Synthesis and characterization of stable polymer-coated C8 stationary phase with high durability under extreme pH conditions for high-performance liquid chromatography.

A highly chemically stable polymer-coated silica-based C8 stationary phase was developed by combining modification with octyl groups and a polymer coating technology. The stationary phase was prepared by the following procedure: (1) introduction of octyl groups to the silica surface; (2) coating the C8 silica with a silicone polymer. 29Si solid-state NMR spectra indicated that a silicone polymer reacted not only with residual silanol groups on the silica surface, but with those generated from silanes used for the introduction of octyl groups.

Direct determination of endogenous melatonin in human saliva by column-switching semi-microcolumn liquid chromatography/mass spectrometry with on-line analyte enrichment.

An analytical method that enables direct and sensitive determination of endogenous melatonin (MLT) in human saliva was developed by means of column-switching semi-microcolumn liquid chromatography (i.d.: 1-2 mm)/mass spectrometry (LC/MS).