Creatine is found in the urine of subjects ingesting creatine monohydrate a
s an ergogenic aid. Creatinine, the catabolic breakdown product of creatine
, is a major constituent of normal urine. It is of interest to follow the e
xcretion of creatine and creatinine in urine as a function of time after cr
eatine ingestion. In this study, creatine and creatinine were analyzed in u
rine by capillary electrophoresis. The optimization of the method was discu
ssed, with the best results being obtained using a 30 mM phosphate-150 mM s
odium dodecyl sulfate buffer at pH 6, with the detector set at 214 nm and a
n applied voltage of 15 kV across a 45 cm capillary. Verification of the me
thod was provided by HPLC analysis and spiking. The application of the meth
od was demonstrated by analysis of creatine and creatinine in urine samples
collected in a 24-h period following creatine ingestion. (C) 1999 Elsevier
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