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.

L Ortega, R López, J Cacho, V Ferreira

Index: J. Chromatogr. A. 931(1-2) , 31-9, (2001)

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Abstract

The solid-liquid distribution coefficients of different analytes--all of which are important aroma compounds--between hydroalcoholic solutions or wines and different sorbents have been determined by measuring the amount of analyte removed by a given mass of sorbent in equilibrium with a given volume of standard solution. These data have shown that the best extraction conditions for non-polar compounds from wine are the use of Porapak-Q resins and 6% (v/v) alcoholic solutions. Phase ratio, hold-up volumes and number of plates for Porapak-Q beds have been measured in different experiments. With all these data it has been possible to calculate breakthrough volumes in good agreement with experimental results. The Lövkvist-Jönsson model is more 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 recovery of 3-alkyl-2-methoxypyrazines and beta-damascenone from 500 ml of wine (diluted to 1000 ml with water). Experimental results confirm the predictions of the model and show that in a single isolation step detection limits below 10 ng/l can be reached for these compounds using GC-MS detection.