CN113252824B - Gas chromatography-electronic capture detector method for determining content of trifluoro-phenylpyrimidine in water body - Google Patents

Abstract

A gas chromatography-electron capture detector method for determining the content of trifluorophenylpyrim in water is to extract a water body sample with dichloromethane and then use acetone to dilute to volume, and use the gas chromatography-electron capture detector method for determination. It is confirmed by experiments that the standard curve equation obtained from the standard working solution in the concentration range of 0.01-1.0 mg/L is y=187085x-2204.5, R ² =0.9994, and the linear correlation is very good. Under the addition concentrations of 0.01, 0.10 and 1.00mg/kg, the obtained addition recoveries were 83.55%-109.53%, the relative standard deviations were 8%-11%, and the lowest detection concentration was 0.01mg/kg. The method is simple to operate, fast, accurate and low in cost, provides a fast and reliable method for the determination of trifluoropyrimidine residues in water, and can meet the quality and progress requirements of mass sample analysis.

Description

Gas Chromatography-Electron Capture Detector Method for Determination of Trifluorophenylpyrimidine in Water

technical field

The invention belongs to the field of chemical analysis and detection, relates to the detection and analysis of trifluoropyrimidine, and in particular relates to a method for measuring the content of trifluoropyrimidine in water by gas chromatography-electron capture detector method (GC-ECD).

Background technique

Trifluorophenylpyrimidine, English common name: triflumezopyrim, chemical name: 3,4-dihydro-2,4-dioxo-1-(pyrimidin-5-ylmethyl)-3-(α,α,α- Trifluorom-tolyl)-2H-pyrido[1,2-α]pyrimidine-1-onium-3-salt, with a relative molecular mass of 398.34 and a chemical formula of C ₂ OH ₁₃ F ₃ N ₄ O ₂ , is a U.S. A mesoionic insecticide developed by DuPont and released in 2013. Trifluoropyrimidine is a new type of pyrimidine compound, which is mainly used in cotton, rice, corn and soybean crops, and can control brown planthopper, leafhopper, etc. The mechanism of action of trifluorophenazine is different from that of neonicotinoid insecticides. It competitively binds to the orthosteric position on the nicotinic acetylcholine receptor (nAChR) of insects, inhibiting the binding site and reducing the insect's Nerve impulses or block nerve transmission, and ultimately affect the physiological behaviors of pests such as feeding and reproduction, resulting in death.

In July 2016, DuPont's trifluoropyrimidine will be listed for the first time in my country. With the increasing use of trifluoropyrimidine, its side effects are becoming increasingly prominent, such as: environmental pollution, pesticide residues and other issues have received attention and attention from various countries. In order to ensure environmental safety monitoring and reduce pesticide pollution, it is very necessary to vigorously carry out research on the analysis and detection technology of trifluoropyrimidine in different environmental matrices (water bodies).

At present, the detection methods of trifluorophenylpyrim at home and abroad are mainly liquid chromatography and liquid chromatography-mass spectrometry. "Pesticide Scientific Management 2019, 40 (6)" discloses the research on high performance liquid chromatography analysis method of 20% trifluoropyrimidine water dispersible granules. "Pesticide 2019, 11(58)" discloses the high performance liquid chromatography analysis of 10% trifluoropyrimidine suspension. "Jiangsu Agricultural Science, 2021, 49(2)" discloses the degradation dynamics and residual analysis of trifluoropyrimidine in paddy fields, using liquid chromatography-mass spectrometry to detect. "Pesticide, 2018, 57(1)" discloses the residual analysis method of trifluoropyrimidine in rice, soil and field water, which is detected by liquid chromatography. However, there is no research report on the determination of trifluoropyrimidine by gas chromatography. Compared with the liquid phase, the gas phase has better resolution, higher sensitivity of the detector, and lower cost of use. Therefore, gas chromatography is still the preferred method for the analysis of trifluoropyrimidine residues in environmental media and various crops in most laboratories in my country.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a gas chromatography-electron capture detector (GC-ECD) method for measuring the content of trifluorophenyl pyrimidine in the water body for the deficiencies of the above-mentioned prior art, to rapidly and accurately measure the trifluorobenzene in the water body. pyrimidine residues.

