A method for detecting organochlorine pesticides in water based on MOSS material solid phase microextraction

Abstract

The invention discloses a method for detecting organochlorine pesticides in water based on solid phase microextraction of MOSS materials, comprising the following steps: S1, preparing a liquid to be detected, S2, synthesizing MOSS, S3, extracting by coating SPME fiber with MOSS, and S4, detecting. The invention solves the problems of relatively low enrichment efficiency of commercial organochlorine pesticides (OCPs) and easy breakage and short service life of commercial needle matrices in solid phase microextraction by utilizing the characteristics of large specific surface area and high enrichment efficiency of MOSS materials. At the same time, the invention provides a detection method with advantages in repeatability, selectivity and sensitivity, thereby realizing efficient, rapid and accurate detection of trace OCPs in water.

Description

Technical Field

[0001] The invention relates to the technical field of pesticide detection, and in particular to a method for detecting organochlorine pesticides in water based on MOSS material solid phase microextraction. Background Art

[0002] Organochlorine pesticides (OCPs) are persistent organic pollutants with stable chemical properties, strong hydrophobicity, and are not easily degradable. Although their production and use have been banned since the 1970s, OCPs residues still exist in the environment and food such as soil, water, crops and vegetables, posing a huge threat to the environment and human health. OCPs enter the human body through the food chain and can cause cancer, endocrine disorders, DNA damage, liver and kidney problems, and other chronic diseases. In addition, their half-life is very long, ranging from a few years to more than ten years. Therefore, there is an urgent need for rapid, efficient and accurate analytical methods to detect OCPs so as to prevent, control and remove them. The most reported methods for detecting organochlorine pesticide residues are gas chromatography (GC), gas chromatography-mass spectrometry (GC-MS), high performance liquid chromatography (HPLC), liquid chromatography-mass spectrometry (LC-MS), etc., among which GC and GC-MS are more widely used.

[0003] The content of OCPs in water is low, and enrichment is necessary to reach the detection limit of the instrument. Therefore, pretreatment is a key step in pesticide residue detection, which directly affects the accuracy and precision of the test results. For the detection of organochlorine pesticides in water, the existing pretreatment methods include liquid-liquid extraction (LLE), solid phase extraction (SPE), Soxhlet extraction, microwave-assisted extraction (MAE), solid phase microextraction (SPME), etc., but they all have obvious disadvantages. Liquid-liquid extraction has poor selectivity, long extraction time, large amount of organic solvent, and easy to cause secondary pollution. Solid phase extraction uses less solvent, but the operation steps are complicated, the repeatability is poor, the stationary phase is easy to clog, and the enrichment efficiency of polluting components is limited. Soxhlet extraction takes a long time to extract and consumes a lot of solvent. Microwave-assisted extraction can only select polar solvents that can absorb microwaves, which is difficult to achieve direct coupling with chromatographic analysis instruments, and other interfering pollutants will be extracted at the same time. The commercial needles used in the solid phase microextraction method have low extraction efficiency, resulting in low sensitivity of the method, inability to detect actual samples in the environment, short service life (40-100 times), and high price (about 800 yuan / piece).

[0004] In contrast, SPME is a solvent-free green technology with high extraction efficiency, easy operation, and direct coupling to instruments, so it has become a widely used sample preparation method. The extraction efficiency of SPME coatings is directly related to the measurement sensitivity, so the selection of appropriate SPME coatings plays an important role in achieving efficient extraction and sensitive determination, but currently only limited commercial SPME fiber coatings are available. Therefore, the development of new SPME coating materials with high extraction efficiency is a hot topic of research to achieve the required measurement sensitivity of target analytes. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a method for detecting organochlorine pesticides in water based on MOSS material solid phase microextraction.

[0006] The technical solution of the present invention is: a method for detecting organochlorine pesticides in water based on MOSS material solid phase microextraction, comprising the following steps:

[0007] S1. Prepare the test solution:

[0008] With the ratio of OCPs mixed standard solution to deionized water being 6 μL:30 mL, add OCPs mixed standard solution with a concentration of 500 ppb into deionized water to obtain a water sample with an OCPs mixed standard solution concentration of 100 ppt;

[0009] S2. Synthetic MOSS:

