On-line concentration of bacteria from tens-microliter sample volumes in roughened fused silica capillary with subsequent analysis by capillary electrophoresis and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

This study presents timely, reliable and sensitive method for identification of pathogenic bacteria in clinical samples based on a combination of capillary electrophoresis with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. In this respect, a part of single-piece fused silica capillary was etched with supercritical water with the aim of using it for static or dynamic cell-surface adhesion from tens of L-sample volumes. The conditions for this procedure were optimized. Adhered cells of Staphylococcus aureus (methicillin-susceptible or methicillin-resistant) and of Pseudomonas aeruginosa were desorbed and pre-concentrated from the rough part of the capillary surface using transient isotachophoretic stacking from a high conductivity model matrix. The charged cells were swept and separated again in micellar electrokinetic chromatography using non-ionogenic surfactant. Static adhesion of the cells onto the roughened part of the capillary is certainly volumetric limited. Dynamic a...