Simultaneous determination of creatine, uric acid and creatinine by high-performance liquid chromatography with direct serum injection and multi-wavelength detection.

An isocratic high-performance liquid chromatographic separation of creatine, uric acid and creatinine with direct on-column application of the serum sample has been developed. The pre-column, used for sample clean-up, is switched out of the eluent flow after a definite time. Simultaneous three-wavelength detection with a diode array detector allows a very precise quantitation of the three compounds at the optimum wavelength for each (210, 234 and 290 nm) with a coefficient of variation of less than 2% (creatine 3-5%). Good linearity and 100% recovery are obtained over a wide range of concentration in biological material. No interferences are observed caused by medication with lidocaine or dobesilate (Ca), or high bilirubin concentrations. This makes the method useful for clinical purposes or even as a reference for other methods.