Abstract:
Watermelon fruits and soil samples (depth of 0 – 20 cm) were analysed for pesticide residues. Residues were extracted from 10.0 g of watermelon fruit using a multi-residue method for extracting pesticides from non fatty foods with acetone as the extracting solvent. Soil and okro from a nearby okro farm which were used as control to study the effect of pesticides on non-target crops were also analysed. Extract cleanup was done using a 10 mm chromatographic column with a 1:1 solvent mixture of Cyclohexane and Dichloromethane as the eluting solvent. Organophosphate pesticides (OPPs), organochlorine pesticides (OCPs) and synthetic pyrethroid pesticides were detected in all the samples. The OPPs levels ranged from 0.90 - 4383.20 μg/kg. OCPs residues occurred in the fruits at levels between 0.70 - 34.50 μg/kg. Synthetic pyrethroid pesticides fell in the range 0.10 - 6.40μg/kg. Non-target crop had residue levels ranging from 2.80 - 2016.80 μg/kg for OPPs, 1.20 - 15.83 μg/kg for OCPs and 3.10 - 7.60 μg/kg for synthetic pyrethroid pesticides. Soil residue levels were in the range 2.0 - 4121.70 μg/kg for OPPs, 1.10 - 12.90 μg/kg for OCPs and 1.10 - 8.20 μg/kg for synthetic pyrethroid pesticides. OPPs levels were appreciably high in all the samples followed by organochlorines and the synthetic pyrethroids. In general, organophosphate pesticides (OPPs) and the organochlorine pesticides (OCPs) levels were significantly higher than the WHO/FAO allowable levels. These show that watermelon fruits were contaminated to significant levels with organochlorine and organophosphate pesticides.
