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Improved Voltammetric Response of L ‐Tyrosine on Multiwalled Carbon Nanotubes‐Ionic Liquid Composite Coated Glassy Electrodes in the Presence of Cupric Ion
Author(s) -
Liu Liqin,
Zhao Faqiong,
Xiao Fei,
Zeng Baizhao
Publication year - 2008
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/elan.200804304
Subject(s) - ionic liquid , hexafluorophosphate , tyrosine , detection limit , anode , cyclic voltammetry , electrode , glassy carbon , histidine , materials science , chemistry , inorganic chemistry , analytical chemistry (journal) , electrochemistry , nuclear chemistry , chromatography , amino acid , organic chemistry , biochemistry , catalysis
L ‐Tyrosine can exhibit a small anodic peak on multiwalled carbon nanotubes (MWCNTs) coated glassy carbon electrodes (GCE). At pH 5.5 its peak potential is 0.70 V (vs. SCE). When an ionic liquid (i.e., 1‐octyl‐3‐methylimidazolium hexafluorophosphate, [omim][PF 6 ]) is introduced on the MWCNT coat, the peak becomes bigger. Furthermore, in the presence of Cu 2+ ion the anodic peak of L ‐tyrosine increases further due to the formation of Cu 2+ ‐ L ‐tyrosine complex, while the peak potential keeps unchanged. Therefore, a sensitive voltammetry based on the oxidation of Cu 2+ ‐ L ‐tyrosine complex on MWCNTs‐[omim][PF 6 ] composite coated electrode is developed for L ‐tyrosine. Under the optimized conditions, the anodic peak current is linear to L ‐tyrosine concentration in the range of 1×10 −8 –5×10 −6 M, and the detection limit is 8×10 −9 M. The modified electrode shows good reproducibility and stability. In addition, the voltammetric behavior of other amino acids is explored. It is found that among them tryptophan (Trp) and histidine (His) can also produce sensitive anodic peak under same experimental conditions, and their detection limits are 4×10 −9 M and 4×10 −6 M, respectively.