Non-Enzymatic Electrochemical Sensor Modified by Nickel Nanoparticles for Urea Determination in Biological Fluids

Urea level determination in biological fluids provides nutritional information regarding the body metabolism and/or the renal condition. In order to propose a rapid determination of this biomarker at low levels in biological fluid samples, the present work developed an electrochemical sensor based on a simple arrangement of a nickel-nanoparticle-modified glassy carbon electrode (GCE/NiNPs). Under optimal conditions for selective urea detection, a linear response was obtained in the range of 0.085 to 3.10 mmol L−1 (R = 0.9993), with a limit of detection of 60.0 µmol L−1 and limit of quantification of 198.0 µmol L−1. The GCE/NiNPs sensor showed recovery rates from samples from 105 ± 0.2% (hemodialysis wastewater) to 111 ± 0.3% (dialysate) for urea determination in biological fluid samples. The results obtained showed that the proposed method is relatively easy to operate and has a good degree of reliability and the satisfactory sensitivity required for monitoring urea, as well as exhibiting excellent detection capacity in the presence of possible interferents in both samples.