted 3,5-dimethylphenol and 2,6-dimethylphenol;

[0046] In an acetonitrile-4.0-10.0 mmol / L ammonia water mobile phase system, the sample is detected by LC-MS to obtain the concentration of 3,5-dimethylphenol, or the standardized concentration of co-eluted 3,5-dimethylphenol and 3-ethylphenol, or the standardized concentration of co-eluted 2,6-dimethylphenol and 2,4-dimethylphenol;

[0047] In a methanol-5.0-6.5 mmol / L ammonia mobile phase system or in an acetonitrile-4.0-10.0 mmol / L ammonia mobile phase system, using LC-MS to respectively detect calibration samples of the co-eluting components, and calculate the conversion factors of the co-eluting components;

[0048] The concentration of one of the coeluting components is calculated based on the normalized concentration of the coeluting components, the conversion factor of the coeluting components, and the concentration of the other component of the coeluting components.

[0049] Preferably, the first component comprises:

[0050] Phenol, 2-methylphenol, 3-methylphenol, 4-methylphenol, 2,3-dimethylphenol, 2,4-dimethylphenol, 2,5-dimethylphenol, 3,4-dimethylphenol, 2-ethylphenol, 3-ethylphenol and 4-ethylphenol.

[0051] The specific steps of the characterization method of the present invention are as follows:

[0052] Step S1: According to the petroleum content range in the oily wastewater sample, select the corresponding sample pretreatment process to prepare the sample.

[0053] If the petroleum in the sample does not exceed 50 mg / L, the sample is filtered through a 0.22 μm filter membrane and then tested;

[0054] If the petroleum in the sample exceeds 50 mg / L, the sample is alkalized with NaOH, extracted with dichloromethane and n-hexane, and the organic phase is separated by centrifugation. The aqueous phase is filtered through a 0.22 μm filter membrane and then neutralized with formic acid before sampling and testing.

[0055] Step S2: LC-MS is performed to detect the sample under a methanol-5.0-6.5 mmol / L ammonia water mobile phase system to obtain the concentrations of 11 components in the sample, including phenol, 2-methylphenol, 3-methylphenol, 4-methylphenol, 2,3-dimethylphenol, 2,4-dimethylphenol, 2,5-dimethylphenol, 3,4-dimethylphenol, 2-ethylphenol, 3-ethylphenol and 4-ethylphenol, as well as the standardized concentrations of co-eluted 2,6-dimethylphenol and 3,5-dimethylphenol.

[0056] In step S2 of the present invention, the elution conditions of the methanol-5.0-6.5mmol / L ammonia water mobile phase system include: a chromatographic column flow rate of 0.20mL / min; gradient elution: an initial volume ratio of methanol of 10%-25%, maintaining zero gradient elution for 1-10min, and then isocratic elution to increase the volume ratio of methanol to 40% within 30min, and maintaining the volume ratio of methanol at 40% until all components flow out.

[0057] Preferably, the elution conditions include: a chromatographic column flow rate of 0.20 mL / min; a gradient elution of: 0-1 min, 20% methanol; 1-31 min, 20%-40% methanol; 31-32 min, 40% methanol; 32-32.1 min, 40%-90% methanol; 32.1-37 min, 90% methanol; 37-37.1 min, 90%-20% methanol; 37.1-42 min, 20% methanol; and a chromatographic column temperature of 35-40° C.; preferably 40° C.

[0058] Step S3: LC-MS is performed to detect the sample in an acetonitrile-4.0-10.0 mmol / L ammonia water mobile phase system to obtain the concentration of 3,5-dimethylphenol in the sample.

[0059] In step S3 of the present invention, the elution conditions of the acetonitrile-4.0-10.0 mmol / L ammonia water mobile phase system include: a chromatographic column flow rate of 0.20-0.25 mL / min; a gradient elution: an initial volume ratio of acetonitrile of 25%-30%, after maintaining zero gradient elution for 1 min, maintaining the elution gradient of acetonitrile in the range of 0.43-1.56% / min for isocratic elution until all components flow out.

[0060] Preferably, the elution conditions include: a chromatographic column flow rate of 0.25 mL / min; an elution process of: 0 to 1 min, 30% acetonitrile; 1 to 9 min, 30% to 42.5% acetonitrile; 9 to 9.1 min, 42.5% to 90% acetonitrile; 9.1 to 13 min, 90% acetonitrile; 13 to 13.1 min, 90% to 30% acetonitrile; 13.1 to 18 min, 30% acetonitrile; and a chromatographic column temperature of 30 to 45° C., preferably 40° C.

[0061] It should be noted that in step S3 of the present invention, the sample is detected by LC-MS to obtain the standardized concentration of co-eluted 3,5-dimethylphenol and 3-ethylphenol, or the standardized concentration of co-eluted 2,6-dimethylphenol and 2,4-dimethylphenol.

[0062] Step S4: performing LC-MS detection on calibration samples of 3,5-dimethylphenol and 2,6-dimethylphenol respectively in a methanol-5.0-6.5 mmol / L ammonia water mobile phase system to obtain a conversion factor of 3,5-dimethylphenol to 2,6-dimethylphenol.

