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Chem. Res. Toxicol. 2007, 20, 88-94
Hplc/Electrospray Ionization Mass Spectrometric Analysis of the Heterocyclic Aromatic Amine Carcinogen 2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine in Human Milk Kara A. Scott,† Robert J. Turesky,| Bruce C. Wainman,§ and P. David Josephy*,‡ Guelph-Waterloo Centre for Graduate Work in Chemistry and Biochemistry, UniVersity of Guelph, Guelph, Ontario, Canada N1G 2W1, Department of Molecular and Cellular Biology, UniVersity of Guelph, Guelph, Ontario, Canada N1G 2W1, Department of Obstetrics and Gynecology, Midwifery Education Program, McMaster UniVersity, Hamilton, Ontario, Canada L8N 4A6, DiVision of EnVironmental Disease PreVention, Wadsworth Center, New York State Department of Health, Empire State Plaza, Albany, New York 12201-0509 ReceiVed August 11, 2006; ReVised Manuscript ReceiVed October 5, 2006
A new procedure has been developed for the extraction of 2-amino-1-methyl-6-phenyl-imidazo[4,5b]pyridine (PhIP) and other heterocyclic aromatic amines from human breast milk samples. Extracts were analyzed by high-performance liquid chromatography/electrospray ionization/tandem mass spectrometry (HPLC/ESI-MS/MS) with selective reaction monitoring detection. Tandem ESI-MS/MS detection provides much improved sensitivity and specificity, compared with those of a previous method that used selected ion monitoring. Milk samples were collected from 48 healthy volunteers, including five vegetarians. Donors completed a detailed dietary questionnaire. The concentrations of PhIP in the milk samples were low and below the limit of quantification (0.68 pg/mL) for all subjects except one, for whom a concentration of 1.0 pg PhIP/mL was measured. Our results indicate that the levels of PhIP in human milk are substantially lower than what was previously reported. Introduction (HAAs1),
More than 25 heterocyclic aromatic amines mutagenic compounds formed during the cooking of meat and fish (1, 2), have been identified and characterized. Polar HAAs are derived from amino acids, carbohydrates, and creatinine or creatine (3), and they are the predominant HAAs at cooking temperatures between 150 and 250 °C. PhIP is one of the most abundant mutagenic HAAs (4, 5). Well-done grilled chicken, for example, may contain g100 parts per billion (ppb) PhIP so that the dose of PhIP ingested with a chicken meal may exceed 10 µg (6). However, levels of PhIP in meats cooked more moderately are much lower (7). Typical human dietary exposures to PhIP can range from
