A method for determining carbazole and nine halogenated carbazoles in sediments by internal standard method

Abstract

The invention discloses a method for determining carbazole and nine halogenated carbazoles in sediments by an internal standard method, and belongs to the technical field of carbazole detection; the determination method comprises the following steps: mixing sediments, internal standard solution, extraction solvent, metal salt and surfactant for ultrasonic extraction to obtain an extract; adding purification material to the extract and obtaining a test solution by purification; and detecting carbazole and halogenated carbazole in the test solution by gas chromatography-tandem mass spectrometry. The invention provides a method for determining carbazole and nine halogenated carbazoles in sediments by an internal standard method, which can not only effectively improve the extraction efficiency of target compounds and reduce the loss in the purification process, but also improve the test efficiency and accuracy.

Description

Technical Field

[0001] The invention relates to the technical field of carbazole detection, and in particular to a method for determining carbazole and nine halogenated carbazoles in sediments by an internal standard method. Background Art

[0002] Carbazole and its derivatives are a class of nitrogen-containing heterocyclic aromatic compounds, which are widely used in many fields such as optoelectronic materials, dyes, medicine and supramolecular recognition. Halogenated carbazole is a carbazole compound substituted with one or more halogens. So far, 135 halogenated carbazole homologues have been found. Toxicological studies have shown that exposure to carbazole and halogenated carbazoles has adverse effects on human health. Halogenated carbazoles have carcinogenic and mutagenic dioxin-like toxicological effects, which can induce carcinogenicity, teratogenicity and mutagenicity in rodents, aquatic animals and humans.

[0003] Halogenated carbazoles are constantly detected in different environmental media such as sediments, soil, natural water bodies, drinking water, air dust, and biological media such as animals and humans. Halogenated carbazoles are stable in the natural environment and can remain in water bodies, soil, sediments and air for a long time, with potential persistence and bioaccumulation. Therefore, it is crucial to develop a method for the determination of carbazole and halogenated carbazoles in sediments. Summary of the invention

[0004] The object of the present invention is to provide a method for determining carbazole and nine halogenated carbazoles in sediments by an internal standard method, which can not only improve the recovery rate of the target compound, but also improve the accuracy of the detection.

[0005] The technical solution adopted by the present invention to achieve the above-mentioned purpose is:

[0006] A surfactant includes a sodium salt of silicon-based carboxylic acid, which contains sulfur elements and siloxy groups. In the preparation of the sodium salt of silicon-based carboxylic acid, vinyl-tris(trimethylsiloxy)silane is first mixed with thioglycolic acid, reacted under the initiation conditions of 2,2-dimethyl-phenylacetophenone, and then salified with anhydrous sodium carbonate to obtain the sodium salt of silicon-based carboxylic acid. The sodium salt of silicon-based carboxylic acid has strong surface activity and can significantly reduce the surface tension of the liquid. Using the sodium salt of silicon-based carboxylic acid to assist the ultrasonic extraction of the target compound can reduce the interfacial tension and wetting angle between the sediment and the solvent, promote the wettability of the sediment surface, and help improve the extraction efficiency of the target compound.

[0007] Preferably, the preparation method of silicon-based carboxylic acid sodium salt is specifically,

[0008] Mix vinyl-tri(trimethylsiloxy)silane and thioglycolic acid, add tetrahydrofuran, stir evenly, add 2,2-dimethyl-phenylacetophenone, react with ultraviolet light, add anhydrous sodium carbonate, react for 2-8 hours, remove the solvent by rotary evaporation, wash the precipitate with n-hexane repeatedly for 3-5 times, and vacuum dry at 50-70°C for 24-72 hours to obtain sodium salt of silicon carboxylic acid.

[0009] More preferably, the weight ratio of vinyl-tris(trimethylsiloxy)silane to thioglycolic acid is 3-4:1.

[0010] More preferably, the liquid-to-solid ratio of thioglycolic acid and tetrahydrofuran is 1 g:2-10 mL.

[0011] More preferably, the weight ratio of thioglycolic acid to 2,2-dimethyl-phenylacetophenone is 10-20:1.

