Method for rapidly and accurately determining content of organochlorine pesticide in water

Abstract

The invention discloses a method for rapidly and accurately determining the content of organochlorine pesticides in water, and belongs to the field of organochlorine pesticide content determination, and the method comprises the following steps: adding a regulator into a water sample, uniformly shaking, adding a substitute, and uniformly shaking again; adding sodium chloride into the water sample treated in the step S1, putting the water sample into a liquid-liquid extraction oscillator, and oscillating until the water sample is completely dissolved; s2, adding an extracting agent into the water sample treated in the step S2, vigorously oscillating, standing for layering, putting the lower-layer water sample into a reagent bottle, transferring an upper-layer extracting solution into a drying column, washing and dehydrating, and then transferring into a concentration bottle; the step S3 is executed again on the remaining water sample in the step S3; and S4, combining the eluents in the steps S3 and S4, transferring into a full-automatic nitrogen blowing instrument, concentrating to 1ml, adding an internal standard solution, and performing gas chromatography-mass spectrometer analysis after volume metering to obtain the content of the organochlorine pesticide in the water sample. The method has the beneficial effects that the method has the advantages of high efficiency, rapidness and accurate detection, and the method is simple to operate, low in cost and high in concentration efficiency and recovery stability.

Description

Technical Field

[0001] The invention relates to the technical field of determination of organochlorine pesticide content in water, in particular to a method for rapidly and accurately determining the organochlorine pesticide content in water. Background Art

[0002] Organochlorine pesticides (OCPs) include alpha-BHC, beta-BHC, C-BHC and D-BHC. Most organochlorine pesticides are white or light yellow crystals or solids, insoluble or slightly soluble in water, easily soluble in fat and most organic solvents, with low volatility, stable chemical properties, high affinity with enzymes and proteins, and strong enrichment in organisms. Organochlorine pesticides are environmental pollutants that play a significant role in preventing diseases and insect pests. They are widely present in the environment and are a type of difficult to degrade organic pollutants (POPS).

[0003] Although my country and most countries in the world have stopped producing and using highly toxic OCPs, their long-term and large-scale use means that OCPs will still be transformed and remain in the environment for a long time. The toxicity and residues of organochlorine pesticides are extremely harmful to the ecosystem and human health. In the analysis of environmental samples, the content of hexachlorocyclohexane is relatively low. Therefore, the pretreatment method is an important step in the entire analysis process, which affects the accuracy and reliability of the measurement results. At present, the common pretreatment methods for organochlorine pesticides in water samples include liquid-liquid extraction, solid phase extraction, solid phase microextraction, etc. The liquid-liquid extraction pretreatment method has the advantages of short time consumption (6 samples per batch, 2.5 hours per batch), high enrichment efficiency, and high target recovery rate (more than 95%), which is particularly suitable for the analysis of multiple residual components in large batches of samples; the solid phase extraction pretreatment method has the disadvantages of long extraction time (6 samples per batch, 4 hours per batch), large analyte loss, and low recovery rate (the recovery rate of tetrachlorometa-xylene is only 30%, and the recovery rate of the target is about 80%); the solid phase microextraction pretreatment method still has the disadvantages of poor organic droplet stability, bubble generation, and reproducibility in actual application. The concentration methods include traditional inert gas slow drying, rotary evaporation, high-throughput vacuum parallel concentration, etc. Among them, rotary evaporation and inert gas slow drying are very convenient for small samples or small solvent amounts. When a large number of samples need to be concentrated at the same time and the amount of solvent is large, it is time-consuming (it takes 1 hour to concentrate 10ml of n-hexane to about 1ml), laborious (it needs to be watched to prevent drying), and the open nitrogen blowing device is extremely harmful to the health of the operator; high-throughput vacuum parallel concentration is greatly affected by the water bath temperature, rotation speed, vacuum degree, and solvent type. It can be seen from the above that the existing determination methods have the disadvantages of long processing time and low target recovery rate. Summary of the invention

[0004] The purpose of the present invention is to provide a method for quickly and accurately determining the content of organochlorine pesticides in water, which has the advantages of rapid, efficient and accurate determination, and effectively solves the current problems of low recovery rate and long detection time in the detection and analysis of such substances, thereby providing technical support for "precision pollution control".

