High-resolution mass spectrometric detection method for chromatography co-outflow of 2, 4-dimethylphenol and 2, 6-dimethylphenol and application of high-resolution mass spectrometric detection method for chromatography co-outflow of 2, 4-dimethylphenol and 2, 6-dimethylphenol

Abstract

The invention discloses a high-resolution mass spectrometry detection method for chromatography co-outflow of 2, 4-dimethylphenol and 2, 6-dimethylphenol and application, and relates to the technical field of environmental detection.The method comprises the steps that according to the petroleum content range in a sample, a corresponding sample pretreatment process is selected to prepare a sample; the method comprises the following steps: under an acetonitrile-5-8.0 mmol / L ammonia water mobile phase system, detecting and collecting primary mass spectrum full scanning (MS1) and selective ion secondary mass spectrum (MS2) data of a standard sequence sample, a conversion factor calibration sample and a sample by utilizing LC-HRMS (Liquid Chromatography-High Resolution Mass Spectrometry); according to MS1 data, standard concentrations of co-effluent components 2, 4-dimethylphenol and 2, 6-dimethylphenol and concentrations of other 11 phenols and alkyl substituted phenols are calculated; according to the MS2 data, the concentration of 2, 4-dimethylphenol is calculated; and according to the MS1 data, calculating a conversion factor of the co-effluent component, and further calculating the concentration of 2, 6-dimethylphenol. The detection limit of the method is lower than 1.0 microgram / L, and the sensitivity of the method is 1-2 orders of magnitude higher than that of a standard HJ744-2015 (derivatization-GC-MS method) phenolic compound testing method.

Description

Technical Field

[0001] The invention relates to the technical field of environmental detection, and in particular to a high-resolution mass spectrometry detection method and application of chromatographic co-elution of 2,4-dimethylphenol and 2,6-dimethylphenol. Background Art

[0002] The stripping water discharged from the sulfur-containing and salt-containing wastewater stripping device is oily wastewater and is the main process wastewater in oil refineries. The unit discharge volume reaches 0.2m 3 / t crude oil, the volatile phenol content is as high as 0.2-0.5kg / m 3 (Yan Song, Li Lingbo, Han Congbi, Zhou Yanhong. Study on organic components of high-sulfur and high-acid crude oil wastewater [J]. Contemporary Chemical Industry, 2015, 44(09): 2081-2083). Coal gasification is an important process in modern coal chemical projects, among which Lurgi pressurized gasification is a relatively mature gasification process. The scrubbing wastewater produced by gasification contains high-concentration difficult-to-degrade organic pollutants such as phenol and ammonia (Li Xueyuan, Wei Danqing. Detection of phenolic compounds in coal gasification wastewater by gas chromatography-mass spectrometry [J]. Modern Chemical Industry, 2015, 35(09): 187-188). The high content of volatile phenolic substances in stripping water and coal gasification wastewater mainly includes phenol, methylphenol (3 isomers) and dimethyl / ethylphenol (9 isomers), which have recovery and reuse value. Clarifying the composition of volatile phenolic substances is the basis for the recovery and comprehensive utilization of volatile phenolic substances.

[0003] Volatile phenol components contain many isomers. 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. Liu Yulong et al. found that the elution order and chromatographic co-elution of dimethylphenol isomers in the same reverse C18 liquid chromatography column changed under two different mobile phase systems, and established a method for calculating the single component content of chromatographic co-elution isomers, realizing the quantitative characterization of the above 13 alkyl-substituted phenol single components in oily wastewater (Liu Yulong, Wang Zixian, Zhang Xiaofei, Shao Zhiguo, Tong Kun. A characterization method and application of C0~C2-alkyl-substituted phenols. Chinese patent: 202211482228.X; Liu Yulong, Shao Zhiguo, Tong Kun, Zhang Xiaofei, Wang Zixian. A detection method and application of C1~C2-alkyl-substituted phenol isomers. Chinese patent: 202211482206.3). In the prior art, whether using gas chromatography separation or liquid chromatography separation technology, it is rare to solve the problem of accurate quantification of a single component of chromatographic co-eluting isomers under only one mobile phase system. Summary of the invention

[0004] The present invention aims to provide a high resolution mass spectrometer for co-eluting 2,4-dimethylphenol and 2,6-dimethylphenol.

