A Gas Chromatography/Electron Capture/Negative Chemical Ionization High-Resolution Mass Spectrometry Method for Analysis of Endogenous and Exogenous N7-(2-Hydroxyethyl)guanine in Rodents and It
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- 作者：Kuen-Yuh Wu ; Nova Scheller ; Asoka Ranasinghe ; Ten-Yang Yen ; Ramiah Sangaiah ; Roger Giese ; and James A. Swenberg
- 刊名：Chemical Research in Toxicology
- 出版年：1999
- 出版时间：August 1999
- 年：1999
- 卷：12
- 期：8
- 页码：722 - 729
- 全文大小：217K
- 年卷期：v.12,no.8(August 1999)
- ISSN：1520-5010
文摘
A gas chromatography/electron capture/negative chemical ionization high-resolution massspectrometry (GC/EC/NCI-HRMS) method was developed for quantitating N7-(2-hydroxyethyl)guanine (N7-HEG) with excellent sensitivity and specificity. [4,5,6,8-13C4]-N7-HEG wassynthesized, characterized, and quantitated using HPLC/electrospray ionization mass spectrometry (HPLC/ESI-MS) so it could serve as an internal standard. After being converted toits corresponding xanthine and derivatized with pentafluorobenzyl (PFB) bromide twice, thePFB derivative of N7-HEG was characterized using GC/EC/NCI-HRMS carried out at full scanmode. The most abundant fragment was at m/z 555, with a molecular formula of C21H9N4O3F10,resulting from the loss of one PFB group. By monitoring m/z 555.0515 (analyte) and m/z559.0649 (internal standard), this assay demonstrated a linear relationship over a range of 1fmol to 1 pmol of N7-HEG versus 20 fmol of [13C4]-N7-HEG on column. The limit of detection(LOD) for the complete assay was 600 amol (S/N = 5) injected on column. The variation of thisassay was within 15% from 1 to 20 fmol of N7-HEG versus 2 fmol of [13C4]-N7-HEG with fourreplications for each calibration standard. Two hundred to three hundred micrograms of spleenDNA of control rats and mice and 100 
g of spleen DNA of rats and mice exposed to 3000 ppmethylene for 6 h/day for 5 days were analyzed using GC/EC/NCI-HRMS. The amounts of N7-HEG varied from 0.2 to 0.3 pmol/mol of guanine in tissues of control rats. Ethylene-exposedanimals had 5-15-fold higher N7-HEG levels than controls. This assay was able to quantitateN7-HEG in 25-30 g of DNA from human lymphocytes with excellent specificity. This wasdue in part to human tissues having 10-15-fold higher amounts of endogenous N7-HEG thanrodents. These results show that this GC/EC/NCI-HRMS method is highly sensitive and specificand can be used in biological monitoring and molecular dosimetry and molecular epidemiologystudies.
g of spleen DNA of rats and mice exposed to 3000 ppmethylene for 6 h/day for 5 days were analyzed using GC/EC/NCI-HRMS. The amounts of N7-HEG varied from 0.2 to 0.3 pmol/mol of guanine in tissues of control rats. Ethylene-exposedanimals had 5-15-fold higher N7-HEG levels than controls. This assay was able to quantitateN7-HEG in 25-30 g of DNA from human lymphocytes with excellent specificity. This wasdue in part to human tissues having 10-15-fold higher amounts of endogenous N7-HEG thanrodents. These results show that this GC/EC/NCI-HRMS method is highly sensitive and specificand can be used in biological monitoring and molecular dosimetry and molecular epidemiologystudies.