Rapid Biomonitoring of Heterocyclic Aromatic Amines in Human Urine by Tandem Solvent Solid Phase Extraction Liquid Chromatography Electrospray Ionization Mass Spectrometry

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• 作者：Ricky D. Holland ; Jason Taylor ; Laura Schoenbachler ; Richard C. Jones ; James P. Freeman ; Dwight W. Miller ; Brian G. Lake ; Nigel J. Gooderham ; and Robert J. Turesky
• 刊名：Chemical Research in Toxicology
• 出版年：2004
• 出版时间：August 2004
• 年：2004
• 卷：17
• 期：8
• 页码：1121 - 1136
• 全文大小：333K
• 年卷期：v.17,no.8(August 2004)
• ISSN：1520-5010

文摘

A rapid and facile tandem solvent solid phase extraction method was established to isolatethe heterocyclic aromatic amines (HAAs) 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (8-MeIQx), 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine, and 2-amino-9H-pyrido[2,3-b]indole from urine. The HAAs were separated byreversed phase liquid chromatography and quantified by electrospray ionization tandem massspectrometry (ESI/MS/MS) using selected reaction monitoring. The limits of detection andquantitation of these HAAs approached 1-3 and 2-8 pg/mL, respectively, using only 0.3 mLof urine for analysis. Full product ion spectra were acquired to corroborate analyte identities.The pretreatment of urine from human volunteers that had consumed a grilled beef meal withacid or base at 70 C increased the concentration of HAAs by as much as 6-fold, indicating thepresence of phase II conjugates of the parent compounds. HAAs containing an N-methylimidazole moiety undergo facile cleavage of the N-methyl group under collision-induced dissociationconditions, and MS/MS analysis in the constant neutral loss scan mode monitoring thetransition [M + H]⁺ [M + H - CH₃]⁺ revealed the presence of two other HAAs. 2-Amino-3-methylimidazo[4,5-f]quinoxaline (IQx) was identified by coelution of the analyte with syntheticIQx and by acquisition of the product ion spectrum. The second HAA was present in a relativelyhigh abundance in urine. The molecule had the same nominal mass as 8-MeIQx (MH⁺ at m/z214), and the product ion spectrum was similar to that of 8-MeIQx. This novel HAA was alsofound in the grilled meat consumed by the volunteers at a concentration of 8 parts per billion.The accurate mass measurement and product ion spectrum of this molecule by ESI quadrupoletime-of-flight mass spectrometry revealed that it was an isomer of 8-MeIQx. This tandemsolvent solid phase extraction LC/ESI/MS/MS procedure may be used to rapidly assess thedaily exposure to a variety of HAAs in urine.