Desolvation systems membrane separators

Desolvation systems can provide three potential advantages for ICP-MS higher analyte transport efficiencies, reduced molecular oxide ion signals, and reduced solvent loading of the plasma. Two different approaches have been used for desolvation in ICP-MS. The heated spray chamber/condenser combination has been discussed it is the most commonly used system. The extent of evaporation of the solvent from the aerosol and cooling to reduce vapor loading varies from system to system. The second approach is the use of a membrane separator to remove solvent vapor before it enters the ICP. 

Mixed Gas Plasmas. Water loading can be reduced by a desolvation system (condenser or membrane separator) only if the vast majority of the water can be removed. One way to eliminate the introduction of water into the plasma during measurement of the analyte signals is with electrothermal vaporization, laser ablation, or other direct solid sampling techniques. Mixed gas plasmas,... 

Synthetic and naturally occurring macrocyclic compounds complex with metal ions selectively both in aqueous and non-aqueous solvents. In non-aqueous solvents, such complex formation leads to anion desolvation and ion-pair separation. The novel chemistry of these macrocyclic compounds as well as their role in ion transport across cell membranes prompted the vigorous recent activity in this area of research (Christensen et al., 1971 Pedersen and Frensdorff, 1972 Lehn, 1973). 13C spectroscopy is used to obtain structural and configurational information on these systems as well as to investigate their molecular dynamics. 

Extensive theoretical and experimental work has previously been reported for supported liquid membrane systems (SLMS) as effective mimics of active transport of ions (Cussler et al., 1989 Kalachev et al., 1992 Thoresen and Fisher, i995 Stockton and Fisher, 1998). This was successfully demonstrated using di-(2-ethyl hexyl)-phosphoric acid as the mobile carrier dissolved in n-dodecane, supported in various inert hydrophobic microporous matrices (e.g., polypropylene), with copper and nickel ions as the transported species. The results showed that a pH differential between the aqueous feed and strip streams, separated by the SLMS, mimics the PMF required for the emulated active transport process that occurred. The model for transport in an SLMS is represented by a five-step resistance-in-series approach, as follows (1) diffusion of the ion through a hydrodynamic boundary layer (2) desolvation of the ion, where it expels the water molecules in its coordination sphere and enters the organic phase via ion exchange with the mobile carrier at the feed/membrane interface (3) diffusion of the ion-carrier complex across the SLMS to the strip/membrane interface (4) solvation of the ion as it enters... 

---