[0012] More preferably, the ultraviolet light irradiation wavelength is 365 nm, and the irradiation time is 10-30 min.

[0013] More preferably, the weight ratio of vinyl-tris(trimethylsiloxy)silane to anhydrous sodium carbonate is 2-10:1.

[0014] A method for determining carbazole and nine halogenated carbazoles in sediments by an internal standard method comprises: mixing sediments, internal standard solution, extraction solvent, metal salt and surfactant, performing ultrasonic extraction to obtain an extract; adding a purification material to the extract and performing purification treatment to obtain a test solution; and detecting carbazole and halogenated carbazole in the test solution by gas chromatography-tandem mass spectrometry.

[0015] Preferably, the internal standard solution includes D8-carbazole standard, and the mass concentration of the internal standard solution is 0.1-0.5 mg / mL; the extraction solvent includes n-hexane and acetone, and the volume ratio of n-hexane to acetone is 2-3:1; the metal salt includes anhydrous magnesium sulfate and sodium chloride, and the weight ratio of anhydrous magnesium sulfate to sodium chloride is 3-5:1.

[0016] Preferably, the usage ratio of the sediment and the internal standard solution is 1 g: 2-5 μL.

[0017] Preferably, the liquid-to-solid ratio of the sediment and the extraction solvent is 1 g: 2-4 mL.

[0018] Preferably, the weight ratio of the sediment to the metal salt is 3-5:1.

[0019] Preferably, the weight ratio of the metal salt to the surfactant is 2-15:1.

[0020] Preferably, the ultrasonic extraction temperature is 20-60°C, and the ultrasonic extraction time is 10-30 min.

[0021] Preferably, the purification material comprises the following components in parts by mass: 30 parts of ethylenediamine-N-propylsilane, 70 parts of octadecylsilane bonded silica gel, 2 parts of graphitized carbon black and 50 parts of anhydrous magnesium sulfate.

[0022] Preferably, the weight ratio of sediment to purification material is 2-4:1.

[0023] Preferably, a method for determining carbazole and nine halogenated carbazoles in sediment by an internal standard method comprises:

[0024] The sediment is added with a D8-carbazole internal standard working solution with a mass concentration of 0.1-0.5 mg / mL, and the mixture is allowed to stand for 20-40 minutes. Hexane and acetone are added and vortexed for 5 minutes. Anhydrous magnesium sulfate, sodium chloride and a surfactant are added. The surfactant includes at least one of silicon-based carboxylic acid sodium salt and ferroferric oxide / cellulose magnetic nanocomposite material. The mixture is immediately mixed by hand shaking for 20-60 seconds, ultrasonically extracted at 20-60°C for 10-30 minutes, and then centrifuged at 4000-8000 rpm for 5-20 minutes. The supernatant is taken and 1.0-3.0 g of purification material is added. The mixture is vortexed for 2-10 minutes, and centrifuged at 4000-8000 rpm for 5-20 minutes. The supernatant is taken and blown to near dryness with liquid nitrogen, and re-dissolved with 0.5-1.5 mL of acetonitrile. The mixture is filtered through a 0.45 μm organic membrane to obtain a test solution. The carbazole and halogenated carbazole in the test solution are detected by gas chromatography-tandem mass spectrometry. The ferroferric oxide / cellulose magnetic nanocomposite material has a large specific surface area, a porous structure and a relatively uniform pore size distribution, which can improve the adsorption effect of the target compound and achieve effective enrichment of the target compound; at the same time, the ferroferric oxide / cellulose magnetic nanocomposite material has extremely high surface energy and is easy to functionalize the surface. When used in combination with sodium silicon carboxylate, the particles can be fully approached and the equilibrium time can be reduced, thereby further improving the extraction efficiency of the target compound.

[0025] More preferably, the surfactant comprises a sodium salt of a silicon-based carboxylic acid.

[0026] More preferably, the surfactant comprises ferrosoferric oxide / cellulose magnetic nanocomposite material.

