Influence of Coverage Density of Chemically Bonded C₁₈ Phases on the Retention Data of Substances Eluted in Dead Volume During RP HPLC Analysis

Abstract

In this paper there are discussed the results of studies relating to the effect of controlled coverage density (α_RP) of silica gel surface with c₁₈ chemically bonded phase (CBP) on the retention of some test substances (H₂o, D₂o, CH₃OH, CH₃OD) most often used to the determination of dead volume (V_o). In the consideration it has regarded the influence of many effects accompanying with RP HPLC elution e. g. specific and unspecific interactions, solvatation, displacement, local concentration changes, diffusion and exclusion. Special attention was paid to the influence of physico-chemical properties of prepared packings. Therefore the packing materials surface before and after chemical modification were characterized by different instrumental methods e. g.: porosimetry, pH-metry, elemental analysis, CP/MAS NMR, GC and HPLC.