Analysis of chlorpyrifos pesticide residue in locally grown vegetables using gas chromatography - mass spectrometry technique

Abstract

Food adulteration refers to the alteration of food quality that takes place either deliberately or accidentally. Pesticides are applied to agricultural crops for protection from pests. Being an agricultural country, overuse of pesticide is very common in Bangladesh which poses a great threat to human health. Chlorpyrifos is one of the most frequently used pesticides in Bangladesh. Till date, only multiresidue method has been applied with various analytical techniques in Bangladesh which yields to lower accuracy than monoresidue method. Gas chromatography-mass spectrometry (GC-MS) has been the most reliable technique till date for both qualitative and quantitative determination of unknown pesticide compounds. In this study, a GC-MS method followed by a suitable extraction process was developed for monoresidue detection and quantification of chlorpyrifos in cauliflower, cabbage and eggplant samples collected from six sources. Pesticide-free control samples were collected from PROSHIKA organic farm, Rangpur for validation study. Samples cultivated with recommended pesticide dose were collected from Bangladesh Agricultural Development Corporation (BADC) Kashimpur farm. Commercially available samples were collected from commercially cultivated agricultural fields of Kashimpur and local markets (Polashi, Hatirpool and Mohakhali kacha bazar). The GC-MS method was developed by trial and error process which included various parameters such as: carrier gas flow rate, injector temperature, mass spectrometry transfer line temperature, mass spectrometry heater temperature, ion source temperature, ion energy, fragment ion selection, molecular weight, retention time and column temperature profile. The extraction process and GC-MS method was validated with respect to accuracy, mean recovery, precision, linearity, limit of detection and limit of quantification parameters. The developed method has a limit of detection (LOD) of 0.011 mg/kg and a limit of quantification (LOQ) of 0.034 mg/kg. Vegetable samples with moisture content were assessed on mg/kg wet basis using the aforementioned technique. Chlorpyrifos residue was found in 33.33% of BADC samples, 73.33% of field samples and 66.67% of samples from local markets. This technique can be used for monoresidue analysis of chlorpyrifos in other vegetables. This study will also help developing monoresidue analysis techniques for other pesticides in vegetables, fruits and other crops.