Publication details

A Multidetection Platform for Microcolumn Separations



Year of publication 2010
MU Faculty or unit

Faculty of Science

Description An instrumental platform based on a universal off-line interface for deposition of capillary electrophoresis (CE) or liquid chromatography (LC) effluent on a suitable target will be described. The deposited fractions of analytes, such as peptides, proteins, metalloproteins or inorganic compounds may be analyzed in off-line mode using matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS). Laser-induced fluorescence (LIF) detection may be used for visualization of analytes on target. Analytes may be subjected to reactions on target, such as digestion for protein identification. Additionally, inductively-coupled plasma mass spectrometry (ICP MS) detection mode, nature of which is complementary to soft MALDI MS, may be exploited. The detection ability is demonstrated on metallothioneins. Information about protein mass, identity and content of elements, such as metals or phosphorus are available from a single sample. LIF detection of proteins is found to be sensitive, fast and generally useful for tryptophan-containing proteins. Although not as sensitive as the on-column LIF detection, on-target LIF detection may be used to select fractions containing proteins. Principle of substrate-assisted laser desorption (SALD) for sample introduction from the target to ICP MS is explained in detail; influence of laser power density, presence of additives and role of substrate is discussed. The limits of detection for common metals are in the range of 50-500 fg, which allows using SALD for off-line coupling of CE to ICP MS. The coupling is demonstrated on separation of Cr(III) and Cr(VI) species; subpicomolar detection limits and high separation resolution have been achieved.[1] SALD has been also applied to investigate the role of copper ions and disulfiram in cytotoxicity regulation in myeloid leukemia cells.[2] Detection limit of ~26 fg for copper was sufficient for determination of copper in U937 cells at physiological levels; processes in cells were elucidated based on the obtained data. Furthermore, a new sample introduction for ICP MS, which is related to SALD, will be presented.
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