Multiresidue determination of pesticides in carrots using pressurized liquid extraction and gas chromatography with mass spectrometry detector

Abstract

Neste estudo, 14 agrotóxicos (captan, clorotalonil, deltametrina, dicloran, fention, folpete, iprodiona, linurom, malationa, prometrina, procloraz, procimidona, triclorfom e trifluralina) foram usados no desenvolvimento de um método multiresíduos (MRM), utilizando extração de cenouras com líquido pressurizado (PLE). A etapa de clean-up foi realizada por dispersão da matriz em fase sólida (MSPD), sendo testados como material dispersante o Florisil, XAD-4, XAD-7 e C18. Diclorometano, acetato de etila e acetona foram empregados como solventes para PLE, a 75 ºC e 1.500 psi. As recuperações dos analitos para cenouras liofilizadas ficaram na faixa de 70 a 133%. Entretanto, os percentuais de recuperação obtidos para as cenouras úmidas não foram satisfatórios (< 70%). Os coeficientes de determinação das curvas analíticas situaram-se na faixa de 0,9821 a 0,9997; os limites de detecção (LOD) e de quantificação (LOQ) para os vários compostos investigados ficaram entre 0,0024-0,1968 mg kg -1 e entre 0,0072-0,5963 mg kg -1 , respectivamente.In this study, 14 pesticides (captan, chlorothalonil, deltamethrin, dicloran, fenthion, folpet, iprodione, linuron, malathion, prometryn, prochloraz, procymidone, trichlorphon and trifluralin) were employed for developing a multiresidue method (MRM) using pressurized liquid extraction (PLE). In situ clean-up was achieved using matrix solid phase dispersion (MSPD), where Florisil, XAD-4, XAD-7 and C18 were tested as dispersing material for carrot samples. Dichloromethane, ethyl acetate and acetone were used as solvents in a PLE unit at 75 ºC and 1,500 psi. Recovery was in the range of 70 to 133 %. Results obtained with wet carrots were not satisfactory, since most of the recovery values were below 70%. Determination coefficients of the analytical curves presented values between 0.9821 and 0.9970. Limits of detection (LOD) and quantification (LOQ) for the various components varied from 0.0024 to 0.1968 mg kg -1 , and 0.0072 to 0.5963 mg kg -1 , respectively. Keywords: multiresidue method, PLE, MSPD, carrots, GC/MS IntroductionIn the last few decades, pesticides have been used on an increasingly wider scale throughout the world. On account of the large number of active ingredients used in agricultural production, complex analytical procedures are required for the detection of a great number of possible compounds, with few number of extraction and clean-up steps. These compounds are characterized by their diversity, their different physical and chemical properties (polarity, solubility, pKa etc) and their low concentrations in real samples. 1 Some of the analytical methods aim to determine a single component (SRM) and others, more sophisticated, are capable of simultaneously determine more than one residue in a single analysis. These last ones are called pesticide multiresidue methods (MRM) and comprise a higher degree of analytical difficulty. Multiresidue methodology by definition requires determinative steps for separating analytes from one another so each one can be detected and measured ...

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