[0027] More preferably, the surfactant comprises silicon-based carboxylic acid sodium salt and ferrosoferric oxide / cellulose magnetic nanocomposite material.

[0028] More preferably, the weight ratio of the silicon-based carboxylic acid sodium salt to the ferrosoferric oxide / cellulose magnetic nanocomposite material is 0.2-4:1.

[0029] More preferably, the method for preparing the ferroferric oxide / cellulose magnetic nanocomposite material comprises:

[0030] The bamboo fiber is soaked in a potassium hydroxide solution for 6-12 hours, filtered out and washed with water until neutral, and ammonium persulfate is added to oxidatively degrade at 60-100°C for 12-24 hours to prepare a cellulose nanomaterial, which is then dispersed in water, and ferroferric oxide and acetone are added in an inert environment. Ammonia water is then added under stirring, and the pH value is adjusted to alkaline. After crystallization at 40-80°C for 0.5-2 hours, the product is collected with a magnet, washed with ethanol for 3-5 times, and dried to obtain a ferroferric oxide / cellulose magnetic nanocomposite material.

[0031] More preferably, the concentration of potassium hydroxide is 0.5-1.5 mol / L.

[0032] More preferably, the weight ratio of bamboo fiber to ammonium persulfate is 1:1-3.

[0033] More preferably, the weight ratio of bamboo fiber to ferrosoferric oxide is 1:1-3.

[0034] More preferably, the liquid-to-solid ratio of ferrosoferric oxide to acetone is 1 g: 2-3 mL.

[0035] The present invention uses silicon-based carboxylic acid sodium salt and magnetic nanomaterials to assist ultrasonic extraction, and has the following beneficial effects: the silicon-based carboxylic acid sodium salt prepared by the present invention has strong surface activity, can significantly reduce the surface tension of the liquid, reduce the interfacial tension and wetting angle between the sediment and the solvent, and promote the wettability of the sediment surface, thereby facilitating the improvement of the extraction effect of the target compound. The ferroferric oxide / cellulose magnetic nanocomposite material prepared by the present invention not only has a large specific surface area, a porous structure and a relatively uniform pore size distribution, which can improve the adsorption effect of the target compound and achieve effective enrichment of the target compound; and has extremely high surface energy, and the surface is easy to be functionalized. When used in combination with silicon-based carboxylic acid sodium salt, the particles can be fully close to each other, and the equilibrium time can be reduced, thereby further improving the extraction efficiency of the target compound. Therefore, the present invention provides a method for determining carbazole and halogenated carbazole in sediment by an internal standard method with high efficiency, simplicity, good recovery rate and precision. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is the total ion current diagram of carbazole, D8-carbazole and 9 halogenated carbazoles.

[0037] Figure 2 The quantitative ion chromatogram and characteristic fragment mass spectrum of carbazole.

[0038] Figure 3 The quantitative ion chromatogram and characteristic fragment mass spectrum of D8-carbazole.

[0039] Figure 4 The quantitative ion chromatogram and characteristic fragment mass spectrum of 3-chlorocarbazole.

[0040] Figure 5 The quantitative ion chromatogram and characteristic fragment mass spectrum of 3-bromocarbazole.

[0041] Figure 6 The quantitative ion chromatogram and characteristic fragment mass spectrum of 3,6-dichlorocarbazole.

[0042] Figure 7 The quantitative ion chromatogram and characteristic fragment mass spectrum of 1,3,6,8-tetrachlorocarbazole.

[0043] Figure 8 The quantitative ion chromatogram and characteristic fragment mass spectrum of 1-bromo-3,6-dichlorocarbazole.

[0044] Fig. 9 The quantitative ion chromatogram and characteristic fragment mass spectrum of 3,6-dibromocarbazole.

[0045] Fig.10 The quantitative ion chromatogram and characteristic fragment mass spectrum of 2,7-dibromocarbazole.

[0046] Fig.11 The quantitative ion chromatogram and characteristic fragment mass spectrum of 1,8-bromo-3,6-dichlorocarbazole.

