Abstract: An ion exchange resin for use as a stationary phase in an ion chromatography column. The ion exchange resin has a negatively charged substrate particle, a positively charged polymer layer bound to the negatively charged substrate particle, a linker, and an ion exchange group. The ion exchange group includes a sulfonamide group and an amine, in which the ion exchange group is coupled to the positively charged polymer layer via the linker. When the sulfonamide is in a neutral form, a positively charged amine group provides retention: while when the sulfonamide is in an anionic form, the sulfonamide anion becomes a counter ion to the positively charged amine group, forming a zwitterion that reduces retention at that site. Accordingly, the retention time is able to be controlled by adjusting the mobile phase pH.

Abstract: An ion exchange resin for use as a stationary phase in an ion chromatography column. The ion exchange resin has a negatively charged substrate particle, a positively charged polymer layer bound to the negatively charged substrate particle, a linker, and an ion exchange group. The ion exchange group includes a sulfonamide group and an amine, in which the ion exchange group is coupled to the positively charged polymer layer via the linker. When the sulfonamide is in a neutral form, a positively charged amine group provides retention; while when the sulfonamide is in an anionic form, the sulfonamide anion becomes a counter ion to the positively charged amine group, forming a zwitterion that reduces retention at that site. Accordingly, the retention time is able to be controlled by adjusting the mobile phase pH.

Abstract: A heat-conducting support for a round or curved bottom vessel is provided. The support comprises a metallic unit having an inner portion, an outer portion, and a base that is adapted to be placed on a heating element. The inner portion is concavely curved to complement the shape of and support a vessel having a round or curved bottom. The outer portion adjoins the inner portion at an upper location remote from the curved bottom of the inner portion. The outer portion extends away from the upper location of the inner portion and toward the base, with which it merges.