[0005] The liquid chromatography-high resolution mass spectrometry (LC-HRMS) technique was used to simultaneously collect the primary mass spectrometry full scan (MS1) and the selected ion secondary mass spectrometry (MS2) in an acetonitrile-ammonia mobile phase system. 2 ) data to achieve the quantitative detection of phenol, three methylphenol isomers and nine dimethyl / ethylphenol isomers in oily wastewater. In addition, the present invention is also applicable to the quantitative detection of phenol, three methylphenols and nine dimethylethylphenol isomers in drinking water, surface water and groundwater, coal gasification 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 high-resolution mass spectrometry detection method for chromatographically co-eluting 2,4-dimethylphenol and 2,6-dimethylphenol, the detection 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] In the mobile phase system of acetonitrile-5.0~8.0mmol / L ammonia water, the standard sequence samples, the conversion factor calibration samples and the sample were detected by LC-HRMS, and the primary mass spectrometer full scan (MS 1 ) and selected ion secondary mass spectrometry (MS 2 )data;

[0010] According to MS 1 The data were used to calculate the standardized concentrations of the coeluting components 2,4-dimethylphenol and 2,6-dimethylphenol, as well as the concentrations of phenol, 2-methylphenol, 3-methylphenol, 4-methylphenol, 2,3-dimethylphenol, 2,5-dimethylphenol, 3,4-dimethylphenol, 3,5-dimethylphenol, 2-ethylphenol, 3-ethylphenol, and 4-ethylphenol by internal standard calibration;

[0011] According to MS 2 Data, 2,4-dimethylphenol-3,5,6-D3 was used as internal standard to calculate the concentration of 2,4-dimethylphenol;

[0012] According to MS 1 The data are used to calculate the conversion factor of the co-eluting component, and the concentration of 2,6-dimethylphenol is calculated based on the conversion factor of the co-eluting component, the standardized concentration of the co-eluting component and the concentration of 2,4-dimethylphenol.

[0013] As a preferred embodiment, the sample preparation process is selected according to the petroleum content range in the sample, specifically including:

[0014] 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;

[0015] 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.

[0016] As a preferred embodiment, the elution conditions of the acetonitrile-5.0-8.0 mmol / L ammonia water mobile phase system include:

[0017] The column flow rate is 0.20-0.25 mL / min;

[0018] Gradient elution: the initial volume ratio of acetonitrile is 20% 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;

[0019] The column temperature is 35-40°C.

[0020] As a preferred embodiment, the elution conditions of the acetonitrile-5.0-8.0 mmol / L ammonia water mobile phase system include:

[0021] The column flow rate was 0.25 mL / min;

[0022] Gradient elution: 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;

[0023] The column temperature was 40°C.

[0024] As a preferred embodiment, the selected ion secondary mass spectrometry (MS 2 ), the parent ion of 2,4-dimethylphenol-3,5,6-D3 is 124.08472 m / z, and the quantitative daughter ion is 94.07415 m / z; the parent ion of 2,4-dimethylphenol is 121.06589 m / z, and the quantitative daughter ion is 91.05532 m / z.

[0025] As a preferred embodiment, the calculation formula of the conversion factor of the co-eluting components is:

[0026]

[0027] Where k is the conversion factor of the co-eluting component, A 2,4 / 2,6-DMP is the peak area of ​​the quantitative precursor ions of the co-eluting components 2,4-dimethylphenol and 2,6-dimethylphenol in the calibration points of the calibration sample series, A 2,4-DMP The peak area of ​​the quantitative parent ion of 2,4-dimethylphenol in the calibration sample is A IS，2,4 / 2,6-DMP and A IS，2,4-DMP The peak area of ​​the internal standard quantitation precursor ion in the calibration sample is calculated for the calibration points and conversion factors of the above calibration sample series.

