Improving Resolution and Column Loading Systematically in Preparative Liquid Chromatography for Isolating a Minor Component from Peppermint Extract

■ At-column dilution alleviates the peak distortion and loss of resolution attributed to the injection of large volumes of strong solvent, leading to improved resolution, column loading, and overall productivity in natural product isolation. IN T RO DU C T IO N Natural products are widely used in the pharmaceutical, food supplement, nutraceutical, and alternative medicine industries. Chromatography has long been an integral part of natural product research, including chemical fingerprinting, structural elucidation, and isolation of bioactive compounds on the preparative scale. Since natural product extracts are usually complex mixtures comprised of many different compound classes with a variety of functional groups, acid-base properties, and molecular sizes, reversed-phase liquid chromatography (RPLC) often lends itself as the technique of choice for the analysis and purification of natural products, largely due to its general applicability.