Rapid determination of orotic acid in urine by a fast liquid chromatography/tandem mass spectrometric method.
Quantification of orotic acid (uracil-6-carboxylic acid) in urine is an important tool to diagnose some inherited diseases, such as urea cycle disorder (OTCD) and hereditary orotic aciduria. New rapid analytical methods are necessary to provide high-throughput orotic acid analyses. A new analytical method has been developed for the rapid analysis of orotic acid in urine by liquid chromatography coupled with ion spray tandem mass spectrometry (LC/MS/MS). After a sample dilution 1:20, the analysis was performed in the selected reaction monitoring mode in which orotic acid was detected through the transition m/z 155 to 111. The retention time was 3.9 min in a 4.5-min analysis. Daily calibration between 0.5-5.0 micromol/L of orotic acid, corresponding to 10-100 micromol/L in urine before the 1:20 dilution, offered consistent linearity and reproducibility. Interassay coefficient of variance (c.v.) was 4.97% at a mean concentration of 10.99 micromol/L. The sensitivity and specificity of tandem mass spectrometry permitted a high volume of analyses of orotic acid. The sample preparation is simple, inexpensive and not time demanding.
la Marca
Giancarlo
G
Metabolic and Neuromuscolar Unit, 1st Pediatric Clinic, A Meyer Children's Hospital, University of Florence, 50132 Florence, Italy. giancalm@yahoo.com
Casetta
Bruno
B
Zammarchi
Enrico
E
D002138:Calibration; D002853:Chromatography, Liquid / Q000379:methods*; D003404:Creatinine / Q000652:urine; D013058:Mass Spectrometry / Q000379:methods*; D015394:Molecular Structure; D009963:Orotic Acid / Q000737:chemistry / Q000652:urine*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013997:Time Factors
D009963:Orotic Acid; D003404:Creatinine