Acid-base reaction-based dispersive liquid-liquid microextraction method for extraction of three classes of pesticides from fruit juice samples

A sample preparation method involving acid-base reaction-based dispersive liquid-liquid microextraction coupled with gas chromatography using nitrogen-phosphorous detection has been developed for the analysis of three classes of pesticides in juice samples. In this method, a basic organic solvent (p-chloroaniline) is used as an extraction solvent. It is dissolved in acidified deionized water and then injected into an alkaline aqueous sample solution. After injection, an acid-base reaction occurs and deprotonation of the organic solvent leads to formation of tiny droplets of the extractant and subsequent extraction of the analytes from sample solution. Under the optimum extraction conditions, the method showed low limits of detection and quantification in the range of 0.05-0.43 ng mL−1 and 0.17-1.43 ng mL−1, respectively. Extraction recoveries and enrichment factors were between 39.2 and 84.1% and between 548 and 1178, respectively. Relative standard deviations of less than 8.6% for the extraction of 2.0 ng mL−1 of each pesticide were obtained for intra- (n = 6) and inter-day (n = 4) precisions. Finally, different juice samples were successfully analyzed using the proposed method, and penconazole, diniconazole, triadimenol, and acetamiprid were determined in some samples at ng mL−1 levels.