title: New methodology for capillary electrophoresis with ESI-MS detection: Electrophoretic focusing on inverse electromigration dispersion gradient. High-sensitivity analysis of sulfonamides in waters.
abstract: This article describes for the first time the combination of electrophoretic focusing on inverse electromigration dispersion (EMD) gradient, a new separation principle described in 2010, with electrospray-ionization (ESI) mass spectrometric detection. The separation of analytes along the electromigrating EMD profile proceeds so that each analyte is focused and concentrated within the profile at a particular position given by its pKa and ionic mobility. The proposed methodology combines this principle with the transport of the focused zones to the capillary end by superimposed electromigration, electroosmotic flow and ESI suction, and their detection by the MS detector. The designed electrolyte system based on maleic acid and 2,6-lutidine is suitable to create an inverse EMD gradient of required properties and its components are volatile enough to be compatible with the ESI interface. The characteristic properties of the proposed electrolyte system and of the formed inverse gradient are discussed in detail using calculated diagrams and computer simulations. It is shown that the system is surprisingly robust and allows sensitive analyses of trace amounts of weak acids in the pKa range between approx. 6 and 9. As a first practical application of electrophoretic focusing on inverse EMD gradient, the analysis of several sulfonamides in waters is reported. It demonstrates the potential of the developed methodology for fast and high-sensitivity analyses of ionic trace analytes, with reached LODs around 3 × 10(-9) M (0.8 ng mL(-1)) of sulfonamides in spiked drinking water without any sample pretreatment.
authors.affiliation: Institute of Analytical Chemistry of the Czech Academy of Sciences, v.v.i., Veveří 97, CZ-602 00, Brno, Czech Republic.
authors.forename: Zdena
authors.initials: Z
authors.lastname: Malá
authors.affiliation: Institute of Analytical Chemistry of the Czech Academy of Sciences, v.v.i., Veveří 97, CZ-602 00, Brno, Czech Republic. Electronic address: gebauer@iach.cz.
authors.forename: Petr
authors.initials: P
authors.lastname: Gebauer
authors.affiliation: Institute of Analytical Chemistry of the Czech Academy of Sciences, v.v.i., Veveří 97, CZ-602 00, Brno, Czech Republic.
authors.forename: Petr
authors.initials: P
authors.lastname: Boček
mesh_terms: D003198:Computer Simulation; D060766:Drinking Water / Q000737:chemistry*; D004573:Electrolytes / Q000737:chemistry; D019075:Electrophoresis, Capillary; D008298:Maleates / Q000737:chemistry; D011725:Pyridines / Q000737:chemistry; D045483:Rivers / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization; D013449:Sulfonamides / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D060766:Drinking Water; D004573:Electrolytes; D008298:Maleates; D011725:Pyridines; D013449:Sulfonamides; D014874:Water Pollutants, Chemical; C013093:2,6-lutidine; C030272:maleic acid
keywords: Capillary electrophoresis; ESI-MS detection; Electromigration dispersion; Electrophoretic focusing; Sulfonamides