Use of solid-liquid distribution coefficients to determine retention properties of Porapak-Q resins - Determination of optimal conditions to isolate alkyl-methoxypyrazines and beta-damascenone from wine

The solid-liquid distribution coefficients of different analytes - all of w hich are important aroma compounds - between hydroalcoholic solutions or wi nes and different sorbents have been determined by measuring the amount of analyte removed by a given mass of sorbent in equilibrium with a given volu me of standard solution. These data have shown that the best extraction con ditions for non-polar compounds from wine are the use of Porapak-Q resins a nd 6% (v/v) alcoholic solutions. Phase ratio, hold-up volumes and number of plates for Porapak-Q beds have been measured in different experiments. Wit h all these data it has been possible to calculate breakthrough volumes in good agreement with experimental results. The Lovkvist-Jonsson model is mor e appropriate for estimating breakthrough volumes of a 2-cm Porapak-Q bed. The model estimates that a 5-cm bed is needed to achieve a quantitative rec overy of 3-alkyl-2-methoxypyrazines and beta -damascenone from 500 ml of wi ne (diluted to 1000 ml with water). Experimental results confirm the predic tions of the model and show that in a single isolation step detection limit s below 10 ng/l can be reached for these compounds using GC-MS detection. ( C) 2001 Elsevier Science BM All rights reserved.