[0063] Alternatively, in an acetonitrile-4.0-10.0 mmol / L ammonia water mobile phase system, 3,5-dimethylphenol and 3-ethylphenol calibration samples or 2,6-dimethylphenol and 2,4-dimethylphenol calibration samples were detected by LC-MS respectively, and the conversion factors of the corresponding co-eluting components were calculated.

[0064] The LC-MS detection conditions in step S4 of the present invention under the mobile phase system of methanol-5.0-6.5 mmol / L ammonia water are consistent with the LC-MS detection conditions in step S2; similarly, the LC-MS detection conditions in the mobile phase system of acetonitrile-4.0-10.0 mmol / L ammonia water are consistent with the LC-MS detection conditions in step S3.

[0065] As in step S4 above, after long-term repeated testing, if the conversion factor value of 3,5-dimethylphenol to 2,6-dimethylphenol remains unchanged, the previous conversion factor value can be used to calculate the content of 2,6-dimethylphenol.

[0066] Step S5: Calculate the contents of phenol and 12 C1-C2-alkyl-substituted phenol isomers in the sample.

[0067] Step S5 of the present invention comprises the following steps:

[0068] Step S51: Calculate the concentration of 2,6-dimethylphenol in the sample according to formula (11).

[0069] x 2,s =(m+1)·c STD,s -m·c 1,s (11)

[0070] In the formula, c 2,s represents the concentration of 2,6-dimethylphenol; m represents the conversion factor; c STD,s represents the normalized concentration of co-eluted 3,5-dimethylphenol and 2,6-dimethylphenol; c 1,s Indicates the concentration of 3,5-dimethylphenol.

[0071] Step S52: Calculate the content of each component in the sample based on the sample amount, sample volume, dilution factor, etc., and the concentration value of each component in the sample.

[0072] It should be noted that the test order of the above steps S2, S3 and S4 can be arbitrarily changed.

[0073] Based on the above method, on the other hand, the present invention also provides an application of a method for detecting C1~C2-alkyl substituted phenol isomers, which is mainly used for the analysis of volatile phenol components in oily wastewater and oily solid waste.

[0074] The specific method and application of detecting phenol and 12 C1-C2-alkyl substituted phenol isomers using the method of the present invention will be further described below with reference to the accompanying drawings through specific examples.

[0075] Example 1

[0076] This example provides two sample pretreatment methods for LC-MS injection testing.

[0077] 1. Oily wastewater with petroleum content ≤50mg / L

[0078] The water sample was filtered through a 0.22 μm filter membrane. Depending on the volatile phenol content, 10 μL to 500 μL of the filtrate was taken to prepare the test sample.

[0079] This process is not only applicable to stripping water samples, but also to the preparation of cleaner water samples such as drinking water, groundwater and surface water.

[0080] 2. Oily wastewater with petroleum content > 50mg / L

[0081] Take 10.00mL of water sample in a 20mL round-bottom screw-mouth sample bottle (with a sample cap of polytetrafluoroethylene liner), add the substitute, add 100μL of 2.5mol / L NaOH to adjust the pH ≥ 12, add 1-3mL of dichloromethane-n-hexane (2+1) mixed solvent, and tighten the cap. Shake for 30 minutes and centrifuge. Take the aqueous phase and add formic acid to neutralize it, pass the aqueous phase through a 0.22μm filter membrane, and take 10μL-500μL of the filtrate to prepare the sample according to the volatile phenol content.

[0082] Example 2

[0083] This example is to optimize the chromatographic elution conditions of 9 C2-alkyl substituted phenols in a methanol-ammonia mobile phase system.

[0084] This example and the following examples all use ACQUITY UPLC BEH C 18 The chromatographic column (1.7 μm, 2.1 mm×150 mm) was used to separate C1-C2-alkyl substituted phenols.

[0085] Under the initial conditions of an initial volume ratio of 10% methanol mobile phase, an ammonia concentration of 6.0 mmol / L and a column temperature of 40°C, the three C1-alkyl substituted phenols can be well chromatographically separated. Therefore, the chromatographic separation effect of the mobile phase elution conditions on C2-alkyl substituted phenols was focused.

[0086] The results showed that when the initial volume ratio of methanol was 10%, maintaining zero gradient elution for 1, 5 and 10 min respectively and then eluting with the same gradient did not improve the chromatographic separation of 9 C2-alkyl substituted phenols much. Therefore, it was sufficient to maintain the initial ratio of the mobile phase for 1 min.

