Gas Chromatography-Mass Spectrometry Analysis of some Organochlorine Pesticides in Cowpea from South-South of Nigeria

Abstract

Background: Organochlorine pesticides used illegally in the storage of cowpeas by some farmers to prevent attack by weevils were known to affect the health of human adversely.

Objectives: This study determined the mean concentration of aldrin, o,p΄-DDT, endosulfan, heptachlor epoxide and γ-HCH collected from some markets in South-South of Nigeria, compared these concentrations with set standards and ascertained the incidence of occurrence in cowpeas.

 Methods: Forty-eight samples of cowpeas were randomly collected from local markets, identified, authenticated, extracted with dichloromethane using Soxhlet apparatus, cleaned-up with silica gel and analysed in a GC-MS using Restek column.

Results: The mean concentration of aldrin (445.08±6.43) µg/kg, heptachlor epoxide (188.84±3.42) µg/kg, o,p΄-DDT (182.24±5.13) µg/kg, endosulfan (142.94±2.05) µg/kg and γ-HCH (243.90±4.01) µg/kg in some markets were high and above the maximum residual limit.

Conclusion: Organochlorine pesticides are used in most of the markets in south-south Nigeria for the preservation of cowpeas and in some cases, two or more were detected in a given sample, which could be due to the addition of a combination of pesticides. The need for regular monitoring by regulatory agencies and for sensitisation of both the farmers and merchants on the danger of using these pesticides in cowpeas preservation is therefore germane.