Heatmap-Based Qualitative Chemical Profiling of Cowpea (Vigna unguiculata) from Multiple Nigerian States Indicates Low Pesticide Incidence: Prospect for Lifting the EU Ban II
DOI:
https://doi.org/10.47941/jfs.3337Keywords:
Food safety, food security, Maximum Residue Limit (MRL), Integrated Pest Management (IPM), cowpea (Vigna unguiculata).Abstract
Purpose: Application of inorganic pesticides in agriculture is a measure often used to mitigate food insecurity due to pest infestation, plant diseases and low weed induced malnutrition of plants. However, with an increasing mortality rate secondary to pesticide poisoning and incidences of novel diseases with idiopathic reference, food safety awareness is on the rise. This study assessed the qualitative incidences of pesticide residues on cowpea seeds randomly sampled from major open markets and storage facilities across 12 Nigerian states where cowpea is predominantly cultivated.
Methodology: Here, we analyzed cowpea samples collected from open markets and storage facilities across 12 States in Nigeria for pesticide residues, using QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) sample preparatory method prior to quantitative analysis by GC-MS. Two hundred and six unique compounds were identified from the sorting and compilation of the 50 most intense chromatographic peaks (>0.5% relative abundance) detected per sample, manually traced to dual databases for benchmarked referencing and categorized into 3 broad classes of chemicals: pesticides, bioactive and inert/ method-associated compounds. The data generated were formatted into a heatmap to enable comprehension at a cursory glance.
Findings: Below 1% of the total number of identified compounds were known pesticides (dichlorvos and chlorpyrifos) with each incidence traceable to two sampling locations out of the 12 Nigerian states covered. The findings indicate low incidence of pesticide contamination on Nigerian cowpea, within the surveyed locations.
Unique Contribution Theory, Policy and Practice: In view of the lingering ban on the export of Nigerian cowpea to the European Union member countries, this study provides information on the adherence of farmers and storers of cowpea to food safety regulations with specific regards to pesticide application prior to harvest and during storage.
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Copyright (c) 2025 Ogah Bliss Idoko, Marcos A. Neves, Vincent Isegbe, Henry Okoro
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