Electrocatalytic flow detection of amino acids at ruthenium dioxide‐modified carbon electrodes

Abstract

Fixed-potential anodic detection of amino acids and peptides can be carried out at ruthenium dioxide (Ru0,)-modified carbon paste and graphite epoq. electrodes. The effect of various experimental rariables on the electrocatal>Tic response is explored. Optimal detection is obtained under strongly alkaline conditions and a low (+0.45 \.' vs. AglAgCl) operating potential. With flow injection, the response is fast. linear, and reproducible (relative standard deviations of 1.5 to 1.7%. zz = 32). Similar advantages are reported for the incorporation of cobalt oxide (Co,O,) into carbon paste detectors.KEY WORDS: Amino acids. Ruthenium dioxide-modified electrode. Flow detection. Electrocatalysis Reagents and ProcedureAmino acids and peptides, purchased from Sigma Chemical Co.. were used as received without further purification. Stock solutions were prepared daily in 1.0 hl KOH.

A modified electrode for the electrochemical detection of biogenic amines and their amino acid precursors separated by microchip capillary electrophoresis

“…Instead, although the use of such a modifier to electrocatalyze the oxidation of amino acids was proposed in some papers [29][30][31], to the best of our knowledge no report dealing with its ability to promote the oxidation of amine groups is available.…”

Electrode Materials (Bulk Materials and Modification)

“…Examples are available for organo-functional groups such as propylamine, 616,712,713 a wide range of functions exhibiting high affinity for Hg(II) species (i.e., mercaptopropyl, 615,714 benzothiazolethiol, 715 3-(2-thiobenzimidazoyl)propyl, 716 2,5-dimercapto-1,3,4-thiadiazole, 717 or 2-aminothiazole 718 ), several groups binding preferably Cu (II) species (i.e., aminopropyl, 616 2-aminothiazole, 719 the carnosine dipeptide, 720 propylsulfonate, 721 salicylidine, 722 or cyclam derivatives 618 ), some functions leading to Pb(II) detection (mercaptopropyl, 714 cyclam-acetamide 619 or 2-aminopyridine 723 ), as well as some others likely to recognize other metal ions, alone or in mixture. 724,725 Finally, nonsiliceous metal oxides have been also used to modify CPEs 726 because of their attractive catalytic properties, such as ruthenium oxides (mainly RuO 2 ), 727 copper oxides (Cu 2 O, CuO), 728,729 and to less extent cobalt and nickel oxides. 730 …”

Electrochemical strategies for the label-free detection of amino acids, peptides and proteins

“…For example, detection systems made of carbon paste electrodes doped with Cu 2 O have been used. 107,108 RuO 2 was also considered as a suitable material for the detection of amino acids [108][109][110] as well as Bi(V)-doped PbO 2 electrodes. 111 Wang and colleagues prepared carbon paste electrodes doped with RuO 2 .…”

“…111 Wang and colleagues prepared carbon paste electrodes doped with RuO 2 . 108,110 Although a response improvement is observed for the detection of amino acids, the signal decayed with repetitive uses. 110 Au electrodes were also modified by forming a metal oxyhydroxide film on their surface.…”

“…108,110 Although a response improvement is observed for the detection of amino acids, the signal decayed with repetitive uses. 110 Au electrodes were also modified by forming a metal oxyhydroxide film on their surface. 112,113 The metal could either be Ni 112 or Cu, 113 and the composite electrodes formed showed good repeatability as well as good sensitivity.…”