For decades, liquid chromatography stationary phase design has been dominated by the idea of elimination of multiple, or "unwanted", interactions that occur in mixed-mode separations. Reverse-phase chromatography is making the point of eliminating silanol interactions with amine-containing analytes by developing base-deactivated phases.

Within the same trend, adsorption interactions are considered undesirable as opposed to steric interactions in size-exclusion chromatography, and non-ionic interactions are generally viewed as complications in ion-exchange and ion-exclusion chromatography.

However, there are ways to benefit from multiple interactions on the stationary phase. SIELC Technologies introduces Primesep® HPLC columns, specifically designed for mixed-mode separations and capable of separating a tremendous range of compounds by different separation modes based only upon mobile phase selection. MORE

Currently, SIELC Technologies offers the following types of silica-based mixed-mode phases.

Columns with negatively charged functional groups due to the embedded anionic ion-pairing reagent. Primesep A Strongest acidic phase Primesep 100 Strong acidic phase Primesep 200 Medium acidic phase	Columns with positively charged functional groups. Primesep B Strong basic column for use with TFA, phosphoric or perchloric acid solutions in a mobile phase. Primesep B2 Weak basic column for ammonium acetate buffered solution. MORE	Column with unique unparallel selectivity. Primesep C Combined reverse-phase and complex formation properties for interaction with amines, sulfonium, phosphonium and metal ions. MORE	Three interactions within one column: reverse phase pi-pi strong cation exchange Primesep P Choose for separation of structural isomers of aromatic compounds. MORE
Choose the correct column by their functional group acidity to match the pKa value of your basic compounds. MORE