Oxidation at a sol-gel composite electrode doped with a dirhodium-substituted polyoxometalate for amperometric detection of peptides separated by HPLC.

Oxidation of a variety of compounds, including methionine (Met), using a complex formed between dirhodium(II) acetate and the lacunary form of phosphotungstic acid as the catalyst is effective over a wide range of conditions, including pH 2-10. Thus, amperometric detection at a composite in which this complex is immobilized in a sol-gel material does not place restrictions on selection of conditions for separations by reverse-phase HPLC. A demonstration of this point is shown by a study of Met, Met-Phe, Phe-Met, Met-Met, and Gly-Met-Gly (Phe, phenylalanine; Gly, glycine). Using a 0.05 M phosphate buffer at pH 6.7, a C18 column, and a flow rate of 1 ml min(-1), capacity factors for Met, Gly-Met-Gly, Met-Met, and Phe-Met were 1.4, 2.1, 5.6, and 34, respectively. Phe-Met and Met-Phe co-eluted.

[1]  Dong Liu,et al.  An optical pH sensor with a linear response over a broad range , 2000 .

[2]  J A Cox,et al.  Flow injection amperometric determination of insulin based upon its oxidation at a modified electrode. , 1989, Analytical chemistry.

[3]  M. T. Pope,et al.  A New General Structural Category of Heteropolyelectrolytes. Unusual Magnetic and Thermal Contraction Phenomena1 , 1966 .

[4]  J. Cox,et al.  Stable modified electrodes for flow injection amperometry: application to the determination of thiocyanate , 1988 .

[5]  Dong Shaojun,et al.  Electrochemical study of isopoly and heteropoly oxometallate film modified microelectrodes: Part 5. Preparation and electrochemical behaviour of a 2:18-molybdodiphosphate anion monolayer modified electrode , 1992 .

[6]  J. Cox,et al.  Controlled-potential electrolysis of bulk solutions at a modified electrode: application to oxidations of cysteine, cystine, methionine, and thiocyanate. , 1990, Analytical chemistry.

[7]  J. Cox,et al.  Electrocatalysis with a Dirhodium-Substituted Polyoxometalate Anchored in a Xerogel-Based Composite: Application to the Oxidation of Methionine and Cystine at Physiological pH , 1998 .

[8]  D. Centonze,et al.  Mixed-Valent Ruthenium Oxide-Ruthenium Cyanide Inorganic Film on Glassy Carbon Electrodes as an Amperometric Sensor of Aliphatic Alcohols , 1995 .

[9]  E. Wang,et al.  Amperometric detection of catecholamines with liquid chromatography at a polypyrrole-phosphomolybdic anion-modified electrode , 1994 .

[10]  E. Steckhan,et al.  Electrochemical Properties of Polyoxometalates as Electrocatalysts. , 1998, Chemical reviews.

[11]  M. T. Pope,et al.  New Routes for Multiple Derivatization of Polyoxometalates. Bis(acetato)dirhodium-11-tungstophosphate, [(PO4)W11O35{Rh2(OAc)2}]5- , 1997 .

[12]  C. Hill,et al.  Homogeneous catalysis by transition metal oxygen anion clusters , 1995 .

[13]  A. Patrut,et al.  PFeW11-doped polymer film modified electrodes and their electrocatalytic activity for H2O2 reduction , 1999 .

[14]  K. Shiu,et al.  Attempts to immobilize catalytically active heteropolytungstates on the surfaces of electrodes , 1991 .

[15]  O. Lev,et al.  Sol-Gel-Derived Ceramic-Carbon Composite Electrodes: Introduction and Scope of Applications , 1994 .

[16]  Z. Tang,et al.  Electrochemistry of heteropolyanions in coulombically linked self-assembled monolayers , 1998 .

[17]  P. Kulesza,et al.  Electrocatalytic oxidation and determination of arsenic(III) on a glassy carbon electrode modified with a thin film of mixed-valent ruthenium(III, II) cyanide , 1984 .

[18]  E. Wang,et al.  Liquid chromatography-amperometric detection of nitrite using a polypyrrole modified glassy carbon electrode doped with tungstodiphosphate anion , 1997 .