[0087] The initial volume proportion of methanol in the mobile phase was set to 10%, 20% and 25% respectively, and zero gradient elution was maintained for 1 min. Then, the volume proportion of methanol was increased to 40% within 30 min by isocratic elution, and the volume proportion of methanol was maintained at 40% until all components were eluted. Figure 2 [MH] is the chromatographic separation of 9 C2-alkyl substituted phenol isomers under different elution conditions in a methanol-ammonia mobile phase system in the present invention. - Extracted ion map, where Figure 2 The specific elution conditions of A include: 0-1min, 10% methanol; 1-31min, 10%-40% methanol; 31-35min, 40% methanol; the specific elution conditions of B include: 0-1min, 20% methanol; 1-31min, 20%-40% methanol; 31-35min, 40% methanol; the specific elution conditions of C include: 0-1min, 25% methanol; 1-31min, 25%-40% methanol; 31-35min, 40% methanol. Figure 2 As shown in the figure, the elution of 9 C2-alkyl substituted phenols under these three elution conditions showed a set of 8 continuous chromatographic peaks that can be integrated. When the initial volume ratio of methanol mobile phase was 10%, the separation of the first eluted components was relatively poor, while the separation of the later eluted components was relatively good; when the initial volume ratio of methanol mobile phase was 25%, the separation of the first eluted components was relatively good, while the separation of the later eluted components was relatively poor, so the elution condition with an initial volume ratio of methanol of 20% was selected.

[0088] The effects of column temperatures of 30, 35, 40 and 45°C on the chromatographic separation of C2-alkyl substituted phenols were further compared. The chromatographic separation of C2-alkyl substituted phenols deteriorated at column temperatures of 30 and 45°C, and better chromatographic separation was obtained at column temperatures of 35 and 40°C. When the column temperature was 40°C, the column pressure decreased by about 40 to 50 bar and the analysis process was shortened by about 1.5 minutes, so the preferred column temperature was 40°C.

[0089] Example 3

[0090] In this example, the effect of ammonia mobile phase concentration in the range of 4.0 to 8.0 mmol / L on the chromatographic separation of C2-alkyl substituted phenols was investigated in a methanol-ammonia mobile phase system.

[0091] Figure 3 The present invention is a method for preparing 9 C2-alkyl substituted phenols [MH] in a methanol-4.0-8.0 mmol / L ammonia mobile phase system. - The extracted ion map of Figure 3 The corresponding ammonia concentration of A is 4.0mmol / L, B is 6.0mmol / L, and C is 8.0mmol / L; the corresponding chromatographic peaks are: 1, 3,4-dimethylphenol; 2, 3-ethylphenol; 3, 3,5-dimethylphenol; 4, 2,6-dimethylphenol; 5, 2,3-dimethylphenol; 6, 4-ethylphenol; 7, 2,5-dimethylphenol; 8, 2-ethylphenol; 9, 2,4-dimethylphenol. Figure 3 As shown, 9 C2-alkyl substituted phenols have 7 peaks when the ammonia concentration is 4.0mmol / L; 8 peaks are separated when the ammonia concentration is 6.0mmol / L, and the peak shape is better; when the ammonia concentration is 8.0mmol / L, only 7 peaks are separated, and it can be clearly seen that the peak width of the first peak becomes wider, which should be a co-elution peak.

[0092] The retention time and elution order of C2-alkyl substituted phenols at different ammonia concentrations were confirmed by a single calibration method, and the co-elution between components was determined. Figure 3 As shown, when the concentration of ammonia water is 6.0 mmol / L, only 3,5-dimethylphenol and 2,6-dimethylphenol co-elute.

[0093] Further experiments determined that when the ammonia concentration was between 5.0 and 6.5 mmol / L, 9 C2-alkyl substituted phenols separated into 8 peaks with good peak shapes and only 3,5-dimethylphenol and 2,6-dimethylphenol co-eluted. Based on this, the appropriate ammonia mobile phase concentration range was determined to be 5.0 to 6.5 mmol / L, and the ammonia mobile phase concentration used for sample testing was 6.0 mmol / L.

[0094] Example 4

[0095] In this example, the chromatographic elution conditions of 9 C2-alkyl substituted phenols were optimized under the acetonitrile-ammonia mobile phase system.

[0096] When the chromatographic mobile phase is acetonitrile-ammonia system, the three C1-alkyl substituted phenol isomers can be well chromatographically separated. Therefore, the chromatographic separation effect of the mobile phase elution conditions on C2-alkyl substituted phenol was investigated in detail.

[0097] Firstly, under the conditions of chromatographic column temperature of 40℃ and ammonia concentration of 6mmol / L, the column flow rate, the initial volume ratio of acetonitrile and the elution gradient were changed, and the retention time and elution order of C2-alkyl substituted phenols were confirmed by single calibration. The chromatographic separation and co-elution of C2-alkyl substituted phenols in acetonitrile-ammonia mobile phase system were investigated.

