Hydroquinone as a buffer additive for suppression of bubbles formed by electrochemical oxidation of the CE buffer at the outlet electrode in capillary electrophoresis/electrospray ionization-mass spectrometry.
Hydroquinone was found to suppress bubble formation at the outlet electrode of a sheathless capillary electrophoresis/electrospray ionization-mass spectrometer by replacing the oxidation of water (2H2O(1)<-->O2(g) + 4H+ + 4e) with that of more easily oxidized hydroquinone (hydroquinone<-->p-benzoquinone + 2H+ + 2e). Formation of p-benzoquinone replaces the formation of oxygen gas, effectively suppressing gas bubble formation. Several electrode materials, including platinum, gold-coated stainless steel, and stainless steel wires, were tested. However, hydroquinone suppressed bubbles only at the platinum electrode. Combination of the in-capillary electrode sheathless interface using platinum wire, hydroquinone as a buffer additive, and pressure programming at the inlet of the capillary electrophoresis provided a rugged high efficiency interface for analysis of protein digests using CE/ESI-MS.
Moini
M
M
Department of Chemistry and Biochemistry, University of Texas at Austin 78712, USA. mmoini@mail.utexas.edu
Cao
P
P
Bard
A J
AJ
D002021:Buffers; D004563:Electrochemistry; D004566:Electrodes; D019075:Electrophoresis, Capillary / Q000295:instrumentation*; D006873:Hydroquinones / Q000737:chemistry*; D013058:Mass Spectrometry / Q000295:instrumentation*; D010084:Oxidation-Reduction
D002021:Buffers; D006873:Hydroquinones