Comparison of LC/MS and SFC/MS for Screening of a Large and Diverse Library of Pharmaceutically Relevant Compounds

Abstract

The search for greater speed of analysis has fueled many innovations in high-performance liquid chromatography (HPLC), such as the use of higher pressures and smaller stationary-phase particles, and the development of monolithic columns. Alternatively, one might alter the chromatographic mobile phase. The low viscosity and high diffusivity of the mobile phase in supercritical fluid chromatography (SFC) allows higher flow rates and lower pressure drops than is possible in traditional HPLC. In addition, SFC requires less organic, or aqueous-organic, solvent than LC (important in preparative-scale chromatography) and provides an alternative, normal-phase retention mechanism. But fluids that are commonly used as the main mobile-phase component in SFC, such as CO2, are relatively nonpolar. As a result, SFC is commonly believed to only be applicable to nonpolar and relatively low-polarity compounds. Here we build upon recent work with SFC of polar and ionic compounds and peptides, and we compare the LC/MS and SFC/MS of a diverse library of druglike compounds. A total of 75.0% of the library compounds were eluted and detected by SFC/MS, while 79.4% were eluted and detected by LC/MS. Some samples provided strong peaks that appeared to be related to the purported compound contained in the sample. When these were added to the "hits", the numbers rose to 86.7 and 89.9%, respectively. A total of 3.7% of the samples were observed by SFC/MS, but not by LC/MS, and 8.1% of the samples were observed by LC/MS, but not by SFC/MS. The only compound class that appeared to be consistently detected in LC/MS, but not in SFC/MS under our conditions, consisted of compounds containing a phosphate, a phosphonate, or a bisphosphonate. The SFC/MS method was at least as durable, reliable, and user-friendly as the LC/MS method. The APCI source required less cleaning during the SFC/MS separations than it did during LC/MS.

Evolution and Current Trends in Liquid and Supercritical Fluid Chromatography

“…Finally, SFC-MS is not restricted to this field and thanks to the versatility of atmospheric pressure ionisation source, is now gradually implemented in many new applications. Comparative studies between LC-MS and SFC-MS have demonstrated that the latter technique was highly competitive for drug analysis [294,295]. In addition, several preliminary studies have recently described some favourable conditions for obtaining sharp peaks and good MS detection of basic pharmaceutical compounds [265,296].…”

Supercritical fluid chromatography‐mass spectrometry for chemical analysis

“…APCI normally generates both [M + H] + and [M -H] -ions to make mass spectral interpretation trivial. The SFC-APCI/MS method was proved to be as durable, reliable, and userfriendly as the LC/MS method for screening of a large and diverse library of pharmaceutically relevant compounds [32]. In addition, the APCI source demanded less cleaning for the SFC-MS systems than the LC-MS systems [32].…”

Clinical and pharmaceutical applications of packed‐column supercritical fluid chromatography

“…Due to its efficiency, speed, and success in chiral separations, SFC has been replacing HPLC in certain drug development projects. A direct comparison of HPLC/MS and SFC/MS analysis of pharmaceutically relevant compounds was conducted by Pinkston et al [17]. SFC/MS under the selected experimental conditions.…”