Capillary electrophoresis with electrochemiluminescence detection for simultaneous determination of proline and fleroxacin in human urine.

The content of free proline (Pro) in body fluids is a biological parameter for patients with renal insufficiency and chronic uraemia. Fleroxacin (FLX) must be used cautiously because of adverse reactions. Its dosage must be adjusted according to the degree of renal insufficiency. In a clinical setting the simultaneous determination of Pro and FLX in body fluids is necessary for the rational utilization of FLX. A capillary electrophoresis (CE) method based on electrochemiluminescence (ECL) detection with Ru(bpy)(3) (2+) was developed for the simultaneous determination of Pro and FLX in human urine. Parameters related to separation and detection were investigated and optimized. The most favourable resolution and high sensitivity were obtained using a 15 mM phosphate buffer at pH 9.6 with the detection potential at 1.15 V. Under optimized conditions, the standard curves were linear in the range of 0.1-80 microg/mL for Pro and 0.1-100 microg/mL for FLX. Detection limits(3sigma) of 0.3 ng/mL for FLX and 0.02 microg/mL for Pro were obtained. Relative standard derivations (RSDs) of the ECL intensity and the migration time were 3.2% and 0.9% for 4 microg/mL Pro and 3.7% and 1.2% for 4 microg/mL FLX, respectively. The recoveries were in the range of 94.8-99.6% for Pro with RSDs of 2.8%-3.6% and 94.7-97.8% for FLX with RSDs of 2.9%-3.7%. The proposed method was successfully applied to determine the amounts of Pro and FLX in human urine.