Adsorption of Tetralkyl Ammonium Ions on Reversed-Phase HPLC Columns

Abstract

A s y s t e m a t i c s t u d y of t h e i n f l u e n c e o f several chromatographic p a r a m e t e r s upon a d s o r p t i o n o f t e t r a l k y l ammonium i o n s on r e v e r s e d -p h a s e s h a s been made. R e s u l t s show t h a t o r p a n i c s o l v e n t c o n t e n t i n mobile p h a s e , t e t r a l k y l ammonium h y d r o p h o b i c i t y and t e t r a l k y l ammonium c o n c e n t r a t i o n i n e l u e n t are t h e most i n f l u e n t v a r i a b l e s . A mathematical e x p r e s s i o n t o c a l c u l a t e t h e adsorbed i o n c o n c e n t r a t i o n f o r d i f f e r e n t combinations of t h e s e v a r i a b l e s i s deduced. R e s u l t s from t h i s s t u d y c a n be. a p p l i e d i n I o n P a i r Reversed-Phase Chromatography t o c a l c u l a t e column e q u i l i b r a t i o n t i m e s , f o r s e t t i n g , p -a d i e n t e l u t i o n s e p a r a t i o n methods and for t h e s t u d y o f r e t e n t i o n mechanisms.

Measuring Reversible Adsorption Kinetics of Small Molecules at Solid/Liquid Interfaces by Total Internal Reflection Fluorescence Correlation Spectroscopy

“…Silanol groups are acidic, leading to strong association with basic solutes including ion-exchange interactions. , In contact with water, the silanols deprotonate to produce a negatively charged surface 14 that causes problems of peak broadening in the separation of cationic species on silica-based phases; this has prompted studies to understand the chemical environment that a cationic probe experiences at a silica/C-18 surface and underlying energetic contributions involved in adsorption . Adsorption of cationic molecules is important not only in standard reversed-phase separations but also in ion-pair separations in which a cationic ion-pairing reagent assists in retention of anionic species. − …”