Analysis of samples containing polar matrix components such as water, glycols, sugars or surfactants by gas chromatography has usually required extensive cleanup such as liquid/liquid extraction, solid phase extraction or distillation. Some polar matrix components like acetic acid or ethanol are highly volatile and difficult to eliminate using traditional sample preparation techniques. Poor analyte peak shapes, interference from large matrix peaks or even column degradation result if some matrix components are introduced into the GC.
Stir bar sorptive extraction [1] using a Polydimethylsiloxane (PDMS) phase on the stir bar prior to GC analysis can eliminate major interference from these polar matrix components. The PDMS selectively extracts nonpolar analytes, discriminating against the polar matrix components present in the sample at even percent levels or higher. Samples that contain high levels of interfering compounds like surfactants and emulsifiers that usually form emulsions when attempting organic solvent extractions can be analyzed directly by SBSE.
Examples include separation of flavor and fragrance components in balsamic vinegar and alcoholic beverages, and analysis of fragrances and other additives in consumer products like soaps and detergents. Trace additive analysis in new and used antifreeze further demonstrates the versatility of SBSE for sample preparation prior to GC analysis.
