Analytical Sciences

Determination of Uric Acid in Plasma by LC-MS/MS and Its Application to an Efficacy Evaluation of Recombinant Urate Oxidase

Xi LUO,* Ningfang CAI,*,** and Zeneng CHENG*

*Research Institute of Drug Metabolism and Pharmacokinetics, School of Pharmaceutical Sciences, Central South University, 410013 Changsha, Hunan, P. R. China
**Zhangzhou Municipal Hospital of Fujian Province, 363000 Zhangzhou, Fujian, P. R. China

A liquid chromatography–tandem mass spectrometry (LC-MS/MS) method for the determination of uric acid in human plasma was developed and validated. Separation was achieved on a C18 column by the mobile phase of 30% water (containing 0.5% formic acid) and 70% methanol. Quantification was done using a multiple reaction monitoring (MRM) mode to monitor the precursor-to-product ion transitions of m/z 169.1 → m/z 141.1 for uric acid and m/z 171 → m/z 143 for 1,3-¹⁵N uric acid (IS) at a positive ionization mode. The calibration curve was established over the range of 0.4096 – 100 mg/L, and the correlation coefficient was better than 0.99. The intra-day and inter-day relative standard deviations were less than 5.1%. The accuracy determined at three concentrations ranged between 92.7 and 102.3%. This method was successfully applied to an efficacy study of intravenous recombinant urate oxidase produced by Escherichia coli in a clinical phase I study.

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