Analysis of histones by on-line capillary zone electrophoresis–electrospray ionisation mass spectrometry

The on-line combination of capillary electrophoresis and electrospray ionisation mass spectrometry was applied for the determination of some basic histones from calf thymus. The separation performance of those basic proteins was significantly improved by coating the capillaries with hydroxypropylmethylcellulose. The coating appeared to mask effectively the underlying silanol groups thus avoiding undesirable adsorption of the histones onto the capillary walls, while it was also shown to be an effective way to avoid contamination of the mass spectrometer. Finally, capillary electrophoresis–electrospray ionisation mass spectrometry with coaxial sheath liquid was successfully applied to the analysis of histones using a simple dialysis step of the sample as sample pretreatment.