Analysis of 2-Methylisoborneol and Geosmin in Catfish by Microwave Distillation−Solid-Phase Microextraction

The semivolatile cyclic alcohols 2-methylisoborneol (MIB) and geosmin (GSM) impart muddy or musty flavors to water and food products. A rapid quantitative analytical technique has been developed whereby microwave distillation is used to remove the volatile organic compounds from a lipophilic matrix into an aqueous matrix. Solid-phase microextraction (MD-SPME) is then used to extract and concentrate the analytes, which are then desorbed in the injection port of a gas chromatograph/mass spectrometer (GC/MS) for analysis. Limits of detection are 0.01 μg/kg and limits of quantification are 0.1 μg/kg. MD-SPME is comparable in precision, requires no solvents, and is faster than current methods of analysis. This methodology allows detection of MIB and GSM at concentrations below human sensory thresholds in fish tissue. Keywords: 2-Methylisoborneol; catfish; geosmin; microwave distillation; off-flavor; solid-phase microextraction