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High-performance liquid chromatographic analysis of basic drugs on silica columns using non-aqueous ionic eluents. I. Factors influencing retention, peak shape and detector response.

Authors
Type
Published Article
Journal
Journal of chromatography
Publication Date
Volume
323
Issue
2
Pages
173–189
Identifiers
PMID: 2987280
Source
Medline
License
Unknown

Abstract

The use of silica columns together with non-aqueous ionic eluents provides a stable yet flexible system for the high-performance liquid chromatographic analysis of basic drugs. At constant ionic strength, eluent pH influences retention via ionisation of surface silanols and protonation of basic analytes, pKa values indicating the pH of maximum retention. At constant pH, retention is proportional to the reciprocal of the eluent ionic strength for fully protonated analytes and quaternary ammonium compounds. The addition of water up to 10% (v/v) has little effect on retention if the protonation of the analytes is unaffected. Thus, it is likely that retention is mediated primarily via cation exchange with surface silanols. However, additional factors must play a part with compounds such as morphine which give tailing peaks at acidic or neutral eluent pHs.

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