Novel methods of separation and detection for columns of capillary dimension.

摘要

A copper vapor laser two-photon excited fluorescence (LTPEF) detector for microcolumn liquid chromatography (LC) is described. Two indirect fluorometric schemes are presented. First, a reserved phase open tubular capillary (OTC) of 50 (mu)m i.d. is dynamically modified with cetylpyridinium chloride to provide anion exchange sites. Similarly, 13--15 (mu)i.d. OTC columns are dynamically modified with cetyltridinium chloride to provide anion exchange sites. Similarly, 13-15 (mu)m i.d. OTC columns are dynamically modified with cetyltrimethylammonium bromide (CTAB) to provide anion exchange sites. Sodium salicylate (probe) at 2 micromolar is the eluent used to separate inorganic anions. Use of an indirect fluorometric detector allows the anions to be detected with a baseline stability (ge)0.1%. By incorporating CTAB into a buffer, enhancement of electroosmotic flow in polymer coated, reversed phase OTC columns is achieved. Using the flow, neutral isomers are separated with resolution >1 in all cases and efficiencies of 230,000 plates generated in less than 4 min. Finally, the separation of anions having similar electrophoretic mobilities by electroosmotically driven electrochromatography is described. Using an OTC column in conjunction with an ion-pairing buffer, anions separate based on differences in retention rather than differences in electrophoretic mobility. 104 refs., 18 figs., 1 tab.