TFJD448-05-163454 703.cls March 13, 2006 21:10 Journal of Environmental Science and Health Part B, 41:1–6, 2006 Copyright C  Taylor & Francis Group, LLC ISSN: 0360-1234 (Print); 1532-4109 (Online) DOI: 10.1080/03601230600634745 Analysis of Organophosphorus Pesticides in Whole Milk by Solid Phase Microextraction Gas Chromatography Method 1 2 3 4 Zenilda de Lourdes Cardeal and Claudia Maria Dias Paes 5 Chemistry Department, ICEx, Federal University of Minas Gerais, Belo Horizonte, M.G., Brazil 6 7 Solid phase microextraction (SPME) was used for the extraction of residual coumaphos 8 and dichlorvos in whole milk. The residues were analyzed by capillary gas chromatog- 9 raphy equipped with nitrogen phosphorus detector (GC-NPD). A manual SPME holder 10 with a 100-μm polyacrylate fiber was used. The optimized conditions for extraction 11 by SPME method were: sample agitation, absorption temperature of 30 ◦ C, absorp- 12 tion time of 40 min, desorption time of 10 min, and sample volume was 16.0 mL in 13 the vial. Under these conditions, the calibration graphs were linear in the range of 14 0.17 μgL −1 to 1.75 μgL −1 for coumaphos and 0.69 μgL −1 to 6.90 μgL −1 for dichlorvos. 15 Precision was good with RSD values of 13% for coumaphos and 14% for dichlorvos. 16 The detection limits (LOD) were 0.060 μgL −1 for dichlorvos and 0.052 for coumaphos. 17 The quantification limits (LOQ) were 0.086 μgL −1 for dichlorvos and 0.066 μgL −1 for 18 coumaphos. The results obtained in this study suggest that SPME is a suitable tech- 19 nique for residual pesticide analysis of milk. The data demonstrate that particular 20 OP pesticides used in dairy farming in the region of Minas Gerais were found to 21 contaminate cow whole milk, and the residues are not removed by treating the milk 22 by boiling. 23 Key Words: Milk analysis; OP residues; Solid phase microextraction; Gas chromatogra- 24 phy. 25 INTRODUCTION 26 The external application of organophosphorus (OP) pesticides as insecticides 27 directly on dairy cattle for ectoparasite control within dairy farms may add to 28 Received January 18, 2005. Address correspondence to Zenilda Cardeal, Chemistry Department, University of Minas Gerais, Belo Horizonte, M.G., C.P. 702, 31270-901, Brazil; E-mail: zenilda@ ufmg.br or x03201@ems.rmit.edu.au or Zenilda@qui.ufmg.br 1