Pressure-Assisted Capillary Electrophoresis Electrospray Ionization Mass Spectrometry for Analysis of Multivalent Anions

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, nicotinamide-adenine 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 micromol/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.

Evaluation of Metabolite Alteration under Flooding Stress in Soybeans

“…Furthermore, capillary electrophoresis-mass spectrometry (CE/MS) has been developed to detect charged compounds such as carboxylic acids, amino acids and nucleotides 48,53,54,55,58 . Metabolites related to anaerobic metabolism, which may be important in flooding conditions, are mainly charged compounds, whichCE/MS can measure.…”

A non-directed approach to the differential analysis of multiple LC–MS-derived metabolic profiles

“…However, GC-MS is less applicable to semi-polar compounds among which are major classes of plant (secondary) metabolites including flavonoids, (glyco-)alkaloids, glucosinolates and saponins. Recent advances in techniques for improving resolution in LC by using capillary electrophoresis (Soga et al, 2002), hydrophilic interaction columns (Tolstikov and Fiehn, 2002) and monolithic columns (Tolstikov et al, 2003) demonstrate a high potential for LC-MS complementing GC-MS in unravelling metabolic profiles. Recently, capillary LC combined with high resolution QTOF-MS has been successfully applied to the analysis of Arabidopsis secondary metabolites (Von Roepenack-Lahaye et al, 2004).…”

Polyelectrolyte‐modified short microchannel for cation separation

“…The separation of small ions is routinely carried out by traditional CE in silica capillaries [11][12][13][14][15][16][17][18][19], the ions being typically separated in minutes when the capillary length ranges from 10 to 80 cm. Analysis of small inorganic/ organic charged species has also been performed on microchip platforms by capillary zone electrophoresis.…”