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[Determination of Urinary Glycolate by Ion Chromatography: Clinical and Experimental Implication]

K Yamaguchi, Y Ogawa

Nihon Hinyokika Gakkai Zasshi. 1997 Dec;88(12):984-91.

PMID: 9465597

Abstract:

Background:
Small changes in the oxalate concentration exert a greater impact on the urinary calcium oxalate saturation than those in the calcium concentration. Urinary oxalate arises from ascorbate in 30-40% and glycolate in 50-60%. Glycolic acid plays and intermediate role in glyoxylate metabolism being involved in both its synthesis and degradation. A large variation in urinary glycolate values reported in the literature and a potential key role in calcium oxalate urolithiasis prompted us to measure accurately urinary glycolate.
Method:
The ion chromatography used was a Model IC-100 lon Chromatoanalyzer (Yokokawa Electric Co., Ltd.), connected to an autosampler, Model KSST-601 (Kyowa Seimitsu Co., Ltd.). The separator column was TSK-gel IC-anion-PW (Tosoh Co., Ltd.). As the eluent, 0.01 mM phthalate and, as the scavenger, 50 mM dodecylbenzenesulfonic acid were used at a flow rate of 2 ml/min. 24-hour urine samples were obtained from 30 normal healthy males, aged from 20 to 57 years, and 20 male Wistar-strain rats (approximately 160 gm.). These samples were treated with charcoal and diluted 100-fold with distilled water for the determination of glycolate.
Results:
The minimum detectable limit for glycolate was 0.4 mumol/l in a standard solution, and the regression line for the standard curve from 0.4 mumol/l to 2.0 mmol/l glycolate had a significant correlation coefficient (In Y = 0.882 x In X-2.304, r = 0.996, p < 0.01). The intra-run coefficient of variation was 3.44%. The overall intra-run and inter-run coefficient of variation, including the sampling and dilution of urine, were 3.92% and 3.38% respectively. The recovery from the addition of a known amount of glycolate to each 10 urine samples was 100.2 +/- 7.41% (mean +/- S.D.). A comparison of our method with the enzymatic method yielded a significant correlation between the results (r = 0.997, p < 0.01). The 24-hour urinary glycolate excretion in 30 normal men was 0.205 to 1.372 mmol/day (0.746 +/- 0.344 mmol/day, mean +/- S.D.), while that in male Wistar rats was 4.868 to 7.347 mumol/day (6.077 +/- 2.289 mumol/day, mean +/- S.D.), as measured in 20 consecutive rat urine samples.
Conclusion:
The urinary glycolate determination by ion chromatography is simple and not time consuming, requiring a 100-fold dilution of charcoal treated urine and 20 minutes at most for analysis. This method has been proven to be sensitive, specific and reproducible.

Chemicals Related in the Paper:

Catalog Number Product Name Structure CAS Number Price
AS23105 Glycolate Standard for IC Glycolate Standard for IC Price
AS23126 Oxalate Standard for IC Oxalate Standard for IC Price
AS23134 Phthalate Standard for IC Phthalate Standard for IC Price
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