[Simultaneous determination of antibiotics and triphenylmethanes veterinary drug residues in fish and shrimp by dispersive solid phase extraction purification-ultra high performance liquid chromatography-tandem mass spectrometry].

A method was established to rapidly determine 20 kinds of veterinary drug residues including three catagories of antibiotics (sulfonamides, quinolones, and chloramphenicols) and two kinds of triphenylmethanes (malachite green (MG) and leucomalachite green (LMG)) in fish and shrimp, based on dispersive solid phase extraction purification-ultra high performance liquid chromatography-tandem mass spectrometry. The samples were first hydrolyzed using a dipotassium hydrogen phosphate solution, and then extracted using acetonitrile. Afterward, the extraction solution was dehydrated and salted out with sodium chloride and condensed to nearly dry using a rotating evaporator. This residue was dissolved in 1.0 mL methanol. The resulting solution was purified by dispersive solid phase extraction method with C18 and PSA sorbents, and filtered through a filter. The target compounds were separated employing a ZORBAX C18 column. The mass spectrometer datas were acquired by multiple reaction monitoring (MRM) of positive and negative modes and quantitated applying the isotope internal standard method. The 20 veterinary drugs showed a good linear relationship in the range of 0.2-300 µg/L. The limits of detection and the limits of quantification were 0.1-0.6 and 0.3-1.8 µg/kg, respectively, while the correlation coefficients were greater than 0.99. The average recoveries at the three spiked levels (1, 5, and 20 times of quantitative limits) ranged between 72.5%-118%, with the relative standard deviations of 1.9%-9.8%. The advantages of method include a simple pretreatment, a high detection efficiency, and a low cost. Moreover, it is suitable for the simultaneous determination of multiple veterinary drug residues in fish and shrimp.

Paclobutrazol Residue Determination in Potato and Soil Using Low Temperature Partition Extraction and Ultrahigh Performance Liquid Chromatography Tandem Mass Spectrometry.

A simple, accurate, and highly sensitive analytical method was developed for determining the paclobutrazol residue in potato and soil, the dynamics dissipation in soil. Extraction was carried out by low temperature partitioning and analyzed by ultrahigh performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS). For a favor extraction yield, the parameters such as temperature and solvent were optimized. The result showed that sample would be easily frozen and separated using acetonitrile under -20°C for 10 min. The limit of detection (LOD) was 0.5 µg/kg, and the limit of quantification (LOQ) was 2 and 5 µg/kg for potato and soil, respectively. The influence of paclobutrazol residue in potato was evaluated. The possible contamination of paclobutrazol from surface can be rinsed by distilled water or peeled off, but the paclobutrazol in potato harvest comes mainly from absorption and transport, which could not be removed by peeling. The half-life of paclobutrazol in soil was 20.64 days, and the residue was below 0.22 mg/kg on 50th day after spraying. According to the risk assessment with Need Maximum Daily Intake (NEDI) and Acceptable Daily Intake (ADI), a Maximum Residue Limit (MRL) of paclobutrazol in potato was recommended as 1.0 mg/kg.

[Determination of 41 pesticide residues in vegetables by QuEChERS-ultra performance liquid chromatography-tandem mass spectrometry].

A multiresidue analytical method for the rapid determination of 41 pesticide residues in vegetables was developed by using QuEChERS-ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), including recessive pesticides, banned pesticides and pesticides with restrict use, plant growth regulators and some other pesticides with high detection rates. The vegetable sample was extracted by 1% (v/v) acetic acid-acetonitrile, cleaned-up by primary secondary amine (PSA) and injected for analysis. The positive and negative ion modes and multiple reaction monitoring (MRM) mode were used in the analysis, and the analytes were quantified by the external standard method. Under the conditions of optimized QuEChERS, chromatography and mass spectrometry, the 41 pesticides showed good linearities in the range of 1.0 µg/L to 100 µg/L, with the correlation coefficients (r2) higher than 0.999. The limits of detection of the method were 0.003 µg/kg to 1.00 µg/kg. The average recoveries of the 41 pesticides in different matrices were in the range of 74.1%-120.4% with the relative standard deviations from 2.8% to 11.9%. The method has the advantages of rapidity, simplici- ty, high sensitivity and better purification effect. It is suitable for the rapid determination of the common pesticides in vegetables, and it provides a strong guarantee for the risk assessment of the quality and safety of vegetables.