Multivariate approach to on-line supercritical fluid extraction - supercritical fluid chromatography - mass spectrometry method development.

Coupling supercritical fluid extraction (SFE) on-line with supercritical fluid chromatography (SFC) - tandem mass spectrometry (MS/MS) provides a single platform for efficient extraction, separation, and detection in a chemical analysis. SFE-SFC-MS/MS requires consideration of many extraction and chromatographic variables to not only provide the most efficient extraction, but also to analytically transfer the extracted analytes to the column for separation. There is a fundamental lack of understanding of how the variables in SFE affect those in SFC. Typically, a univariate approach is taken in on-line SFE-SFC-MS/MS method development, but this provides little insight into the relative importance of variables and their potential interactions. Here, a multivariate approach was used to develop a better understanding of the synergistic relationship between the extraction and separation processes by focusing on the optimization of extraction parameters for target analytes with a wide range of physicochemical properties in matrices of variable retentivity. The methodology used a set of optimal on-line SFE-SFC-MS/MS extraction parameters for 18 analytes of variable physicochemical properties in three different silica gel-based sample matrices are presented.