In order to achieve the above-mentioned purpose, the technical scheme adopted in the present invention is: a gas chromatography-electron capture detector method for measuring the content of trifluoropyrimidine in a water body, and the method steps are as follows:

(1) Sample extraction: after filtering the water body sample to remove impurities, add 10-20% NaCl solution by mass concentration to the water body sample after removing impurities, and the volume ratio of the water body sample after removing impurities and the NaCl solution is 5:2, After shaking, add dichloromethane, and the volume ratio of dichloromethane to the water sample after removing impurities is 4:5. After shaking, let stand, and collect the lower layer of dichloromethane; add dichloromethane to the water phase and extract twice, The volume ratio of the dichloromethane added each time to the impurity-removed water sample is 2:5, the lower dichloromethane phase is collected, and all the dichloromethane phases are combined; wherein, the shaking time is 1-2min; the standing time is 8-12min.

(2) Sample constant volume: the combined dichloromethane phase is concentrated to near dryness, constant volume with acetone, and filtered to obtain the test sample solution; wherein, a rotary evaporator is used for concentration, and the temperature is 55° C.; 0.22 μm is used for filtration. organic filter membranes.

(3) The content of trifluorophenylpyrimidine in the test sample solution was measured by gas chromatograph.

The above gas chromatography conditions when using a gas chromatograph are: DB1701 chromatographic column, 30m × 320μm × 1μm; temperature program: the initial temperature is 180 ° C for 5 minutes, and the rate of 20 ° C / min is raised to 280 ° C and maintained for 3 minutes; 260°C; carrier gas is nitrogen; splitless injection, injection volume is 1 μL; flow rate is 2mL/min; makeup gas is nitrogen, flow rate is 45mL/min; detector is electron capture detector, and the detector temperature is 300°C.

The standard working curve equation of trifluorophenyl pyrimidine drawn under the above gas chromatographic conditions is y=187085x-2204.5, R ² =0.9994, and the standard curve is drawn with the chromatographic peak area as the ordinate and the concentration of the trifluoropyrimidine standard solution as the abscissa After fitting, the concentration of the standard working solution of trifluoropyrimidine prepared when drawing the standard working curve equation was 0.01, 0.05, 0.10, 0.50, 1.00 mg/L.

The present invention establishes a detection method for the residual amount of trifluoropyrimidine in water by optimizing the gas chromatography-electron capture detector instrument and the preparation conditions of the test sample. The standard working solution of 0.10, 0.50 and 1.00 mg/L can obtain the standard curve equation as y=187085x-2204.5 (correlation coefficient R ² =0.9994), and its linear correlation is very good. At the three added concentrations of 0.01, 0.10, and 1.00 mg/kg, the obtained additive recoveries and relative standard deviations were between 83.55%-109.53% and 8%-11%, respectively. The lowest detectable concentration was 0.01 mg/kg. Meet the requirements of pesticide residue testing methods. The established method has high accuracy, strong specificity and good reproducibility, and can effectively detect trifluoropyrimidine residues in water. And it has been proved by experiments that this method can be used in various water bodies with different properties, and its recovery, sensitivity, detection limit, etc. have good accuracy and precision in each batch of water bodies.

Description of drawings

Fig. 1 is the standard working curve diagram of trifluorophenylpyrimidine of the present invention.

Fig. 2 is the GC-ECD chromatogram of the trifluorophenylpyrimidine standard solution of the present invention (0.5 mg/L).

Fig. 3 is a blank sample GC-ECD chromatogram of the water body of the present invention.

Fig. 4 is the GC-ECD chromatogram of the blank sample of the water body of the present invention added with 0.1 mg/kg trifluoropyrimidine.

In Figures 2-4, the abscissa represents time (unit: minutes), and the ordinate represents the response value.

Detailed ways

The following examples are further detailed descriptions of the present invention, but the examples are not limited to the protection scope of the present invention.

The establishment of the method of embodiment 1

Instrument: Agilent-6890N gas chromatograph (Agilent, USA) ECD detector.

Chromatographic conditions: DB1701 gas chromatographic column, 30m × 320μm × 1μm; temperature program: the initial temperature was 180°C for 5min, then increased to 280°C at a rate of 20°C/min, and kept for 3min; the inlet temperature was 260°C; the carrier gas was nitrogen ( Purity 99.999%); splitless injection, injection volume 1 μL; flow rate 2mL/min; makeup gas is nitrogen, flow rate 45mL/min; detector is electron capture detector, and the detector temperature is 300°C.

1) Preparation of the test sample solution

After filtering the water sample with filter paper to remove impurities, accurately measure 50 mL of the water sample, put it into a 250 mL separatory funnel, add 20 mL of 20% mass concentration NaCl solution, shake and add 40 mL of dichloromethane, shake for 1 min and let stand 10 min, collect the lower layer of dichloromethane; add dichloromethane to the aqueous phase and extract twice, each time the amount of dichloromethane added is 20 mL, collect the lower layer of dichloromethane, and combine all the dichloromethane phases; The methyl chloride phase was concentrated to near dryness on a rotary evaporator (55° C.), adjusted to volume with 2.0 mL of acetone, and filtered with a 0.22 μm organic filter to obtain the test sample solution.

