Incremental samples (50, 100, and 500 g) were systematically collected from
large shipments of copra meal pellets, copra cake, and palm kernel cake to
study the distribution of aflatoxin B-1 and evaluate adherence of distribu
tion to the model, CVis2 (EQ) = A + B/M-is (where CVis = coefficient of var
iation of the true concentration of aflatoxin B-1 within the incremental sa
mples; M-is = mass of the incremental samples; and A and B are constants),
Also evaluated was the distribution of aflatoxin B-1 among 1 kg composite s
amples, produced both by random combination of existing incremental samples
and by collection of 1 kg composite samples (composed of 10 x 100 g increm
ents) from additional batches of copra meal pellets and cottonseed cake. Th
e efficiency of selected sample preparation (grinding and subdivision) proc
edures was compared, culminating in the development and description of a va
riety of sampling plans, The coefficient of variation (CV) among incrementa
l samples varied from 0 to 38%, and was independent of incremental sample s
ize, No significant difference (F-test, 5% significance level) was found be
tween the efficacy of 4 sample preparation methods when these methods were
applied to the commodities described above, Various sampling plans were eva
luated with estimated CVs from 4.0 to 12.5%, for the aflatoxin B-1 content
of the composite samples.