[0010] S2-1, zirconium chloride, [1,1':3',1"-terphenyl]-4,4"-dicarboxylic acid, and acetic acid are sequentially added to N,N-dimethylformamide at a ratio of zirconium chloride: [1,1':3',1"-terphenyl]-4,4"-dicarboxylic acid: acetic acid: N,N-dimethylformamide of 10 mg: 60 mg: 120 μL: 2 mL to form a mixture, the mixture is sealed and heated at 100° C. for 1 h, and then cooled to room temperature;

[0011] S2-2, adding 1,3,6,8-tetrakis[p-benzoic acid]pyrene, acetic acid and deionized water to the mixture obtained in step S2-1 at a ratio of 10 mg: 160 μL: 20 μL of 1,3,6,8-tetrakis[p-benzoic acid]pyrene: acetic acid: deionized water to form a prepared solution; wherein the mass of the added 1,3,6,8-tetrakis[p-benzoic acid]pyrene is the same as the mass of the zirconium chloride in step S2-1;

[0012] S2-3, the solution obtained in step S2-2 is sealed and heated at 120°C for 24 hours; then centrifuged at 8000 r / min for 5 minutes, the yellow product is collected, and the yellow product is washed with N,N-dimethylformamide and acetone for 3 times respectively, and then dried at 80°C under vacuum conditions for 10 to 12 hours to obtain MOSS powder;

[0013] S3. Extraction using MOSS coated SPME fiber:

[0014] The MOSS powder obtained in step S2-3 is coated on the SPME fiber to obtain a MOSS-coated SPME fiber, and then the MOSS-coated SPME fiber is placed in the water sample obtained in step S1 for extraction for 40 minutes at a temperature of 40° C. and a rotation speed of 1200 r / min;

[0015] S4. Detection:

[0016] The SPME fiber coated with MOSS after extraction in step S3 was placed in a gas phase injection port for desorption at 260° C. for 3 min, and the desorbed gas was detected by GC-ECD.

[0017] Description: Through the above method, [1,1':3',1"-terphenyl]-4,4"-dicarboxylic acid ligand is used as the key to the formation of MOSS. The distance between the two carboxylic acid groups of [1,1':3',1"-terphenyl]-4,4"-dicarboxylic acid ligand is slightly larger than the distance between the two carboxylic acids in 1,3,6,8-tetra[p-benzoic acid]pyrene ligand. By mixing the zirconium chloride metal source and these two ligands, the obtained MOSS coating has a uniform pore size distribution, a well-adjusted ratio of mesopores to micropores, and thus has the advantages of high separation ability and unique separation selectivity.

[0018] Furthermore, in step S1, the OCPs mixed standard solution with a concentration of 500 ppb is obtained by diluting a 1000 mg / L organochlorine pesticide mixed standard solution produced by Shanghai Anpu Laboratory Technology Co., Ltd. using toluene as solvent.

[0019] Note: By using the above OCPs mixed standard solution, the six organochlorine pesticides of α-HCH, β-HCH, γ-HCH, δ-HCH, 4,4'-DDE, and 4,4'-DDD in water can be objectively simulated.

[0020] Furthermore, in step S2, N,N-dimethylformamide is subjected to molecular sieve to remove water.

[0021] Note: By removing water with N,N-dimethylformyl, the solvent purity can be higher, the reaction is not affected by other substances, and the synthesis effect of MOSS is better.

[0022] Further, the method of coating the MOSS powder on the SPME fiber in step S3 is:

[0023] S3-1, take the steel wire and place it in an ultrasonic cleaning container, add hydrochloric acid that covers the steel wire into the ultrasonic cleaning container, ultrasonically treat it at 40KHz for 30 to 60 minutes, take out the steel wire and rinse it with deionized water; put the rinsed steel wire into a clean ultrasonic cleaning container, add methanol that covers the steel wire into the ultrasonic cleaning container, and ultrasonically treat it at 40KHz for 8 to 10 minutes, take out the steel wire and place it in a clean ultrasonic cleaning container, add deionized water that covers the steel wire into the ultrasonic cleaning container, and ultrasonically treat it at 40KHz for 5 to 8 minutes to obtain the treated steel wire;

[0024] S3-2, dissolving silicone glue in toluene at a ratio of 0.6 g:1 mL of silicone glue:toluene to obtain a diluted silicone glue liquid, inserting the treated steel wire obtained in S3-1 into the diluted silicone glue liquid for 1 to 2 seconds, and then quickly withdrawing the steel wire, repeating the process several times until a uniform silicone glue layer is formed on the surface of the steel wire;

[0025] S3-3, using filter paper to absorb excess solution on the surface of the silicone adhesive layer, rotating the steel wire with the silicone adhesive layer in the MOSS powder obtained in step S2 until the MOSS powder is evenly coated on the surface of the steel wire, thereby obtaining a loaded steel wire;

[0026] S3-4. The loaded steel wire obtained in S3-3 is dried at 110-120° C. for 40-60 min, and aged at 260-280° C. to obtain a MOSS-coated SPME fiber.

