Simultaneous Voltammetric Measurement of Ascorbic Acid, Epinephrine, Uric Acid and Tyrosine at a Glassy Carbon Electrode Modified with Nanozeolite-Multiwall Carbon Nanotube

In this study, incorporation of iron ion-doped natrolite nanozeolite, multi-wall carbon nanotubes into chitosan-coated glassy carbon electrode for the simultaneous determination of ascorbic acid, epinephrine, uric acid and tyrosine is studied. The results show that the combination of multi-wall carbon nanotubes and iron ion-doped natrolite zeolite causes a dramatic enhancement in the sensitivity of ascorbic acid, epinephrine, uric acid and tyrosine quantification. The sensor gave the separated and sharp voltammetric responses of analytes in four well-defined linear sweep voltammetry peaks. Under the optimum conditions, the calibration curve were linear up to 1.82 × 10-3, 3.15 × 10-3 , 1.50 × 10-4 and 6.29 × 10-4 M with detection limits 1.82 × 10-6, 1.33× 10-6, 4.09 × 10-8 and 2.01× 10-7 M (S/N= 3) for ascorbic acid, epinephrine, uric acid  and tyrosine, respectively. The analytical performance of this sensor has been evaluated for simultaneous detection of four analytes in human serum and urine samples.