Ic. Casella et al., Amperometric determination of underivatized amino acids at a nickel-modified gold electrode by anion-exchange chromatography, J CHROMAT A, 878(1), 2000, pp. 57-67
A nickel-based composite electrode obtained by anodic electrodeposition of
nickel (III) oxyhydroxide film on the gold electrode substrate was characte
rized as an amperometric sensor and successfully applied to the determinati
on of underivatised amino acids in flow-through systems. The electrodeposit
ion of nickel oxyhydroxide films was obtained by cycling a gold electrode b
etween 0.0 V and +1.0 V vs. a saturated calomel electrode in a 80 mu M Ni2 solution buffered at pH 10 with NaHCO3/Na2CO3. The resulting Au-Ni composi
te electrode exhibits good stability in alkaline medium and can be used as
an amperometric sensor of underivatised amino acids at a fixed applied pote
ntial (+0.55 V vs. Ag/AgCl). The detection limits (S/N=3) for all investiga
ted compounds ranged between 5 and 30 pmol injected, while the linear range
s spanned over two or three orders of magnitude. The contents of several fr
ee amino acids in two sample cheeses from different brands were evaluated b
y calibration graphs. (C) 2000 Elsevier Science B.V. All rights reserved.