2) draw a standard curve

Accurately weigh 0.0100g (accurate to 0.0001g) of trifluorophenyl pyrimidine standard (purity 99.4%), place it in a 100mL brown volumetric flask, dissolve it with acetone and prepare it into trifluorobenzene with a mass concentration of 1000.0mg/L Pyrimidine standard stock solution. Then adopt the gradient dilution method to take the standard mother liquor of trifluoropyrimidine to prepare standard working solution, so that the mass concentrations of trifluoropyrimidine are all 0.01, 0.05, 0.10, 0.50, 1.00 mg/L. Detection was performed using a gas chromatography-electron capture detector (GC-ECD) apparatus according to the aforementioned chromatographic conditions. And then obtain the peak area of trifluoropyrimidine as shown in Table 1, take the mass concentration of trifluoropyrimidine (x, mg/L) as the abscissa and the corresponding peak area (y) as the ordinate to draw the value of trifluoropyrimidine. Standard working curve, the standard curve equation of trifluorophenylpyrimidine is y=187085x-2204.5 (R ² =0.9994), and the standard curve diagram is shown in Figure 1 .

Table 1 Standard curve of trifluoropyrimidine

It can be seen from Table 1 that the peak area of trifluoropyrimidine in a certain linear range has a good linear relationship with the mass concentration, and the correlation coefficient is 0.9994.

3) Determination

Inject the above standard working solution and the test sample solution into a gas chromatograph-electron capture detector (GC-ECD) instrument to obtain a chromatogram. The GC-ECD chromatogram of trifluorophenylpyrimidine standard solution (0.5mg/L) is shown in the figure 2. Qualitatively according to the peak time, the retention time of trifluoropyrimidine is about 12.05min, and the external standard method is used to quantitatively calculate the residual amount of trifluoropyrimidine.

Embodiment 2 adds recovery test to carry out method verification

Add the standard working solution of trifluorophenyl pyrimidine to the blank sample of the water body (without trifluorophenyl pyrimidine), and set 3 addition levels with concentrations of 0.01, 0.1, and 1 mg/kg, and repeat 5 times for each addition level. The blank sample (that is, the blank sample of the water body without adding the standard working solution of trifluoropyrimidine, it is required that the time when the peak of trifluoropyrimidine in the blank sample spectrum does not appear in the chromatographic peak, that is, the specificity of the method is better) is used as a control. In the preparation method of the test sample solution in Example 1, extraction and constant volume were carried out to obtain the solution to be tested of the added recovery test sample and the solution to be tested of the blank sample, and the chromatographic conditions of Example 1 were used for determination.

The formula for calculating the residual amount of trifluoropyrimidine: X=(C×V)/m, in the formula, X: the residual amount of trifluoropyrimidine in the recovered sample, mg/kg; C: according to the peak area of the sample by the standard curve Calculated sample injection concentration, mg/L; V: the final constant volume of the added and recovered experimental sample, mL; m: the weight of the added and recovered experimental sample, g.

The calculation of the recovery rate of addition is an existing conventional technology, and the measurement results are shown in Table 2. Typical chromatograms of the addition and recovery experiments of trifluoropyrimidine in water samples are shown in Figures 3 and 4.

As can be seen from Table 2, at the three spike levels, the addition recovery of trifluoropyrimidine on water samples was between 83.55-109.53%, and the relative standard deviation was between 9.3-10.2%; from Figure 3 - As can be seen in Figure 4, in the blank sample of the water body, there is no peak at the time of the trifluorophenylpyrimidine peak, indicating that the specificity of the method is good. According to the addition recovery experiment, under the aforementioned chromatographic conditions, the minimum detectable concentration of trifluoropyrimidine in water samples was 0.01 mg/kg. The correlation coefficient of the linear equation is 0.9994, indicating that the sensitivity, accuracy, precision and specificity of the established detection method meet the requirements of pesticide residue detection.

Table 2 The recovery rate and relative standard deviation of trifluoropyrimidine in water

Example 3 Application

(1) Determination of trifluoropyrimidine residues in paddy field water to which trifluoropyrimidine was applied

In 2019, a field experiment was conducted at the experimental base of Hunan Agricultural University, Furong District, Changsha City, Hunan Province, and each plot area was 30m ² . The application form is 20% trifluoropyrimidine water-dispersible granules, and the application dose is 27 g/ha (the dosage of the preparation is 9.0 g/mu). 3-5cm deep), the direct spraying method was used for spraying, and the paddy field water was collected at 2h, 1, 3, 5, 7, 10, 14, 21, 28, 35, and 42d after spraying, and the experiment was repeated three times.

