Peter Scholl Johns Hopkins School of Public Health, Baltimore, MD Office: 410-955-4235 FAX: 410-955-0617 E-mail: pscholl@jhpsh.edu Job Title: Senior Scientist Ph.D. Environmental Health Sciences from the Johns Hopkins University

Speaker: Peter Scholl, the Johns Hopkins School of Public Health, Baltimore, MD

Topic: Development of an Immunoaffinity Based LCMS Method for Measuring Lysine-AFB1 Albumin Adduct Concentrations in Serum

Place: Building 549, Auditorium, NCI at Frederick, Frederick, MD

Time: Tuesday, December 14, 2004, at 2:00 PM

Abstract: Aflatoxin B1 (AFB1) is a potent hepatocarcinogenic mycotoxin implicated in the etiology of liver cancer in Asia and Sub-Saharan Africa. Exposure is most often estimated in human molecular epidemiologic studies by measuring the AFB1-albumin adduct concentration in blood using RIA and ELISA protocols. However, these methods can yield AFB1 exposure estimates 3 to 10-fold greater than when HPLC with fluorescent detection is used to detect lysine-AFB1. Mass spectrometry can be used to quantitatively detect aflatoxin-albumin adducts with greater specificity than any of these methods. Here we report a convenient method for the preparation of 4,4,5,5-D4-lysine-AFB1 and the development of an isotopic dilution LCMS method to measure the concentration of lysine-AFB1 in serum. Pronase digested serum samples are processed, after spiking with the internal standard, using aflatoxin immunoaffinity resin and reverse phase chromatography. Lysine-AFB1 and the D4 internal standard are detected via positive ion ESI with select reaction monitoring. This assay shows potential for use in future molecular epidemiologic studies of liver cancer to more accurately and precisely measure AFB1 albumin adduct concentrations.