Coupling of capillary zone electrophoresis to mass spectrometry (MS and MS/MS) via a nanoelectrospray interface for the characterisation of some β-agonists

Abstract

Capillary zone electrophoresis (CZE) was coupled to mass spectrometry (MS) via a nanoelectrospray interface (nESI), using conductively coated tips (8 mm orifice) butted to the end of a fused-silica capillary. The CZE/nESI-MS system was carefully optimised to achieve a stable operation of the arrangement in order to run also MS/MS experiments. Mixtures of b-agonists were successfully separated using 5 mmol/L ammonium acetate in 80% MeOH as a buffer. The limit of detection was 500 attomole of a substance injected. The system was also investigated from the point of view of quantification of the substances. Careful measures were taken to avoid any systematic errors (evaporative loss during the electrokinetic injection and reduction of migration times due to the electrospray pull during the CE run). The data show that the response of a mass spectrometric detector in the low-femtomole range not only depends on the concentration of the analyte but also on the properties of the nanoelectrospray process itself, that is why the linearity of the response can be compromised.

Performance of a sheathless porous tip sprayer for capillary electrophoresis–electrospray ionization-mass spectrometry of intact proteins

“…As the sprayer served as the common ground for the CE and ion source, voltages for both the separation and ESI process could be independently altered. When performing sheathless CE-ESI-MS, a significant and stable EOF is of great importance to obtain good analyte signal intensities [22,[38][39][40]. Furthermore, a typical problem in CE of proteins is that they tend to adsorb onto the fused-silica capillary wall causing band broadening and changes in EOF [41,42].…”

Capillary electrochromatography/nanoelectrospray mass spectrometry for attomole characterization of peptides

“…A home‐assembled CEC arrangement was used in the study, as already described in our previous paper on CZE/nESI‐MS 30. Briefly, it comprises a high voltage power supply (Spellman, Hauppauge, NY, USA) and a CEC box which was kindly provided by the University of Wales, Swansea, UK.…”

“…Nevertheless, the simplest approach tends to be to attach a conductively coated tip to the end of capillary where the tip serves as a nanospray emitter 29,. 30…”

Protein glycosylation analysis with capillary-based electromigrative separation techniques

“…It was applied for the characterization of the alpha subunit of recombinant human chorionic gonadotropin by CE-MS [125]. Neutral coatings may give rise to problems with spray stability of electrospray ionization mass spectrometry, sheathless interfacing is not feasible [182,[188][189][190].…”