Chromatographic methods, membrane

Goodwin et al. [82] determined trace sulphides in turbid waters by a gas dialysis-ion chromatographic method. The sulphide is converted to hydrogen sulphide which is then isolated from the sample matrix by diffusion through a gas dialysis membrane and trapped in a dilute sodium hydroxide solution. A 200pL portion of this solution is injected into an ion chromatograph for determination with an electrochemical detector. Detection limits were >1.9ng/mL... 

Upon incorporation of cyclodextrins in membranes, or dissolution of cyclodextrins in one or the membrane-separated liquid phases, the permeation rate of the complexed guest-molecule can be modified considerably (7-9). This offers another possibility for the enrichment of the selected component, nevertheless no rapid quantitative separation can be attained. Therefore separations which satisfy the requirements of the separation scientist can be achieved only by chromatographic methods. 

ORD-CD ], potentiometry, microcalorimetry, surface tension, membrane permeation, electro-phoresis, and freezing point depression. Chromatographic methods include HPLC, paper, and TLC techniques. 

Despite the limitations mentioned above, the chromatographic method is easy to handle and generates adsorption isotherm data quickly for a large number of combinations of polymers and gases or vapors. These data are important when membrane gas separation and pervaporation data are interpreted, and polymer materials are chosen for the preparation of membranes used for the above separation processes. 

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