[0098] In the optimization experiments, gradient elution was started 1 min after the initial zero gradient elution. Figure 4 The present invention shows nine C2-alkyl substituted phenols [MH] under different elution conditions in the acetonitrile-6.0mmol / L ammonia mobile phase system. - The extracted ion map of Figure 4 The elution conditions corresponding to A are: column flow rate 0.20 mL / min; 0-1 min, 20% acetonitrile; 1-24 min, 20%-30% acetonitrile; the elution conditions corresponding to B are: column flow rate 0.25 mL / min; 0-1 min, 25% acetonitrile; 1-24 min, 25%-35% acetonitrile; the elution conditions corresponding to C are: column flow rate 0.25 mL / min; 0-1 min, 25% acetonitrile; 1-17 min, 25%-50% % acetonitrile, the corresponding elution conditions of D are: column flow rate 0.25mL / min; 0-1min, 30% acetonitrile; 1-17min, 30%-55% acetonitrile; the corresponding chromatographic peaks are: 1, 3,4-dimethylphenol; 2, 3-ethylphenol; 3, 3,5-dimethylphenol; 4, 2,6-dimethylphenol; 5, 2,3-dimethylphenol; 6, 4-ethylphenol; 7, 2,5-dimethylphenol; 8, 2-ethylphenol; 9, 2,4-dimethylphenol.

[0099] The results show that when the column flow rate is 0.20 mL / min and the initial volume ratio of acetonitrile is 20%, the elution gradient (defined as the percentage increase rate of acetonitrile in the mobile phase) is 0.43% / min. Figure 4 As shown in Figure A, 9 C2-alkyl substituted phenols were separated into 6 peaks from the beginning to the end of peak elution, which took about 5.8 minutes. Among them, 3,5-dimethylphenol and 3-ethylphenol, 4-ethylphenol and 2,3-dimethylphenol, 2,5-dimethylphenol and 2,6-dimethylphenol were co-eluted.

[0100] Maintaining the elution gradient at 0.43% / min, the column flow rate was increased to 0.25mL / min, and the initial volume ratio of acetonitrile was increased to 25%. Figure 4As shown in B, the time from the beginning to the end of the elution of 9 C2-alkyl substituted phenols was about 3.8 min, and a total of 7 peaks were separated. Among them, 3,5-dimethylphenol and 3-ethylphenol were separated, and 4-ethylphenol and 2,3-dimethylphenol, 2,4-dimethylphenol and 2,6-dimethylphenol were co-eluted as two groups of components.

[0101] Then increase the elution gradient from 0.43% / min to 1.56% / min, such as Figure 4 As shown in Figure C, the time from the beginning to the end of the elution of 9 C2-alkyl substituted phenols was shortened to about 2.3 min, and 8 peaks were separated. 4-ethylphenol and 2,3-dimethylphenol were separated, and only 2,4-dimethylphenol and 2,6-dimethylphenol co-eluted.

[0102] It can be seen that increasing the column flow rate, the initial volume ratio of acetonitrile and the elution gradient not only shortens the elution time but also improves the chromatographic separation effect of the nine C2-alkyl-substituted phenols.

[0103] Maintaining the elution gradient at 1.56% / min, the initial volume ratio of acetonitrile was increased to 30%. Figure 4 As shown in D, the time from the beginning to the end of the elution of 9 C2-alkyl substituted phenols is about 2 minutes. Although only 8 peaks are separated, the overall chromatographic separation effect is good and can be used for quantitative analysis. Under this condition, the chromatographic peak of 2,6-dimethylphenol co-elutes with 2,4-dimethylphenol in the form of a tailing peak.

[0104] Under the optimized elution conditions, the effects of column temperatures of 30, 35, 40 and 45°C on the chromatographic separation of C2-alkyl substituted phenols were further compared. Figure 5 The [MH] of chromatographic separation of 9 C2-alkyl substituted phenol isomers in acetonitrile-6.0mmol / L ammonia water mobile phase system at different chromatographic column temperatures in the present invention is shown in FIG. - Extracted ion diagram, where the column temperature corresponding to A is 30°C; B is 35°C; C is 40°C; D is 45°C; the corresponding chromatographic peaks are: 1, 3,4-dimethylphenol; 2, 3-ethylphenol; 3, 3,5-dimethylphenol; 4, 2,6-dimethylphenol; 5, 2,3-dimethylphenol; 6, 4-ethylphenol; 7, 2,5-dimethylphenol; 8, 2-ethylphenol; 9, 2,4-dimethylphenol. Figure 5As shown in the figure, the increase of column temperature did not change the elution order of 9 C2-alkyl substituted phenols; with the increase of column temperature, the separation degree of 3,5-dimethylphenol and 3-ethylphenol increased, and the chromatographic separation effect improved; while the number of peaks of 4-ethylphenol, 2,3-dimethylphenol and 2,5-dimethylphenol were 2, 3, 3 and 2 respectively, and the co-elution of the above three components changed when the column temperature was 30 and 45℃. When the column temperature was 40℃, the chromatographic separation effect was better, so the preferred column temperature of the chromatographic column was 40℃.

[0105] In summary, preferably, the chromatographic elution conditions include: chromatographic column flow rate of 0.25 mL / min, chromatographic column temperature of 40°C; elution process: 0-1 min, 30% acetonitrile; 1-9 min, 30%-42.5% acetonitrile; 9-9.1 min, 42.5%-90% acetonitrile; 9.1-13 min, 90% acetonitrile; 13-13.1 min, 90%-30% acetonitrile; 13.1-18 min, 30% acetonitrile.

