Multi-Residue Analysis of Pesticides in Vegetables and Soil

Gupta, Rahul Kumar (2014) Multi-Residue Analysis of Pesticides in Vegetables and Soil. Masters thesis, Indian Institute of Science Education and Research Kolkata.

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Abstract

The objective of the study was to determine and compare the current level of exposure of the population to hazardous pesticide through consumption of fresh vegetables produced in around Nadia district (Kalyani, Barasat and Kolkata).The residual levels of pesticides were determined in 36 samples of 4 varieties of vegetables and 8 soil samples collected from selected sites around Nadia (Kalyani, Barasat and Kolkata).The procedure involves initial single-phase extraction of 10 g sample with 10 ml acetonitrile, followed by liquid–liquid partitioning formed by addition of 4 g anhydrous MgSO4 plus 1 g NaCl. Removal of residual water and cleanup are performed simultaneously by using a rapid procedure called dispersive solid-phase extraction (dispersive-SPE), in which 150 mg anhydrous MgSO4 and 25 mg primary secondary amine (PSA) sorbent are simply mixed with 1 ml Acetonitrile extract. The dispersive- SPE with PSA Effectively removes many polar matrix components, such as organic acids, certain polar pigments, and sugars, to some extent from the food extracts. Gas chromatography/mass spectrometry (GC/MS) is then used for quantitative and confirmatory analysis of GC-amenable pesticides. The data obtained was compared with that of a referenced pesticide by matching molecular weight to a library of known pesticides. The results indicated that all the vegetable samples have high concentration (>MRL) of one or more pesticides in them. Because many vegetables are consumed fresh or only slightly cooked, the study shows that intensive vegetable production, common in study site, threatens public health from the pesticide dimensions. Standard recommendations to address this situation (better legislations, law enforcement, or integrated pest management) often do not match the capabilities of farmers and authorities. The most appropriate entry point for risk decrease that also addresses post-harvest contamination is washing vegetables before food preparation at the household.

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