Profiling clinically important metabolites in human urine by an electrochemical system containing disposable electrodes

A wall-jet and low-dead-volume electrochemical cell specifically designed for disposable copper-plated screen-printed carbon electrodes is developed and applied for the determination of urinary metabolites by anion-exchange chromatography. Separation and detection was performed directly on urine samples without extensive cleanup and without derivatization. Under the optimized chromatographic conditions using a phosphate buffer (ionic strength = 0.11 M, pH 7.5) mobile phase, important urine metabolites namely creatinine, cystine, uric acid, oxalic acid, and citric acid could be successfully separated in approximately 8 min. Amperometric detection at a low potential of −0.05 V versus Ag/AgCl resulted in detection limits (S/N = 3) in the low μM levels with linear dynamic ranges spanning two to three orders of magnitude. We obtained different chromatographic profiles of selected metabolites from the urine specimens of unhealthy and healthy individuals. The separation and detection of human urine metabolites is an interesting and challenging topic in analytical chemistry as these compounds are involved in many biochemical, physiological, or pathological processes. Analysis of human urine metabolites is very useful in the diagnosis of inborn errors of metabolism. This work is a first step toward analyzing clinical samples by a disposable electrode. Disposable electrodes make it possible to avoid polishing and reconditioning, which are required with nondisposable electrodes. Due to its simplicity and reproducibility, the present method can be of clinical value in diagnosis of disorders to provide a prompt and simple technique in routine analysis.