Matrix Solid-Phase Dispersion Extraction for Analysis of Cypermethrin Residue in Cows’ Milk Adriana N. Macedo 1 , Ana R. A. Nogueira 2 , Silvia Helena Govoni Brondi 2,& 1 Universidade Federal de Sa ˜o Carlos, Rodovia Washington Luiz, km 235, Sa ˜o Carlos CEP 13565-905, Brazil 2 Embrapa Pecua ´ria Sudeste, Rodovia Washington Luiz, km 234, Sa ˜o Carlos CEP 13560-970, Brazil; E-Mail: shgb@uol.com.br Received: 25 April 2007 / Revised: 28 September 2008 / Accepted: 28 October 2008 Online publication: 8 February 2009 Abstract A method of extraction based on matrix solid-phase dispersion has been developed, opti- mized, and validated by chromatographic analysis of cypermethrin pesticide residues in samples of cows’ milk. Milk (0.25 g) was fortified with cypermethrin and blended with 1 g each of C 18 (octadecylsilane) silica and Na 2 SO 4 (anhydrous sodium sulfate), used to trap fats and water, respectively. The homogenized material was transferred to a commercial SPE cartridge containing 1 g activated Florisil with 5 mL acetonitrile. Cypermethrin was eluted under vacuum with 5 9 2 mL acetonitrile and the extract was concentrated to 1 mL and analyzed by gas chromatography–mass spectrometry. The limits of detection and quantifi- cation of the method were 0.025 and 0.08 mg kg -1 , respectively. Keywords Gas chromatography Mass spectrometry Matrix solid-phase dispersion Milk Cypermethrin Introduction Treatment of food-producing animals, for example swine, chickens, and lactat- ing cows, with veterinary drugs can affect public health and international trade in food products, because of the presence of drug residues or their metabolites in milk, eggs, meat, etc. Depending upon the time between drug administration and collection of the animal products, drug-related residues may be present in the matrix [1]. In particular, use of veterinary medicines in cattle health programs for prevention or treatment of diseases, for example use of antibiotics (b-lactam, aminoglycosides, tetracyclines) and antiparasitics (aver- mectins, pyrethroids, organophos- phates), which can affect milk, dairy products, and beef, is the biggest chal- lenge faced by public health agencies and the world food industry [2]. Because of the sparse literature on analytical meth- od development for drug-residue analy- sis, such studies are very important, especially to Brazil, which is the second and sixth largest world producer of beef and milk, respectively. Pyrethroids are synthetic pesticides widely used in Brazil to treat lactating dairy cows, mainly against ticks, flies, lice, and dermatobia [3]. Cypermethrin is a pyrethroid classified as a class II, moderately hazardous, pesticide accord- ing to the World Health Organization (WHO). Because it may be dangerous to human health, maximum residue levels (MRL) in milk have been stipulated by different organizations, for example 0.2 mg kg -1 by the European Union [4] and 0.10 mg kg -1 by the Joint FAO/ WHO Expert Committee on Food Additives (JECFA) [5]. Methods for monitoring veterinary drugs, for example pesticide residues, should be rapid, specific, and sensitive enough to enable detection at very low levels. Because of the low MRL for cypermethrin in milk established by leg- islation [4, 5], it is necessary to develop and optimize analytical methods for detection of residues of this compound 2009, 69, 571–573 DOI: 10.1365/s10337-009-0953-y 0009-5893/09/03 Ó 2009 Vieweg+Teubner | GWV Fachverlage GmbH Full Short Communication Chromatographia 2009, 69, March (No. 5/6) 571