Though it is best known as a chemical compound in the spirit absinthe, it is unlikely to be responsible for absinthe's alleged stimulant and psychoactive effects due to the small quantities present. Thujone acts on GABA as an antagonist (opposite to the effects of alcohol). As a competitive antagonist of GABA, thujone alone is considered to be convulsant, though by interfering with the inhibitory transmitter GABA, it may convey stimulating, mood-elevating effects at low doses. It is also used in perfumery as a component of several essential oils. In the past, absinthe was thought to contain up to 260–350 mg/l thujone, but modern tests have shown this estimate to be far too high. A 2008 study of 13 pre-ban (1895–1910) bottles of absinthe using gas chromatography-mass spectrometry (GC-MS) found that the bottles had between 0.5 and 48.3 mg/l and averaged 25.4 mg/l. A 2005 study recreated three 1899 high-wormwood recipes and tested with GC-MS, and found that the highest contained 4.3 mg/l thujone. GC-MS testing is important in this capacity, because gas chromatography alone may record an inaccurately high reading of thujone as other compounds may interfere with and add to the apparent measured amount.