Biomonitoring of DietaryHeterocyclic Amines and Metabolitesin Urine by Liquid Phase Microextraction: 2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), a Possible Biomarker of Exposure to DietaryPhIP.

Heterocyclic amines (HCAs) are mutagenic/carcinogeniccompoundsformed at ng/g levels during frying meat or fish. The effect of thenormal intake of dietary HCAs in humans and their involvement in theetiology of cancer are currently unknown. In this work, a new extractionmethod, liquid phase microextraction (LPME) with hollow fibers, andLC-MS/MS have been used for the first time to determine HCAs and metabolitesin nonspiked human urine following a single meal of chicken cookedat 180 °C for 6 min. The total intake of HCAs was estimated tobe 6 μg, of which 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) accounted for about 1 μg. The concentrationsof PhIP in nonhydrolyzed urine samples ranged from 11.7 to 59.4 pg/g.The total amount of PhIP in urine ranged between 9.3 and 21.1 ng,which corresponds to 0.91–2.1% of the ingested PhIP. In addition,the urine levels of 4′-OH-PhIP (2-amino-1-methyl-6-(4′-hydroxy)phenylimidazo[4,5-b]pyridine) and 5-OH-PhIP (2-amino-1-methyl-6-(5-hydroxy)phenylimidazo[4,5-b]pyridine) also showed a narrow variation between the samples.The analysis of urine samples after acid hydrolysis did not give additionalinformation but showed a notable increase in norharman in some cases.The obtained results suggest PhIP in urine as a possible biomarkerof exposure to HCAs and the LPME and LC-MS/MS method as an appropriatestrategy to biomonitor HCAs in urine. [ABSTRACT FROM AUTHOR]