[0106] In addition, when the column flow rate is 0.25 mL / min, the initial volume ratio of acetonitrile is 25% to 30%, and the column temperature is 30 to 45°C, 3,5-dimethylphenol can be chromatographically separated from 3-ethylphenol and quantified separately.

[0107] Example 5

[0108] In this example, the effect of ammonia concentration in the range of 4.0 to 10.0 mmol / L on the chromatographic separation of C2-alkyl substituted phenols was investigated under an acetonitrile-ammonia mobile phase system; and the retention time and elution order of C2-alkyl substituted phenols under different ammonia concentrations were confirmed by a single calibration method, and the co-elution between components was determined.

[0109] Figure 6 The chromatographic separation of 9 C2-alkyl substituted phenol isomers in the mobile phase system of acetonitrile-4.0~10.0mmol / ammonia water in the embodiment of the present invention is [MH] - Extracted ion map, where the ammonia concentration corresponding to A is 4.0mmol / L; B is 5.0mmol / L; C is 6.0mmol / L; D is 8.0mmol / L; E is 10.0mmol / L, and the corresponding chromatographic peaks are: 1, 3,4-dimethylphenol; 2, 3-ethylphenol; 3, 3,5-dimethylphenol; 4, 2,6-dimethylphenol; 5, 2,3-dimethylphenol; 6, 4-ethylphenol; 7, 2,5-dimethylphenol; 8, 2-ethylphenol; 9, 2,4-dimethylphenol. Figure 6 , when the ammonia concentration was in the range of 4.0 to 10.0 mmol / L, the elution order of the nine C2-alkyl-substituted phenols was the same, and the chromatographic co-elution phenomenon of isomers still existed.

[0110] like Figure 6 As shown in Figure A, 9 C2-alkyl substituted phenols were separated into 7 peaks when the ammonia concentration was 4.0 mmol / L, among which 4-ethylphenol and 2,5-dimethylphenol, 2,4-dimethylphenol and 2,6-dimethylphenol were co-eluted in two groups; Figure 6 As shown in Figures B to D, when the concentration of ammonia water was 5.0 to 8.0 mmol / L, 8 peaks were separated, among which 2,4-dimethylphenol and 2,6-dimethylphenol co-eluted; Figure 6 As shown in E, when the concentration of ammonia water is 10.0 mmol / L, only 7 peaks are separated, among which 3,5-dimethylphenol and 3-ethylphenol, 2,4-dimethylphenol and 2,6-dimethylphenol are two groups of components eluting together.

[0111] In summary, when the ammonia concentration is 5.0-8.0 mmol / L, the chromatographic separation of the nine C2-alkyl substituted phenols is relatively good, and it is even better when the ammonia concentration is 6.0 mmol / L; in addition, when the ammonia concentration is 4.0-8.0 mmol / L, 3,5-dimethylphenol can be chromatographically separated from 3-ethylphenol and quantified separately.

[0112] Compared with the methanol-ammonia mobile phase system, the elution order and co-elution of the nine C2-alkyl substituted phenols in the acetonitrile-ammonia mobile phase changed greatly. In the methanol-5-6.5mmol / L ammonia mobile phase, 3,5-dimethylphenol and 2,6-dimethylphenol co-eluted; while in the acetonitrile-4.0-10.0mmol / L ammonia mobile phase, 3,5-dimethylphenol and 2,6-dimethylphenol were completely chromatographically separated (resolution>1.5), which provided a basis for the accurate quantification of 3,5-dimethylphenol and 2,6-dimethylphenol as single components.

[0113] It should be noted that in the acetonitrile-ammonia mobile phase, even if 3,5-dimethylphenol or 2,6-dimethylphenol co-elutes with other components, accurate quantification of single components of 3,5-dimethylphenol and 2,6-dimethylphenol can be achieved.

[0114] For example, Figure 4 As shown in A, 3,5-dimethylphenol and 3-ethylphenol co-elute. The concentration of 3,5-dimethylphenol can be calculated based on the concentration of 3-ethylphenol in the methanol-5-6.5mmol / L ammonia mobile phase, and then the concentration of 2,6-dimethylphenol can be calculated.

[0115] For example, Figure 6As shown in E, 2,6-dimethylphenol and 2,4-dimethylphenol co-elute. The concentration of 2,6-dimethylphenol can be calculated based on the concentration of 2,4-dimethylphenol in the mobile phase of methanol-5-6.5 mmol / L ammonia water, and then the concentration of 3,5-dimethylphenol can be calculated.

[0116] To achieve the above calculation, it is also necessary to test the calibration samples of the relevant co-eluting components in the acetonitrile-4.0~10.0mmol / L ammonia water mobile phase system to obtain the conversion factors of the co-eluting components.

[0117] In fact, 3,5-dimethylphenol can be quantified separately in the mobile phase system of acetonitrile-4.0~8.0mmol / L ammonia, which provides a better solution for the quantification of the single components of 3,5-dimethylphenol and 2,6-dimethylphenol co-eluted in the mobile phase of methanol-5.0~6.5mmol / L ammonia. That is, the standardized concentrations of co-eluted 3,5-dimethylphenol and 2,6-dimethylphenol are measured in the mobile phase system of methanol-5.0~6.5mmol / L ammonia, and then the content of 3,5-dimethylphenol is measured in the mobile phase system of acetonitrile-4.0~8.0mmol / L ammonia, so as to calculate the content of 2,6-dimethylphenol.

