The Value of Oxalate Determination by High-Performance Liquid Chromatography in Clinical Practice
Approximately 70% of human urinary calculi contain calcium oxalate. Therefore, measurement of oxalate in urine is important clinically. Various methods for measuring oxalate have been reported, but most are unsuitable for clinical practice. Recently, high-performance liquid chromatography (HPLC) has enabled excellent separation of fatty acids and other low molecular substances to be made from biological fluids. The method is simple and accurate but because the UV detection of fatty acids (at 210 nm or below) is poor in terms of sensitivity and selectivity, they have to be derivatized to produce a stronger absorbance. Some investigators have labeled oxalate with a UV-absorbing compound and with it have assayed oxalate directly in urine. We have used 9-anthryldiazomethane (ADAM) as a labeling reagent for carboxylic acids1and found that oxalate reacted smoothly with it to form a fluorescent diester derivative. Aliquots of the reaction mixture were chromatrographed directly on HPLC and analyzed.
KeywordsHPLC Acetonitrile Carboxyl Oxalate Xylene
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