Rationalisation of unusual changes in efficiency and retention with temperature shown for bases in reversed-phase high-performance liquid chromatography at intermediate pH

被引:46
作者
Buckenmaier, SMC
McCalley, DV [1 ]
Euerby, MR
机构
[1] Univ W England, Ctr Biomed Res, Bristol BS16 1QY, Avon, England
[2] AstraZeneca R&D Charnwood Lund, Pharmaceut & Analyt R&D, Loughborough LE11 5RH, Leics, England
关键词
retention behaviour; temperature effects; pH; column efficiency;
D O I
10.1016/j.chroma.2004.04.019
中图分类号
Q5 [生物化学];
学科分类号
071010 ; 081704 ;
摘要
Despite the possibility of poorer peak shapes, analysis of pharmaceuticals and other bases using reversed-phase high-performance liquid chromatography (RP-HPLC) at intermediate pH gives useful increases in retention, selectivity and column loading capacity compared with low pH. Retention times of some bases showed anomalous increases with column temperature. Peak shapes for bases improved significantly at elevated temperature (up to 70degreesC), with the weakest bases studied (pK(a) similar to 8) giving greater improvement than the strongest bases (pK(a) similar to 10). In contrast, quaternary ammonium compounds showed reduced retention with increasing column temperature (normal behaviour) and only modest improvements in peak shape. Considering these results, and pK(a) measurements of the bases made using capillary electrophoresis, it appears that increases in retention and improvement in efficiency may be influenced significantly by reduction in the pK(a) of bases with temperature, leading to reduction in protonation. It is less likely that efficiency improvements are due to the speeding up of the kinetics of silanol ion exchange, at least in the temperature range studied here. (C) 2004 Elsevier B.V. All rights reserved.
引用
收藏
页码:117 / 126
页数:10
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