An enzymeless electrochemical sensor for the selective determination of creatinine in human urine

Determination of creatinine in various biological fluids is useful for evaluation of renal, muscular and thyroid dysfunctions. An enzymeless electrochemical approach for the selective and quantitative recognition of creatinine in human urine has been demonstrated by using a preanodized screen-printed carbon electrode (SPE*). During a preconcentration step (at 1.8 V versus Ag/AgCl), the formation of a stable carbon–carbon bond between the electro-generated CO of SPE* and the active methylene group of creatinine was identified by XPS. By using the SPE* together with a medium exchange procedure, the creatinine was selectively detected in the window of 0.37–3.6 mM with a slope and regression coefficient of 16.7 μA/mM and 0.998, respectively, by square-wave voltammetry. Ten successive detection of 0.37 mM creatinine showed a relative standard deviation of 3.4%, indicating a detection limit (signal/noise = 3) of 8.6 μM. Real human urine samples were analyzed by this method and compared with the results obtained from the Jaffé reaction procedure.