title: Determination of metabolic organic acids in cerebrospinal fluid by microchip electrophoresis.
abstract: A new MCE method for the determination of oxalic, citric, glycolic, lactic, and 2- and 3-hydroxybutyric acids, indicators of some metabolic and neurological diseases, in cerebrospinal fluid (CSF) was developed. MCE separations were performed on a PMMA microchip with coupled channels at lower pH (5.5) to prevent proteins interference. A double charged counter-ion, BIS-TRIS propane, was very effective in resolving the studied organic acids. The limits of detection (S/N = 3) ranging from 0.1 to 1.6 μM were obtained with the aid of contact conductivity detector implemented directly on the microchip. RSDs for migration time and peak area of organic acids in artificial and CSF samples were <0.8 and <9.7%, respectively. Recoveries of organic acids in untreated CSF samples on the microchip varied from 91 to 104%. Elimination of chloride interference, a major anionic constituent of CSF, has been reached by two approaches: (i) the use of coupled channels microchip in a column switching mode when approximately 97-99% of chloride was removed electrophoretically in the first separation channel and (ii) the implementation of micro-SPE with silver-form resin prior to the MCE analysis, which selectively removed chloride from undeproteinized CSF samples.
authors.affiliation: Department of Analytical Chemistry, Faculty of Natural Sciences, Comenius University in Bratislava, Bratislava, Slovak Republic.
authors.forename: Ladislav
authors.initials: L
authors.lastname: Danč
authors.forename: Róbert
authors.initials: R
authors.lastname: Bodor
authors.forename: Peter
authors.initials: P
authors.lastname: Troška
authors.forename: Michal
authors.initials: M
authors.lastname: Horčičiak
authors.forename: Marián
authors.initials: M
authors.lastname: Masár
mesh_terms: D000144:Acids, Acyclic / Q000134:cerebrospinal fluid* / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D004553:Electric Conductivity; D046209:Electrophoresis, Microchip / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D015203:Reproducibility of Results; D052617:Solid Phase Microextraction
chemical_list: D000144:Acids, Acyclic
keywords: Cerebrospinal fluid; MCE; Micro-SPE; Organic acids