Voltammetry method was developed to determine the concentration of L-tryptophan and L-tyrosine in urine sample was used on copper nanoparticles coated on poly (ortho-phenylenediamine) nanocomposite modified glassy carbon electrode (CuNPs@PoPD/GCE). The voltammetry behaviour of L-tryptophan and L-tyrosine on modified GCE was investigated in phosphate buffer medium (PBS) and the electron transfer properties were studied. It is found that the CuONPs@PoPD/GCE can catalyze the oxidation of glycine and aromatic group present in L-tryptophan and L-tyrosine molecule. Quantitative detection of L-tryptophan and L-tyrosine present in urine sample was carried out by linear sweep voltammetry (LSV) method. The LSV method showed an excellent performance with a detection limit of 10 .8 × 10-7 M and 15 × 10^-7 M. A linear calibration graph was constructed in the ranging 1.0 × 10^-6 to 0.98 × 10^-5 M (R2 = 0.9511) and 1.2 × 10^-6 to 1.0 × 10^-5 M (R2 = 0.9441) for L-Trp and L-Tyr, respectively. The method was successfully applied for the determination of L-tryptophan and L-tyrosine molecule in urine sample.

Keywords: CuNPs@PoPD; Nanocomposite; L-Tryptohan; L-Tyrosine; LSV; Urine Sample;