[0047] Fig.12 The quantitative ion chromatogram and characteristic fragment mass spectrum of 1,3,6,8-tetrabromocarbazole. DETAILED DESCRIPTION

[0048] The present invention is further described in detail below in conjunction with specific embodiments, and the examples provided are only for illustrating the present invention, rather than for limiting the scope of the present invention. The examples provided below can be used as a guide for further improvements by those of ordinary skill in the art, and do not constitute a limitation of the present invention in any way.

[0049] The experimental methods in the following examples are conventional methods unless otherwise specified. The materials, reagents, etc. used in the following examples are commercially available unless otherwise specified.

[0050] Embodiment 1:

[0051] S1. Preparation of standard solution, including:

[0052] Accurately weigh or pipette carbazole, D8-carbazole, 3-chlorocarbazole, 3-bromocarbazole, 3,6-dichlorocarbazole, 3,6-dibromocarbazole, 2,7-dibromocarbazole, 1-bromo-3,6-dichlorocarbazole, 1,8-bromo-3,6-dichlorocarbazole, 1,3,6,8-tetrachlorocarbazole, 1,3,6,8-tetrabromocarbazole standards, add acetonitrile to dissolve and dilute to the standard scale to prepare a mixed standard stock solution with a mass concentration of 100 mg / L; accurately pipette 50 μL of the standard stock solution, add acetonitrile to dilute to the standard scale to prepare a standard intermediate solution with a mass concentration of 500 ng / mL, and store at -20°C in the dark; accurately weigh the D8-carbazole standard, add acetonitrile to dissolve and dilute to the standard scale to prepare a mixed standard stock solution with a mass concentration of 100 mg / L; accurately pipette 50 μL of the standard stock solution, add acetonitrile to dilute to the standard scale to prepare a standard intermediate solution with a mass concentration of 500 ng / mL, and store at -20°C in the dark; accurately weigh the D8-carbazole standard, add acetonitrile to dissolve and dilute to the standard scale to prepare a mixed standard stock solution with a mass concentration of 100 The internal standard stock solution is 100 mg / L, and it is stored in the dark at -20°C; 100 μL of the internal standard stock solution is accurately drawn, and acetonitrile is added to make up to the standard scale to prepare an internal standard intermediate solution with a mass concentration of 1 mg / L, and it is stored in the dark at -20°C; 100 μL of the internal standard stock solution is drawn, acetonitrile is added and the volume is made up to the standard scale to prepare an internal standard working solution with a mass concentration of 0.1 mg / L; the standard intermediate solution is diluted with acetonitrile to a standard series of working solutions with concentrations of 1 ng / ml, 2 ng / mL, 5 ng / mL, 10 ng / mL, 20 ng / mL, 50 ng / mL, and 100 ng / mL, respectively, wherein the mass concentration of the D8-carbazole internal standard working solution is 10 ng / mL to be tested.

[0053] S2. Preparation of sodium salt of silicon-based carboxylic acid, comprising:

[0054] Mix 3.22 g of vinyl-tri(trimethylsiloxy)silane and 1.01 g of thioglycolic acid, add 5 mL of tetrahydrofuran, stir evenly, add 0.0698 g of 2,2-dimethyl-phenylacetophenone, irradiate with 365 nm ultraviolet light for reaction for 15 min, add 0.53 g of anhydrous sodium carbonate, react for 5 h, remove the solvent by rotary evaporation, wash the precipitate with n-hexane repeatedly for 3 times, and vacuum dry at 60 ° C for 48 h to obtain sodium salt of silicon carboxylic acid.

[0055] S3. Preparation of ferroferric oxide / cellulose magnetic nanocomposite material, comprising:

[0056] 1g of bamboo fiber was soaked in a 1mol / L potassium hydroxide solution for 8h, filtered out and washed with water until neutral, 2.28g of ammonium persulfate was added and oxidized and degraded at 80℃ for 16h to prepare cellulose nanomaterials, which were dispersed in water, 2g of ferrosoferric oxide was added in an inert environment, 5mL of acetone was added, and then ammonia water was added under stirring, the pH value was adjusted to 10, and after crystallization at 60℃ for 1h, the product was collected with a magnet, washed with ethanol 4 times, and dried to obtain ferrosoferric oxide / cellulose magnetic nanocomposite materials.

