title: Dynamic behaviour and residual pattern of thiamethoxam and its metabolite clothianidin in Swiss chard using liquid chromatography-tandem mass spectrometry.
abstract: A simultaneous method was developed to analyse thiamethoxam and its metabolite clothianidin in Swiss chard using tandem mass spectrometry (in the positive electrospray ionisation mode using multiple reaction monitoring mode) to estimate the dissipation pattern and the pre-harvest residue limit (PHRL). Thiamethoxam (10%, WG) was sprayed on Swiss chard grown in two different areas under greenhouse conditions at the recommended dose rate of 10 g/20 L water. Samples were collected randomly up to 14 days post-application, extracted using quick, easy, cheap, effective, rugged, safe (QuEChERS) acetate-buffered method and purified via a dispersive solid phase extraction (d-SPE) procedure. Matrix matched calibration showed good linearity with determination coefficients (R(2)) ⩾ 0.998. The limits of detection (LOD) and quantification (LOQ) were 0.007 and 0.02 mg/kg. The method was validated in triplicate at two different spiked concentration levels. Good recoveries (n=3) of 87.48-105.61% with relative standard deviations (RSDs) < 10 were obtained for both analytes. The rate of disappearance of total thiamethoxam residues in/on Swiss chard was best described by first-order kinetics with half-lives of 6.3 and 4.2 days. We predicted from the PHRL curves that if the residues were <19.21 or 26.98 mg/kg at 10 days before harvest, then total thiamethoxam concentrations would be below the maximum residue limits during harvest.
authors.affiliation: Biotechnology Research Institute, College of Agriculture and Life Sciences, Chonnam National University, 300 Yongbong-dong, Buk-gu, Gwangju 500-757, Republic of Korea.
authors.forename: Md Musfiqur
authors.initials: MM
authors.lastname: Rahman
authors.affiliation: Biotechnology Research Institute, College of Agriculture and Life Sciences, Chonnam National University, 300 Yongbong-dong, Buk-gu, Gwangju 500-757, Republic of Korea.
authors.forename: Waziha
authors.initials: W
authors.lastname: Farha
authors.affiliation: Biotechnology Research Institute, College of Agriculture and Life Sciences, Chonnam National University, 300 Yongbong-dong, Buk-gu, Gwangju 500-757, Republic of Korea; Department of Pharmacology, Faculty of Veterinary Medicine, Cairo University, 12211 Giza, Egypt; Department of Veterinary Pharmacology and Toxicology, College of Veterinary Medicine, Konkuk University, 1 Hwayang-dong, Kwangjin-gu, Seoul 143-701, Republic of Korea. Electronic address: abdelaty44@hotmail.com.
authors.forename: A M
authors.initials: AM
authors.lastname: Abd El-Aty
authors.affiliation: Biotechnology Research Institute, College of Agriculture and Life Sciences, Chonnam National University, 300 Yongbong-dong, Buk-gu, Gwangju 500-757, Republic of Korea.
authors.forename: Md Humayun
authors.initials: MH
authors.lastname: Kabir
authors.affiliation: Biotechnology Research Institute, College of Agriculture and Life Sciences, Chonnam National University, 300 Yongbong-dong, Buk-gu, Gwangju 500-757, Republic of Korea.
authors.forename: So Jeong
authors.initials: SJ
authors.lastname: Im
authors.affiliation: Biotechnology Research Institute, College of Agriculture and Life Sciences, Chonnam National University, 300 Yongbong-dong, Buk-gu, Gwangju 500-757, Republic of Korea.
authors.forename: Da-I
authors.initials: DI
authors.lastname: Jung
authors.affiliation: Biotechnology Research Institute, College of Agriculture and Life Sciences, Chonnam National University, 300 Yongbong-dong, Buk-gu, Gwangju 500-757, Republic of Korea.
authors.forename: Jeong-Heui
authors.initials: JH
authors.lastname: Choi
authors.affiliation: Biotechnology Research Institute, College of Agriculture and Life Sciences, Chonnam National University, 300 Yongbong-dong, Buk-gu, Gwangju 500-757, Republic of Korea.
authors.forename: Sung-Woo
authors.initials: SW
authors.lastname: Kim
authors.affiliation: Food Standard Division, Ministry of Food and Drug Safety, Chungcheongbuk-do 363-700, Republic of Korea.
authors.forename: Young Wook
authors.initials: YW
authors.lastname: Son
authors.affiliation: Food Standard Division, Ministry of Food and Drug Safety, Chungcheongbuk-do 363-700, Republic of Korea.
authors.forename: Chan-Hyeok
authors.initials: CH
authors.lastname: Kwon
authors.affiliation: Department of Veterinary Pharmacology and Toxicology, College of Veterinary Medicine, Konkuk University, 1 Hwayang-dong, Kwangjin-gu, Seoul 143-701, Republic of Korea.
authors.forename: Ho-Chul
authors.initials: HC
authors.lastname: Shin
authors.affiliation: Biotechnology Research Institute, College of Agriculture and Life Sciences, Chonnam National University, 300 Yongbong-dong, Buk-gu, Gwangju 500-757, Republic of Korea. Electronic address: jhshim@chonnam.ac.kr.
authors.forename: Jae-Han
authors.initials: JH
authors.lastname: Shim
mesh_terms: D027461:Beta vulgaris / Q000737:chemistry*; D002853:Chromatography, Liquid / Q000379:methods*; D006146:Guanidines / Q000032:analysis*; D000073943:Neonicotinoids; D009574:Nitro Compounds / Q000032:analysis*; D010078:Oxazines / Q000032:analysis*; D010573:Pesticide Residues / Q000032:analysis*; D053719:Tandem Mass Spectrometry / Q000379:methods*; D000077922:Thiamethoxam; D013844:Thiazoles / Q000032:analysis*
chemical_list: D006146:Guanidines; D000073943:Neonicotinoids; D009574:Nitro Compounds; D010078:Oxazines; D010573:Pesticide Residues; D013844:Thiazoles; C480342:clothianidin; D000077922:Thiamethoxam
keywords: Clothianidin; Dissipation; Half-life; LC/MS/MS; Metabolite; Swiss chard; Thiamethoxam