Riboflavin as a green sorbent in dispersive micro-solid-phase extraction of several pesticides from fruit juices combined with dispersive liquid-liquid microextraction.

A vortex-assisted dispersive micro-solid-phase extraction procedure using a new and green sorbent was developed as a simple, fast, and efficient sample preparation method for the extracting five pesticides in several fruit juice samples. In this study, for the first time, riboflavin was used as an efficient sorbent. A few milligrams of riboflavin was directly added into the aqueous solution containing the analytes to adsorb them. After adsorption the analytes, they were desorbed and more concentrated by a dispersive liquid-liquid microextraction procedure. The influence of several effective parameters such as amount of riboflavin, pH, vortex time, eluent nature and volume, and extraction solvent type and volume on the extraction efficiency was investigated. In optimal conditions, linear ranges of the calibration curves were broad. The limits of detection and quantification were attained in the ranges of 0.56-1.5  and 1.9-0.52 ng mL -1 , respectively. The proposed method demonstrated to be suitable for concurrent extraction of the studied pesticides in various fruit juice samples with high enrichment factors (320-360) and precision (relative standard deviation ≤7.8% for intra- [n = 6] and interday [n = 4] precisions at a concentration of 25 ng mL -1 of each pesticide).