[0028] As a preferred embodiment, the calculation formula for the concentration of 2,6-dimethylphenol is:

[0029]

[0030] In the formula, c 2,6-DMP represents the concentration of 2,6-dimethylphenol, k represents the conversion factor of the co-eluting components, c STD represents the normalized concentration of coeluted 2,4-dimethylphenol and 2,6-dimethylphenol, c 2,4-DMP Indicates the concentration of 2,4-dimethylphenol.

[0031] On the other hand, the present invention also provides an application of a high-resolution mass spectrometry detection method for chromatographic co-elution of 2,4-dimethylphenol and 2,6-dimethylphenol, which is applied to the quantitative detection of single components of phenol, three methylphenols and nine dimethylphenol isomers in oily wastewater, coal gasification wastewater, oily solid waste, drinking water, surface water and groundwater.

[0032] Technical effects and advantages of the present invention:

[0033] (1) Use a single injection and collect a full mass spectrometer scan (MS 1 ) and selected ion secondary mass spectrometry (MS 2 )

[0034] The data were used to accurately quantify the single components of the chromatographically co-eluted 2,4-dimethylphenol and 2,6-dimethylphenol isomers.

[0035] (2) It was found that when the collision energy NCE ≥ 80, only the parent ion of 2,4-dimethylphenol 121.06589 m / z ([C8H9O] - ) fragmented to produce a high intensity daughter ion 91.05532m / z ([C7H7] -), and this daughter ion can be applied to the quantification of 2,4-dimethylphenol.

[0036] (3) The samples were not enriched or derivatized. The detection limits of the single-component method for phenol, three methylphenols, and nine dimethylphenol isomers were less than 1.0 μg / L. Compared with the standard HJ744-2015 (derivation-GC-MS method) for testing phenolic compounds, the sensitivity of this method was 1 to 2 orders of magnitude higher.

[0037] Other features and advantages of the present invention will be described in the following description, and partly become obvious from the description, or be understood by implementing 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 and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 The present invention is a flow chart of a high-resolution mass spectrometry detection method for chromatographically co-eluting 2,4-dimethylphenol and 2,6-dimethylphenol;

[0039] Figure 2 The present invention shows nine kinds of dimethyl / ethylphenol [MH] under different elution conditions in the acetonitrile-6.0mmol / L ammonia mobile phase system. - Extracted ion map of

[0040] Figure 3 The [MH] of 9 dimethyl / ethyl phenols separated in the mobile phase system of acetonitrile-4.0~10.0mmol / ammonia water in the embodiment of the present invention - Extracted ion map. DETAILED DESCRIPTION

[0041] 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.

[0042] In order to solve the deficiencies of the prior art, the present invention discloses a high-resolution mass spectrometry detection method for chromatographic co-elution of 2,4-dimethylphenol and 2,6-dimethylphenol. Figure 1 The flowchart of the high-resolution mass spectrometry detection method of chromatographic co-elution of 2,4-dimethylphenol and 2,6-dimethylphenol of the present invention is as follows: Figure 1 As shown, the method comprises the following steps:

[0043] Step S1, according to the petroleum content range in the sample, select the corresponding sample pretreatment process to prepare the sample;

[0044] Step S2, using LC-HRMS to detect the standard sequence samples, the conversion factor calibration samples and the sample in an acetonitrile-5.0-8.0 mmol / L ammonia water mobile phase system, collecting a primary mass spectrometer full scan (MS 1 ) and selected ion secondary mass

[0045] Spectral scanning (MS 2 )data;

[0046] Step S3: According to MS 1 The data were used to calculate the standardized concentrations of the coeluting components 2,4-dimethylphenol and 2,6-dimethylphenol, as well as the concentrations of phenol, 2-methylphenol, 3-methylphenol, 4-methylphenol, 2,3-dimethylphenol, 2,5-dimethylphenol, 3,4-dimethylphenol, 3,5-dimethylphenol, 2-ethylphenol, 3-ethylphenol, and 4-ethylphenol by internal standard calibration;

[0047] Step S4: According to MS 2 Data, 2,4-dimethylphenol-3,5,6-D3 was used as internal standard to calculate the concentration of 2,4-dimethylphenol;

[0048] Step S5: According to MS 1 The data are used to calculate the conversion factor of the co-eluting component, and the concentration of 2,6-dimethylphenol is calculated based on the conversion factor of the co-eluting component, the standardized concentration of the co-eluting component and the concentration of 2,4-dimethylphenol.