[0027] Description: By using steel wire as the fiber matrix, the cost is low and it is not easy to break. Silicone glue has strong adhesion and high tensile strength. It is also weather-resistant, vibration-resistant, moisture-proof, odor-resistant and adaptable to large changes in temperature. Using silicone glue as the sol solution can make the MOSS powder uniformly and firmly bonded to the steel wire, thereby obtaining an SPME fiber with a better MOSS coating effect.

[0028] Furthermore, in step S3, the steel wire is 304 stainless steel wire, and its length and diameter are 10 cm and 0.15 mm respectively.

[0029] Description: 304 stainless steel wire is used, which has good processing performance and high toughness.

[0030] Further, in step S3-2, the step of dissolving the silicone gel in toluene to obtain a diluted silicone gel liquid is as follows: weigh the silicone gel and add it to a test tube, add toluene to the test tube, oscillate with a vortexer for 3 minutes until the silicone gel is dispersed in the toluene, and then place the test tube in an ultrasonic generator at 2.3 to 2.5 W / cm 2The silicone glue and toluene in the test tube were ultrasonically dissolved at a power of 10 minutes until the silicone glue was evenly dissolved in the toluene.

[0031] Note: Through the above method, the distribution of silicone glue can be made more uniform, the dispersibility in the solvent toluene can be improved, and the uniformity of the glue layer generated on the steel wire can be improved.

[0032] Furthermore, the aging treatment method in step S3-4 is: after drying, the load steel wire is subjected to hot and cold cycle aging, firstly irradiated with primary ultraviolet light, and cooled at a rate of 10°C / min. When the temperature drops to 20-30°C, the secondary ultraviolet light irradiation is turned on, and the temperature is increased to 260-280°C at a rate of 10°C / min. The primary ultraviolet light irradiation and cooling are repeated three times; wherein the wavelength of the primary ultraviolet light is 354nm, and the wavelength of the secondary ultraviolet light is 265nm.

[0033] Note: Through the above treatment of the loaded steel wire, the surface of the loaded steel wire can be aged and activated, making the coating surface uniform and rough, which is beneficial to increase its specific surface area, improve adsorption efficiency, increase the contact area between the target analyte and the coating, and thus enhance the enrichment effect of the MOSS coated SPME fiber.

[0034] Further, in step S4, the detection conditions of the GC-ECD detection are: maintaining the gas chromatography column temperature at 60°C for 1 min; heating to 180°C at a rate of 20°C / min and maintaining for 2 min; heating to 220°C at a rate of 10°C / min and maintaining for 2 min; heating to 240°C at a rate of 2°C / min; heating to 280°C at a rate of 30°C / min and maintaining for 1 min, and the detector temperature is 300°C.

[0035] Note: The above method can be used for detection, which can not only separate the extracted substances completely, but also make the peak shape normal, the number of peaks unchanged, and can be repeated, so that the detection data is more accurate.

[0036] The beneficial effects of the present invention are:

[0037] (1) The present invention solves the problems of relatively low commercial enrichment efficiency for organochlorine pesticides in solid phase microextraction and easy breakage and short service life of commercial needle substrates by utilizing the large specific surface area and high enrichment efficiency of MOSS materials and the characteristics of steel wire.

[0038] (2) The present invention uses zirconium chloride as a metal source and N,N-dimethylformamide as a solvent. By using [1,1':3',1"-terphenyl]-4,4"-dicarboxylic acid and 1,3,6,8-tetrakis[p-benzoic acid]pyrene ligands, the pore size distribution of the MOSS coating is uniform, the ratio of mesopores to micropores is well adjusted, and thus the MOSS coating has the advantages of high separation ability and unique separation selectivity.

[0039] (3) The present invention uses silicone gel as the sol solution to make the MOSS powder uniformly and firmly bonded to the steel wire, and through aging treatment, obtains an SPME fiber with uniform MOSS coating effect and good adsorption and enrichment effects; and uses stainless steel wire as the fiber matrix, which is low in cost and not easy to be broken.

