| Liquid chromatograph-mass spectrometer(LC-MS)is a relatively mature technology,which plays a very important role in the identification and detection of compounds in the laboratory.The pretreatment has the characteristics of complementary advantages,simple sample treatment and reducing the pressure of sample pretreatment,so it is suitable for the analysis of complex matrix samples.In the qualitative and quantitative analysis of compounds,high sensitivity,fast analysis speed,outstanding specificity,suitable for the analysis of various types of compounds,can get rich information,quantitative and qualitative results are reliable,fast and simple,high automation,high recovery rate.In this paper,19 pesticide residues in cosmetics and agricultural products were studied by LC-MS.The main contents are as follows:(1)The cosmetics of 19 kinds of pesticide residues in the establishment of the extraction and detection method19 kinds of pesticide residues in cosmetics were extracted by ultrasonic wave,and their concentrations were measured by liquid chromatography-mass spectrometry,and the extraction rate was obtained.in the experiment,the effects of three single factors,namely,the amount of extractant,salt and ultrasonic time,on the extraction efficiency were investigated,and the positive price experiment was designed based on this.According to the comparison of the extraction rate,the optimum extraction conditions were obtained as follows: acetonitrile addition10 mL,sodium chloride 3g,ultrasonic extraction time 5min.A method for the analysis of 19 kinds of pesticide residues in cosmetics was established by LC-MS/MS technology.19 pesticides were separated by ChromCore C18100 mm X2.1mm(particle size 1.8μm),mass spectrometry data were collected by multi-reaction monitoring mode,and suitable chromatographic and mass spectrometry conditions and ideal mobile phase elution gradient were adopted.Finally,the quantitative limit of all substances is not higher than 0.1mg/kg.Using the external standard method to quantify,when adding three low,medium and high levels of0.02,0.06 and 0.1mL standard mixed solution respectively,the recovery rate is 70%-109%,and the relative standard deviation(nasty 3)is0.83%-11.43%,indicating that the established method has high recovery,high precision and good accuracy.In 30 kinds of real samples of three kinds of cosmetics,two substances contained 19 kinds of substances.It was found that fluconazole and chlorphenazine were detected in the water.The concentrations of fluconazole were 0.292 μg / L and 0.310 μg / L,respectively.The concentration of chlorphenazine was 0.117 μg / L and0.134 μg / L.(2)Analysis of 19 kinds of substances in agricultural productsThe optimum extraction conditions were applied to the detection of agricultural products,and the appropriate chromatographic and mass spectrometry conditions were used to detect the residual concentrations of19 pesticides in agricultural products.Because agricultural products contain a lot of substances and the matrix is very complex,such as extremely difficult plant pigments and some broken organelles,the QuEChERS method is used to pre-treat 15 kinds of samples bought in the market,and the external standard method is used to accurately quantify19 kinds of pesticides.Finally,in one of the 15 samples,the concentration of carbendazim was 1.535 μg / L and 1.495 μg / L.The concentrations of trimethoprim in another vegetable were 2.680 μg / L and 2.777 μg / L,respectively. |
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