Uric acid spectrometry

Ellerbe P, Cohen A, Welch MJ, and White V E (1990) Determination of serum uric acid by isotope dilution mass spectrometry as a candidate definitive method. Anal. Chem 62 2173-2177. 

Volk, K. J., Yost, R. A., and Brajter-Toth, A. (1989). On-line electrochemistry/thermospray/ tandem mass spectrometry as a new approach to the study of redox reactions The oxidation of uric acid. Anal. Chem. 61 1709-1717. 

Chen, X.B. Calder, A.F. Prasitkusol, P. Kyle, D.L. Jayasuriya, M.C.N. Determination of isotopic enrichment and concentrations of allantoin and uric acid in urine by gas chromatography/mass spectrometry. J. Mass Spectrom. 1998, 33, 130-137. 

Specific Method for Determining Uric Acid in Serum Using High Perform- 2403. ance Liquid Chromatography and Gas Chromatography-Mass Spectrometry J. Chromatogr. 149 711-720 (1978) CA 89 38949s... 

Other methods employed. The activity of OAD in patient leukocytes was determined by a method described by Ohnuma and Holland (17). Quantification of orotic acid and orotidine was made by column chromatography (8). Urinary uric acid was measured by the technique of Pileggi al. (18). Orotic acid, orotidine, and urinary uric acid were also separated by high pressure liquid chromatography (19) using a u-C 3 column and O.IM formic acid at a flow rate of 0.5 ml/min. Constituents were collected, evaporated to dryness with dry nitrogen, derivatized into the trimethylsilyl derivative as described above and positively identified by mass spectrometry. 

The feasibility of on-line electrochemistry mass spectrometry in the study of electrode processes has recently been demonstrated by Heitbaum et al. . We have tested the potential of on-line mass spectrometry in the study of redox reactivity of biological compounds with uric acid as a probe. Electrochemical oxidation of uric acid has been studied extensively . The scheme in Figure 6 shows the electrochemical oxidation pathway of uric acid and indicates intermediates and products which were identified by on-line electrochemistry thermospray mass spectrometry (EC/TSP/MS/MS) . In our studies, tandem mass spectrometry (MS/MS) was used to obtain structurally informative fragmentation patterns (daughter spectra) of standards for comparison to the mass spectra of intermediates and products obtained by EC/TSP/MS/MS. This, for example, allowed identification of allantoin through its characteristic daughter spectrum. It also allowed confirmation of the structural features of the intermediate, bicyclic carboxylic acid, which apparently forms from the imine alcohol in the oxidation of uric acid. The intermediates and products which were identified in this way are indicated in the scheme, and mass spectral results are summarized in Table 1. 

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