Placing supercritical fluid chromatography one step ahead of reversed-phase high performance liquid chromatography in the achiral purification arena: A hydrophilic interaction chromatography cross-linked diol chemistry as a new generic stationary phase

A major driving force hindering the application of supercritical fluid chromatography (SFC) to achiral medium-throughput (MT) and/or high-throughput (HT) purification in the pharmaceutical industry is the absence of a widely applicable column for the analysis and purification of structurally diverse research compounds. As a result, method development is more time-consuming compared to reversed-phase high-performance liquid chromatography (RP-HPLC) where 2 stationary phases, each one used at a different pH, can successfully resolve the majority of mixtures, and SFC is considered a step behind this traditional tool. In early 2010, our group identified a hydrophilic interaction chromatography (HILIC) cross-linked diol chemistry as the most generic column tested so far for achiral SFC application. Analytical and semi-preparative pilot studies using internal research mixtures exceeded our best expectations and allowed for the reduction of our initial 5 column screen on diol, 2-ethyl pyridine, benzenesulfonamide, diethylaminopropyl and dinitrophenyl to a one column (HILIC cross-linked diol) or two column (HILIC cross-linked diol and 2-ethyl pyridine) screen for MT and HT purification. This very high-efficiency and cost-effective approach was immediately implemented as our routine process. Since then, scope, generality and robustness have been validated: 85–90% of samples received in our labs can be purified by SFC, 98% of them using the new 1–2 column simplified screening strategy and in a single pass. In addition, the compound of interest (COI) is isolated at greater than 95% purity and with 85–90% recovery. The success of the new approach has enabled the group to shift from RP-HPLC/MS to SFC/MS as the primary technique for purification within the achiral area.