Determination of organochlorine pesticides from juice samples using magnetic biochar-based dispersive micro-solid phase extraction in combination with dispersive liquid-liquid microextraction

Abstract

Analysis of pesticide residue levels in juice beverages is important to ensure safe consumption and avoid global trade concerns associated to pesticide contaminations. A simple, inexpensive and effective method was developed for the determination of organochlorine pesticides (OCPs) in bottled juice drinks using GC-MS. Sample pretreatment was performed using dispersive solid-phase microextraction (D-μ-SPE) for matrix desorption and dispersive liquid-liquid microextraction (DLLME) for analyte enrichment. In this study, an affordable and effective sorbent for the adsorption of OCPs from juice samples was synthesized from avocado seeds mixed with magnetic precursors for D-μSPE. The ground avocado seeds combined with a magnetic precursor nanocomposite were characterized using various instruments including scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Brunauer-Emmett-Teller (BET) analysis. The solution obtained from D-μ-SPE desorption was used as a dispersant for the subsequent DLLME, which made the combination of D-μ-SPE with DLLME much easier. The effectiveness of the method was enhanced by optimizing the influential parameters in both D-μ-SPE and DLLME. Then after, the optimal values were determined for the real sample analysis. Accordingly, there was good linear dynamic range with a coefficient of determination (r2) ≥ 0.9989. The limit of detection and quantification were 0.02–0.69 and 0.06–2.10 ng/L respectively. The method showed high enrichment factors ranging from 96 to 313 with recoveries of 87–100 %. Intraday and interday precisions were ≤4 %. Compared with other reported methods, this method is a one-step, simple, cheap, fast, and environmentally friendly alternative and straightforward method for adsorbing organochlorine pesticides from sample solutions. These results demonstrates the high potential of the proposed method for the extraction and cleanup of contaminants in selected juices and other related samples.