[0005] The purpose of the present invention is achieved through the following technical solutions: A method for rapidly and accurately determining the content of organochlorine pesticides in water comprises the following processing steps: S1. Add the regulator to the water sample and shake well, then add the substitute and shake well again; S2, adding sodium chloride to the water sample treated in step S1, and shaking in a liquid-liquid extraction oscillator until it is completely dissolved; S3, add the extractant to the water sample treated in step S2, shake vigorously and let it stand to separate, put the lower layer of water sample into the reagent bottle, transfer the upper layer of extract into the drying column, elute and transfer to the concentration bottle; S4, performing step S3 again on the remaining water samples in step S3; S5. Combine the eluates from steps S3 and S4, transfer them into a fully automatic nitrogen blower and concentrate them to 1 ml. Add the internal standard solution, adjust the volume, and then analyze them by gas chromatography-mass spectrometry to obtain the content of organochlorine pesticides in the water sample.

[0006] Conventional organochlorine pesticides take a long time to analyze. Each batch of samples (6-8) takes about 11 hours to analyze (including instrument performance check, standard curve establishment, liquid-liquid extraction, dehydration, nitrogen concentration, machine testing, and original records). However, the method of this patent only takes 6 hours to analyze the same number of samples, and the efficiency of sample analysis is increased by about 1 times. In addition, the recovery rate of organochlorine pesticides and substitutes is highly stable and is not affected by ambient temperature, solvent type, and the ratio of different solvents.

[0007] Furthermore, in the gas chromatography-mass spectrometer analysis, the gas chromatography conditions were as follows: the chromatographic column was DB-5MS, 30 m long, 250 μm thick, 0.5 μm inner diameter, the gas chromatography inlet temperature was 280°C, the carrier gas was 99.999% pure helium, the column flow rate was 1.0 mL / min, the injection volume was 1 μL, the split ratio was 5:1, and the heating program was as follows: the initial temperature was 120°C, and after holding for 1 min, the temperature was increased to 285°C at a rate of 25°C / min, and then increased to 300°C at a rate of 40°C / min, and held for 2 min. The single-needle sample running time was 9.975 min. The mass spectrometry conditions were as follows: the ion source was an Extractor high-sensitivity ion source, the electron energy was 70 ev, the ion source temperature was 280°C, the quadrupole temperature was 150°C, the transmission line temperature was 280°C, and the solvent delay was 5 min.

[0008] Furthermore, the fully automatic nitrogen blowing instrument controls the nitrogen blowing pressure to 8-35 psi and the temperature to 35-45°C.

[0009] Furthermore, the regulator is methanol, and the volume fraction of methanol is 10-20% based on the water sample.

[0010] Furthermore, the volume fraction of methanol is 15%.

[0011] Furthermore, the extractant is n-hexane, and the volume fraction of n-hexane is 15% based on the water sample.

[0012] Furthermore, in the drying column elution water, the drying column is a glass sand chromatography column filled with anhydrous sodium sulfate, the anhydrous sodium sulfate is 2-8g, and the eluent is dichloromethane.

[0013] Furthermore, in step S3, the frequency of violent oscillation of the liquid-liquid extraction oscillator is 260-300 times / minute.

[0014] Further, the substitute is tetrachlorom-xylene solution.

[0015] Furthermore, the original concentration of the tetrachloro-meta-xylene solution is 1000 mg / L, and the solvent is acetone, which is diluted to 10 mg / L with a regulator. Based on the water sample, the volume fraction of the diluted tetrachloro-meta-xylene solution is 0.02%.

[0016] The present invention has the following advantages: 1. The present invention adds a large dose of a regulator before extraction, extracts again after sodium chloride treatment, and determines the content of the target substance in the water sample after automatic nitrogen blowing and concentration, which has the advantages of high efficiency, rapidness and accurate detection.

[0017] 2. This method is simple to operate, low in cost, and has high concentration efficiency and recovery stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the process of the present invention.

[0019] Figure 2 It is the chromatogram of the standard sample of the present invention.

[0020] Figure 3 The effect of nitrogen blowing pressure and temperature on the recovery rate of tetrachlorom-xylene.

[0021] Figure 4 The effect of nitrogen blowing pressure and temperature on the recovery rate of acetyl hexachloride.

[0022] Figure 5 The effect of nitrogen blowing pressure and temperature on the recovery rate of ethyl hexachloride.

[0023] Figure 6 The effect of nitrogen blowing pressure and temperature on the recovery rate of BHC.

[0024] Figure 7 The effect of nitrogen blowing pressure and temperature on the recovery rate of BHC.

[0025] Figure 8 The effect of the dehydration method of the extract on the recovery rate of the target compound.

[0026] Fig. 9 The effect of the type of regulator on the recovery rate of the target compound.