[0040] (4) The present invention integrates extraction, concentration, desorption and injection by adopting solid phase microextraction, which greatly simplifies the sample pretreatment process and can be directly coupled with a chromatographic analyzer; at the same time, the present invention provides a detection method with advantages in repeatability, selectivity and sensitivity, and realizes efficient, rapid and accurate detection of trace OCPs in water. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 is a 400 μm micrograph of the steel wire after hydrochloric acid ultrasonic treatment in Example 1 of the present invention;

[0042] Figure 2 is a 200 μm micrograph of the MOSS-coated SPME fiber in Example 1 of the present invention;

[0043] Figure 3 is a 30 μm micrograph of the MOSS-coated SPME fiber in Example 1 of the present invention;

[0044] Figure 4 is a 5 μm micrograph of the MOSS-coated SPME fiber in Example 1 of the present invention;

[0045] Figure 5 This is a GC-ECD test result diagram of six OCPs organochlorine pesticides (α-HCH, β-HCH, γ-HCH, δ-HCH, 4,4'-DDE, 4,4'-DDD) in Example 1 of the present invention;

[0046] Figure 6 It is a comparison chart of the extraction effects of MOSS and PDMS / DVB in the experimental examples of the present invention;

[0047] Figure 7 This is the pore distribution diagram in Example 1 of the present invention. DETAILED DESCRIPTION

[0048] The present invention is further described in detail below in conjunction with specific implementation methods to better reflect the advantages of the present invention.

[0049] Embodiment 1:

[0050] A method for detecting organochlorine pesticides in water based on MOSS material solid phase microextraction comprises the following steps:

[0051] S1. Prepare the test solution:

[0052] Take 6 μL of a 500 ppb OCPs mixed standard solution and add it to 30 mL of deionized water to obtain a water sample with an OCPs mixed standard solution concentration of 100 ppt; the 500 ppb OCPs mixed standard solution is obtained by diluting a 1000 mg / L organochlorine pesticide mixed standard solution produced by Shanghai Anpu Experimental Technology Co., Ltd. with toluene as solvent.

[0053] S2. Synthetic MOSS:

[0054] S2-1, 10 mg of zirconium chloride, 60 mg of [1,1':3',1"-terphenyl]-4,4"-dicarboxylic acid and 120 μL of acetic acid were added to 2 mL of N,N-dimethylformamide in sequence to form a mixture, the mixture was sealed and heated at 100°C for 1 hour and then cooled to room temperature; wherein the N,N-dimethylformamide was passed through a 5a molecular sieve to remove water;

[0055] S2-2, adding 10 mg of 1,3,6,8-tetrakis[p-benzoyl]pyrene, 160 μL of acetic acid and 20 μL of deionized water to the mixture obtained in S2-1 to form a solution;

[0056] S2-3, the solution obtained in step S2-2 was sealed and heated at 120°C for 24h; then centrifuged at 8000r / min for 5min, the yellow product was collected, and the yellow product was washed with N,N-dimethylformamide and acetone for 3 times respectively, and then dried at 80°C under vacuum for 11h to obtain MOSS powder;

[0057] S3. Extraction using MOSS coated SPME fiber:

[0058] The MOSS powder obtained in step S2-3 is coated on the SPME fiber to obtain a MOSS-coated SPME fiber, and then the MOSS-coated SPME fiber is placed in the water sample obtained in step S1 for extraction for 40 minutes at a temperature of 40° C. and a rotation speed of 1200 r / min;

[0059] MOSS powder is coated on the SPME fiber as:

[0060] S3-1. Place the steel wire in an ultrasonic cleaning container, add hydrochloric acid to the ultrasonic cleaning container to cover the steel wire, and perform ultrasonic treatment at 40 KHz for 40 minutes. Take out the steel wire and rinse it with deionized water. Figure 1; Place the rinsed steel wire in a clean ultrasonic cleaning container, add methanol that does not cover the steel wire into the ultrasonic cleaning container, and perform ultrasonic treatment at 40KHz for 8 minutes; take out the steel wire and place it in a clean ultrasonic cleaning container, add deionized water that does not cover the steel wire into the ultrasonic cleaning container, and perform ultrasonic treatment at 40KHz for 6 minutes to obtain the treated steel wire; the steel wire is 304 stainless steel wire, and its length and diameter are 10cm and 0.15mm respectively;

