The simplified synthesis of AFB1-lys/ AFG1-lys to produce analytical standards for human exposure analysis

Aflatoxin B₁ (AFB₁) is a carcinogenic mycotoxin that can be found contaminating crops such as maize and ground nuts worldwide. It is a carefully monitored for mycotoxin with 99 countries, accounting for 87% of the global population, having in place systems to monitor for AFB₁. The most common estimate for human exposure to aflatoxin is by urinary excretion of the hydroxylated AFB1 metabolite AFM1 however it only provides an estimate of recent AFB1 exposure. Chronic AFB1 exposure can be measured by quantifying the AFB1-human serum albumin adduct. This is reported with techniques like ELISA, HPLC, or LC-MS/MS and measures the amount of AFB₁-lysine released after proteolysis of serum albumin. Although measuring this toxic is very important from a human health perspective, analytical standards and reference materials are not commercially available. This work goes outlines a simplified synthesis of, unlabelled and isotopically labelled, AFB₁-lys without the production of AFB₁-lysine epoxide, a potent carcinogen. Additionally, the stability of these standards under long-term storage was determined. We also synthetically linked AFB1 to human serum albumin in order to make reference material.