[0049] In step S1 of the present invention, the sample is prepared by selecting a corresponding sample pretreatment process according to the petroleum content range in the sample, which specifically includes:

[0050] 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;

[0051] 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.

[0052] In step S2 of the present invention, the elution conditions of the acetonitrile-5.0-8.0 mmol / L ammonia water mobile phase system include:

[0053] The column flow rate is 0.20-0.25 mL / min;

[0054] Gradient elution: the initial volume ratio of acetonitrile is 20% 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;

[0055] The column temperature is 35-40°C.

[0056] Preferably, the elution conditions of the acetonitrile-5.0-8.0 mmol / L ammonia water mobile phase system include:

[0057] The column flow rate was 0.25 mL / min;

[0058] Gradient elution: 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;

[0059] The column temperature was 40°C.

[0060] In step S4 of the present invention, the selected ion secondary mass spectrometry (MS 2 ), the parent ion of 2,4-dimethylphenol-3,5,6-D3 is 124.08472 m / z, and the quantitative daughter ion is 94.07415 m / z; the parent ion of 2,4-dimethylphenol is 121.06589 m / z, and the quantitative daughter ion is 91.05532 m / z.

[0061] In step S5 of the present invention, the calculation formula of the conversion factor of the co-eluting component is:

[0062]

[0063] Where k is the conversion factor of the co-eluting component, A 2,4 / 2,6-DMP is the peak area of ​​the quantitative precursor ions of the co-eluting components 2,4-dimethylphenol and 2,6-dimethylphenol in the calibration points of the calibration sample series, A 2,4-DMP The peak area of ​​the quantitative parent ion of 2,4-dimethylphenol in the calibration sample is A IS，2,4 / 2,6-DMP and A IS，2,4-DMP The peak area of ​​the internal standard quantitation precursor ion in the calibration sample is calculated for the calibration points and conversion factors of the above calibration sample series.

[0064] The calculation formula of the concentration of the 2,6-dimethylphenol is:

[0065]

[0066] In the formula, c2,6-DMP represents the concentration of 2,6-dimethylphenol, k represents the conversion factor of the co-eluting components, c STD represents the normalized concentration of coeluted 2,4-dimethylphenol and 2,6-dimethylphenol, c 2,4-DMP Indicates the concentration of 2,4-dimethylphenol.

[0067] Example 1

[0068] This example provides two sample pretreatment methods for LC-HRMS injection testing.

[0069] 1. Stripping water or coal gasification wastewater with petroleum content ≤50mg / L;

[0070] The water sample was filtered through a 0.22 μm filter membrane. Depending on the volatile phenol content, 10 to 900 μL of the filtrate was taken to prepare the sample.

[0071] This process is also applicable to the sample preparation of relatively clean water samples such as drinking water, groundwater and surface water; or the sample preparation of oil-water mixtures such as oily wastewater.

[0072] 2. Stripping water or coal gasification wastewater with petroleum content > 50 mg / L;

[0073] Take 10.00mL of water sample in a 20mL round-bottom screw-mouth sample bottle (with a sample cap of polytetrafluoroethylene liner), add 100μL of 2.5mol / L NaOH solution to adjust 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, filter the aqueous phase through a 0.22μm filter membrane, and take 10-900μL of the filtrate to prepare the sample according to the volatile phenol content.

[0074] Example 2

[0075] In this example, chromatographic elution conditions of nine kinds of dimethyl / ethyl phenols were optimized under the mobile phase system of acetonitrile-ammonia water.

[0076] When the chromatographic mobile phase is acetonitrile-ammonia system, the three methylphenol isomers can be well chromatographically separated. Therefore, the chromatographic separation effect of the mobile phase elution conditions on dimethyl / ethylphenol was investigated in detail.