[0027] Fig.10 is the effect of the volume fraction of the regulator on the recovery rate of the target compound.

[0028] Fig.11 This is the effect of the mass of anhydrous sodium sulfate on the recovery rate of the target substance.

[0029] Fig.12 The effect of eluent type on the recovery rate of the target compound.

[0030] Fig.13 This is the effect of the frequency of liquid-liquid extraction oscillation on the recovery rate of the target compound. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0032] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. 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.

[0033] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0034] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0035] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or the positions or positional relationships in which the product of the invention is usually placed when in use, or the positions or positional relationships commonly understood by those skilled in the art, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0036] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0037] Embodiment 1

[0038] refer to Figure 1 The process diagram shown is a method for quickly and accurately determining the content of organochlorine pesticides in water, including the following processing steps: S1. Take 100 ml of water sample, add the regulator to the water sample and shake well, then add the substitute and shake well again; The regulator is methanol, and its volume fraction is 15%, that is, 15 ml of methanol is added; the substitute is tetrachloro-meta-xylene solution, and its stock concentration is 1000 mg / L, and the solvent is acetone. When used, it is diluted to 10 mg / L with methanol. Based on the water sample, the volume fraction of the diluted tetrachloro-meta-xylene solution is 0.02%, that is, 20 ul of tetrachloro-meta-xylene solution is added; S2. Add 10 g of sodium chloride to the water sample treated in step S1, and place it in a liquid-liquid extraction oscillator and shake until it is completely dissolved; S3, add the extractant to the water sample treated in step S2, shake vigorously for 15 minutes, let it stand for 15 minutes to separate the layers, put the lower layer of water sample into the reagent bottle, transfer the upper layer of extract to the drying column, elute the water, and then move it into the concentration bottle; The extractant is n-hexane, and the volume fraction of n-hexane is 15% based on the water sample, that is, 15 ml of n-hexane is added; the oscillation frequency of the liquid-liquid extraction oscillator is controlled to be 270 times / min, and after vigorous oscillation for 15 minutes, it is allowed to stand for 15 minutes to separate the layers, and the lower layer of the water sample is placed in a reagent bottle for standby use, and the upper layer is the extract, which is transferred to a glass sand core chromatography column filled with 4 g of anhydrous sodium sulfate, and quickly eluted with the eluent dichloromethane, and then moved to a concentration bottle for standby use; S4, performing step S3 again on the remaining water samples in step S3; S5. Combine the eluates from steps S3 and S4, transfer to an automatic nitrogen blower and concentrate to 1 ml, add the internal standard solution, make the volume to 1 ml, transfer to a 1.5 ml injection vial for gas chromatography-mass spectrometry analysis to obtain the organochlorine pesticide content in the water sample.

[0039] The nitrogen blowing pressure of the fully automatic nitrogen blowing instrument is 30psi, the temperature is 44℃, after being concentrated to 1ml, the internal standard solution (phenanthrene-d10) is added, the volume is fixed to 1ml with n-hexane, and after mixing, it is transferred into a 1.5ml injection vial for gas chromatography-mass spectrometry analysis. The gas chromatography conditions are as follows: the chromatographic column is DB-5MS, 30m long, 250μm thick, 0.5μm inner diameter, the gas chromatography injection port temperature is 280℃, the carrier gas is 99.999% pure helium, the column flow rate is 1.0mL / min, the injection volume is 1μL, and the split ratio is 5 :1, the heating program is: initial temperature 120℃, after holding for 1 min, heat to 285℃ at a rate of 25℃ / min, and then heat to 300℃ at a rate of 40℃ / min, hold for 2 min, single needle sample running time is 9.975min; mass spectrometry conditions: ion source is Extractor high sensitivity ion source, electron energy is 70ev, ion source temperature is 280℃, quadrupole temperature is 150℃, transmission line temperature is 280℃, solvent delay is 5min, the solution is measured to obtain the organochlorine pesticide content of the water sample.

