An innovative continuous sample drop flow microextraction for GC–MS determination of pesticides in grape juice and water samples

Abstract

In this work, for the first time, low-density organic solvents were employed in continuous sample drop flow microextraction (CSDF-ME) by changing the design of extraction vessel. To examine the effectiveness of the modified extraction method, different organophosphorus pesticides (OPPs) were extracted using proposed method followed by detection by gas chromatography–mass spectrometry (GC–MS). In fact, unlike conventional CSDF approach, in this study, we applied halogen-free organic solvents that are lighter than water for analytes extractions. These solvents are not only less toxic but also more environmentally friendly compared to the halogenated solvents. A conical open-end vial fixed in a small container filled with double-distilled water was used as the extraction vessel. A small amount of extraction solvent was placed at the bottom of the vial and the sample solution was pumped into the extraction vessel through a needle located inside the vial using a peristaltic pump. The sample droplets were continuously passed through the extraction solvent (hexane; 13 μL) to extract the analytes. Once the extraction was completed, the extraction solvent left at the top of aqueous phase was collected and injected into the GC–MS for further analysis. Under optimized conditions, the repeatability of the proposed method was found to be in range of 3.9–5.8 % for samples with low concentration of 5.0 μg L−1. The LOD (limit of detection) and LOQ (limit of quantification) of the method were determined in the ranges of 0.02−0.30 and 0.07–1.0 μg L−1, respectively. The EF (enrichment factor) was found to be between 510 and 960 for 8.0 mL sample solutions. The proposed method allows an extraction recovery ranging between 25.5 % and 48.0 %.