title: Influence of different planting seasons of six leaf vegetables on residues of five pesticides.
abstract: To investigate the influence of different planting seasons on the dissipation of pesticides, field experiments of thiophanate-methyl, metalaxyl, fluazifop-P-butyl, chlorpyrifos, and λ-cyhalothrin on six crops including pakchoi, rape, crown daisy, amaranth, spinach, and lettuce were designed and conducted. In this study, a high-performance liquid chromatography and electrospray ionization-tandem mass spectrometer with multiple reaction monitoring was used to simultaneously determine thiophanate-methyl and its metabolite carbendazim, metalaxyl, and fluazifop-P-butyl in various samples; gas chromatography with an electron capture detector was used to detect chlorpyrifos and λ-cyhalothrin. The limits of quantitation (LOQs) of these six pesticides were in the range of 0.001-0.01 mg kg(-1) for all samples, and the average recoveries of all pesticides ranged from 60.1 to 119.1% at 0.01 and 0.1 mg kg(-1) spiked levels. The relative standard deviation (RSD) ranged from 1.1 to 13.9%. All maximal concentrations of the six pesticides in six leaf vegetables in autumn were higher than in summer in Beijing. For most pesticides half-lives in autumn were longer than in summer. The results showed that the initial concentration, maximal concentration, and half-lives of pesticides were influenced not only by environmental factors such as light, heat, moisture, and rainy climate but also by plant matrices.
authors: Department of Applied Chemistry, College of Science, China Agricultural University , Beijing 100193, People's Republic of China.
authors: Sufang
authors: S
authors: Fan
authors: Kailin
authors: K
authors: Deng
authors: Chuanshan
authors: C
authors: Yu
authors: Pengyue
authors: P
authors: Zhao
authors: Aijuan
authors: A
authors: Bai
authors: Yanjie
authors: Y
authors: Li
authors: Canping
authors: C
authors: Pan
authors: Xuesheng
authors: X
authors: Li
mesh_terms: D000383:Agriculture; D002851:Chromatography, High Pressure Liquid; D005506:Food Contamination / Q000032:analysis; D010573:Pesticide Residues / Q000032:analysis*; D018515:Plant Leaves / Q000737:chemistry*; D012621:Seasons; D053719:Tandem Mass Spectrometry; D014675:Vegetables / Q000737:chemistry* / Q000254:growth & development
chemical_list: D010573:Pesticide Residues