Polymethionine modified carbon nanotube sensor for sensitive and selective determination of L-tryptophan

Abstract

The electrochemically initiated catalytic oxidation of amino acid L-tryptophan (L-TPN) in phosphate buffer solution has been scrutinized using highly conductive polymethionine modified carbon nanotube paste sensor (PMETCNTPS) through cyclic voltammetry (CV) technique. Compared to the bare carbon nanotube paste sensor (BCNTPS), PMETCNTPS exhibited a quantifiable current signal by CV method. PMETCNTPS was found sensitive to L-TPN concentrations within the linear segment of detection range 1.5 - 8.0×10-5 M. By employing the calibration plot, the detection limit was determined as 6.99×10-7 M. In addition, PMETCNTPS was successfully exploited and validated in determining L-TPN in the pharmaceutical supplement.

Keywords

• electrochemical sensor
• tryptophan
• electro-polymerization
• cyclic voltammetry