Preliminary Study on Reverse Pulse Amperometric Detection in Capillary Electrophoresis for Simultaneous Determination of Cysteine and Cystine

Abstract

Simultaneous determination of cysteine (RSH) and cystine (RSSR), two important sulfur-containing amino acids, in capillary electrophoresis (CE) has been an analytical task. Dual-microelectrode amperometric detection seems to be a good scheme, but significant difficulty in electrode construction and poor detection limit for RSSR determination remain major short-comings. In reverse pulse amperometric (RPA) detection, the applied potentials are repeatedly pulsed back and forth between the reducing initial potential (e.g., Ei =-1.4 V) and the oxidizing final potential (e.g., E r =0.0 V) at a single, gold-mercury amalgam (AuIHg) microelectrode. At E;, RSSR is reduced to RSH which Causes catalytical oxidation of the Au/Hg amalgam microelecuode when the potential is pulsed to E f • The resulting anodic current is then recorded. Therefore, by using RPA detection after CE separation, RSH and RSSR can be simultaneously determined.

Mercury film electrodes: developments, trends and potentialities for electroanalysis

“…Reports of MFE's exist for the coulometric detection of lead, 212 the stripping coulometric detection of arsenic, 213 the voltammetic detection of fomaldehyde, 214 and metronidazole, 215 the amperometric detection in capillary FIA, 216 FIA detection of bromofenoxim 217 and methylmercury, 218 the amperometric HPLC analysis of cysteine and cystine, 219 nitro and quinone compounds, 220 propane-1,2-diol-nitrates, 221 nitramines, nitrotoluenes and nitrate esters, 222 hydrophilic thiols 18 and for the detection of metals after separation by capillary electrophoresis. [223][224][225] MFE's have been used in hyphenated electrochemicalspectroscopic methods as preconcentrating devices for atomic spectroscopy [226][227][228][229][230] and chemiluminescence 231 as well as in thin-layer chromatography-stripping voltammetry 232,233 and anion exchange-stripping voltammetry.…”