Determination of organophosphorus pesticides in fruit jams by sugar-assisted liquid-liquid microextraction followed by high performance liquid chromatography

Pesticides are chemicals that are widely used in agriculture to increase crop quality and yield, and are known to cause adverse health effects on consumers. In the past years, pesticide residues have been detected in a variety of fruits and vegetables, both raw and processed. Jam is a processed food product commonly produced from a variety of fresh fruits and vegetables for the consumption during all seasons. It is prepared by boiling some ingredients such as sugar, fruit pulp, acidity regulator and preservatives until a viscous mixture is obtained. The fact that it contains various agricultural products raises the suspicion of pesticide residues that can be found in jam products. There have been some published reports of pesticide residues being detected in fruit jams. In this study, a sugar-assisted liquid-liquid microextraction (SULLME) method for the determination of some organophosphorus pesticides (fenitrothion, phosalone, profenofos and chlorpyrifos) in fruit jams has been presented. SULLME is a sample preparation method based on the extraction of analytes with a water-miscible organic solvent followed by the separation of the organic phase by externally added or naturally occurring sugar in the sample matrix. The procedure presented in this study included brief shaking of a jam sample with acetonitrile-water mixture, followed by centrifugation for phase separation and direct analysis of the collected acetonitrile phase by high performance liquid chromatography. Acetonitrile was the only chemical used in the sample pretreatment step and the high sugar content of the sample matrix highly accelerated the extraction process as it triggered phase separation. Some parameters that influence the extraction efficiency, including the type of water-miscible solvent, the composition and volume of the solvent-water mixture, shaking time and pH were investigated. Under the optimal experimental conditions, the extraction recoveries in the range of 81–89% were achieved for the analytes. In addition, good linearity in a range of 50–5000 μg/kg (r2 ≥ 0.9992) and method detection limits (LODs) less than 25 μg/kg were obtained. The accuracy of the method was investigated with commercially available cherry, strawberry, blackberry, apricot and blueberry jams. Good recoveries in the range of 89-107% were obtained from the spiked jam samples.