IOSR Journal of Environmental Science, Toxicology and Food Technology (IOSR-JESTFT) e-ISSN: 2319-2402,p- ISSN: 2319-2399.Volume 15, Issue 7 Ser. I (July 2021), PP 41-46 www.iosrjournals.org DOI: 10.9790/2402-1507014146 www.iosrjournals.org 41 | Page GC-ECD Organophosphate Pesticide Residues Analysis In Water, Fish And Sediment in River LOKO, Nasarawa State, Nigeria Osuegba, S.O 1 , Tukura B.W 2 , Eluyera, I.M 3 , Kadriri, H.G 4 , Anyim, P.BG 5 1,2,3,5, Chemistry Department, Nasarawa State University, Keffi, Nigeria Abstract: Levels of organophosphate pesticide residues (OPPs) in sediment, water and fish in Benue River at Loko Nasarawa State, Nigeria were evaluated for possible pollution of the aquatic ecosystem. Water and sediment samples were collected were collected at from the river at 3 locations. Fish caught in the river were bought from fishermen at the bank of the river. Liquid-liquid extractions of samples were carried out, and then quantified using gas chromatography coupled electron caption detector (GC-ECD). Concentrations of OPPs ranged from 0.09±0.04 to 1.84±0.02, 0.04±0.03 to 1.79±0.01 and 0.01 to 1.81 μ ɡ/kɡ in sediment, water and fish respectively. Concentrations of dichlorovos was the highest in the samples; with the highest and lowest levels also recorded in sediment (1.84±0.02) and water (1.79±0.01 μ ɡ/kɡ) respectively. Level of OPPs Analysis of Variance (ANOVA) shows that the concentrations of OPPs in sediment and fish were not significantly different (p ≤ 0.05) except for dichlorovos, triazophos and fenitrothion. Correlations for OPPs in sediment and water were almost perfectly positive (0.919 – 0.999) except for methidathion which was negatively weak (- 0.331). Between sediment and fish samples, correlations varied from negatively strong to moderately positive were weak and negative (-0.81 to 0.500). Concentrations of OPPs were within the FAO/WHO acceptable limits. However, strict law enforcement is still needed to manage the environmental hazards as a result of this toxic chemicals, for the protection of the aquatic ecosystem. Keywords: Accumulation, Organophosphate, Pesticides, Aquatic environment. --------------------------------------------------------------------------------------------------------------------------------------- Date of Submission: 28-06-2021 Date of Acceptance: 12-07-2021 --------------------------------------------------------------------------------------------------------------------------------------- I. Introduction Environmental pollution is the introduction of harmful contaminants to the environment through various means such as gases, liquids and wastes, thereby making the surrounding unhealthy for living organisms. Because of the widespread of these contaminants (organic or inorganic), the ecosystem is at great risk 1 . The majority of these pollutants most especially the organic (herbicides and insecticides) are potentially toxic for organisms some being connected to disease development, including cancer and other related diseases in humans 2, 3, 4 . Organophosphates are insecticides containing phosphorus. They are often called organic phosphates, phosphorus insecticides, nerve gas relatives, phosphates, phosphate insecticides, and phosphorus esters or phosphoric acid esters 5 . Organophosphates (OPP) are less persistent in the environment than the organochlorine pesticides, because they are relatively soluble in water, and are mobilized by precipitation therefore, they tend to have virtually replaced the persistent organochlorine compounds 6, 7 . This research, therefore evaluates the levels of OPPs in water, sediment and fish samples in Loko River.