[0040] The chromatogram of the standard sample is as follows Figure 2 As shown in Table 1, the target ion, auxiliary ion, method detection limit, linear range and correlation coefficient are shown in Table 1

[0041] Table 1 Analytical performance of the method Taking surface water and groundwater as environmental media, when the target organochlorine spiked amount was 1.50μg / L, the recovery rate of tetrachloro-meta-xylene was 90.5%, the recovery rate of alpha hexachloride was 96.8%, the recovery rate of beta hexachloride was 98.7%, the recovery rate of 3 hexachloride was 99.4%, and the recovery rate of 4 hexachloride was 98.1%; when the target organochlorine spiked amount was 2.00μg / L, the recovery rate of tetrachloro-meta-xylene was 97.5%, the recovery rate of alpha hexachloride was 98.8%, the recovery rate of beta hexachloride was 98.7%, the recovery rate of 3 hexachloride was 99.4%, and the recovery rate of 4 hexachloride was 98.1%. The recovery rate was 99.5%, the recovery rate of the spiked hexachlorocyclohexane was 100%, the recovery rate of the spiked hexachlorocyclohexane was 99.0%, and the recovery rate of the spiked hexachlorocyclohexane was 98.0%; when the spiked amount of the target organochlorine was 2.50 μg / L, the spiked recovery rate of tetrachlorometa-xylene was 94.0%, the spiked recovery rate of the hexachlorocyclohexane was 95.2%, the spiked recovery rate of the hexachlorocyclohexane was 97.3%, the spiked recovery rate of the hexachlorocyclohexane was 99.6%, and the spiked recovery rate of the hexachlorocyclohexane was 98.0%.

[0042] Embodiment 2

[0043] The control process steps were consistent with Example 1, only the nitrogen gas flow pressure and water bath temperature were adjusted to study the effect of different nitrogen blowing temperatures (35-45°C) and pressures (8-35psi) on the recovery rate. The experimental results are shown in Figure 3-7 shown.

[0044] Specifically, the fully automatic nitrogen blowing instrument (VortexVap A12 model) adopts vortex shear airflow technology, and uses the combined effect of uniform heating in a water bath and vortex nitrogen blowing to accelerate the evaporation and concentration of the sample, and automatically and quantitatively concentrate it to 1 ml. It has the advantages of uniform heat transfer, fast concentration speed (60 ml of n-hexane only takes 12 minutes), good parallelism (the concentration parallelism time error does not exceed 5%), and good recovery rate (the recovery rate of concentration is stable and guaranteed to be as high as 98% or more).

[0045] The change of nitrogen flow is achieved by adjusting the nitrogen inlet pressure. The pipe diameter remains unchanged, and the flow rate is proportional to the pressure. The greater the pressure of the nitrogen flow, the greater the nitrogen flow rate. The nitrogen flow hits the wall of the test tube to form a vortex. The larger the solvent contact surface area and the vortex shear force, the faster the solvent evaporates. At the same time, continuous nitrogen purge can avoid chemical reactions between the solvent and the air, but the pressure cannot be too high. Excessive pressure will cause loss of the target object.

[0046] The concentrator is immersed in a water bath, and the temperature of the solution in the concentrator is controlled by heat transfer. The water bath temperature is usually controlled in the range of 30°C to 60°C. The temperature setting depends on the boiling point of the solvent in the concentrator and the properties of the substance to be analyzed. The water bath temperature is generally lower than the boiling point of the solvent, otherwise the evaporation rate may be too fast and the recovery rate may be reduced. However, if the temperature is set too low, the concentration time will be too long, and long-term nitrogen purging will also cause the substance to be tested to volatilize. The boiling point and volatility of the solvent should be fully considered when setting the water bath temperature.

[0047] The present application fully considers the influence of nitrogen blowing temperature and pressure under different conditions on the recovery rate of the target product, and obtains the optimal combination of temperature and pressure. As shown in the figure, the recovery rate of the target product is above 95% when the pressure is 25psi and the temperature is 39°C and when the pressure is 30psi and the temperature is 44°C. However, when the pressure is 30psi and the temperature is 44°C, the concentration time of the extract is the shortest, which is the most preferred. Embodiment 3

[0048] The control process steps were consistent with those in Example 1, except that the dehydration method of the extract was adjusted. Different dehydration methods of the extract were selected to study the effects of glass triangular funnel + filter paper, sand core funnel + glass wool, and glass sand core chromatography column on the recovery rate of the target product. The experimental results are shown in Figure 8 As shown, the use of glass sand core chromatography columns can effectively improve the recovery rate of the target product, and the recovery rate is above 95%, which is the most preferred.

[0049] Embodiment 4

[0050] The control process steps were consistent with those in Example 1, only the type and content of the regulator were adjusted, and different regulators (no regulator, methanol, acetone) and regulator contents (10%, 15%, 20%) were selected to study the effect of the regulator on the recovery rate of the target product. The experimental results are shown in Figure 9-10 shown.

