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Mechanistic understanding of abnormal reverse phase chromatographic behavior of basic analytes in the presence of sodium dodecyl sulfate

Socia, Adam, Liu, Yong, Abend, Andreas, Wuelfing, W. Peter
Journal of chromatography 2019 v.1595 pp. 108-116
chromatography, pH, sodium dodecyl sulfate, surfactants
In the process of dissolution method development for Merck proprietary compound A, a basic analyte, abnormal chromatographic behavior involving peak splitting and retention time shifting in the presence of sodium dodecyl sulfate (SDS) in the sample solution was observed. A mechanistic study was conducted and the level and type of surfactant, along with the pKa of the analyte, were determined to be the critical variables in the degree of effect seen. Chromatographically, the effect was further impacted by the injection volume used, the pH and identity of the mobile phase buffer and the amount of system volume between the autosampler and the column. A simple resolution using a basic mobile phase pH was identified to be an effective way to eliminate abnormal chromatographic behavior and produce robust and reproducible analysis.