title: Development of a polymer-coated stationary phase with improved chemical stability in alkaline mobile phases.
abstract: An endcapped stationary phase is prepared by thermal immobilization of poly(methyltetradecylsiloxane) (PMTDS) onto a doubly zirconized silica support followed by endcapping using a mixture of hexamethyldisilazane and trimethylchlorosilane. The preparation of the Si-Zr(PMTDS)ec phase shows good repeatability with RSD <3.0% for carbon loadings and column efficiency. This new stationary phase has a lower density of residual hydroxyl groups, according to spectroscopic methods while basic compounds from the Tanaka and Engelhardt test mixtures are eluted with essentially symmetric peaks. Furthermore, the stability of the Si-Zr(PMTDS)ec stationary phase, measured using an accelerated aging test, is twice as great as the stability of a similar nonendcapped phase. The new phase shows promise for the separation of basic pharmaceuticals.
authors.affiliation: Instituto de Química, Universidade Estadual de Campinas, SP, Brazil.
authors.forename: Anizio M
authors.initials: AM
authors.lastname: Faria
authors.forename: César R
authors.initials: CR
authors.lastname: Silva
authors.forename: Carol H
authors.initials: CH
authors.lastname: Collins
authors.forename: Isabel C S F
authors.initials: IC
authors.lastname: Jardim