[0057] S4. Sample pre-treatment, including:

[0058] 5.00 g of sediment was weighed, 15 μL of D8-carbazole with a mass concentration of 0.1 mg / L was added, and the mixture was allowed to stand for 30 min. 10.5 mL of n-hexane and 4.5 mL of acetone were added and vortexed for 5 min. 1 g of anhydrous magnesium sulfate, 0.25 g of sodium chloride and a surfactant were added. The surfactant included 0.3 g of sodium silyl carboxylate and 0.2 g of ferroferric oxide / cellulose magnetic nanocomposite. The mixture was immediately mixed by hand shaking for 30 s, ultrasonically extracted at 30 °C for 15 min, and then centrifuged at 6000 rpm for 10 min. The supernatant was taken and 300 mg of ethylenediamine-N-propylsilane, 700 mg of octadecylsilane bonded silica gel, 20 mg of graphitized carbon black and 500 mg of anhydrous magnesium sulfate were added. The mixture was vortexed for 5 min, and centrifuged at 6000 rpm for 10 min. The supernatant was taken and blown to near dryness with liquid nitrogen, re-dissolved with 1.0 mL of acetonitrile, filtered through a 0.45 μm organic membrane, and tested.

[0059] S5. Chromatographic conditions, including:

[0060] Chromatographic column: Agilgent DB-5MS, specification: 30m×250μm×0.25μm; temperature program: starting temperature is 50℃, and maintained for 3min, then heated to 300℃ at a rate of 10℃ / min, and maintained for 10min; carrier gas is helium, with a flow rate of 1.0mL / min; constant pressure, pressure: 8.4679psi; injection port temperature: 280℃, injection volume 1µL; injection mode is splitless injection.

[0061] S6. Mass spectrometry conditions, including:

[0062] The electron bombardment ion source has an electron energy of 70 eV; the collision gas is nitrogen; the data acquisition mode is the multiple reaction monitoring mode; the ion source temperature is 280°C; the quadrupole temperature is 280°C; and the solvent delay time is 5 min. The mass spectrometry parameters of each carbazole and halogenated carbazole compound are shown in Table 1.

[0063] Table 1 Mass spectrometric parameters of carbazole, D8-carbazole and nine halogenated carbazole compounds

[0064]

[0065] S7, Linearity and sensitivity, including,

[0066] An appropriate amount of mixed standard stock solution was taken, and the internal standard working solution was added, and the mixed series standard working solution of the required concentration was diluted step by step with acetonitrile, and the analysis and detection were performed under the instrument conditions of steps S5 and S6. The detection limit was calculated with a 3-fold signal-to-noise ratio (S / N), and the quantification limit was calculated with a 10-fold signal-to-noise ratio (S / N). The determination results are shown in Table 2.

[0067] As shown in Table 2, the linear range of carbazole and 9 halogenated carbazole compounds is 0.2-20.0μg / kg, and the detection limit and quantification limit are 0.10μg / kg and 0.20μg / kg, respectively, which shows that the detection method established in this study can meet the quantitative requirements.

[0068] Table 2 Linear range, detection limit and quantification limit of carbazole and nine halogenated carbazole compounds

[0069]

[0070] Embodiment 2:

[0071] Except for the change of the component of the surfactant in the sample pretreatment step S4, other conditions are the same as those in Example 1. In this example, the surfactant includes 0.1 g of silicon-based carboxylic acid sodium salt and 0.2 g of ferroferric oxide / cellulose magnetic nanocomposite material.

[0072] Embodiment 3:

[0073] Except for the change of the component of the surfactant in the sample pretreatment step S4, other conditions are the same as those in Example 1. In this example, the surfactant includes 0.3 g of silicon-based carboxylic acid sodium salt and 0.1 g of ferrosoferric oxide / cellulose magnetic nanocomposite material.

