| 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. |