Supercritical fluid chromatography- Nanospray ionization-mass spectrometry (SFC-nSI-MS).

• First development of nanospray supercritical fluid chromatography-MS. • Rapid separation of positional isomers in unsaturated fatty acids. • Changes to fatty acid levels upon pharmacological inhibitors in mammalian cell culture. A nanospray emitter coupled to a supercritical fluid chromatograph (SFC-nSI-MS) for mass spectrometric (MS) analysis of fatty acids (FA) positional isomers is introduced. The experimental setup uses conventional bore columns before the SF back-pressure regulator (pre-BPR). The flow is then split and nanosprayed using a short emitter post-BPR. A C18 column was used to resolve positional isomers of unsaturated FA with a 5 min gradient. Chromatographic resolution of the nSFC was compared to a LC-MS system with superior resolving power demonstrated in the nSFC MS system. This system has proven quantitative performance for analyzing pharmaceutical effects on FA composition in a complex biological matrix like E coli l ysate. [ABSTRACT FROM AUTHOR]