Comparison of procedures for isolation of monoterpene hydrocarbons from fresh needles of Picea abies and Picea omorica

Extraction procedures (steam distillation, supercritical fluid extraction a nd solvent extraction) for isolation of monoterpene hydrocarbons from fresh needles of Picea abies and Picea omorica were optimised. The procedures we re compared with the aim of minimizing consumption of needles and improving the extraction efficiency and repeatability. An influence of homogenisatio n procedures and storage conditions (liquid nitrogen, -18 and 4 degrees C) on the total content and composition of essential oils was studied. Cryogen ic grinding (liquid nitrogen) combined with the extraction with cold hexane (extraction time 2 h) and subsequent GC-MS determination in freshly homoge nised needles gives the best results (1.5-4 times better extraction efficie ncy, RSD < 10% for P. abies and < 25% for P. omorica). Limits of detections (3 S/N) for individual monoterpene hydrocarbons from units to tens of ng/g and recoveries 97.2-101.4% were found in fresh needles (calculated to fres h weight). While cooling to 4 degrees C is unacceptable, freezing at -18 de grees C for the period of 18 days in the dark gives also good results.