Right-first-time isocratic preparative liquid chromatography-mass spectrometry purification

Preparative RP-LCMS is widely used to purify compounds from crude reaction mixtures in drug discovery today. Method development for preparative Liquid Chromatography-Mass Spectrometry (LCMS) consists of finding the right balance between speed and quality, often leading to the use of fast generic gradients (5-95% organic mobile phase) to purify compounds of various structures and polarity, which can be sometimes detrimental to the purity of the isolated compound. Isocratic elution is the best method to obtain high purity, but it usually requires a long trial and error method development to find the right eluent composition. Therefore it is mostly used to purify large quantities of product using for instance stack injections, but not for routine purification of structurally diverse compounds. Herein, we describe an empirical method that allows "right-first-time" purifications with isocratic elution on preparative RP-LCMS, permitting isolation of compounds in high purity and yield.