Gradient anion chromatography with hydroxide and carbonate eluents using simultaneous conductivity and pH detection

Abstract

High exchange capacity membrane suppressors make gradient anion chromatography practical, with submicromolar detection limits attainable for a number of common anions when a data acquisition system is used to store a blank run and perform background subtraction. With hydroxide eluents, pH measurement yields attractive detection limits. Postsuppressors, based on a porous polypropylene tubular membrane as is, or coated with silicone rubber, permit acceptable performance with the more commonly used carbonate-based eluents. For isocratic elution with hydroxide eluents, direct potentiometric pH detection allows limits of detection only slightly worse than conductometry and is adequate for most purposes.