The seeds of leave and root celery (Apium graveolens) were extd. for 22 h with soyabean oil and CO(2) in a liq. and supercritical state to recover 3-Bu phthalide and 3-Bu dihydrophthalide (sedanolide) (concns. in the extract 0.5 and 0.9%, resp., yield 3.40-3.96%). The extracts were applied on the ground seeds and used for prepg. solid formulations. The formulation contg. 2% of supercrit. CO(2) or 1% of soyabean oil extracts were capsulated and recommended for pract. use. Both root and leave celery seeds were good raw materials for processing.