Unit Code 80313:
Xanthine and Hypoxanthine, Urine
Method Description
Diluted, filtered urine is mixed with an internal standard (8-13 C Adenine)
and analyzed for xanthine and hypoxanthine by liquid chromatography
tandem mass spectrometry (LC-MS/MS). LC-MS/MS is performed using
a mobile phase composed of 50 mM ammonium formate, ph=5, and 1:1
mixture of 50 mM ammonium formate, ph=5: methanol and run using a
gradient. An Xterra MS C18 column (2.1 x 150 mm) is used to separate
xanthine and hypoxanthine from the bulk of the specimen matrix. The
MS/MS is operated in the selected reaction monitoring (SRM) scanning
mode. The ratios of the extracted peak areas of xanthine and hypoxanthine
to an internal standard are used to calculate the concentration of xanthine
and hypoxanthine present. (Ito T, van Kuilenburg AP, Bootsma AH, et al:
Rapid screening of high-risk patients for disorders of purine and pyrimidine
metabolism using HPLC-electrospray tandem mass spectrometry of
liquid urine or urine-soaked filter paper strips. Clin Chem 2000;46:445-452)
Performing Laboratory Location
Rochester
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