title: Electromembrane extraction of amino acids from body fluids followed by capillary electrophoresis with capacitively coupled contactless conductivity detection.
abstract: Electromembrane extraction (EME) proved to be a simple and rapid pretreatment method for analysis of amino acids and related compounds in body fluid samples. Body fluids were acidified to the final concentration of 2.5 M acetic acid and served as donor solutions. Amino acids, present as cations in the donor solutions, migrated through a supported liquid membrane (SLM) composed of 1-ethyl-2-nitrobenzene/bis-(2-ethylhexyl)phosphonic acid (85:15 (v/v)) into the lumen of a porous polypropylene hollow fiber (HF) on application of electric field. The HF was filled with 2.5 M acetic acid serving as the acceptor solution. Matrix components in body fluids were efficiently retained on the SLM and did not interfere with subsequent analysis. Capillary electrophoresis with capacitively coupled contactless conductivity detection was used for determination of 17 underivatized amino acids in background electrolyte solution consisting of 2.5 M acetic acid. Parameters of EME, such as composition of SLM, pH and composition of donor and acceptor solution, agitation speed, extraction voltage, and extraction time were studied in detail. At optimized conditions, repeatability of migration times and peak areas of 17 amino acids was better than 0.3% and 13%, respectively, calibration curves were linear in a range of two orders of magnitude (r(2)=0.9968-0.9993) and limits of detection ranged from 0.15 to 10 μM. Endogenous concentrations of 12 amino acids were determined in EME treated human serum, plasma, and whole blood. The method was also suitable for simple and rapid pretreatment and determination of elevated concentrations of selected amino acids, which are markers of severe inborn metabolic disorders.
authors.affiliation: Institute of Analytical Chemistry of the Academy of Sciences of the Czech Republic, v.v.i., Veveří 97, CZ-60200 Brno, Czech Republic.
authors.forename: Lenka
authors.initials: L
authors.lastname: Strieglerová
authors.forename: Pavel
authors.initials: P
authors.lastname: Kubáň
authors.forename: Petr
authors.initials: P
authors.lastname: Boček
mesh_terms: D019342:Acetic Acid; D000596:Amino Acids / Q000097:blood / Q000302:isolation & purification* / Q000652:urine; D005591:Chemical Fractionation; D004553:Electric Conductivity; D019075:Electrophoresis, Capillary / Q000295:instrumentation / Q000379:methods*; D004867:Equipment Design; D006801:Humans; D008567:Membranes, Artificial; D009578:Nitrobenzenes; D015203:Reproducibility of Results; D013997:Time Factors
chemical_list: D000596:Amino Acids; D008567:Membranes, Artificial; D009578:Nitrobenzenes; D019342:Acetic Acid