Optimization and validation of a minicolumn method for determining aflatoxins in copra meal.

A minicolumn (MC) method for determining aflatoxins in copra meal was optimized and validated. The method uses methanol-4% KCl solution as extractant and CuSO4 solution as clarifying agent. The chloroform extract is applied to an MC that incorporates "lahar," an indigenous material, as substitute for silica gel. The "lahar"-containing MC produces a more distinct and intense blue fluoresence on the Florisil layer than an earlier MC. The method has a detection limit of 15 micrograms total aflatoxins/kg sample. Confirmatory tests using 50% H2SO4 and trifluoroacetic acid in benzene with 25% HNO3 showed that copra meal samples contained aflatoxins and no interfering agents. The MC responses of the copra meal samples were in good agreement with their behavior in thin-layer chromatography. This modified MC method is accurate, giving linearity-valid results; rapid, being done in 15 min; economical, using low-volume reagents; relatively safe, having low-exposure risk of analysts to chemicals; and simple, making its field application feasible.

Fusarium mycotoxins (fumonisins, nivalenol, and zearalenone) and aflatoxins in corn from Southeast Asia.

Corn samples collected from the Philippines, Thailand, and Indonesia were surveyed for the natural occurrence of Fusarium mycotoxins (fumonisins, trichothecenes, and zearalenone) and aflatoxins. Fumonisins B1 and B2 were found in over 50% of corn samples in individual countries, and their co-occurrences with aflatoxins at the incidence of 48% were noted. In addition to these mycotoxins, a trichothecene, nivalenol, and an estrogen, zearalenone, both mycotoxins of Fusarium species, were detected in these Southeast Asian samples. This is the first report on the simultaneous occurrence of two carcinogenic mycotoxins, fumonisins and aflatoxins, together with Fusarium mycotoxins (nivalenol and zearlenone) in corn from Asian tropics.

Present status of the aflatoxin situation in the Philippines.

Aflatoxin research in the Philippines started at the FNRI in 1967 with a survey on the aflatoxin content of various foods. Local researchers from government institutions and academe also conducted studies on the aflatoxin contamination of agricultural crops and their products/by-products. The data indicated that corn and peanuts are the two commodities that contain toxic levels of aflatoxin. Past and current research in the country is documented. Problems and research needs for the surveillance and/or control of aflatoxin contamination are discussed.

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.