Randomly collect paddy field water (not less than 10 points) in each experimental plot, and the sample volume of each plot is not less than 1L. After mixing evenly, take 500mL and put it in a clean sealed plastic bottle as a sample of paddy field water; then First filter with filter paper, after filtration, accurately measure 50 mL of water sample and transfer it to a 250 mL separatory funnel filled with 20 mL of 20% NaCl solution, add 40 mL of dichloromethane after shaking, shake for 1 min, and let stand for 10 min to collect the lower layer The dichloromethane phase and the aqueous phase were added with 20 mL and 20 mL of dichloromethane to extract twice, respectively, and the lower dichloromethane phase was collected. Combine all the dichloromethane phases and concentrate them on a rotary evaporator (55° C.) to near dryness, use 2.0 mL of acetone to make up the volume, and then pass through a 0.22 μm organic membrane to obtain the test sample solution, and finally use the GC-ECD of the present invention. Detection conditions The water sample solution to be tested was detected, and the results are shown in Table 3.

Table 3 Dynamic test results of trifluoropyrimidine digestion in paddy field water

(2) Determination of natural water bodies and living water bodies

Using the method of the present invention, the water quality of 5 parts of the river water near the Binhe community of Hunan Agricultural University, the flowing water in the community, the nearby paddy field water, the tap water of teachers' homes, the tap water of teaching buildings and the purified water of the supermarket were tested, and no trifluoropyrimidine was detected in the results.

Claims (7)

1. a gas chromatography-electron capture detector method for measuring trifluorophenylpyrimidine content in a water body, is characterized in that, the method steps are as follows: (1) Sample extraction: after filtering the water body sample to remove impurities, add 10-20% NaCl solution by mass concentration to the water body sample after removing impurities, and the volume ratio of the water body sample after removing impurities and the NaCl solution is 5:2, After shaking, add dichloromethane, and the volume ratio of dichloromethane to the water sample after removing impurities is 4:5. After shaking, let stand, and collect the lower layer of dichloromethane; add dichloromethane to the water phase and extract twice, The volume ratio of the dichloromethane added each time to the impurity-removed water sample is 2:5, the lower layer of the dichloromethane phase is collected, and the dichloromethane phase is combined; (2) sample constant volume: the combined dichloromethane phase is concentrated to near dryness, constant volume with acetone, and filtered to obtain the test sample solution; (3) adopt gas chromatograph to measure the trifluorophenylpyrimidine content in the test sample solution; Among them, the above gas chromatography conditions are: DB1701 chromatographic column, 30m × 320μm × 1μm; temperature program: the initial temperature is 180 °C for 5 minutes, and the temperature is increased to 280 °C at a rate of 20 °C/min, and maintained for 3 minutes; The gas was nitrogen; splitless injection, the injection volume was 1 μL; the flow rate was 2 mL/min; the makeup gas was nitrogen, the flow rate was 45 mL/min; the detector was an electron capture detector, and the detector temperature was 300 °C. 2. the gas chromatography-electron capture detector method of measuring trifluorophenylpyrimidine content in water body as claimed in claim 1, it is characterized in that, the standard working curve equation of the trifluorophenylpyrimidine drawn under described gas chromatographic condition is y =187085x-2204.5, R ² =0.9994. 3. the gas chromatography-electron capture detector method of measuring trifluorophenylpyrimidine content in water body as claimed in claim 2, it is characterized in that, the trifluorophenylpyrimidine standard working solution concentration of preparing when described drawing standard working curve equation is 0.01, 0.05, 0.10, 0.50, 1.00 mg/L. 4 . The gas chromatography-electron capture detector method for determining the content of trifluorophenylpyrimidine in water according to claim 1 , wherein, in the step (2), a 0.22 μm organic filter membrane is used for filtration. 5 . 5. The gas chromatography-electron capture detector method for measuring trifluorophenylpyrimidine content in water as claimed in claim 1, characterized in that, in the step (2), a rotary evaporator is used for concentration, and the temperature is 55°C. 6. The gas chromatography-electron capture detector method for measuring trifluorophenylpyrimidine content in water as claimed in claim 1, wherein the shaking time in the step (1) is 1-2min. 7. The gas chromatography-electron capture detector method for measuring trifluorophenylpyrimidine content in water as claimed in claim 1, characterized in that, in the step (1), the standing time is 8-12min.

Images