Effect of sample solvent on the chromatographic peak shape of analytes eluted under RPLC conditions

S. KEUNCHKARIAN, M. R. RETA AND C.B. CASTELLS

Estocolmo (Suecia)

Congreso; 29th International Symposium on High Performance Liquid Phase Separations and Related Techniques; 2005

Comité Organizador

Peak-shape distortions represent one of the most common problems in liquid chromatography. In many cases, the chromatographer accepts non-gaussian peak shapes, as long as the peak distortion is not excessive. As it is known, distorted peaks are causes for integration problems and, sometimes, for poor resolution. Sample solvent different from that of the mobile phase is one of the possible reasons for anomalous peak-shape. In fact, it is well known that the injected sample should be dissolved in the mobile phase. However, the pre-treatment of the sample often ends with the analytes dissolved in a solvent different from that of the eluent and changing to the composition of the mobile phase could not be a simple task. It is well accepted that a sample solvent stronger than the mobile phase can cause bad peak shape. However, a viscosity mismatch between both sample solvent and mobile phase produces very distorted peaks especially for earlier eluted analytes. The goal of the present work was to critically evaluate the significant role of sample solvent upon the chromatographic band distortion, with emphasis on high-throughput HPLC analysis. We also discuss practical solutions for situations where chromatographic analysis are performed under conditions far from ideal as a result of time constrains related to sample preparation.