Abstract:
Twenty five different brands of rice from Lagos markets in Nigeria were sampled and assessed for Ochratoxin A (OTA) contamination using High Performance Liquid Chromatography (HPLC). Samples were homogenized by grinding and extracted with 12.5 mL of 0.1 M phosphoric acid and 125 mL of methylene chloride. The extracts were cleaned-up with a syringe packed with acid washed Celite 545 column fitted to a solid phase extraction vacuum manifold and the analyte was eluted with methylene chloride/formic acid. The extract was pre-concentrated prior to HPLC analysis. Result indicated that OTA level in pic rice was non-detectable. Twenty four of the twenty five brands of rice analyzed contained trace levels of OTA, the content of which ranged from 0.01 ng g-1 in miss lily parboiled rice to maximum concentration of 2.18 ng g-1 in rice king. The mean concentration was 0.34 ng g-1. The low level of contamination evident from the study suggested that consumption of rice available in Lagos markets was relatively safe. Results indicated that the levels of OTA in the rice samples were within acceptable limits. Recovery of Ochratoxin A in selected samples on spiking ranged from 84.6-92.5%, the mean recovery being 89.8%.