[0077] Under the conditions of column temperature of 40℃ and ammonia concentration of 6mmol / L, the optimization experiment was carried out by changing the column flow rate, the initial volume ratio of acetonitrile and the elution gradient. In the optimization experiment, the gradient elution was started 1min after the initial zero gradient elution. Figure 2 The [MH] of 9 dimethyl / ethyl phenols in the embodiment of the present invention under different elution conditions of acetonitrile-6.0mmol / L ammonia water mobile phase system -Extracted ion map, where Figure 2 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.

[0078] 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 2 As shown in Figure A, there are three groups of components co-eluting, namely: 3,5-dimethylphenol and 3-ethylphenol, 4-ethylphenol and 2,3-dimethylphenol, 2,5-dimethylphenol and 2,6-dimethylphenol.

[0079] 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 2 As shown in B, there are two groups of components eluting together, namely: 4-ethylphenol and 2,3-dimethylphenol, 2,4-dimethylphenol and 2,6-dimethylphenol.

[0080] Then increase the elution gradient from 0.43% / min to 1.56% / min, such as Figure 2 As shown in C, only 2,4-dimethylphenol and 2,6-dimethylphenol co-eluted.

[0081] Maintaining the elution gradient at 1.56% / min, the initial volume ratio of acetonitrile was increased to 30%. Figure 2 As shown in D, the overall chromatographic separation effect of the nine dimethyl / ethyl phenols 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.

[0082] Under the optimized elution conditions, the effects of column temperatures of 30℃, 35℃, 40℃ and 45℃ on the chromatographic separation of 9 dimethyl / ethylphenols were further compared. The results showed that the chromatographic separation effect was better when the column temperature was between 35℃ and 40℃, so the preferred column temperature was 40℃.

[0083] 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.

[0084] Example 3

[0085] In this example, the effect of ammonia concentration in the range of 4.0 to 10.0 mmol / L on the chromatographic separation of nine dimethyl / ethyl phenols was investigated in an acetonitrile-ammonia mobile phase system.

[0086] Figure 3 The [MH] obtained by chromatography of 9 dimethyl / ethylphenols in the embodiment of the present invention in the mobile phase system of acetonitrile-4.0-10.0mmol / ammonia water is shown in FIG. - 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; and 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.

[0087] like Figure 3 As shown in Figure A, 9 dimethyl / ethylphenols 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. Figure 3 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 3 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.

[0088] In summary, when the concentration of ammonia water is 5.0-8.0 mmol / L, the chromatographic separation of 9 dimethyl / ethyl phenols is relatively good, and it is better when the concentration of ammonia water is 6.0 mmol / L.

[0089] Example 4

[0090] This embodiment provides a method for detecting 13 phenolic single components including phenol, methylphenol, dimethylphenol and ethylphenol in stripping water by ultra high performance liquid chromatography-orbitrap high resolution mass spectrometry (UPLC-Orbitrap HRMS).

[0091] 1. Instrument conditions

[0092] UPLC-Orbitrap HRMS: Vanquish C-H10 ultra-high performance liquid chromatograph, Q-Exactive Plus electrostatic field orbitrap high-resolution mass spectrometer (ThermoFisher, USA).

[0093] (1) Liquid chromatography conditions

[0094] 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.

[0095] (2) Orbitrap HRMS conditions

[0096] Heated electrospray ion source: negative ion mode; sheath gas flow rate: 35Arb; auxiliary gas flow rate: 10Arb; spray voltage 2.6kV; ion transfer tube temperature: 320°C; S-lens RF voltage: 50V; auxiliary gas heater temperature: 380°C.

[0097] Full scan mass spectrometry (MS 1 ) acquisition parameters: resolution: 70000; maximum capacity of C-trap ion number (AGCTarget): 1×10 6 . C-trap maximum injection time (Maximum IT): 200ms; mass range: m / z 90~155;

[0098] Selected ion secondary mass spectrometry (MS 2) acquisition parameters: selected ions were 121.06589 m / z and 124.08472 m / z; resolution: 17500; maximum capacity of C-trap ion number (AGC Target): 1×10 5 ; C-trap maximum injection time (Maximum IT): 100ms; isolation window: 1m / z; normalized collision energy (steppedNCE): 80.

