COMPARISON OF SOFTWARES USED FOR THE DETECTION OF ANALYTES PRESENT AT LOW LEVELS IN LIQUID CHROMATOGRAPHIC MASS SPECTROMETRIC EXPERIMENTS

摘要

A comparison has been made between different approaches for detecting low-level analytes in the TIC traces of sample mixtures analysed by different liquid chromatographic-mass spectrometric (LC-MS) techniques. The approaches studied were contour mapping or ''eagle's view'' and a background treatment software, TICFilt, recently developed. Typical pharmaceutical samples including standards and plasma containing common drugs such as propranolol, phenothiazine, acetaminophen have been analysed in LC-MS experiments using ionspray, atmospheric-pressure chemical ionization and direct liquid introduction interfaces. The data obtained were examined by contour mapping and treated by TICFilt in order to detect low level elution peaks. Contour mapping can be efficient at higher masses (> M(r) 250) where the background is generally weaker but cannot always detect elution peaks at lower masses where background contribution is important. Furthermore, it cannot distinguish actual peaks from spikes which are often present in these experiments. Background treatment algorithms such as TICFilt, however, can not only eliminate spikes from the TIC trace but also offer a peak detection efficiency for unknown compounds which is constant throughout the mass range and independent of the mobile phase composition and the ionization technique used. Furthermore, background treatment algorithms also provide mass spectra with enhanced spectral information which is important in the identification of unknown drug-related species. [References: 23]