[0118] Example 6

[0119] This embodiment provides a method for calculating the single component content of co-eluting isomers from two chromatograms.

[0120] In the same mobile phase system, two isomers, component 1 and component 2, are co-eluted. The linear calibration relationships of component 1, component 2 and the mixed co-eluted components are established, as shown in formulas (1) to (3):

[0121] A1=k1·c1 (1)

[0122] A2=k2·c2 (2)

[0123] A=k·c STD (3)

[0124] Where A, A1 and A2 are the response values ​​of the co-eluting component, component 1 and component 2, respectively; k, k1 and k2 are the calibration coefficients of the co-eluting component, component 1 and component 2, respectively; c1 and c2 are the concentrations of component 1 and component 2, and c STD Defined as the normalized concentration of the coeluting components.

[0125] The responses of the coeluting components are simply additive, with:

[0126] A=A1+A2 (4)

[0127] k.cSTD =k1·c1+k2·c2 (5)

[0128] When the prepared concentrations of the co-eluting components at each calibration point are equal (i.e., c1 = c2), and c STD =c i =c2, then:

[0129] k=k1+k2 (6)

[0130] For components 1 and 2 in the sample,

[0131] A s =A 1，s +A 2，s (7)

[0132] k.c STD，s =k1·c 1，s +k2·c 2，s (8)

[0133]

[0134] In the formula, A s , A 1，s and A 2，s is the response value of the co-eluting component, component 1 and component 2 in the sample, c STD，s 、c 1，s and c 2，s is the standardized concentration of the co-eluting components in the sample, the concentration of component 1 and component 2.

[0135] Assume m = k1 / k2, where m is defined as the conversion factor of component 1 to component 2,

[0136]

[0137] c 2，s =(m+1)·c STD，s -m·c 1，s (11)

[0138] Under the same experimental conditions, the m value remains unchanged within the linear calibration range; the m value can be obtained by testing two co-eluting single-component calibration sample series or the intermediate concentration point of the calibration sample sequence in the first mobile phase system. STD，s , the sample was tested in another mobile phase system to obtain c 1，s According to formula (11), c 2，s .

[0139] Example 7

[0140] This embodiment provides a method for detecting phenol and 12 C1-C2-alkyl substituted phenol single components in stripping water using ultra-high performance liquid chromatography-orbitrap high resolution mass spectrometry (UPLC-Orbitrap HRMS).

[0141] 1. Test samples

[0142] The stripping water sample was collected in a 40mL VOA sample bottle with a polytetrafluoroethylene liner. When sampling, the water sample was required to fill the sample bottle and not overflow outside the bottle, and no protective agent was added. The sample was refrigerated at 4-6℃, and the sample preparation was completed within 24 hours. The pH of the test sample was 7.0-10.5, and the petroleum was ≤50mg / L.

[0143] 2. Instrument conditions

[0144] UPLC-Orbitrap HRMS: Vanquish C-H10 ultra-high performance liquid chromatograph, Q-Exactive Plus electrostatic field orbitrap high-resolution mass spectrometer.

[0145] (1) Liquid chromatography conditions

[0146] Method 1: Mobile phase system: methanol-6.0mmol / L ammonia water. Column temperature: 40℃; Column flow rate: 0.20mL / min; Sample chamber temperature: 6℃; Injection volume: 2μL. Gradient elution: 0-1min, 20% methanol; 1-31min, 20%-40% methanol; 31-32min, 40% methanol; 32-32.1min, 40%-90% methanol; 32.1-37min, 90% methanol; 37-37.1min, 90%-20% methanol; 37.1-42min, 20% methanol.

[0147] Method 2: Mobile phase system: acetonitrile-6.0mmol / L ammonia water. Column temperature: 40℃; Column flow rate: 0.25mL / min; Sample chamber temperature: 6℃; Injection volume: 2μL. Gradient elution: 0-1min, 30% acetonitrile; 1-13min, 30%-48.75% acetonitrile; 13-13.1min, 48.75%-30% acetonitrile; 13.1-17min, 30% acetonitrile.

[0148] (2) Orbitrap HRMS conditions

[0149] Heated electrospray ion source: negative ion mode; sheath gas flow rate: 30Arb; auxiliary gas flow rate: 10Arb; spray voltage 2.5kV; ion transfer tube temperature: 320℃; S-lens RF voltage: 50V; auxiliary gas heater temperature: 380℃. MS acquisition: one-stage full scan (Full MS); resolution: 70000; mass range: m / z90~155; C-trap maximum injection time (MaximumIT): 200ms; C-trap ion number maximum capacity (AGC Target): 1×10 6 .