[0074] Embodiment 4:

[0075] Except for the change of the composition of the surfactant in the sample pretreatment step S4, other conditions are the same as those in Example 1. In this example, the surfactant includes 0.3 g of sodium silicon carboxylate.

[0076] Embodiment 5:

[0077] Except for the change of the composition of the surfactant in the sample pretreatment step S4, other conditions are the same as those in Example 1. In this example, the surfactant includes 0.1 g of sodium silicon carboxylate.

[0078] Embodiment 6:

[0079] Except for the change of the composition of the surfactant in the sample pretreatment step S4, other conditions are the same as those in Example 1. In this example, the surfactant includes 0.2 g of ferroferric oxide / cellulose magnetic nanocomposite material.

[0080] Embodiment 7:

[0081] Except for the change of the composition of the surfactant in the sample pretreatment step S4, other conditions are the same as those in Example 1. In this example, the surfactant includes 0.1 g of ferroferric oxide / cellulose magnetic nanocomposite material.

[0082] Comparative Example 1:

[0083] Except that no surfactant was added in the sample pretreatment step S4, other conditions were the same as those in Example 1.

[0084] Experimental example:

[0085] 1. Detection of carbazole and 9 halogenated carbazoles.

[0086] Carbazole and 9 halogenated carbazoles were detected according to the method of Comparative Example 1.

[0087] Figure 1 is the total ion current diagram of carbazole, D8-carbazole and 9 halogenated carbazoles, in which a is the ion peak of D8-carbazole and carbazole, b is the ion peak of 3-chlorocarbazole, c is the ion peak of 3-bromocarbazole, d is the ion peak of 3,6-dichlorocarbazole, e is the ion peak of 1,3,6,8-tetrachlorocarbazole, f is the ion peak of 1-bromo-3,6-dichlorocarbazole, g is the ion peak of 3,6-dibromocarbazole, h is the ion peak of 2,7-dibromocarbazole and 1,8-bromo-3,6-dichlorocarbazole, and i is the ion peak of 1,3,6,8-tetrabromocarbazole; Figure 2 The quantitative ion chromatogram and characteristic fragment mass spectrum of carbazole, with a retention time of 20.739 min and a mass-to-charge ratio ranging from 167.1 amu to 115.1 amu; Figure 3 The quantitative ion chromatogram and characteristic fragment mass spectrum of D8-carbazole, with a retention time of 20.703 min and a mass-to-charge ratio ranging from 175.1 amu to 122.1 amu; Figure 4 The quantitative ion chromatogram and characteristic fragment mass spectrum of 3-chlorocarbazole, the retention time is 23.533min, and the mass-to-charge ratio ranges from 201.0amu to 140.1amu; Figure 5 The quantitative ion chromatogram and characteristic fragment mass spectrum of 3-bromocarbazole, the retention time is 24.672min, and the mass-to-charge ratio ranges from 244.9amu to 139.1amu; Figure 6 The quantitative ion chromatogram and characteristic fragment mass spectrum of 3,6-dichlorocarbazole, the retention time is 26.031min, and the mass-to-charge ratio ranges from 234.9amu to 164.1amu; Figure 7 The quantitative ion chromatogram and characteristic fragment mass spectrum of 1,3,6,8-tetrachlorocarbazole, the retention time is 26.350min, the mass-to-charge ratio ranges from 304.8amu to 232.0amu; Figure 8 The quantitative ion chromatogram and characteristic fragment mass spectrum of 1-bromo-3,6-dichlorocarbazole, the retention time is 27.116min, and the mass-to-charge ratio ranges from 314.8amu to 164.0amu; Fig. 9 The quantitative ion chromatogram and characteristic fragment mass spectrum of 3,6-dibromocarbazole, the retention time is 28.070, and the mass-to-charge ratio ranges from 324.9amu to 165.1amu; Fig.10 The quantitative ion chromatogram and characteristic fragment mass spectrum of 2,7-dibromocarbazole, the retention time is 28.173min, and the mass-to-charge ratio ranges from 324.9amu to 165.1amu; Fig.11 The quantitative ion chromatogram and characteristic fragment mass spectrum of 1,8-bromo-3,6-dichlorocarbazole, the retention time is 28.182min, the mass-to-charge ratio ranges from 392.8amu to 198.1amu; Fig.12 The quantitative ion chromatogram and characteristic fragment mass spectrum of 1,3,6,8-tetrabromocarbazole are shown in Figure 1,3,6,8-tetrabromocarbazole. The retention time is 30.576 min, and the mass-to-charge ratio ranges from 482.7 amu to 322.9 amu. This shows that this method can accurately detect carbazole and nine halogenated carbazoles in sediments at the same time.

