An SPME–GC–MS Method for Determination of Organochlorine Pesticide Residues in Medicinal Plant Infusions

Abstract

A simple method, direct-immersion sampling by solid-phase microextraction and gas chromatography–mass spectrometry (DI-SPME–GC–MS), has been developed for determination of organochlorine pesticides (OCP) in plant infusions. The optimum conditions for SPME with a 100-μm PDMS-coated fiber were established by using a central composite design. The extraction time and sample temperature established were 60 min and 50 °C, respectively. The method was validated and used to determine hexachlorobenzene, lindane, 4,4’-DDE, aldrin, dieldrin, endrin, heptachlor, heptachlor epoxide, and 4,4’-DDT in infusions of Mikania laevigata and Maytenus ilicifolia. Limits for quantitation for the OCP were between 0.2 and 2.0 ng g⁻¹ except for lindane, for which the LOQ was higher (12 ng g⁻¹), because of its low affinity for the PDMS fiber. Recovery was in the range 90 to 108% and the intra-assay precision was below 17%. Transfer of the OCP from the plant to the infusion was in the range 0.34 to 3.4% and was correlated with the solubility of each compound in water.