Figure 3.

Pioneers of AFB₁ discovery and biomarker development. (A) Proposed structures of AFB₁ and AFG₁ by George Büchi on 22 March 1963 and reported later that year by Büchi, Wogan and colleagues [6]. Professor Gerald Wogan was the doctoral mentor for Prof. Groopman. Courtesy of Prof John Essigmann, MIT. (B) Initial chromatography of aflatoxin–N⁷–guanine by HPLC and photodiode array detection in human urine in 1987 by Groopman. (C) Dr Groopman with his first HPLC (1981). Courtesy of Prof. John Groopman. (D) Mass spectrometry of aflatoxin–lysine adduct standard and in rat serum. * Indicates position of stable isotope labels for internal standard. (E) John Groopman with his first mass spectrometer for biomarker quantification, a Thermo LCQ (2000). Photo courtesy of Thomas Kensler. (F) John Groopman measuring volumes of urine in samples collected during molecular epidemiology studies and chemoprevention clinical trials in Qidong, China, an endemic area for aflatoxin exposure, with a high incidence of liver cancer (2016). Photo courtesy of Thomas Kensler.