[0088] 2. Average recoveries and relative standard deviations of carbazole and nine halogenated carbazoles at different spike concentrations

[0089] Carbazole and 9 halogenated carbazoles were detected according to the method of Comparative Example 1. The spiked levels were 1 times, 3 times and 10 times the quantification limits of carbazole and 9 halogenated carbazoles, respectively. Six test solutions were prepared in parallel at each concentration level. The test results are shown in Table 3.

[0090] As shown in Table 3, the average recoveries of carbazole and 9 halogenated carbazole compounds detected in Comparative Example 1 were 85.67%-103.90%, and the relative standard deviations were 2.72%-8.17%. This indicates that the method is stable, reliable, has good accuracy and precision, and can meet the requirements for simultaneous detection of carbazole and 9 halogenated carbazole compounds in sediment samples.

[0091] Table 3 Average recoveries and relative standard deviations of carbazole and nine halogenated carbazoles in Comparative Example 1

[0092]

[0093] 3. Average recoveries and relative standard deviations of carbazole and nine halogenated carbazoles in different treatment groups

[0094] Carbazole was detected according to the methods of Examples 1-7 and Comparative Example 1, with a spike level of 0.20 µg / kg. Six groups of parallel test solutions were prepared, and the test results are shown in Tables 4-5.

[0095] Table 4 Average recovery rates of carbazole and nine halogenated carbazoles (%)

[0096]

[0097] Table 5 Relative standard deviations of carbazole and nine halogenated carbazoles (%)

[0098]

[0099] It can be seen from Tables 4 and 5 that the average recoveries and relative standard deviations of carbazole and nine halogenated carbazoles in Example 1 of the present invention are better than those in Comparative Example 1. This is because in Example 1 of the present invention, a surfactant is added to assist ultrasonic extraction in the pretreatment of the sediment sample, and the surfactant includes sodium silicon carboxylate and ferrosoferric oxide / cellulose magnetic nanocomposite materials, while in Comparative Example 1, no surfactant is added to assist ultrasonic extraction. This indicates that the method provided in Example 1 of the present invention can improve the average recoveries of carbazole and nine halogenated carbazoles, as well as the accuracy of their detection.

[0100] The average recoveries and relative standard deviations of carbazole and nine halogenated carbazoles in Example 1 of the present invention are better than those in Examples 2-3. This is because the amounts of silicon-based carboxylic acid sodium salt and ferrosoferric oxide / cellulose magnetic nanocomposites added in the pretreatment of sediment samples in Example 1 and Example 2-3 are different. This indicates that adding an appropriate amount of silicon-based carboxylic acid sodium salt and ferrosoferric oxide / cellulose magnetic nanocomposites can help improve the average recoveries of carbazole and nine halogenated carbazoles in sediments, as well as the accuracy of their detection.

[0101] The average recoveries and relative standard deviations of carbazole and nine halogenated carbazoles in Example 1 of the present invention are better than those in Examples 4-7. This is because in Example 1, sodium silicon carboxylate and ferroferric oxide / cellulose magnetic nanocomposites are used in conjunction with ultrasonic extraction in the pretreatment of sediment samples, while in Examples 4-5, only sodium silicon carboxylate is added to assist ultrasonic extraction in the pretreatment of sediment samples, and in Examples 6-7, only ferroferric oxide / cellulose magnetic nanocomposites are added to assist ultrasonic extraction in the pretreatment of sediment samples; the average recoveries and relative standard deviations of carbazole and nine halogenated carbazoles obtained in Examples 4-5 are better than those in Examples 6-7, which indicates that on the basis of using sodium silicon carboxylate as a surfactant to assist ultrasonic extraction, further adding ferroferric oxide / cellulose magnetic nanocomposites can improve the average recoveries of carbazole and nine halogenated carbazoles in sediments, as well as the accuracy of their detection.