[0150] 3. Calibration sample sequence and sample preparation

[0151] Thirteen phenols (phenol and C0-C2-alkyl substituted phenols) with a purity greater than 98% and an internal standard (phenol- 13 C6) Prepare single standard stock solutions of standard samples, dilute with methanol to prepare 13 kinds of phenol mixed working solutions and internal standard working solutions, and then use the working solutions to prepare calibration sample series. The concentrations of phenol components in the calibration sample series are 10, 100, 500, 1000 and 2500 μg / L, the internal standard concentration is 200 μg / L, and the total amount of methanol in the calibration standard solution is 100 μL / mL.

[0152] Pre-add 90 μL of methanol to a 2 mL sample bottle. Take out the refrigerated water sample, wait for the sample temperature to return to room temperature, and filter it through a 0.22 μm nylon filter. Depending on the volatile phenol content, take 10 to 500 μL of the filtrate and add it to the sample bottle. Add pure water to make the total volume of the sample 990 μL, then add 10 μL of the internal standard working solution, shake well, and store at 4 to 6 °C for testing.

[0153] 4. Qualitative confirmation, data collection and analysis

[0154] By [MH] - The target compounds in the sample were qualitatively confirmed by matching the accurate mass and retention time. Table 1 shows the qualitative confirmation information of the internal standard and 13 phenolic components. RT1 is the retention time under the mobile phase of methanol-6.0mmol / L ammonia water, and RT2 is the retention time under the mobile phase of acetonitrile-6.0mmol / L.

[0155] Table 1 Qualitative confirmation information of internal standards and 13 phenolic components

[0156] Serial number Compound RT1 / min RT2 / min <![CDATA[[M-H] - Theoretical accurate mass value (m / z)]]> 1 <![CDATA[Phenol- 13 C6]]> 6.27 2.91 99.05472 2 phenol 6.26 2.91 93.03459 3 3-Methylphenol 14.07 4.51 107.05024 4 4-Methylphenol 15.40 4.68 107.05024 5 2-Methylphenol 15.96 5.09 107.05024 6 3,4-Dimethylphenol 26.04 6.53 121.06589 7 3-Ethylphenol 26.55 7.02 121.06589 8 3,5-Dimethylphenol 27.25 6.89 121.06589 9 2,6-Dimethylphenol 27.25 7.70 121.06589 10 2,3-Dimethylphenol 27.72 7.40 121.06589 11 4-Ethylphenol 28.30 7.27 121.06589 12 2,5-Dimethylphenol 28.94 7.52 121.06589 13 2-Ethylphenol 29.63 8.17 121.06589 14 2,4-Dimethylphenol 30.13 7.70 121.06589

[0157] Two sets of consistent calibration sample sequences and test samples were prepared and tested in the mobile phase systems of methanol-6.0mmol / L ammonia and acetonitrile-6.0mmol / L ammonia, respectively. Xcalibur 4.4 software was used to collect data, and TraceFinder 5.1 software was used for data analysis. Figure 7 The [MH] of phenol and 12 C1-C2-alkyl substituted phenols in the methanol-6.0 mmol / L ammonia mobile phase system according to the present invention is shown in FIG. - Extracted ion map, Figure 8 The [MH] of phenol and 12 C1-C2-alkyl substituted phenols in the acetonitrile-6.0 mmol / L ammonia mobile phase system according to the present invention is shown in FIG. - Extracted ion map; Figure 7 and Figure 8 The corresponding chromatographic peaks are: 1, phenol; 2, 3-methylphenol; 3, 4-methylphenol; 4, 2-methylphenol; 5, 3,4-dimethylphenol; 6, 3-ethylphenol; 7, 3,5-dimethylphenol; 8, 2,6-dimethylphenol; 9, 2,3-dimethylphenol; 10, 4-ethylphenol; 11, 2,5-dimethylphenol; 12, 2-ethylphenol; 13, 2,4-dimethylphenol.

[0158] 5. Method performance indicators

[0159] (1) Calibration range and detection limit

[0160] Using phenol- 13 C6 was used as the internal standard, and the calibration curve of the target compound was fitted by linear regression method. The correlation coefficients (R 2 ) are all greater than 0.997. Table 2 shows the method detection limits of 13 phenolic components in the embodiment of the present invention. As shown in Table 2, the method detection limits of 13 phenolic components are 0.3-1.0 μg / L. This method is applied to the quantification of volatile phenolic components. The water sample is not enriched or derivatized. The sensitivity is 1-2 orders of magnitude higher than that of the derivatization-GC-MS method (HJ744-2015).

[0161] Table 2 Method detection limits of phenolic components

[0162] Serial number Compound Method detection limit (μg / L) 1 phenol 1.0 2 3-Methylphenol 0.4 3 4-Methylphenol 0.3 4 2-Methylphenol 0.5 5 3,4-Dimethylphenol 0.3 6 3-Ethylphenol 0.4 7 2,6 / 3,5-Dimethylphenol 0.4 8 2,3-Dimethylphenol 0.4 9 4-Ethylphenol 0.3 10 2,5-Dimethylphenol 0.4 11 2-Ethylphenol 0.4 12 2,4-Dimethylphenol 0.3 13 3,5-Dimethylphenol* 0.4

[0163] Note: * is tested under liquid chromatography conditions Method 2.

