Screening for sensory quality in foods using solid phase micro-extraction tandem mass spectrometry.

Abstract

Tandem mass spectrometry has proven a useful technique for the elucidation of chemical structures. However, there are no applications of tandem mass spectrometry for routine applications. This is in part due to the limitation of samples being introduced into the ion source in the presence of a solvent. The relative large amount of solvent molecules overwhelms the presence of the analyte and the signal, if any, is lost in the chemical noise. With the introduction of solid phase microextraction (SPME), the analyte can now be placed in the mass spectrometric source in a solvent free environment (Belardi and Pawliszyn, 1989; Eisert and Levsen, 1996; Kataoka et al., 2000). The major contributors to the muddy/musty off-flavor in drinking water systems are 2- methylisoborneol (2-MIB) and geosmin (Lovell, 1983). These compounds are generally placed in the water column by blue-green algae, but are also produced by bacteria and fungi. Associated with algae blooms in late summer, the compounds are perceptible to the human nose at the low parts per trillion range (Persson, 1980). They plague drinking water systems and are particularly problematic in the warm water aquaculture production of farm-raised catfish. The current method for analysis of 2-MIB and geosmin is closed loop stripping (McGuire et al., 1981) and purge and trap (Johnsen and Lloyd, 1992) with GC/MS analysis. However, a technique employing SPME-GC/MS has recently been reported for the analysis of these compounds at the parts per trillion level (Lloyd et al., 1998; Watson et al., 2000). The SPME technique has proven to be an excellent method for the concentration of volatile compounds, and in combination with gas chromatography for separation and mass spectrometry for detection, provides a state-of- the-art analytical tool.