國家衛生研究院 NHRI:Item 3990099045/2464

NHRI > National Institute of Environmental Health Sciences > Louis W. Chang(1999-2009) > Periodical Articles > Item 3990099045/2464

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Title:	Rapid and sensitive quantification of urinary N7-methylguanine by isotope-dilution liquid chromatography/electrospray ionization tandem mass spectrometry with on-line solid-phase extraction
Authors:	Chao, MR;Wang, CJ;Yang, HH;Chang, LW;Hu, CW
Contributors:	Division of Environmental Health and Occupational Medicine
Abstract:	A rapid, highly specific and sensitive isotope-dilution liquid chromatography/tandem mass spectrometry (LC/MS/MS) method coupled with an on-line solid-phase extraction (SPE) system was developed to measure N7-methylguanine (N7-MeG) in urine. N-15(5)-Labeled N7-MeG was synthesized to serve as an internal standard, and an on-line SPE cartridge was used for on-line sample cleanup and enrichment. The urine sample can be directly analyzed within 15 min without prior sample purification. The detection limit for this method was estimated as 8.0 pg/mL (4.8 pmol) on-column. This method was further applied to study exposure to methylating agents arising from cigarette smoke. Sixty-seven volunteers were recruited, including 32 regular smokers and 35 nonsmokers. Urinary cotinine, a major metabolite of nicotine, was also determined using an isotope-dilution LC/MS/MS method. The results showed that urinary levels of N7-MeG observed in smokers (4215 +/- 1739 ng/mg creatinine) were significantly (P < 0.01) higher than those in nonsmokers (3035 +/- 720 ng/mg creatinine). It was further noted that the urinary level of N7-MeG was found to be correlated with that of cotinine for smokers, implying that cigarette smoking resulted in increased DNA methylation, followed by depurination and excretion of N7-MeG in urine. As a result of the on-line extraction system, this method is capable of routine high-throughput analysis and accurate quantitation of N7-MeG, and could be a useful tool for health surveillance of methylating agent exposure.
Keywords:	Chemistry, Analytical;Spectroscopy
Date:	2005
Relation:	Rapid Communications in Mass Spectrometry. 2005;19(17):2427-2432.
Link to:	http://dx.doi.org/10.1002/rcm.2082
JIF/Ranking 2023:	http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=NHRI&SrcApp=NHRI_IR&KeyISSN=0951-4198&DestApp=IC2JCR
Cited Times(WOS):	https://www.webofscience.com/wos/woscc/full-record/WOS:000231654100008
Cited Times(Scopus):	http://www.scopus.com/inward/record.url?partnerID=HzOxMe3b&scp=24644470533
Appears in Collections:	[Louis W. Chang(1999-2009)] Periodical Articles

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