[0102] The conventional operations in the operating steps of the present invention are well known to those skilled in the art and will not be described in detail here.

[0103] The embodiments described above provide a detailed description of the technical solutions of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, supplements or similar substitutions made within the scope of the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for determining carbazole and nine halogenated carbazoles in sediments by an internal standard method, comprising: The sediment, the internal standard solution, the extraction solvent, the metal salt and the surfactant are mixed and ultrasonically extracted to obtain an extract; A purification material is added to the extract and a test solution is obtained through purification treatment; carbazole and halogenated carbazole in the test solution are detected by gas chromatography-tandem mass spectrometry; The surfactant comprises a sodium salt of silicon-based carboxylic acid, and the sodium salt of silicon-based carboxylic acid contains sulfur elements and siloxy groups. In the preparation of the sodium salt of silicon-based carboxylic acid, vinyl-tris(trimethylsiloxy)silane is first mixed with thioglycolic acid, reacted under the initiation conditions of 2,2-dimethyl-phenylacetophenone, and then subjected to a salification reaction with anhydrous sodium carbonate to obtain the sodium salt of silicon-based carboxylic acid. The weight ratio of vinyl-tris(trimethylsiloxy)silane to thioglycolic acid is 3-4:1, the liquid-solid ratio of thioglycolic acid to tetrahydrofuran is 1g:2-10mL, the weight ratio of thioglycolic acid to 2,2-dimethyl-phenylacetophenone is 10-20:1, the ultraviolet light irradiation wavelength is 365nm, the irradiation time is 10-30min, and the weight ratio of vinyl-tris(trimethylsiloxy)silane to anhydrous sodium carbonate is 2-10:

1.

2. The method for determining carbazole and nine halogenated carbazoles in sediments by an internal standard method according to claim 1, characterized in that: The internal standard solution includes a D8-carbazole standard, and the mass concentration of the internal standard solution is 0.1-0.5 mg / mL; the extraction solvent includes n-hexane and acetone, and the volume ratio of n-hexane to acetone is 2-3:1; the metal salt includes anhydrous magnesium sulfate and sodium chloride, and the weight ratio of anhydrous magnesium sulfate to sodium chloride is 3-5:

1.

3. The method for determining carbazole and nine halogenated carbazoles in sediments by an internal standard method according to claim 1, characterized in that: The usage ratio of the sediment and the internal standard solution is 1 g: 2-5 μL.

4. The method for determining carbazole and nine halogenated carbazoles in sediments by an internal standard method according to claim 1, characterized in that: The liquid-to-solid ratio of the sediment to the extraction solvent is 1 g: 2-4 mL.

5. The method for determining carbazole and nine halogenated carbazoles in sediments by an internal standard method according to claim 1, characterized in that: The weight ratio of the sediment to the metal salt is 3-5:

1.

6. The method for determining carbazole and nine halogenated carbazoles in sediments by an internal standard method according to claim 1, characterized in that: The weight ratio of the metal salt to the surfactant is 2-15:

1.

7. The method for determining carbazole and nine halogenated carbazoles in sediments by an internal standard method according to claim 1, characterized in that: The ultrasonic extraction temperature is 20-60°C, and the ultrasonic extraction time is 10-30 minutes.

8. The method for determining carbazole and nine halogenated carbazoles in sediments by an internal standard method according to claim 1, characterized in that: The purification material comprises the following components in parts by mass: 30 parts of ethylenediamine-N-propylsilane, 70 parts of octadecylsilane bonded silica gel, 2 parts of graphitized carbon black and 50 parts of anhydrous magnesium sulfate.

9. The method for determining carbazole and nine halogenated carbazoles in sediments by an internal standard method according to claim 1, characterized in that: The weight ratio of the sediment to the purification material is 2-4:1.

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