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High‐performance liquid chromatography of some basic drugs on a n ‐octadecylphosphonic acid modified magnesia‐zirconia stationary phase
Author(s) -
He HaiBo,
Feng YuQi,
Da ShiLu,
Hu ZhiXiong,
Qu Li
Publication year - 2005
Publication title -
journal of separation science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.72
H-Index - 102
eISSN - 1615-9314
pISSN - 1615-9306
DOI - 10.1002/jssc.200500042
Subject(s) - chemistry , selectivity , phase (matter) , lewis acids and bases , ion exchange , chromatography , hydrophilic interaction chromatography , adsorption , cubic zirconia , reversed phase chromatography , inorganic chemistry , high performance liquid chromatography , organic chemistry , catalysis , ion , ceramic
The high‐performance liquid chromatographic behavior of some basic drugs was studied on a n ‐octadecylphosphonic acid modified magnesia‐zirconia (C 18 PZM) stationary phase. The effect of mobile phase variables such as methanol content, ionic strength, and pH on their chromatographic behavior was investigated. The retention mechanism of basic drugs on the stationary phase was elucidated. The results indicate that both hydrophobic and cation‐exchange interactions contribute to solute retention under most chromatographic conditions. The inherent Brönsted‐acid sites and also the adsorbed Lewis base anionic buffer constituents on accessible ZM surface Lewis acid sites play a role in the retention of ionized solutes by cation‐exchange interaction. However, especially at high mobile phase pH, the retention of basic drugs depends mainly on hydrophobic interactions between solutes and support. Separations of the basic drugs on the C 18 PZM phase by a predominantly reversed‐phase retention mode were very promising. The mixed‐mode retention feature on this phase, as a result of the adsorbed Lewis base anionic buffer constituents acting as sites for cation‐exchange, could also be very useful, e.g. for enhancing the chromatographic selectivity of such analytes. The C 18 PZM seems to be an excellent alternative to silica‐based reversed‐phase stationary phase for the separation of strongly basic solutes.