Simultaneous and sensitive determination of a quaternary mixture of AA, DA, UA and Trp using a modified GCE by iron ion-doped natrolite zeolite-multiwall carbon nanotube

Abstract

The evaluation of a novel modified glassy carbon electrode modified with iron ion-doped natrolite zeolite-multiwalled carbon nanotube for the simultaneous and sensitive determination of ascorbic acid (AA), dopamine (DA), uric acid (UA) and tryptophan (Trp) has been described. The measurements were carried out using cyclic voltammetry in buffer solution with pH 1. This modified electrode exhibits potent and persistent electroxidation behavior followed by well-separated oxidation peaks towards AA, DA, UA and Trp with increasing of the oxidation current. For the quaternary mixture containing AA, DA, UA and Trp, the 4 compounds can well separate from each other at the scan rate of 100mVs−1 with a potential difference of 270mV, 150mV and 260mV for the oxidation peak potentials of AA–DA, DA–UA and UA–Trp, respectively, which was large enough to simultaneous determine AA, DA, UA and Trp. The catalytic peak current obtained, was linearly dependent on the AA, DA, UA and Trp concentrations in the range of 7.77–833μM, 7.35–833μM, 0.23–83.3μM and 0.074–34.5μM and the detection limits for AA, DA, UA and Trp were 1.11, 1.05, 0.033 and 0.011μM, respectively. The analytical performance of this sensor has been evaluated for simultaneous detection of AA, DA, UA and Trp in human serum and urine samples.