caa a22 4500 44588133X CHVBK 20180317145544.0 cr unu---uuuuu 170323e20110901xx s 000 0 eng 10.1007/s00604-011-0631-2 doi (NATIONALLICENCE)springer-10.1007/s00604-011-0631-2 Pyrolytic graphite electrode modified with a thin film of a graphite/diamond nano-mixture for highly sensitive voltammetric determination of tryptophan and 5-hydroxytryptophan [Elektronische Daten] [Saeed Shahrokhian, Maryam Bayat] We have prepared a pyrolytic graphite electrode (PGE) whose surface is covered with a thin film of a nano-mixture of graphite/diamond (NGD). The electrode is shown to be capable of electrochemically sensing of tryptophan (TRP) and 5-hydroxytryptophan (HTRP). The presence of the NGD film resulted in a remarkable increase in the peak currents and sharpness of the waves so that submicromolar concentrations of TRP and HTRP become detectable. Potential scan rates, the pH of the solution, the accumulation conditions and the amount of the modifier were optimized via cyclic voltammetry. Linear sweep voltammetry, under optimized accumulation time and in open circuit operation, was applied to the determination of TRP and HTRP with detection limits (S/N = 3) of 30nM (TRP) and 6nM (HTRP). The electrode can be easily prepared, displays high sensitivity, sharp peaks, long-term stability, and remarkable voltammetric reproducibility and repeatability. These properties make the sensor suitable for the trace analysis of TRP and HTRP in pharmaceutical and clinical preparations. Figure A pyrolytic graphite electrode modified with a thin film of a nano-mixture of graphite/diamond. This electrochemical sensor applied for determination of tryptophan and 5-hydroxytryptophan in aqueous solutions. The modified electrode showed a remarkable increase in the peak currents and sharpness of the waves. Springer-Verlag, 2011 Tryptophan nationallicence 5-Hydroxytryptophan nationallicence Graphite/diamond nanoparticles nationallicence Modified electrodes nationallicence Voltammetry nationallicence Shahrokhian Saeed Department of Chemistry, Sharif University of Technology, 11155-9516, Tehran, Iran aut Bayat Maryam Department of Chemistry, Sharif University of Technology, 11155-9516, Tehran, Iran aut Microchimica Acta Springer Vienna 174/3-4(2011-09-01), 361-366 0026-3672 174:3-4<361 2011 174 604 https://doi.org/10.1007/s00604-011-0631-2 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s00604-011-0631-2 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Shahrokhian Saeed Department of Chemistry, Sharif University of Technology, 11155-9516, Tehran, Iran aut NATIONALLICENCE 700 1- Bayat Maryam Department of Chemistry, Sharif University of Technology, 11155-9516, Tehran, Iran aut NATIONALLICENCE 773 0- Microchimica Acta Springer Vienna 174/3-4(2011-09-01), 361-366 0026-3672 174:3-4<361 2011 174 604 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer