A sensitive determination of triazole pesticides in grape juice by combining solid phase extraction–dispersive liquid–liquid microextraction followed by gas chromatography–flame ionisation detection

Abstract

ABSTRACT In this study, a solid phase extraction method followed by dispersive liquid–liquid microextraction has been developed for the extraction and preconcentration of five triazole pesticides (penconazole, hexaconazole, diniconazole, tebuconazole, and triticonazole) in grape juice. Initially, a high volume of the sample solution is passed through the solid phase extraction cartridge and then the absorbed analytes are eluted by an appropriate solvent (methanol) which acts as a dispersive solvent in the following microextraction procedure. Then, the eluate is mixed with 1,1,2,2,–tetrachloroethane as an extraction solvent and the mixture is rapidly injected into sodium chloride solution. After centrifugation, an aliquat of the obtained sedimented phase is injected into gas chromatography–flame ionisation detection. Some effective parameters on performance of the method such as washing and elution solvents type and volume, extraction solvent, etc were investigated. Under optimum conditions (sample solution volume, 100 mL; flow rate, 10 mL min–1; elution solvent (volume), methanol (1.0 mL); extraction solvent (volume), 1,1,2,2–tetrachlorothene (25 µL); aqueous phase in DLLME, sodium chloride solution (30%, w/v); and centrifugation time (speed), 5 min (3000 rpm)), the method showed high enrichment factors (4101–9566) and low limits of detection (0.053–0.890 ng mL–1) and quantification (0.178–2.96 ng mL–1). Finally, ten grape juices were successfully analysed by this method and hexaconazole was detected in some of them in the concentration range of 19–29 ng mL–1.