SIMULTANEOUS DETECTION OF VITAMIN C AND URIC ACID IN NORMAL AND ABNORMAL HUMAN AQUEOUS HUMOR AND PLASMA SAMPLES BY CAPILLARY ELECTROPHORESIS

CHENG ML1 LEE HWH2, HSU BRS3, LIU TZ4, CHIU DTY1.

1School of Medical Technology, Chang Gung University & 2Department of Ophthalmology, and 3Department of Endocrinology & Metabolism, Chang Gung Memorial Hospital, Kwei-san, Tao-yuan, Taiwan and 4Yuan's General Hospital, Kaohsiung Taiwan

Ascorbic acid (vitamin C) is a very important nutrient and biological antioxidant. Uric acid is an important metabolite and has also been proposed to provide antioxidant defense in human against radical-caused aging and cancer. An improved rapid and simple method for the simultaneous determination of ascorbic acid and uric acid by capillary electrophoresis (CE) is described. The analysis was performed by a commercial CE apparatus having a 40 cm long fused-silica capillary with an inside-diameter of 75 mm in 50 mM tricine running buffer, pH 8.8. Both compounds were monitored by UV absorbance at 254 nm. This method required less than 50 ml of sample and had a detection limit of less than 2.0 mg/ml for both ascorbic acid and uric acid. Applying this method to various normal and pathologic human specimens, we found that diabetic patients had significantly (p<0.05) lower plasma ascorbic acid level (4.84 0.34 mg/ml, mean SD, N=47) than normal controls (11.23 0.68 mg/ml, mean SD, N=42). We also found that patients with acute anterior uveitis had significantly (p<0.05) lower ascorbic acid level (65.9 43.5 mg/ml, mean SD, N=13) than normal controls (152.03 56.30 mg/ml, mean SD, N=8) but significantly (p<0.05) higher uric acid level (39.15 19.37 mg/ml, mean SD, N=13) than normal controls (9.00 5.12 mg/ml, mean SD, N=8) in their aqueous humor.


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