Use of Dispersive Solid-Phase Extraction in Combination with Dispersive Liquid-Liquid Microextraction for the Assessment of Organophosphorus Pesticides in Fruit Juice Samples Using Gas Chromatography-Nitrogen-Phosphorus Detector

Use of various pesticides to protect agricultural products increases likelihood of residues of these compounds entering the human body through the consumption of food products. In this study, an efficient method was developed for the extraction and preconcentration of organophosphorus pesticides from packed juice samples using gas chromatography-nitrogen-phosphorus detector.

In this study, a combination of dispersive solid-phase extraction and dispersive liquid-liquid microextraction was used for the extraction of pesticides from fruit juice samples. Chitosan-Ni/Fe layered double hydroxide composite was synthesized and used after characterization as adsorbent in dispersive solid-phase extraction step. To achieve high extraction efficiency, effects of various factors in the two extraction stages were investigated and optimized.

Interaction of chitosan with the produced layered double hydroxide was verified using Fourier-transform infrared spectroscopy and its crystallographic structure was verified using X-ray diffraction. In addition, porous structure of the synthesized adsorbent, indicating large surface areas and high extraction capacities, was verified via morphological study of the composite. Developed extraction method was successfully carried out on juice samples as the sample matrix included no significant effects on the separation of analytes and limits of detection and limit of quantification of the method included 0.011–0.019 and 0.043–0.063 ng/ml, respectively. Linear range of the suggested method was wide (0.36–0.250) and the method included an appropriate precision with RSD% less than 5.6 for intra and inter-day precisions. Values ​​were also desirable for the extraction efficiency (72–76%).

In general, dispersive solid-phase extraction in combination with dispersive liquid-liquid microextraction included a wide linear range and appropriate repeatability. In addition, this method included desirable values for enrichment factor, limits of detection and extraction efficiency and hence is recommended for the assessment of target pesticides in juice samples.