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Mixed-mode Stationary Phases

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 Choose the correct column by their functional group acidity to match the pKa value of your basic compounds. MORE	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 unparalleled 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