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Pulsed electrochemical detection of nonchromophoric compounds following capillary electrophoresis
Author(s) -
Lacourse William R.,
Owens George S.
Publication year - 1996
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/elps.1150170205
Subject(s) - capillary electrophoresis , amperometry , chemistry , detection limit , chromatography , electrophoresis , amine gas treating , electrochemistry , electrolyte , oxide , microelectrode , electrode , organic chemistry
Abstract Pulsed electrochemical detection (PED) following capillary electrophoresis (CE) has been applied to the direct detection of polar aliphatic compounds. These compounds typically have poor optical detection properties and are considered to be electroinactive under constant applied potentials. The voltammetric responses at microelectrodes of model compounds were studied under various buffers and pH conditions. The detection of unsubstituted carbohydrates requires highly alkaline conditions, whereas amine‐containing compounds ( e.g. , glycopeptides, peptides, and amino acids) and thiocompounds can best be detected at mildly alkaline ( i.e. , pH 9.0) and mildly acidic ( i.e. , pH 5.5) conditions, respectively. In a comparative study of pulsed amperometric detection (PAD) and integrated pulsed amperometric detection (IPAD), IPAD is determined to be better suited to manage the large oxide‐formation backgrounds, which accompany oxide‐catalyzed detections of amine‐ and sulfur‐ containing compounds. IPAD results in more stable baselines, eliminates oxide‐induced artifacts, and often yields lower limits of detection. Mass detection limits under optimal conditions are typically 10 fmole or less. This paper delineates PED waveform parameters for the optimal detection of underivatized nonchromophoric compounds of biological significance in various operating buffers and electrolytes.