Analytical Sciences

Kinetic Determination of Uric Acid in Urine Based on Single-Line Flow-System with Multi-Site Detection

Alberto N. ARAÚJO * , José A. M. CATITA and José L. F. C. LIMA

CEQUP/Dep. Química-Física, Faculdade de Farmácia, Universidade do Porto, Rua Aníbal Cunha 164, 4050 Porto, Portugal

A flow injection system based on multi-site detection for kinetic spetrophotometric determination of uric acid in urine is described. The system was studied regarding physical dispersion, elimination of sample matrix interferences and applica-bility to real samples. In the optimized system, the sample is inserted into a water stream which merged downstream with the reagent solution containing iron(II) chloride and TPTZ. This system enables the determination of about 30 samples/h, and yields precise results (RSD usually <2.9%). Sensitivity is 212 mAU l/mmol up to 0.60 mmol/l uric acid. Accuracy was assessed by running 32 samples already analyzed by a conventional enzymatic procedure. No statistical difference between methods was found at the 95% confidence level. (Keywords: Multi-site detection, continuous flow kinetic determination, uric acid, urine)

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