Simultaneous Spectrophotometric Determination of Xanthine, Hypoxanthine and Uric Acid in Real Matrix by Orthogonal Signal Correction-Partial Least Squares

The simultaneous determination of xanthine (XA), hypoxanthine (HXA) and uric acid (UA) mixture using spectrophotometric methods is a difficult task in analytical chemistry because of the spectral interferences. Partial least squares (PLS) modeling, as a powerful rnultivariate statistical tool, were applied to the spectrophotometric simultaneous determination of these substances. The concentration ranges for XA, HXA and UA were 3.0-24.3, 2.7-19.0 and 3.4-25.2 mu g ml(-1), respectively. The experimental calibration set consisted of 21 sample solutions with a mixture design for three-component mixtures. The absorption spectra were recorded from 220 to 320 nm. After orthogonal signal correction (OSC), the unrelated information was removed and the results were proved. The root mean square error of prediction (RMSEP) for xanthine, hypoxanthine and uric acid with OSC were 0.5161, 0.2997 and 0.5739 and without OSC were 1.6087, 0.8580 and 1.4009, respectively. This process afforded the simultaneous determination of XA, HXA and UA in human urine and human serum.