Pressure-assisted capillary electrophoresis electrospray ionization mass spectrometry for analysis of multivalent anions

Tomoyoshi Soga, Yuki Ueno, Hisako Naraoka, Keiko Matsuda, Masaru Tomita, Takaaki Nishioka

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Abstract

We describe a method, based on pressure-assisted capillary electrophoresis coupled to electrospray ionization mass spectrometry (PACE/ESI-MS), that allows the simultaneous and quantitative analysis of multivalent anions, such as citrate isomers, nucleotides, nicotinamideadenine dinucleotides, and flavin adenine dinucleotide, and coenzyme A (CoA) compounds. Key to the analysis was using a noncharged polymer, poly(dimethylsiloxane), coated to the inner surface of the capillary to prevent anionic species from adsorbing onto the capillary wall. It was also necessary to drive a constant liquid flow toward the MS by applying air pressure to the inlet capillary during electrophoresis to maintain a conductive liquid junction between the capillary and the electrospray needle. Although theoretical plates were inferior to those obtained by CE/ESI-MS using a cationic polymer-coated capillary, the PACE/ESI-MS method improved reproducibility and sensitivity of these anions. Eighteen anions were separated by PACE and selectively detected by a quadrupole mass spectrometer with a sheath-flow electrospray ionization interface. The relative standard deviations (n = 6) of the method were better than 0.6% for migration times and between 1.4% and 6.2% for peak areas. The detection limits for these species were between 0.4 and 3.7 μmol/L with pressure injection of 50 mbar for 30 s (30 nL), that is, mass detection limits calculated in the range from 12 to 110 fmol at a signal-to-noise ratio of 3. The utility of the method was demonstrated by analysis of Citrate isomers, nucleotides, dinucleotides, and CoA compounds extracted from Bacillus subtilis cells.

Original languageEnglish
Pages (from-to)6224-6229
Number of pages6
JournalAnalytical Chemistry
Volume74
Issue number24
DOIs
Publication statusPublished - 2002 Dec 15

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ASJC Scopus subject areas

  • Analytical Chemistry

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