Fused silica capillaries with two segments of different internal diameters and inner surface roughnesses prepared by etching with supercritical water and used for volume coupling electrophoresis

Abstract

In this work, single-piece fused silica capillaries with two different internal diameter segments featuring different inner surface roughness were prepared by new etching technology with supercritical water and used for volume coupling electrophoresis. The concept of separation and online pre-concentration of analytes in high conductivity matrix is based on the online large-volume sample pre-concentration by the combination of transient isotachophoretic stacking and sweeping of charged proteins in micellar electrokinetic chromatography using non-ionogenic surfactant. The modified surface roughness step helped to the significant narrowing of the zones of examined analytes. The sweeping and separating steps were accomplished simultaneously by the use of phosphate buffer (pH 7) containing ethanol, non-ionogenic surfactant Brij 35, and polyethylene glycol (PEG 10000) after sample injection. Sample solution of a large volume (maximum 3.7 μL) dissolved in physiological saline solution was injected into the wider end of capillary with inlet inner diameter from 150, 185 or 218 μm. The calibration plots were linear (R ∼ 0.9993) over a 0.060-1 μg/mL range for the proteins used, albumin and cytochrome c. The peak area RSDs from at least 20 independent measuremens were below 3.2%. This online pre-concentration technique produced a more than 196-fold increase in sensitivity, and it can be applied for detection of, e.g. the presence of albumin in urine (0.060 μg/mL).

Identification of Aspergillus Conidia in Bronchoalveolar Lavage Using Offline Combination of Capillary Electrophoresis in Supercritical Water-Treated Fused Silica Capillary and Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry

“…The combination of polymer-enhanced tITP (utilizing PEG) from the high conductivity matrix and sweeping of charged conidia in MEKC using nonionogenic surfactant Brij 35 was used for the analysis of the conidia adsorbed onto the roughened part of FS capillary. In this CE method, conidia self-stacking occurred and the Brij micelles were stacked at the anodic interface. − Negatively charged conidia (pH 7) were swept into the stacked micelle front and migrated together into the low conductivity BGE. − ,, …”

Recent advances in enhancing the sensitivity of electrophoresis and electrochromatography in capillaries and microchips (2016–2018)

“…To combine sweeping and tITP, a BGE containing a pseudostationary phase is used and the sample is devoid of this phase, with typically the ITP stage occurring prior to the psuedophase sweeping and separating the ITP‐stacked analytes. tITP‐sweeping was applied for the analysis of proteins in artificial urine, bacteria in urine and blood , and seven hydrophobic chlorophenol residues in wines samples .…”

Recent progress in analytical capillary isotachophoresis

“…This novel online combination of preconcentration strategies for cells produced up to 680‐fold increase in sensitivity for E. coli or S. aureus cells (BGE = TE: 5 mM phosphate buffer, 5% ethanol, and 0.3% Brij 35, pH 7; LE: Cl − present in the sample, UV detection at 280 nm). The same system was used for the detection of albumin in urine with a more than 196‐fold increase in sensitivity . Ivanov and co‐workers described a tITP method for the determination of aminothiols in blood plasma.…”