[0061] S3-2, dissolving 0.6 g of silicone glue in 1 mL of toluene to obtain a diluted silicone glue liquid, inserting the treated steel wire obtained in S3-1 into the diluted silicone glue liquid for 1 to 2 seconds, and then quickly withdrawing the steel wire, repeating three times until a uniform silicone glue layer is formed on the surface of the steel wire; the steps of dissolving silicone glue in toluene to obtain a diluted silicone glue liquid are as follows: weighing silicone glue and adding it to a test tube, adding toluene to the test tube, oscillating with a vortex instrument for 3 minutes until the silicone glue is dispersed in the toluene, and then placing the test tube in an ultrasonic generator at 2.4 W / cm 2 The silicone glue and toluene in the test tube were ultrasonically dissolved at a power of 10 minutes until the silicone glue was uniformly dissolved in toluene;

[0062] S3-3, using filter paper to absorb excess solution on the surface of the silicone adhesive layer, rotating the steel wire with the silicone adhesive layer in the MOSS powder obtained in step S2 until the MOSS powder is evenly coated on the surface of the steel wire, thereby obtaining a loaded steel wire;

[0063] S3-4, drying the loaded steel wire obtained in S3-3 at 115°C for 50 min, and aging the loaded steel wire at 270°C to obtain a MOSS-coated SPME fiber; the aging method is as follows: after drying, the loaded steel wire is subjected to hot and cold cycle aging, firstly irradiated with primary ultraviolet light, and cooled at a rate of 10°C / min, when cooled to 25°C, secondary ultraviolet light is turned on, and the temperature is raised to 270°C at a rate of 10°C / min, and primary ultraviolet light irradiation and cooling are repeated three times; wherein the wavelength of the primary ultraviolet light is 354nm, and the wavelength of the secondary ultraviolet light is 265nm;

[0064] S4. Detection:

[0065] The MOSS-coated SPME fiber extracted in step S3 is placed in a gas phase injection port at 260°C for desorption for 3 minutes, and the desorbed gas is detected by GC-ECD; the detection conditions of the GC-ECD detection are: the gas chromatography column is kept at 60°C for 1 minute; the temperature is increased to 180°C at a rate of 20°C / min and maintained for 2 minutes; the temperature is increased to 220°C at a rate of 10°C / min and maintained for 2 minutes; the temperature is increased to 240°C at a rate of 2°C / min; the temperature is increased to 280°C at a rate of 30°C / min and maintained for 1 minute, and the detector temperature is 300°C.

[0066] Example 2

[0067] The present embodiment is different from the embodiment 1 in that the drying time in step S2-3 is different, and the MOSS powder is obtained by drying at 80° C. under vacuum conditions for 10 hours.

[0068] Example 3

[0069] The present embodiment is different from the embodiment 1 in that the drying time in step S2-3 is different, and the MOSS powder is obtained by drying at 80° C. under vacuum conditions for 12 hours.

[0070] Example 4

[0071] The difference between this embodiment and embodiment 1 is that the ultrasonic treatment time in step S3-1 is different, the steel wire is placed in an ultrasonic cleaning container, hydrochloric acid is added to the ultrasonic cleaning container to cover the steel wire, and ultrasonic treatment is performed at 40KHz for 30 minutes, the steel wire is taken out and rinsed with deionized water; the rinsed steel wire is placed in a clean ultrasonic cleaning container, methanol is added to the ultrasonic cleaning container to cover the steel wire, and ultrasonic treatment is performed at 40KHz for 10 minutes, the steel wire is taken out and placed in a clean ultrasonic cleaning container, deionized water is added to the ultrasonic cleaning container to cover the steel wire, and ultrasonic treatment is performed at 40KHz for 8 minutes to obtain the treated steel wire.

[0072] Example 5

[0073] The difference between this embodiment and embodiment 1 is that the ultrasonic treatment time in step S3-1 is different, the steel wire is placed in an ultrasonic cleaning container, hydrochloric acid is added to the ultrasonic cleaning container to cover the steel wire, and ultrasonic treatment is performed at 40KHz for 60 minutes, the steel wire is taken out and rinsed with deionized water; the rinsed steel wire is placed in a clean ultrasonic cleaning container, methanol is added to the ultrasonic cleaning container to cover the steel wire, and ultrasonic treatment is performed at 40KHz for 8 minutes, the steel wire is taken out and placed in a clean ultrasonic cleaning container, deionized water is added to the ultrasonic cleaning container to cover the steel wire, and ultrasonic treatment is performed at 40KHz for 5 minutes to obtain the treated steel wire.

