Comparison of techniques for extracting volatile compounds from conifer needles.

Five extraction techniques were used to obtain quantitative measurements of monoterpenes from blue spruce and grand fir needles. Multivariate analysis of variance indicated that there was a significant difference in the amount of each monoterpene extracted by using different techniques. For both species, an 8-hr steam distillation of 10 g of material yielded the greatest amount of each monoterpene. This technique was also the most reproducible in that the coefficients of variation were lowest. A rapid steam distillation was relatively effective for grand fir, but not for blue spruce. A CO2 extraction was unreliable for both species.