[0051] This application is based on the fact that water has the strongest polarity of 10.2, and organochlorine pesticides (hexachlorocyclohexane alpha, hexachlorocyclohexane beta, hexachlorocyclohexane propyl, hexachlorocyclohexane butadiene) and substitutes (tetrachloromethane) have relatively small polarities. By adding methanol or acetone reagents (methanol has a polarity of 6.6, and acetone has a polarity of 5.4), the polarity of the sample before extraction can be changed, thereby enriching the target and substitutes in the water sample, which is conducive to the extraction of the target and substitutes from the sample into hexane by the extractant n-hexane (polarity 0.06), thereby improving the recovery rate of the target organochlorine pesticides and substitutes. The sodium chloride added subsequently adjusts the polarity of the solution again, reduces the solubility of organic matter in water, improves the extraction effect of polar pesticides, and at the same time, it can destroy the surface tension of the liquid, making it easier to separate the two phases, and can effectively avoid emulsification during extraction.

[0052] like Figure 9-10It can be seen that when the sample is pre-treated without adding a regulator in advance, the recovery rate of the target is low, while the recovery rate of the target and the substitute is significantly improved when the regulator is added to the water sample before the sample is treated. Further comparison of the effects of methanol and acetone on the recovery rate of the target shows that the advantage of methanol is more obvious. Further comparison of different volume fractions of methanol as a regulator shows that the recovery rate of the target and the substitute is significantly improved when the volume fraction of the regulator is 15%.

[0053] Embodiment 5

[0054] The control process steps are consistent with Example 1, only the mass of anhydrous sodium sulfate is adjusted, and different doses (2g, 4g, 6g, 8g) of anhydrous sodium sulfate are controlled to study the effect on the recovery rate of the target product. The experimental results are as follows: Fig.11 shown.

[0055] Since the extract still contains trace amounts of water in the n-hexane phase, trace amounts of water are not conducive to the concentration of the extract and will also damage the chromatographic column if it enters the gas chromatograph-mass spectrometer. Anhydrous sodium sulfate has a strong ability to absorb water and is added to the funnel or chromatography column to dehydrate the extract. However, too much anhydrous sodium sulfate will adsorb the target substance, thereby affecting the recovery rate of the target substance. Fig.11 As shown, when the mass of anhydrous sodium sulfate is selected as 4 g, the loss of the target product is minimal and the target recovery rate is above 95%.

[0056] Embodiment 6

[0057] The control process steps were consistent with those in Example 1, except that the type of eluent was adjusted. Different eluents (n-hexane and dichloromethane) were selected to study the effect on the recovery rate of the target product. The experimental results are shown in FIG. Fig.12 shown.

[0058] Through the analysis of the above examples, it can be seen that when the glass sand core chromatography column and the mass of anhydrous sodium sulfate are selected to be 4g, the loss of the target is minimal. When the extractant is n-hexane, the eluent is compared with n-hexane and dichloromethane. When dichloromethane is used as the eluent, the recovery rate of the target is higher. Moreover, due to its high density, dichloromethane can quickly elute the anhydrous sodium sulfate target into the concentration bottle, reducing the probability of anhydrous sodium sulfate caking the chromatography column when it encounters water, and the concentration speed is faster, which is better than n-hexane.

[0059] Embodiment 7

[0060] The control process steps were consistent with those in Example 1, except that the oscillation frequency was adjusted to control the frequency of the liquid-liquid extraction oscillator (MWV-1000W model) (260 times / min, 270 times / min, 280 times / min, 300 times / min) to study the effect on the recovery rate of the target product. The experimental results are shown in FIG. Fig.13 shown.

[0061] The frequency of the liquid-liquid extraction oscillator has a great influence on the extraction effect. If the frequency is too high, the recovery rate of more volatile organic compounds will be reduced; if the frequency is too low, the extraction will be incomplete, affecting the recovery rate of the target compound. Fig.13 As shown, when the frequency of the liquid-liquid extraction oscillator is controlled to 270 times / min, the loss of the target is minimal and the target recovery rate is above 95%.

[0062] Since the content of hexachlorocyclohexane is relatively low in the analysis of environmental samples, the pretreatment method, as an important step in the entire analysis process, has a significant impact on the accuracy and reliability of the measurement results. Using the measurement method of the present application, a large dose of methanol regulator is first added to the water sample before sample treatment. Compared with the high-throughput vacuum parallel evaporation concentration pretreatment method, the recovery rate of hexachlorocyclohexane is increased from the current 80% to more than 95%, and the recovery rate of tetrachlorometa-xylene is increased from the current 30~70% to more than 90%, which greatly improves the accuracy of organochlorine pesticides (hexachlorocyclohexane alpha, hexachlorocyclohexane beta, hexachlorocyclohexane C, hexachlorocyclohexane B) and substitutes (tetrachlorometa-xylene).