[0074] Example 6

[0075] The difference between this embodiment and embodiment 1 is that the dissolution power in step S3-2 is different, and the dissolution power is 2.3 W / cm 2 The silicone glue and toluene in the test tube were ultrasonically dissolved at a power of.

[0076] Example 7

[0077] The difference between this embodiment and embodiment 1 is that the dissolution power in step S3-2 is different, and the dissolution power is 2.5 W / cm 2The silicone glue and toluene in the test tube were ultrasonically dissolved at a power of.

[0078] Example 8

[0079] The difference between this embodiment and embodiment 1 is that the aging treatment parameters of step S3-4 are different. The loaded steel wire obtained in S3-3 is dried at 110°C for 60 minutes and aged at 260°C to obtain a MOSS-coated SPME fiber. The aging treatment method is as follows: after drying, the loaded steel wire is subjected to hot and cold cycle aging. First, it is irradiated with primary ultraviolet light and cooled at a rate of 10°C / min. When the temperature drops to 30°C, the secondary ultraviolet light is turned on, and the temperature is increased to 260°C at a rate of 10°C / min. The primary ultraviolet light irradiation and cooling are repeated three times.

[0080] Example 9

[0081] The difference between this embodiment and embodiment 1 is that the aging treatment parameters of step S3-4 are different. The loaded steel wire obtained in S3-3 is dried at 120°C for 40 minutes and aged at 280°C to obtain a MOSS-coated SPME fiber. The aging treatment method is as follows: after drying, the loaded steel wire is subjected to hot and cold cycle aging. First, it is irradiated with primary ultraviolet light and cooled at a rate of 10°C / min. When the temperature drops to 20°C, the secondary ultraviolet light is turned on, and the temperature is increased to 280°C at a rate of 10°C / min. The primary ultraviolet light irradiation and cooling are repeated three times.

[0082] Experimental example

[0083] 1. Comparison of the extraction effects of MOSS coated SPME fiber and PDMS / DVB:

[0084] Comparative Example 1: A commercially available PDMS / DVB solid phase microextraction fiber was used to perform the test in step S4 of Example 1 to obtain the extraction efficiency of each organochlorine pesticide;

[0085] Using Example 1 and Comparative Example 1, the extraction effects of MOSS-coated SPME fiber and PDMS / DVB were compared. Figure 6 As shown in FIG. 1 , it can be seen that the detection values ​​of various organochlorine pesticides extracted by MOSS coated SPME fiber in Example 1 are higher than those of commercial needles, which proves that it has good enrichment effect and higher detection sensitivity; the pore distribution of MOSS in Example 1 is as shown in FIG. Figure 7 , graded pore distribution, including both micropores and mesopores.

[0086] 2. Using the MOSS coated SPME fibers prepared in Examples 1 to 9, the low-temperature nitrogen isothermal adsorption performance of each material was tested for its specific surface area. The results are as follows:

[0087] 1) Investigate the effect of MOSS powder under drying time on the specific surface area of ​​the prepared MOSS coated SPME fiber; compare Example 1, Example 2, and Example 3 for investigation;

[0088] Table 1 Specific surface area of ​​MOSS coated SPME fiber at different drying times

[0089] parameter <![CDATA[Specific surface area (m 2 / g)]]> Example 1 1349 Example 2 1319 Example 3 1335

[0090] As can be seen from Table 1, by comparing Examples 1 to 3, it is proved that treating MOSS powder at different drying times does have an effect on the specific surface area of ​​the prepared MOSS coated SPME fiber, and the parameters of Example 1 are better.

[0091] 2) To explore the effect of different ultrasonic treatment times on the specific surface area of ​​the prepared MOSS-coated SPME fiber; to compare Example 1, Example 4 and Example 5;

[0092] Table 2 Specific surface area of ​​MOSS-coated SPME fibers at different ultrasonic treatment times

[0093]

[0094]

[0095] As can be seen from Table 2, by comparing Example 1, Example 4 and Example 5, it is proved that cleaning the steel wire surface at different ultrasonic treatment times has an effect on the specific surface area of ​​the prepared MOSS coated SPME fiber, and the parameters of Example 1 are better.

