Design Of On-line Purification System And Its Application In The Detection Of Pesticide And Veterinary Drugs Residues In Food

Currently,food safety problems in our country has been stable,but various food safety accidents still occur occasionally.Specially,pesticide and veterinary drug residues in food is an important factor affecting food quality and safety,which is harmful to people's health and the ecological environment.Pesticide residue becomes the focus of social attention.The rapid and accurate detection of pesticide and veterinary drug residues in food is of great significance for monitoring and ensuring food safety.The analysis of pesticide and veterinary drug residues is usually at the trace level,which requires the pretreatment process to purify the target components,remove the impurities,and improve the accuracy and precision of the results as much as possible.In this paper,a new method of online solid phase extraction combined with high performance liquid chromatography-tandem mass spectrometry was established for the determination of carbamate pesticide residues,quinolones and ?-lactam antibiotics residues in food.This method realizes the automation of sample pretreatment,reduces the tedious manual operation,and reduces the time of pretreatment effectively,which can provide reference for the analysis of pesticide and veterinary drug residues in food.The main contents are listed as follows.An online solid phase extraction/purification system was designed and built to make the traditional offline SPE online automatic based on the principle of chromatographic separation.The process of enrichment and purification of the target analyte was realized by controlling the flow rate and solvent ratio of the two infusion pumps by computer software after the sample extract was injected into the system.A method for the determination of 8 carbamate pesticides in tomato,rice and cabbage by online solid phase extraction/purification-high performance liquid chromatography tandem mass spectrometry was established.The samples were extracted with 0.5% formic acid acetonitrile solvent,and the extracted solution was blown dry with nitrogen and then redissolved.Then the sample extract was directly purified online and analyzed by liquid chromatography/tandem mass spectrometry system.The extraction solvent and on-line purification conditions were optimized.The results showed that the eight carbamate pesticides have good linearity(r>0.995).The recoveries of online purification were 73.76% ? 112.32%,the RSDs(n=6)were 1.41% ? 13.14%,the LODs were 0.01 ?g/kg ? 0.3 ?g/kg,and the LOQs were 0.05 ?g/kg ? 1.0 ?g/kg.The recoveries were 55.68% ? 99.13% and RSDS were 1.48% ?26.46% when using off-line purification.LODs were 0.05 ?g/kg ? 0.3 ?g/kg and LOQs were0.2 ?g/kg ? 0.9 ?g/kg,and the purification process took about 80 min.The online purification method greatly improves the efficiency of pretreatment.It only takes 12 min to complete the sample purification without nitrogen blowing resolution.This method has high recovery rate,good reproducibility,rapid environmental protection compared with the off-line extraction method,and can be used for the detection of 8 carbamate pesticides in plant food.A method for the determination of 9 quinolones and 4 ?-lactam antibiotics in pork by online solid phase extraction/purification-high performance liquid chromatography tandem mass spectrometry was established.The samples were extracted with acetonitrile,and the supernatant was concentrated and redissolved with acetonitrile-water(1:19,v/v).The extraction solvent and on-line purification conditions were optimized.The results showed that the 13 antibiotics have good linearity(r>0.995).LODs were 0.06 ?g/kg ? 0.4 ?g/kg,LOQs were 0.2 ?g/kg ? 1.3 ?g/kg,the recoveries of online purification were 75.17% ? 114.03%,and the RSDs were 0.72% ?9.72%.The recoveries of off-line purification were 72.03% ? 112.01%,and RSDS were 2.29%? 10.34%.Compared with the off-line purification method,the online SPE method has high degree of automation and improves the efficiency of sample treatment.The results are accurate,reliable and sensitive,which can meet the qualitative and quantitative analysis requirements of9 kinds of quinolones and 4 kinds of ?-lactam antibiotics.In conclusion,the on-line purification system can be applied to the purification analysis of carbamate pesticide residues and quinolones and ?-lactam antibiotic residues in food.The online SPE purification method can effectively shorten the pretreatment time,save the steps of experimental steps,avoid the sample loading,leaching,elution and nitrogen blowing resolution.The on-line SPE purification method has obvious advantages in accuracy,sensitivity and reproducibility compared with the off-line extraction method.