ANYL 314 |
| Several challenges were encountered in the development of a robust procedure to quantify capecitabine and three metabolites, 5'-deoxy-5-fluorocytidine (5DFC), 5'-deoxy-5-fluorouridine (5FUR), and 5-fluorouracil (5FU) in human plasma The assay demanded both positive and negative electrospray ionization to achieve desired quantification limits. “Mass spec reequilibration” emerged in which the recovery time for mass spec ionization was longer than column reequilibration. Column lifetimes were short. One analyte required on-line column switching for analysis. Not only are 5FUR and 5FU highly polar and not very well retained, but both are also ionized in negative mode which is different than capecitabine and 5DFC. The assay was finally achieved with two extractions: a SPE extraction for capecitabine, 5DFC, and 5FUR, with two separate isocratic injections with a positive/negative switch, and a liquid/liquid extraction for 5FU with online column switching. Both methods were successfully validated and have been used to analyze clinical samples. |
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Analytical Approaches: Mass Spectrometry
8:30 AM-11:20 AM, Thursday, 14 September 2006 Moscone Center -- Room 124, Oral
Division of Analytical Chemistry |