Comparison of three methods for the determination of aflatoxin in copra meal

A comparison of the methods of the Association of Official Analytical Chemists (AOAC), the American Oil Chemists' Society (AOCS), and the European Community (EC) was carried out on a batch of randomly collected copra meal (CM) samples from a selected copra miller. Only aflatoxin (AF) B1 was found in the CM sample analysed. Precision tests showed the AFB1 mean value, standard deviation (SD) and coefficient of variation (CV), respectively, to be 8.9 micrograms/kg +/- 1.4 and 16.5% by the AOAC method; 10.4 micrograms/kg +/- 1.1 and 10.9% by the AOCS method; and 11.3 micrograms/kg +/- 0.9 and 8.1% by the EC method. Accuracy experiments done by spiking the CM samples with 10 micrograms standard AFB1 yielded mean recovery, SD and CV, of 106% +/- 10.7 and 10.1%, respectively, by the AOAC; 96% +/- 25.4 and 26.4%, by the AOCS; 91% +/- 10.4 and 11.4%, by the EC methods. The three methods were also compared in terms of their cost, time of analysis, skills and equipment requirements. The precision, accuracy and practicality data obtained indicated that the EC and AOCS methods are more appropriate for the analysis of copra meal aflatoxin under present FNRI conditions. The EC method was also found to be comparable with the high performance thin layer chromatography (HPTLC) (Camag TLC Scanner with Integrator) method employed by two aflatoxin laboratories, one based at the Philippine Coconut Authority in the Philippines and another at the Natural Resources Institute in the UK.