[0063] At the same time, the analysis time of a batch of samples (including instrument performance check, standard curve establishment, liquid-liquid extraction, dehydration, nitrogen concentration, on-machine testing, and issuance of original records) was reduced from 11 hours to 6 hours. It can efficiently, quickly and accurately detect the content of organochlorine pesticides in environmental water samples, and has the advantages of simple operation, low cost and high concentration efficiency. The recovery rate of organochlorine pesticides and substitutes is highly stable, and the recovery rate is not affected by ambient temperature, solvent type and the proportion of different solvents.

[0064] 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 method for quickly and accurately determining the content of organochlorine pesticides in water, characterized in that: The processing steps include: S1. Add the regulator to the water sample and shake well, then add the substitute and shake well again; S2, adding sodium chloride to the water sample treated in step S1, and shaking in a liquid-liquid extraction oscillator until it is completely dissolved; S3, add the extractant to the water sample treated in step S2, shake vigorously and let it stand to separate into layers, put the lower layer of water sample into the reagent bottle, transfer the upper layer of extract into the drying column, elute with water and then transfer it into the concentration bottle; S4, performing step S3 again on the remaining water samples in step S3; S5. Combine the eluates from steps S3 and S4, transfer them into a fully automatic nitrogen blower and concentrate them to 1 ml. Add the internal standard solution, adjust the volume, and then analyze them by gas chromatography-mass spectrometry to obtain the content of organochlorine pesticides in the water sample.

2. A method for quickly and accurately determining the content of organochlorine pesticides in water according to claim 1, characterized in that: In the gas chromatography-mass spectrometer analysis, the gas chromatography conditions are as follows: the chromatographic column is DB-5MS, 30 m long, 250 μm thick, 0.5 μm inner diameter, the gas chromatography injection port temperature is 280°C, the carrier gas is 99.999% pure helium, the column flow rate is 1.0 mL / min, the injection volume is 1 μL, the split ratio is 5:1, and the heating program is as follows: the initial temperature is 120°C, and after maintaining for 1 min, the temperature is increased to 285°C at a rate of 25°C / min, and then increased to 300°C at a rate of 40°C / min, and maintained for 2 min, and the single-needle sample running time is 9.975 min; mass spectrometry conditions: the ion source is an Extractor high-sensitivity ion source, the electron energy is 70 ev, the ion source temperature is 280°C, the quadrupole temperature is 150°C, the transmission line temperature is 280°C, and the solvent delay is 5 min.

3. The method for quickly and accurately determining the content of organochlorine pesticides in water according to claim 1, characterized in that: The fully automatic nitrogen blowing instrument controls the nitrogen blowing pressure to be 8-35 psi and the temperature to be 35-45°C.

4. The method for quickly and accurately determining the content of organochlorine pesticides in water according to claim 1, characterized in that: The regulator is methanol, and based on the water sample, the volume fraction of the methanol is 10-20%.

5. A method for rapidly and accurately determining the content of organochlorine pesticides in water according to claim 4, characterized in that: The volume fraction of the methanol is 15%.

6. The method for quickly and accurately determining the content of organochlorine pesticides in water according to claim 1, characterized in that: The extractant is n-hexane, and based on the water sample, the volume fraction of the n-hexane is 15%.

7. The method for quickly and accurately determining the content of organochlorine pesticides in water according to claim 1, characterized in that: In the drying column elution water, the drying column is a glass sand chromatography column filled with anhydrous sodium sulfate, the anhydrous sodium sulfate is 2-8g, and the eluent is dichloromethane.

8. The method for quickly and accurately determining the content of organochlorine pesticides in water according to claim 1, characterized in that: In step S3, the liquid-liquid extraction oscillator has a violent oscillation frequency of 260-300 times / minute.

9. The method for quickly and accurately determining the content of organochlorine pesticides in water according to claim 1, characterized in that: The substitute is a tetrachloro-m-xylene solution.

10. The method for quickly and accurately determining the content of organochlorine pesticides in water according to claim 9, characterized in that: The original concentration of the tetrachloro-meta-xylene solution is 1000 mg / L, and the solvent is acetone, which is diluted to 10 mg / L with a regulator. Based on the water sample, the volume fraction of the diluted tetrachloro-meta-xylene solution is 0.02%.

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