Facile preparation of carbonized cellulose nanoparticles and their application for the dispersive solid phase extraction prior to dispersive liquid-liquid microextraction of pesticide residues from vegetable and fruit juices

In this work, carbonized cellulose nanoparticles have been prepared easily by heating filter paper in a mixture of sulfuric acid and water. The nanoparticles were utilized as the dispersive solid phase extraction sorbent for the extraction of diniconazole, clodinafob-propargyl, oxadiazon, chlorpyrifos, fenpropathrin, and fenoxaprop-p-ethyl residues from orange, grape, pomegranate, and peach juices and fresh cucumber and onion juices. Initially, the analytes in the aqueous sample were adsorbed onto the carbonized cellulose nanoparticles by vortex mixing. Then the sorbent particles were isolated from the solution by centrifuging. Acetonitrile was used for elution of the adsorbed analytes. Then, the obtained eluate was mixed with 1,2-dibromoethane and rapidly injected into an aqueous solution. A turbid solution was obtained. It was centrifuged and an aliquot of the sedimented extractant was injected into gas chromatography-flame ionization detector. The large surface area and hydrophilic nature of the prepared sorbent provided its high extraction efficiency for the selected analytes and easy dispersibility into the aqueous solutions. Performance characteristics of the proposed method were determined under the best extraction conditions. The enrichment factor for all of the studied pesticides was more than 257. Limits of detection and quantification were obtained in the ranges of 0.31-0.53 and 1.0-1.5 mu g L-1, respectively. The relative standard deviations were in the ranges of 3-5 and 5-7% for intra- and inter-day precisions, respectively, for six replicated determinations at a concentration of 50 mu g L-1 of each analyte. The presented method was used for determination of the selected pesticides in various vegetable and fruit juices and oxadiazon was found in onion juice at mu g L-1 level.