[0096] 3) Explore the effect of different ultrasonic power dissolution on the specific surface area of ​​the prepared MOSS-coated SPME fiber; compare Example 1, Example 6 and Example 7;

[0097] Table 3 Specific surface area of ​​MOSS coated SPME fiber under different ultrasonic powers

[0098] parameter <![CDATA[Specific surface area (m 2 / g)]]> Example 1 1349 Example 6 1306 Example 7 1310

[0099] As can be seen from Table 3, by comparing Example 1, Example 6 and Example 7, it is proved that the dissolution of silicone glue and toluene under different ultrasonic powers has an effect on the specific surface area of ​​the prepared MOSS coated SPME fiber, and the parameters of Example 1 are better.

[0100] 4) To explore the effects of different drying and aging treatment parameters on the specific surface area of ​​the prepared MOSS-coated SPME fiber;

[0101] Comparative Example 2: The difference from Example 1 is that the aging treatment is drying at 270°C for 60 minutes;

[0102] Comparative Example 3: The difference from Example 1 is that the aging treatment is to irradiate with primary ultraviolet light and secondary ultraviolet light at 270°C for 30 minutes respectively.

[0103] Comparative Example 1, Example 8 and Example 9, Comparative Example 2 and Comparative Example 3;

[0104] Table 4 Specific surface area of ​​MOSS coated SPME fiber under different drying and aging treatment parameters

[0105] parameter <![CDATA[Specific surface area (m 2 / g)]]> Example 1 1349 Example 8 1301 Example 9 1298 Comparative Example 2 1107 Comparative Example 3 1098

[0106] As can be seen from Table 4, by comparing Example 1, Example 8 and Example 9, it is proved that different drying and aging treatments of MOSS coated SPME fiber have an effect on its specific surface area, and the parameters of Example 1 are better; by comparing Example 1, Comparative Example 2 and Comparative Example 3, it can be seen that different aging methods have a greater effect on the specific surface area of ​​MOSS coated SPME fiber, among which the treatment method of Example 1 is better, and the increase in specific surface area proves that the contact area between the coating and the analyte is larger, which is beneficial to increase its extraction capacity on the coating and improve the extraction effect.

