Phase-system switching: A new approach in liquid chromatography/mass spectrometry coupling

Abstract

A new approach is presented to overcome the problems imposed by the use of non-volatile mobile phase constituents, such as buffers, in liquid chromatographic/mass spectrometric applications. The approach, called phase-system switching (PSS), is based on the use of valve switching techniques. The peak of interest is heart-cut from the effluent of the analytical column and trapped on a short trapping column, the buffer constituents are washed off, and subsequently the compound of interest is desorbed in a solvent favourable for the liquid chromatograph/mass spectrometer interface. The potential of the phase-system switching technique is explored in the liquid chromatographic/mass spectrometric analysis of the anti-cancer drug mitomycin C, which is chromatographed with an aqueous phosphate buffer as the mobile phase on a reversed-phase column. In addition to the phase-system switching itself, the PSS technique shows the interesting possibilities of peak compression and changes in flow rate.