[0099] 2. Preparation of standard sequence samples and conversion factor calibration samples

[0100] Thirteen phenols (phenol, methylphenol, dimethylphenol / ethylphenol) with a purity of more than 98% and internal standards (phenol- 13 C6 and 2,4-dimethylphenol-3,5,6-D3) standard samples were used to prepare single standard stock solutions, and 13 phenol mixed working solutions, 2,4-dimethylphenol working solution and mixed internal standard working solution were prepared by stepwise dilution with methanol. The working solutions were then used to prepare standard sequence samples and conversion factor calibration samples.

[0101] Standard series samples: Add 900 μL of pure water to 6 2mL sample bottles respectively, add 13 kinds of phenol mixed working solutions and mixed internal standard working solutions in sequence with a micro syringe, and add methanol to make the total amount of methanol in the calibration standard solution 100 μL. Shake well and store at 4-6℃ for testing. The concentrations of the 13 phenol components in the standard series are 10, 100, 500, 1000, 2500 and 5000 μg / L respectively, and the concentration of each internal standard component is 200 μg / L.

[0102] Conversion factor calibration sample: Add 900 μL of pure water to a 2mL sample bottle, use a microsyringe to add 2,4-dimethylphenol working solution and mixed internal standard working solution in sequence, and add methanol to make the total amount of methanol in the calibration standard solution 100 μL. Shake well and store at 4-6°C for testing. The concentration of 2,4-dimethylphenol in the conversion factor calibration sample is 1000 μg / L, and the concentration of each component of the internal standard is 200 μg / L.

[0103] 3. Sample collection and specimen preparation

[0104] The stripping water or coal gasification wastewater samples were collected in 40mL VOA sample bottles with polytetrafluoroethylene liners. When sampling, the water sample was required to fill the sample bottle and not overflow outside the bottle. No protective agent was added. The sample was refrigerated at 4-6℃ and the sample preparation was completed within 48 hours.

[0105] Take out the refrigerated water sample, wait for the sample temperature to return to room temperature, and filter it through a 0.22μm nylon filter. Pre-add 90μL of methanol to a 2mL sample bottle. Depending on the volatile phenol content, take 10-900μL of the filtrate and add it to the sample bottle, add pure water to make the total volume of the sample 990μL, then add 10μL of the mixed internal standard working solution, shake well, and store at 4-6℃ for testing.

[0106] 4. Data collection and result calculation

[0107] Xcalibur 4.4 software was used to collect data, and TraceFinder 5.1 software was used for data analysis. The target compounds in the samples were qualitatively confirmed based on retention time matching, and the parent ion [MH] - The concentration of the target compound is calculated based on the peak area of ​​the product ion.

[0108] Table 1 shows the retention time, quantitative parent ion and quantitative daughter ion information of the mixed internal standard and 13 phenol components. In the acetonitrile-6.0mmol / L ammonia water mobile phase system, the effects of different collision energies on the secondary mass spectrometry fingerprint characteristics of dimethylphenol and 2,6-dimethylphenol were investigated. The study found that at lower collision energies (NCE≤50), 2,4-dimethylphenol

[0109] The fragmentation of 2,6-dimethylphenol and 2,6-dimethylphenol produced the same characteristic product ion 93.03459 m / z ([C6H5O] - ), the intensity of other daughter ions is very low compared with the parent ion and can be ignored; by increasing the collision energy (NCE ≥ 80), only the parent ion of 2,4-dimethylphenol 121.06589 m / z ([C8H9O] - ) fragmented to produce 91.05532 m / z ([C7H7] - ) has a high relative intensity and can be used for the quantification of 2,4-dimethylphenol. At the same time, interfering ions such as 91.01899 m / z and 90.98577 m / z were found. For low-resolution mass spectrometry (such as triple quadrupole mass spectrometer), it is impossible to distinguish the interference of 91 m / z. The relative error of mass accuracy of high-resolution mass spectrometry (HRMS) is better than 5×10 -6 , which can effectively eliminate this interference.

