Smaller laboratory sample masses yield lower measured aflatoxin concentrations in heterogeneous maize and groundnut lots.

Aflatoxin contamination in cereals and oilseeds is highly heterogeneous, making representative laboratory sampling a major challenge. Although laboratory sample mass is recognised as an important determinant of sampling uncertainty, its relationship with the aflatoxin concentration obtained from heterogeneous lots has received limited direct investigation. This study evaluated the association between laboratory sample mass and measured aflatoxin concentration in groundnut and maize lots. Groundnut slurry samples were assessed at laboratory sample masses of 3 and 7 kg, while maize samples were assessed at 1, 5, and 10 kg. Aflatoxins were quantified using VICAM AflaTest immunoaffinity clean-up and fluorometric detection. Across the studied lots, larger laboratory sample masses generally yielded higher measured aflatoxin concentrations than smaller masses, with statistically significant differences in most comparisons. These findings indicate that laboratory sample mass can influence the aflatoxin concentration obtained from heterogeneous lots and should therefore be clearly specified in experimental design, method reporting, and interpretation.