Most of what is perceived as flavors in foods are actually the aromas and odors that are being detected by our sense of smell. The human nose is far more sensitive to most flavor and odor compounds than are GCMS systems, so proper detection, identification and quantitation of these compounds requires sample enrichment. Prior to the development of SPME (Solid Phase Micro Extraction), Flavor Chemists had only loop injection, solvent extraction, and thermal desorption as the means of detecting and measuring flavor and “off-flavor” compounds. Although direct measurement of headspace aromas using Thermal Desorption provided the needed sample enrichment, adsorbents create a far too reactive environment to allow recovery of all GC compatible compounds, as many of these aroma compounds are thermally labile and decompose at the high temperatures needed to release them from the adsorbent. With the introduction of SPME, many compounds that were previously undetected using thermal desorption were recovered and identified. Unfortunately, SPME was found to be qualitative in its measurements due to issues involving carryover and inconsistent sample absorption caused by factors affecting rates of diffusion both into the headspace and then to the SPME fiber.
Entech has introduced new tools allowing Flavor and Fragrance Chemists to obtain a more complete characterization of aroma compounds than ever before. Two new technologies called Active SPME and Large Volume SPME (LV SPME) combine to create the most effective means for recovering the greatest number of aroma and fragrance compounds at the highest possible sensitivity. Both of these techniques utilize trapping materials that are the same as those coating the inside of GC columns, providing the gentlest means of sample enrichment that will ensure maximum recovery during transfer to the GCMS. Active SPME draws the sample through the SPME stage, eliminating the diffusion process that is otherwise occurring with classical SPME. Rather than “extracting” compounds during analysis, which causes the vial + SPME fiber system to be in a non-equilibrium state, Active SPME allows equilibrium between the sample and the headspace to be achieved at a specific temperature, followed by rapid extraction of the headspace to the external Active SPME system. This creates far better reproducibility that classical SPME, and allows equal representation of both the light and heavy aroma and fragrance compounds. Large Volume SPME operates much like classical SPME, but utilizes a combination of larger surface area and thinner film thicknesses to create a SPME device with increased loading capacity and faster desorption rates.