Comparison of matrix solid-phase dispersion and liquid–liquid extraction for the chromatographic determination of fenthion and its metabolites in olives and olive oils

Abstract

Matrix solid-phase dispersion (MSPD) methodology has been developed to extract fenthion and its metabolites from olives and olive oils, and the technique compared with conventional liquid–liquid extraction (LLE). The method was applied to olives and olive oil samples obtained from olive groves treated with fenthion. Pesticide residues were analysed by gas chromatography (GC) using a nitrogen–phosphorus detector. Both extraction methods gave a linear response over the concentration range assayed (0.03–1 mg kg−1 for MSPD and 0.1–1 mg kg−1 for LLE). Recoveries and RSD (n = 6) values in olives were 85–112% and 2–6% for MSPD, and 68–108% and 4–16% for LLE, respectively. In the case of olive oil, recoveries and RSD (n = 6) values were 67–98% and 5–11% for MSPD, and 63–115% and 6–14% for LLE, respectively. When compared to LLE, the newly developed MSPD method was twice as sensitive and required 10 times less sample weight.