ANYL 279 |
| It is common practice in DMPK applications in which biological samples such as serum and plasma are processed and cleaned up by protein precipitation or solid phase extraction to remove the interfering endogenous materials, and the analytes of interest are then recovered in strong organic solvent such as acetonitrile and methanol. Similarly in drug synthesis process, the drugs of interest are most often prepared in dimethyl sulfoxide (DMSO) that is a commonly used strong organic solvent. In both cases, large volume of samples in high organic content is often injected onto HPLC column for analysis unless the samples are dried down and reconstituted with weaker diluents, a time-consuming process, before injection. When using low pH mobile phases in the generic HPLC gradient method typically starting with 5% organic modifier, the injection of large volume of sample with strong organic solvent often results in peak distortion and insufficient retention, especially for the poorly retained polar basic analytes, and making quantitations impossible. It is well documented that extended retention and improved peak shapes for polar basics can be achieved when using high pH mobile phases in HPLC, and thus analysis in such conditions might be able to withstand the adverse effects of peak distortion and insufficient retention. Therefore, it is the purpose of this study to investigate and contrast the effect of injecting samples in large volume of strong sample solvent on the chromatographic performance of the separation of polar basic analytes when low and high pH mobile phases are used. |
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Analytical Approaches: Separation Science
1:30 PM-5:00 PM, Wednesday, 13 September 2006 Moscone Center -- Room 130, Oral
Division of Analytical Chemistry |