Direct electrochemical reduction of graphene oxide and its application to determination of l-tryptophan and l-tyrosine

Directly electrochemically reduced graphene oxide (ERGO) was obtained by potentiostatic reduction of exfoliated graphene oxide sheets on a glassy carbon electrode (GCE). The ERGO-modified electrode (ERGO/GCE) displayed greatly improved voltammetric response to the amino acids l-tryptophane (Trp) and l-tyrosine (Tyr) compared with the chemically reduced graphene oxide (CRGO) modified electrode. The ERGO/GCE separated the voltammetric responses of ascorbic acid (AA) and uric acid (UA) from that of Trp and Tyr. It eliminated the interference from AA and UA. The electrode showed good reproducibility and was used to determine Trp and Tyr with linear ranges of 0.2–40.0 μmol L−1and 0.5–80.0 μmol L−1, detection limits of 0.1 μmol L−1 and 0.2 μmol L−1, respectively.