title: In-channel amperometric detection for microchip electrophoresis using a wireless isolated potentiostat.
abstract: The combination of microchip electrophoresis with amperometric detection leads to a number of analytical challenges that are associated with isolating the detector from the high voltages used for the separation. While methods such as end-channel alignment and the use of decouplers have been employed, they have limitations. A less common method has been to utilize an electrically isolated potentiostat. This approach allows placement of the working electrode directly in the separation channel without using a decoupler. This paper explores the use of microchip electrophoresis and electrochemical detection with an electrically isolated potentiostat for the separation and in-channel detection of several biologically important anions. The separation employed negative polarity voltages and tetradecyltrimethylammonium bromide (as a buffer modifier) for the separation of nitrite (NO₂⁻), glutathione, ascorbic acid, and tyrosine. A half-wave potential shift of approximately negative 500 mV was observed for NO₂⁻ and H₂O₂ standards in the in-channel configuration compared to end-channel. Higher separation efficiencies were observed for both NO₂⁻ and H₂O₂ with the in-channel detection configuration. The limits of detection were approximately two-fold lower and the sensitivity was approximately two-fold higher for in-channel detection of nitrite when compared to end-channel. The application of this microfluidic device for the separation and detection of biomarkers related to oxidative stress is described.
authors: Ralph N. Adams Institute for Bioanalytical Chemistry, University of Kansas, Lawrence, Kansas, USA.
authors: Dulan B
authors: DB
authors: Gunasekara
authors: Matthew K
authors: MK
authors: Hulvey
authors: Susan M
authors: SM
authors: Lunte
mesh_terms: D000838:Anions / Q000737:chemistry; D001205:Ascorbic Acid / Q000302:isolation & purification; D046209:Electrophoresis, Microchip / Q000295:instrumentation* / Q000379:methods*; D005978:Glutathione / Q000302:isolation & purification; D030421:Peroxynitrous Acid / Q000737:chemistry; D050337:Trimethyl Ammonium Compounds / Q000737:chemistry; D014443:Tyrosine / Q000302:isolation & purification
chemical_list: D000838:Anions; D050337:Trimethyl Ammonium Compounds; D030421:Peroxynitrous Acid; D014443:Tyrosine; D005978:Glutathione; D001205:Ascorbic Acid; C009410:tetradecyltrimethylammonium