UHPLC Enables Enhanced Resolution Separations of Complex Drug Mixtures

Thermo Fisher Scientific (UK) has issued a new application note to demonstrate superior ultra high performance liquid chromatography (UHPLC) capabilities for the separation of drugs of abuse in complex drug mixtures. Illustrated in the application note is the advanced ability of the Thermo Scientific Accela UHPLC system to perform efficient, improved resolution separations using a unique quaternary UHP mixing pump. The new application note, entitled “A Comparison of Binary and Ternary Gradients Using Stage 1 Illicit Drugs,” is available for download via www.thermo.com/accela.

When using an HPLC method to separate a complex drug mixture, a simple binary solvent gradient can often fail to provide sufficient resolution of all analytes. In order to improve the resolution, the separation factor has to be manipulated by using a third solvent. However, this approach is not possible with typical high-pressure binary solvent mixing equipment. The Accela UHPLC system overcomes this limitation, featuring a newly introduced quaternary mixing pump that facilitates the use of up to four solvents for convenient method development, system flushing and eluent preparation. Changing of solvents, buffers and pH values is quick and easy, greatly simplifying the method development process.

The new application note describes an effective method for the separation of drugs using the Accela UHPLC in conjunction with the Thermo Scientific MSQ Plus Mass Detector, a fast-scanning single quadrupole mass spectrometer (MS). A mixture of 14 drugs is separated and baseline resolved by UHPLC/MS within eight minutes on a Thermo Scientific Hypersil GOLD PFP column using a ternary solvent gradient, which is not possible using a conventional binary solvent gradient. Methanol was found to provide improved resolution for most of the drug compounds compared with other eluents.