An aptamer affinity column for purification and enrichment of aflatoxin B1 and aflatoxin B2 in agro-products

We have developed an aptamer affinity column (AAC) for the purification and enrichment of trace aflatoxin B-1 (AFB(1)) and aflatoxin B-2 (AFB(2)) in genuine agro-products through the covalent conjugation of amino modified aptamer and NHS-activated Sepharose. The coupling and working conditions found to be suitable for this AFB-AAC were examined in regard to coupling time (2 min), loading volume (30 mL), and the methanol concentration (< 10%) used in the loading step. The performance of AFB-AAC was then further evaluated in terms of capacity (329.1 +/- 13.7 ng for AFB(1) and 162.5 +/- 8.9 ng for AFB(2)), selectivity (excellent), reusability (twenty-three times for AFB(1) and twelve times for AFB(2)), and repeatability (92.7% +/- 2.9% for AFB(1) and 71.5% +/- 3.4% for AFB(2)). Furthermore, the AAC clean-up combined with HPLC-FLD demonstrated excellent linearity over a wide range, good sensitivity with an LOD of 50 pg mL(-1) for AFB(1) and 15 pg mL(-1) for AFB(2), and acceptable recovery with different spiking levels in different matrices. Finally, the AAC was successfully applied to analyte AFB(1) and AFB(2) in four types of agro-products as well as a maize flour reference material, and the results were found to be in accordance with those of commercial IACs. This study provides a reference for the analysis of other trace analytes by merely changing the corresponding aptamer and represents a strong contender for immune affinity columns. An aptamer affinity column for purification and enrichment of aflatoxin B-1 and aflatoxin B-2 in agro-products with the aid of HPLC-FLD and a post-column photochemical derivatization reactor