[0164] (2) Sample matrix spike recovery and precision

[0165] In the stripping water sample matrix spike, benzene and 12 C1-C2-alkyl substituted phenols were added at concentrations of 20-500 μg / L, and the recoveries of the target analytes were 72%-117%, with RSDs of 2.4%-10.3%. This indicates that petroleum in water samples does not interfere with the test when the concentration is ≤50 mg / L; this method is quantitatively accurate and has good repeatability.

[0166] It should be noted that this embodiment is only a preferred example. The present invention does not limit the type and specification of the chromatographic column and the type of LC-MS instrument. Other similar reverse chromatographic columns and low-resolution LC-MS can be used to implement the present invention according to the technical solution disclosed in the present invention.

[0167] It should be noted that for oily wastewater with a petroleum content of ≤50 mg / L, this process can still be used for sample preparation. Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments, or replace some of the technical features therein by equivalents. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for detecting C1~C2-alkyl substituted phenol isomers, characterized in that: The method comprises the following steps: According to the petroleum content range in the sample, select the corresponding sample pretreatment process to prepare the sample; The sample was detected by LC-MS in a methanol-5.0~6.5mmol / L ammonia water mobile phase system to obtain the concentration of the first component and the standardized concentrations of the co-eluted 3,5-dimethylphenol and 2,6-dimethylphenol; the first component includes: Phenol, 2-methylphenol, 3-methylphenol, 4-methylphenol, 2,3-dimethylphenol, 2,4-dimethylphenol, 2,5-dimethylphenol, 3,4-dimethylphenol, 2-ethylphenol, 3-ethylphenol, and 4-ethylphenol; In an acetonitrile-4.0-10.0 mmol / L ammonia water mobile phase system, the sample is detected by LC-MS to obtain the concentration of 3,5-dimethylphenol, or the standardized concentration of co-eluted 3,5-dimethylphenol and 3-ethylphenol, or the standardized concentration of co-eluted 2,6-dimethylphenol and 2,4-dimethylphenol; In a methanol-5.0~6.5mmol / L ammonia water mobile phase system, the calibration samples of the co-eluting components are respectively detected by LC-MS, and the conversion factors of the co-eluting components are calculated; Based on the standardized concentration of the co-eluting component, the conversion factor of the co-eluting component and the concentration of one component in the co-eluting component, the concentration of another component in the co-eluting component is calculated, and the calculation formula is: ； In the formula, represents the concentration of the co-eluting component 2; m represents the conversion factor; represents the normalized concentrations of co-eluted components 1 and 2; Represents the concentration of co-eluting component 1.

2. The method for detecting C1~C2-alkyl substituted phenol isomers according to claim 1, characterized in that: The method of selecting a corresponding sample pretreatment process to prepare the sample according to the petroleum content range in the sample includes: When the petroleum content in the sample does not exceed 50 mg / L, the sample is filtered through a 0.22 μm filter membrane before sampling and testing; When the petroleum content in the sample exceeds 50 mg / L, the sample is alkalized with NaOH and extracted with dichloromethane and n-hexane, and the organic phase is separated by centrifugation. The aqueous phase is filtered through a 0.22 μm filter membrane, and then neutralized with formic acid before sampling and testing.

3. The method for detecting C1~C2-alkyl substituted phenol isomers according to claim 1, characterized in that: The elution conditions of the methanol-5.0~6.5mmol / L ammonia water mobile phase system include: The column flow rate was 0.20 mL / min; Gradient elution: the initial volume ratio of methanol is 10%~25%, zero gradient elution is maintained for 1~10min, and then isocratic elution is performed to increase the volume ratio of methanol to 40% within 30min, and the volume ratio of methanol is maintained at 40% until all components are eluted; The column temperature is 35~40℃.

4. The method for detecting C1~C2-alkyl substituted phenol isomers according to claim 1, characterized in that: The elution conditions of the acetonitrile-4.0~10.0mmol / L ammonia water mobile phase system include: The column flow rate is 0.20~0.25mL / min; Gradient elution: the initial volume ratio of acetonitrile is 25%~30%, after maintaining zero gradient elution for 1 min, the elution gradient of acetonitrile is maintained in the range of 0.43~1.56% / min for isocratic elution until all components are eluted; The column temperature is 30~45℃.

5. The method for detecting C1~C2-alkyl substituted phenol isomers according to claim 1, characterized in that: The calculation formula of the concentration of the 2,6-dimethylphenol is: ； In the formula, represents the concentration of 2,6-dimethylphenol; m represents the conversion factor; represents the normalized concentration of coeluted 3,5-dimethylphenol and 2,6-dimethylphenol; Indicates the concentration of 3,5-dimethylphenol.

6. Use of a method for detecting C1~C2-alkyl substituted phenol isomers, the detection method according to any one of claims 1 to 5, characterized in that: Applied to the analysis of volatile phenol components in oily wastewater and oily solid waste.

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