Claims

1. A method for detecting organochlorine pesticides in water based on MOSS material solid phase microextraction. It is characterized in that The following steps are involved: S1. Prepare the test solution: With the ratio of OCPs mixed standard solution to deionized water being 6 μL:30 mL, add OCPs mixed standard solution with a concentration of 500 ppb into deionized water to obtain a water sample with an OCPs mixed standard solution concentration of 100 ppt; S2. Synthetic MOSS: S2-1, zirconium chloride, [1,1':3',1"-terphenyl]-4,4"-dicarboxylic acid, and acetic acid are sequentially added to N,N-dimethylformamide at a ratio of zirconium chloride: [1,1':3',1"-terphenyl]-4,4"-dicarboxylic acid: acetic acid: N,N-dimethylformamide of 10 mg: 60 mg: 120 μL: 2 mL to form a mixture, the mixture is sealed and heated at 100° C. for 1 h, and then cooled to room temperature; S2-2, adding 1,3,6,8-tetrakis[p-benzoic acid]pyrene, acetic acid and deionized water to the mixture obtained in step S2-1 at a ratio of 10 mg: 160 μL: 20 μL of 1,3,6,8-tetrakis[p-benzoic acid]pyrene: acetic acid: deionized water to form a prepared solution; wherein the mass of the added 1,3,6,8-tetrakis[p-benzoic acid]pyrene is the same as the mass of the zirconium chloride in step S2-1; S2-3, the prepared solution obtained in step S2-2 is sealed and heated at 120°C for 24 hours; then centrifuged at 8000 r / min for 5 minutes, the yellow product is collected, and the yellow product is washed with N,N-dimethylformamide and acetone for 3 times respectively, and then dried at 80°C under vacuum conditions for 10 to 12 hours to obtain MOSS powder; S3. Extraction using MOSS coated SPME fiber: The MOSS powder obtained in step S2-3 is coated on the SPME fiber to obtain a MOSS-coated SPME fiber, and then the MOSS-coated SPME fiber is placed in the water sample obtained in step S1 for extraction for 40 minutes at a temperature of 40° C. and a rotation speed of 1200 r / min; The preparation method of coating MOSS on SPME fiber is as follows: S3-1, taking a steel wire and placing it in an ultrasonic cleaning container, adding hydrochloric acid that covers the steel wire into the ultrasonic cleaning container, ultrasonically treating it at 40KHz for 30 to 60 minutes, taking out the steel wire and rinsing it with deionized water; placing the rinsed steel wire in a clean ultrasonic cleaning container, adding methanol that covers the steel wire into the ultrasonic cleaning container, ultrasonically treating it at 40KHz for 8 to 10 minutes, taking out the steel wire and placing it in a clean ultrasonic cleaning container, adding deionized water that covers the steel wire into the ultrasonic cleaning container, and ultrasonically treating it at 40KHz for 5 to 8 minutes to obtain a treated steel wire; S3-2, dissolving silicone glue in toluene at a ratio of 0.6 g:1 mL of silicone glue:toluene to obtain a diluted silicone glue liquid, inserting the treated steel wire obtained in S3-1 into the diluted silicone glue liquid for 1 to 2 seconds, and then quickly withdrawing the steel wire, repeating the process several times until a uniform silicone glue layer is formed on the surface of the steel wire; S3-3, using filter paper to absorb excess solution on the surface of the silicone adhesive layer, rotating the steel wire with the silicone adhesive layer obtained in step S3-2 in the MOSS powder obtained in step S2 until the MOSS powder is evenly coated on the surface of the steel wire, thereby obtaining a loaded steel wire; S3-4, drying the loaded steel wire obtained in S3-3 at 110-120° C. for 40-60 min, and aging the steel wire at 260-280° C. to obtain a MOSS-coated SPME fiber; S4. Detection: The MOSS-coated SPME fiber extracted in step S3 was placed in a gas phase injection port at 260°C for desorption for 3 minutes, and the desorbed gas was detected by GC-ECD. The detection conditions of the GC-ECD detection were as follows: the gas chromatography column temperature was maintained at 60°C for 1 minute; the temperature was increased to 180°C at a rate of 20°C / min and maintained for 2 minutes; the temperature was increased to 220°C at a rate of 10°C / min and maintained for 2 minutes; the temperature was increased to 240°C at a rate of 2°C / min; the temperature was increased to 280°C at a rate of 30°C / min and maintained for 1 minute, and the detector temperature was 300°C.

2. A method for detecting organochlorine pesticides in water based on MOSS material solid phase microextraction as claimed in claim 1, It is characterized in that In step S1, the OCPs mixed standard solution with a concentration of 500 ppb is obtained by diluting a 1000 mg / L organochlorine pesticide mixed standard solution using toluene as a solvent.

3. A method for detecting organochlorine pesticides in water based on MOSS material solid phase microextraction as claimed in claim 1, It is characterized in that In step S2, N,N-dimethylformamide is subjected to molecular sieve to remove water.

4. A method for detecting organochlorine pesticides in water based on MOSS material solid phase microextraction as claimed in claim 1, It is characterized in that In step S3, the steel wire is 304 stainless steel wire, and its length and diameter are 10 cm and 0.15 mm respectively.

5. A method for detecting organochlorine pesticides in water based on MOSS material solid phase microextraction as claimed in claim 1, It is characterized in that In step S3-2, the step of dissolving the silicone glue in toluene to obtain a diluted silicone glue liquid is as follows: weigh the silicone glue and add it into a test tube, add toluene to the test tube, vortex for 3 minutes until the silicone glue is dispersed in the toluene, and then place the test tube in an ultrasonic generator at 2.3 to 2.5 W / cm 2 The silicone glue and toluene in the test tube were ultrasonically dissolved at a power of 10 minutes until the silicone glue was evenly dissolved in the toluene.

6. A method for detecting organochlorine pesticides in water based on MOSS material solid phase microextraction as claimed in claim 1, It is characterized in that The aging treatment method in step S3-4 is: after drying, the load steel wire is subjected to hot and cold cycle aging, firstly, it is irradiated with primary ultraviolet light and cooled at a rate of 10°C / min. When the temperature drops to 20-30°C, the secondary ultraviolet light is turned on and the temperature is increased to 260-280°C at a rate of 10°C / min. The primary ultraviolet light irradiation and cooling are repeated three times; wherein, the wavelength of the primary ultraviolet light is 354nm, and the wavelength of the secondary ultraviolet light is 265nm.

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