The measurement of the aflatoxin B1-lysine serum albumin adduct in human blood samples is the most facile biomarker for the assessment of chronic exposure to aflatoxin B1. Many technologies have been developed for the measurement of this protein adduct including immunoassays, high-performance liquid chromatography (HPLC) with fluorescence detection, and a newly developed isotope-dilution mass spectrometry method. Irrespective of the technology used to determine this adduct level, an important question remains about the long-term stability of this damage product in stored samples. To address this issue, 19 human serum samples that had been previously analyzed for the aflatoxin B1-lysine adduct by high-performance liquid chromatography-fluorescence in 1989 were re-analyzed by isotope dilution mass spectrometry after storage at -80°C. The adduct concentrations measured by these two techniques were identical within 4% over the range 5 to 100 pg of aflatoxin B1-lysine/mg albumin. In addition, the specific chemical structure of the aflatoxin B1-lysine adduct in human samples was confirmed for the first time by collision-induced dissociation full scan mass spectrometry analysis of the protonated adduct molecular ion. These results illustrate that the aflatoxin B1-lysine serum albumin adduct can be stable in human serum stored at -80°C since 1989, and this provides confidence for the measurement of this biomarker in repository samples from epidemiologic investigations.
ASJC Scopus subject areas