BACKGROUND AND OBJECTIVE

Aflatoxin (AF) contamination is one of the major regulatory concerns for animal feed. As feed is a complex analytical matrix, validated methods on AFs in feed are scanty. The available methods involve a derivatization step before AF analysis by high-performance liquid chromatography (HPLC) with fluorescence detection (FLD). The aim of this study was thus to develop and validate a simple and rapid method for direct analysis of AFs (AFB1, AFB2, AFG1, AFG2) in a range of animal feed matrices.

METHODS

Feed samples were extracted with 80% methanol, followed by dilution with water and immmunoaffinity column cleanup. AFs were estimated using an ultra-high performance liquid chromatography (UHPLC) instrument. Use of a large volume flow cell in FLD allowed direct analysis of all AFs with high sensitivity. The method was thoroughly validated in a range of feed matrices.

RESULTS

This sample preparation workflow minimized co-extractives, along with matrix interferences. In pigeon pea husk feed, the method provided a limit of quantification (LOQ) of 0.5 ng/g for each AF with recoveries of AF- B1, B2, G1, and G2 as 71.5, 75.6, 82.4, and 78.2%, respectively. The precision (relative standard deviation, RSD) was below 5%. A similar method performance was also recorded in other matrices, including wheat bran feed and poultry feed.

CONCLUSIONS

The optimized method is suitable for regulatory testing because it is simple, robust, cost-effective, and high throughput in nature, with high sensitivity and selectivity.

HIGHLIGHTS

Our workflow has provided a straightforward method for the analysis of AFs in a wide range of animal feed matrices with high sensitivity, selectivity, throughput, and cost-effectiveness. The method allowed a direct analysis of AFs by UHPLC-FLD without a step of derivatization.