Abstract:
The use of pesticide for effective pests control has generated a lot of concerns relating to public health and environmental pollution. With the new European Union legislation on maximum residue limits allowed on food, effort are now intensified to seek measures towards it reduction. This research is focused on identifying and quantifying pesticide residue in kola nut samples obtained from four major markets in Akure metropolis and comparing it with the maximum residue limit. The Kola samples were purchased from Irese, Owena, Ogbese and Akure markets respectively. Sample from each markets were air dried and pulverized and about 4g of the pulverized samples was extracted with cold extraction (acetonitrile saturated with hexane) and hot extraction (hexane). Pesticide residue determination was done using Liquid chromatography- Mass Spectroscopy (LC-MS) and Electrospray Ionization (ESI) as the interface. Both cold and hot extraction methods were used to ascertain pesticides found in the samples. Results represented on each chromatogram showed various peaks with carbamates as the0 major pesticides identified; the study showed there was no matrix effect which could cause enhancement and suppression of the peaks. However, comparing the mass to charge ratio of compounds present in the samples with available standards, pesticides including Carbaryl (0.007-0.057mg/kg), Carbofuran (0.0005-0.0460g/kg), Abamectin (0.002-0.003mg/kg), Thiabendazole (0.0049-0.0081mg/kg), Methiocarb (0.00046-0.0031mg/kg), Mercaptodimethur (0.0010-0.0041mg/kg), 4, 4 DDE (0.00018mg/kg), and Carbendazim (0.0018-0.0398mg/kg) were identified using both extraction methods. With quantification, it was discovered that these pesticides were found below the typical maximum residue limits (MRLs) in the range of 0.01 and 5mg/kg. The identified pesticides belong to the class Carbamates, Organochlorines and Nitrogen Heterocyclic. With the pesticides identified
above falling below the typical maximum residue limit, the farmers and traders may have been enlightened on the use of eco-friendly pesticides which are easily degradable. The presence of the pesticides is an indication that kola nuts processors use hazardous pesticides in the storage of fresh kola nuts, which its persistence in the Kola nut could pose serious health threat to the consumers of the commodity. Despite having the amount of pesticide residue below maximum residue limit, continuous monitoring of all the food products with Kola nut inclusive is recommended.
