Comparison of gas chromatography-based approaches after fast miniaturised sample preparation for the monitoring of selected pesticide classes in fruits.

The feasibility of a miniaturised generic sample preparation method based on matrix solid-phase dispersion for the determination of three relevant classes of pesticides (organophosphorus pesticides, triazines and pyrethroids) in selected fruits, i.e. orange, apple, pear and grape, have been demonstrated. Satisfactory results were obtained with gas chromatography coupled to mass spectrometry with recoveries of 78-113% in orange, 62-102% in grape, 71-116% in apple and 91-110% in pear, and reproducibilities in general below 20%. The feasibility of simultaneous separation of the three families of pesticides by comprehensive two-dimensional gas chromatography with micro-electro-capture detector was also evaluated. Columns with different polarity and selectivity, including ZB-5, HT-8 and DB-17, were assayed as first dimension and combined with columns of increasing polarity in the second dimension, i.e. HT-8, BPX-50 and Supelcowax-10. The best results for real-life samples after treatment by the proposed miniaturised method were achieved with ZB-5 x BPX-50 column combination. The low limits of detection achieved with this technique (in general, below 0.56 microg/kg) proved its suitability for accurate monitoring of the pesticides classes included in the study at the maximum residue levels set in the European Union.