Hugh Cramer

In reversed-phase liquid chromatography (LC), C18 alkyl-based stationary phases have been the favourite of method developers. Phenyl stationary phases are an alternative that are thought to benefit from additional π-π mechanisms. Recently, there has been a growing interest in the use of phases based on the biphenyl moiety. This instalment of “Column Watch” looks at the retention mechanisms of biphenyl phases and contrasts them with those of more-common alkyl phases.

In biphenyl phases, the surface chemistry often makes it possible to separate compounds not well resolved by C18 or phenyl phases.

Understanding the chemistry of embedded polar group and perfluorophenyl phases leads to better decisions during method developement

Many problems encountered executing HPLC methods are a result of decisions made during early method development. This article discusses one critical variable in method development, the choice of stationary phase chemistry.

Beverages, such as sodas and energy drinks, can include a number of polar ingredients, which are easily soluble in the water matrix of the drinks. These ingredients include sweeteners (sugars and sugar substitutes), caffeine, vitamin supplements, amino acids, organic acids, and plant extracts. Because the analytes are already in solution, there is no need for extensive sample preparation. Dilution followed by direct injection into an HPLC is typically suitable.