POLYCYCLIC AROMATIC HYDROCARBON CONCENTRATIONS IN FOREIGN AND LOCAL RICE SAMPLES FROM ENUGU MARKETS, NIGERIA

Abstract

Concentration levels of sixteen polycyclic aromatic hydrocarbons, PAHs were determined in the Foreign and Local rice from markets in Enugu state Nigeria. Samples of various types of Foreign rice (Indian, Royal stallion, Thailland and Peoples’ choice) and Local rice (Abakaliki, Nzam, Lafia and Adani) were purchased from various markets in Enugu. The samples were extracted by sonication using 3:1 dichloromethane –hexane mixture as solvent followed by clean – up with activated alumina. The measurement of the concentration levels of PAHs was carried out using a gas chromatograph coupled with flame ionization detector (GC- FID). The mean concentrations (× 10-2 µg/kg) of different types of Foreign rice ranged from 25.01 to 28.72 and from 20.01 - 32.66 in Local rice. Anthracene showed the highest concentration in the analyzed Foreign rice at the average of 5.10 while naphthalene showed the lowest concentration at the average of 0.035. Benzo[a]pyrene showed highest concentration in the analyzed Local rice at the average of 4.83 and naphthalene also showed the lowest concentration at 0.08. The PAHs concentrations detected in this study were much lower than 1.0 µg/kg which is the permissible limit established by European Food Safety Authority. This indicates that both the Foreign and Local rice sold in Enugu markets are free from PAHs contamination.Keywords: Rice, Foreign, Gas Chromatography, Local, Polycyclic aromatic hydrocarbons.