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Journal of Analytical Methods in Chemistry
Volume 2012 (2012), Article ID 245415, 8 pages
http://dx.doi.org/10.1155/2012/245415
Research Article

LC-MS-MS Measurements of Urinary Creatinine and the Application of Creatinine Normalization Technique on Cotinine in Smokers’ 24 Hour Urine

1China National Tobacco Quality Supervision and Test Center, Zhengzhou 450001, China
2Department of Urology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, China

Received 14 February 2012; Revised 29 August 2012; Accepted 31 August 2012

Academic Editor: Josep Esteve-Romero

Copyright © 2012 Hongwei Hou et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

A simple and sensitive high performance liquid chromatography-tandem mass spectrometry (HPLC-ESI-MS-MS) method was developed and validated for the quantification of creatinine in human urine. The analysis was carried out on an Agilent Zorbax Eclipse XDB-C18 column (  mm, 3.5 μm). The mobile phase was 0.1% formic acid in water and 0.1% formic acid in acetonitrile (50/50, v/v). Linear calibration curves were obtained in the concentration range of 1–2000.0 ng/mL, with a lower limit of quantification of 0.99 ng/mL. The intra- and interday precision (RSD) values were below 3%. The method was successfully applied to a bioequivalence study of creatinine in Chinese smokers and nonsmokers. The total cotinine in 24 h urine and cotinine : creatinine ratio were also positively associated (Pearson , ). However, cotinine : creatinine ratio varied significantly across smoking groups for the difference of individual. 24 h urinary cotinine was more appropriate for expressing correlation with tar than cotinine : creatinine ratio.