[0110] Table 1 Retention time, quantitative parent ion and quantitative daughter ion of mixed internal standard and 13 phenolic components

[0111]

[0112] When the concentrations of 2,4-dimethylphenol (2,4-DMP) and 2,6-dimethylphenol (2,6-DMP) are equal at each calibration point, a calibration curve is drawn with the sum of the concentrations of 2,4-dimethylphenol and 2,6-dimethylphenol as the independent variable and the sum of the responses of 2,4-dimethylphenol and 2,6-dimethylphenol (such as the peak area of ​​the quantitative ion) as the dependent variable.

[0113] The concentration value of the coeluting component calculated by the calibration curve is defined as the standardized concentration of coeluting 2,4-dimethylphenol and 2,6-dimethylphenol, and is expressed as c STD express.

[0114] The conversion factor of 2,6-dimethylphenol to 2,4-dimethylphenol is represented by k and is calculated according to formula (1):

[0115]

[0116] In the formula, A 2,4 / 2,6-DMP A is the peak area of ​​the quantitative parent ion of the co-eluting components 2,4-dimethylphenol and 2,6-dimethylphenol at the calibration point (e.g. 1000 μg / L) of the calibration sample series, 2,4-DMP The peak area of ​​the quantitative parent ion of 2,4-dimethylphenol in the calibration sample (e.g. 1000 μg / L) is the corresponding conversion factor, A IS，2,4 / 2,6-DMP and A IS，2,4-DMP is the peak area of ​​the internal standard quantitative parent ion corresponding to the calibration point and conversion factor calibration sample of the above calibration sample series; wherein, the calibration samples related to the conversion factor can be repeatedly measured, and the average value thereof is taken as k.

[0117] About MS 1 The data were processed and the peak area of ​​the parent ion was used to calculate the standardized concentration c of the co-eluted 2,4-dimethylphenol and 2,6-dimethylphenol by the internal standard method. STD , as well as the concentrations of phenol, 2-methylphenol, 3-methylphenol, 4-methylphenol, 2,3-dimethylphenol, 2,5-dimethylphenol, 3,4-dimethylphenol, 3,5-dimethylphenol, 2-ethylphenol, 3-ethylphenol, and 4-ethylphenol;

[0118] About MS 2 The data was processed and the peak area of ​​the quantified daughter ion was used to calculate the concentration of 2,4-dimethylphenol in the sample by the internal standard method, which was recorded as c 2,4-DMP .

[0119] The concentration of 2,6-dimethylphenol in the sample c 2,6-DMP Calculate according to formula (2):

[0120]

[0121] 5. Method performance indicators

[0122] (1) Calibration range and detection limit

[0123] The linear regression correlation coefficients (R) of 13 phenolic components in the range of 10 to 5000 μg / L 2 ) were all greater than 0.997. The detection limits of the 13 phenolic components were all ≤1.0μg / L. Compared with the standard HJ744-2015 (derivative-GC-MS method) for testing phenolic compounds, the sensitivity of this method was 1 to 2 orders of magnitude higher.

[0124] (2) Sample matrix spike recovery and precision

[0125] In the stripping water sample matrix spike, the concentrations of 13 phenolic compounds were 10, 500 and 2000 μg / L, and the recoveries of the target analytes were 77% to 117.8%, with RSDs of 0.4% to 10.2%, indicating that the method was quantitatively accurate and had good repeatability.

[0126] 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-HRMS instrument. Other similar reverse chromatographic columns can be used to implement the present invention according to the technical solution disclosed in the present invention.

