QUANTIFICATION OF PESTICIDE RESIDUES IN GRAINS FROM FOUR MAJOR MARKETS IN ADO-EKITI

Abstract

The study evaluated the occurrence, type and amount of pesticide residues in grains from four major markets in Ado-Ekiti and also compared the amount of pesticides residues in the grains to the maximum residue limit (MRL) for each of the pesticides. Samples of maize (Zea mays), cowpea (Vigna unguiculata), wheat (Triticum aestivum;L) and sorghum (Sorghum bicolor), were purchased from six sales outlet from four markets in Ado-Ekiti. Samples were sourced and kept separately in sterilized containers, labelled appropriately and transported to the laboratory. The determination of pesticide residue followed the multiresidue pesticide analysis technique called QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe). The results of the analysis indicated the presence of 30 types of pesticides belonging to the four major classes namely Organochlorine, Organophosphate, Carbamate and Pyrethroid. Organophophates such as Dichlorvos were detected in Beans (0.13), Maize (0.12), sorghum (0.05) wheat (0.01), there was significant difference (P<0.05) between the values of sorghum (0.05) and wheat (0.01). Chlorpyrifos was recorded in all the grains, with the concentration in maize being significantly different (P<0.05) from that of wheat. Pirimiphos methyl was present in all the grains sampled and had the highest concentration among the organophosphate residues. Its values ranged from (0.08-0.27). Of the organophosphates, mevinphos had the lowest concentration which was only detected in wheat. For the organochlorine pesticides, Aldrin had the highest concentration in the beans and wheat samples and the lowest concentration occurred in maize and sorghun. For Carbamate, carbaryl (0.18) had the highest concentration in beans and propoxur (0.03) had the lowest concentration. Pyrethroids had the highest concentration in cypermethrin for beans and maize. Generally, wheat samples had the highest amounts of residues according to this study. Although the concentration found in the grains were below the maximum residue limits, their detection is an evidence of their presence. Hence, this calls for the need for regulatory agencies for more stringent monitoring and regulation in the use of pesticides.