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Insecticide paint, also known as insecticide paint, is a protective coating containing biotoxic drugs, but also a functional architectural coating, with easy to use, rapid insecticidal, clean and safe characteristics, insecticidal paint not only has the general architectural paint decoration and protection functions, but also kill flies, mosquitoes, cockroaches, bed bugs and spiders and other insects; Environmentally friendly insecticidal coatings are generally added to water-based coatings high-efficiency, low-toxic, broad-spectrum insecticides, through the film of insecticidal drugs and pests after contact, so that the nerves of pests and paralysis to death, and harmless to people, animals. Pythyroid insecticide is a kind of broad-spectrum insecticide, with strong killing activity, and has gastric toxicity, egg killing, rejection and expulsion effect, small dosing, high potency, low toxicity, mild environmental pollution, moderate residual effect period, no unpleasant odor, does not affect the appearance quality and intrinsic quality of the coating, is the ideal insecticide for
coatings
. At present, there are more studies on the determination methods of pyroidic insecticides, such as: gas chromatography (GC) , gas chromatography-mass spectrometry (GCMS), and high-efficiency liquid chromatography (HPLC) And enzyme-linked immunoanalysis method, which is more used GC-ECD method, through retention time qualitative, but sometimes false positive phenomenon, affecting GC test results, at the same time, it is difficult to meet the current rapid and easy detection of a variety of pyrethroid insecticide requirements. GC-MS, as an important means of detecting pyridropy pesticides, has been more and more widely used, such as GC-MS to detect the residue of pyridide in water bodies, aquatic products, fruits and vegetables. However, there are few literatures on the detection of pyrethroid insecticides in insecticidal coatings, and this paper focuses on the GC-MS detection methods of 6 kinds of pyrethroid insecticides commonly found in insecticidal coatings (acrylamide, pyrethroids, amines, chlorpyrgides, chloramphenidates and bromocyanides);
1 Test Part
1.1 Instruments and Reagents
Agilent 6890N-5975 Gas Chromatography-Mass Spectrometry Joint Instrument (Agilent, UNITED States); Ketone (chromatography pure, United States Tedia), positive hexane (chromatography pure, U.S. Burdick and Jackson), acetylene (chromatography pure, Tianjin Guangfu Fine Chemical Research Institute); Standards: Allethrin, Resmethrin, Tetramethrin, Permethrin, Cypermethrin, Deltamethrin, all pure chromatography, Augsburg, Germany.
1.2 chromatography and mass spectrometry conditions
chromatography conditions: HP-5MS capillary column (30 m×0.32 mm ×0.25 m); mL/min; Sample size: 1 μL; Ingress temperature: 250 degrees C; Detector temperature: 250 degrees C; column head pressure: 42 689.6 Pa (normal pressure mode); column flow rate: 0.8 mL/min; sample method: no flow in.
mass spectrometry conditions: EI source: 70 eV; transmission line temperature: 280 degrees C; ion source temperature: 230 degrees C; four-stage rod temperature: 150 degrees C; mass spectrometry detection: full scan; solvent delay: 3 min; Tuning mode: auto-tuning.
1.3 Preparation of standard reserve fluid
accurately named acrylic chrysanthemum, pyridine, chlorpyride, chloramphenidate, bromocyanide esters 0.05 g (accurate to 0.2 mg) In a 50 mL brown capacity bottle, a mixture of V (acetone) : V (positive hexane) and 1:1 is dissolved and settled, and is made into a mixed standard reserve liquid of 1 000 mg/L, spare.
1.4 sample pre-treatment
said to take 0.5 g sample in the glass sample bottle, add the appropriate amount of sodium sulfate for stirring, add 5 mL V (acetone): V (positive hexane) - 1:1 mixed solvent, extraction 2 times, combined extraction liquid to 10 mL color tube, fixed capacity, filtered with organic film in the sample bottle, to be measured.
2 Results and Discussion
2.1 Choice of Extraction Solvents
The insecticides to be destethylated are mostly non-polar compounds, and the solvents used for sample extraction are mainly positive hexane, ethylene, petroleum ether, acetone, etc.; The national standard GB/T 5009.146-2003 provides for the use of acetone and petroleum ether as extraction solvents, but there are more purification steps, solvent consumption, pre-treatment cycle is too long and other shortcomings. In this test, acetone, positive hexane, ethyl acetylene and V (acetone) : V (positive hexane) , a mixture of 1:1 solvents were selected as extraction solvents, and the recovery rate data of each compound were found in Table 1.
As can be known from Table 1: the extraction effect of acetylene is better, less impurities, but the toxicity of acetylene is greater, not easy to use; Therefore, the test selected V (acetone) : V (positive hexane) - 1:1 mixed solvent as the extraction solvent.
2.2 GC-MS condition optimization
this test selected Agilent's HP-5MS column as the analysis column, and examined the separation of 6 compounds under different column temperature conditions and carrier airflow. The test showed that all six compounds could be completely separated according to the following analytical conditions: the initial temperature of 180 degrees C, maintain 2 min, at 20 degrees C/min to 240 degrees C, maintain 3 min, at 10 degrees C/min to 280 degrees C, maintain 10 min;
2.3 Addition of sodium aphuric sulphate
This test adds sodium a waterless sulphate to the sample to remove moisture from the sample and reduces interference with impurities; Just remove the moisture in the sample and slightly excessive is appropriate, if the moisture adsorption in the sample is not complete, the water contained in the liquid to be tested may damage the column and detector, but too much waterless sodium sulfate needs more solvent immersion, not only resulting in waste, treatment of the extraction rate of the test parts will also have an impact. The test showed that the effect of adding 2 to 4 g of sodium sulfate to the sample was best.
2.4 Linear relationship and detection limit
dilute the mixed standard reserve fluid into 10 mg/L, 30 mg/L, 50 mg/L, 80 mg/L and 100 mg/L standard solutions, respectively, and are determined according to the method determined in this test, the legal quantity of the external standard. The results show that the peak area y of each compound has a good linear relationship with its mass concentration x (mg/L), and the detection limit of this method is determined according to the concentration of each compound corresponding to the signal-to-noise ratio of S/N=3. The regression equation, correlation coefficient and check-out limit of this method can be found in Table 3.
2.5 method precision and sample mark recovery rate
select the market generally sold water varnish and water-based wood coating, respectively, 10 mg/L, 50 mg/L, 100 mg/L 3 concentration levels of mixed standard added recovery test, each level to do 6 parallel samples, calculated average recovery rate and precision data table 4. The results show that the average recovery rate of 3 levels is 80.0% to 99.6%, which shows that the accuracy and precision of this method are good.
2.6 sample detection
the actual sample was tested using the method established in this paper, each group made 8 parallel samples, the sample was measured to contain amine and chlorpyride, the average mass concentration was 8.68 mg/L, 7.16 mg/L, and the relative standard deviation was 2.55% and 4.02%, respectively. The total ion flow chromatography of the actual sample is shown in Figure 2.
3 Conclusion
This paper establishes the gas chromatography-mass spectrometry detection method of 6 kinds of python-ester-type insecticides in insecticidal coatings, and systematically studies the extraction efficiency of 6 kinds of python-ester-type insecticides by organic solvents such as acetone, erthylene, etc. Process and chromatography analysis conditions, the recovery rate of various compounds is 80.0% to 99.6%, the relative standard deviation (RSD) of the method is less than 5.0%, the detection limit of the method is 0.38 to 1.96mg/L. The test of the actual sample is applied to this method, and the results show that the method is selective, accurate, fast analysis and repeatable, and is suitable for the detection and quality control of harmful substances in insecticidal coatings.