[0127] 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, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, 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 high-resolution mass spectrometry detection method for chromatographic co-elution of 2,4-dimethylphenol and 2,6-dimethylphenol, characterized in that: The detection method comprises the following steps: According to the petroleum content range in the sample, select the corresponding sample pretreatment process to prepare the sample; In the mobile phase system of acetonitrile-5.0~8.0mmol / L ammonia water, the standard sequence samples, the conversion factor calibration samples and the sample were detected by LC-HRMS, and the primary mass spectrometer full scan (MS 1 ) and selected ion secondary mass spectrometry (MS 2 )data; According to MS 1 The data were used to calculate the standardized concentrations of the coeluting components 2,4-dimethylphenol and 2,6-dimethylphenol, as well as the concentrations of phenol, 2-methylphenol, 3-methylphenol, 4-methylphenol, 2,3-dimethylphenol, 2,5-dimethylphenol, 3,4-dimethylphenol, 3,5-dimethylphenol, 2-ethylphenol, 3-ethylphenol, and 4-ethylphenol by internal standard calibration; According to MS 2 Data, 2,4-dimethylphenol-3,5,6-D3 was used as internal standard to calculate the concentration of 2,4-dimethylphenol; According to MS 1 The data are used to calculate the conversion factor of the co-eluting component, and the concentration of 2,6-dimethylphenol is calculated based on the conversion factor of the co-eluting component, the standardized concentration of the co-eluting component and the concentration of 2,4-dimethylphenol.

2. The high-resolution mass spectrometry detection method for chromatographic co-elution of 2,4-dimethylphenol and 2,6-dimethylphenol according to claim 1, characterized in that: According to the petroleum content range in the sample, the corresponding sample pretreatment process is selected to prepare the sample, which specifically 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 high-resolution mass spectrometry detection method for chromatographic co-elution of 2,4-dimethylphenol and 2,6-dimethylphenol according to claim 1 or 2, characterized in that: The elution conditions of the acetonitrile-5.0-8.0 mmol / L ammonia water mobile phase system include: The column flow rate is 0.20-0.25 mL / min; Gradient elution: the initial volume ratio of acetonitrile is 20% 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; The column temperature is 35-40°C.

4. The high-resolution mass spectrometry detection method for chromatographic co-elution of 2,4-dimethylphenol and 2,6-dimethylphenol according to claim 1, characterized in that: The elution conditions of the acetonitrile-5.0-8.0 mmol / L ammonia water mobile phase system include: The column flow rate was 0.25 mL / min; Gradient elution: 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; The column temperature was 40°C.

5. The high-resolution mass spectrometry characterization method for chromatographically co-eluting dimethylphenol isomers according to claim 1, characterized in that: The selected ion secondary mass spectrometry (MS 2 ), the parent ion of 2,4-dimethylphenol-3,5,6-D3 is 124.08472 m / z, and the quantitative daughter ion is 94.07415 m / z; the parent ion of 2,4-dimethylphenol is 121.06589 m / z, and the quantitative daughter ion is 91.05532 m / z.

6. The high-resolution mass spectrometry detection method for chromatographic co-elution of 2,4-dimethylphenol and 2,6-dimethylphenol according to claim 1, characterized in that: The calculation formula of the conversion factor of the co-eluting component is: Where k is the conversion factor of the co-eluting component, A 2,4 / 2,6-DMP is the peak area of ​​the quantitative precursor ions of the co-eluting components 2,4-dimethylphenol and 2,6-dimethylphenol in the calibration points of the calibration sample series, A 2,4-DMP The peak area of ​​the quantitative parent ion of 2,4-dimethylphenol in the calibration sample is A IS，2,4 / 2,6-DMP and A IS，2,4-DMP The peak area of ​​the internal standard quantitation precursor ion in the calibration sample is calculated for the calibration points and conversion factors of the above calibration sample series.

7. The high-resolution mass spectrometry detection method for chromatographic co-elution of 2,4-dimethylphenol and 2,6-dimethylphenol according to claim 1, characterized in that: The calculation formula of the concentration of the 2,6-dimethylphenol is: In the formula, c 2,6-DMP represents the concentration of 2,6-dimethylphenol, k represents the conversion factor of the co-eluting components, c STD represents the normalized concentration of coeluted 2,4-dimethylphenol and 2,6-dimethylphenol, c 2,4-DMP Indicates the concentration of 2,4-dimethylphenol.

8. An application of the high-resolution mass spectrometry detection method for chromatographic co-elution of 2,4-dimethylphenol and 2,6-dimethylphenol as claimed in any one of claims 1 to 7, characterized in that: The detection method is applied to the quantitative detection of single components of phenol, three methylphenols and nine dimethylphenol isomers in oily wastewater, coal gasification wastewater, oily solid waste, drinking water, surface water and groundwater.

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