CE-ICP-MS for the determination of metal complexes

The submitted project involves coupling of capillary electrophoresis (CE) to inductively coupled plasma sector field mass spectrometry (ICP-SMS). Since the introduction of CE-ICP-MS it has been demonstrated to be a promising tool for metal speciation offering excellent resolution and separation efficiency of CE combined with highly sensitive and selective elemental detection of ICP-MS. The utilization of a high resolution instrument eliminates common spectral interferences from polyatomic species and has been recognized as prerequisite for accurate determination of elements as e. g. Fe, Mn, Cu, Al. However, at the present an efficient interface to connect the capillary and the nebulizer of the plasma detector is still a challenge. Hence the project aims at first to implement a dependable and stable CE-ICP-SMS interface. For a successful union parameters that influence both the separation efficiencies and the sensitivity will be considered. Total dead volumes, composition of buffers and low compatibilities regarding flow rates are among these parameters to be optimized. In a second phase the research will focus on methodology of metal-ligand complexation studies by CE-ICP-SMS. Metal complexation in solution is claimed to play an important role in the Lyocell process for cellulosic fiber production. The Lyocell process employs N-methylmorpholine-N-oxide (NMMO) as solvent for cellulose, which undergoes unwanted homolytic degradation reactions, not yet completely elucidated. As a matter of fact it has been observed that metal traces present in the cellulose can cause degradation reactions in the NMMO / cellulose / water mixture resulting in immediate discoloration of the solutions or in the worst case even thermal runaway reactions. In our group it is of particular interest to perform fundamental studies on complexation of metal-NMMO and metal¿NMMO oxidation products (N-methylmorpholine and morpholine), respectively, considering different trace metals and consequently a wide range of complex stabilities. Basic knowledge of equilibrium conditions and the association behavior of these dynamic chemical systems is important in order to evaluate and control the process.