Analysis of heterocyclic amines in hair by on-line in-tube solid-phase microextraction coupled with liquid chromatography-tandem mass spectrometry

Mutagenic and carcinogenic heterocyclic amines (HCAs) are formed during heating of various protein-aceous foods, but human exposure to HCAs has not yet been elucidated in detail. To assess long-term exposure to HCAs, we developed a simple and sensitive method for measuring HCAs in hair by automated on-line in-tube solid-phase microextraction (SPME) coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS). Using a Zorbax Eclipse XDB-C8 column, 16 HCAs were analyzed within 15 min. The optimum in-tube SPME conditions were 20 draw/eject cycles of 40 mu L sample at a flow rate of 200 mu L min(-1) using a Supel-QPLOT capillary column as an extraction device. The extracted HCAs were easily desorbed from the column by passage of the mobile phase, with no carryover observed. This in-tube SPME LC-MS/MS method showed good linearity for HCAs in the range of 10-2000 pg mL(-1), with correlation coefficients above 0.9989 (n = 18), using stable isotope-labeled HCA internal standards. The detection limits (SIN = 3) of 14 HCAs except for MeA alpha C and Glu-P-1 were 0.10-0.79 pg mL(-1). This method was successfully utilized to analyze 14 HCAs in hair samples without any interference peaks, with quantitative limits (SIN = 10) of about 0.17-1.32 pg mg(-1) hair. Using this method, we evaluated the exposure to HCAs in cigarette smoke and the suitability of using hair HCAs as exposure biomarkers. (C) 2013 Elsevier B.V. All rights reserved.