A study was performed to confirm suspected artifactual formation of acetone derivatives during the Soxhlet extraction of soil samples with acetone. The conditions employed simulated very closely those normally employed for the extraction of soils for neutral and moderately polar organic compounds such as pesticides. A series of acidic, neutral, and basic organic-free soils were extracted with hexane/acetone solvent mixture and the extracts concentrated in a Kuderna-Danish apparatus. The extracts were analyzed by capillary column gas chromatographic mass spectrometry. In nearly all cases, simple dimeric products such as diacetonecohol and mesityl oxide were formed in varying amounts. The acidified and basic soils yielded complex mixtures of dimers, trimers, tetramers and other complex homologs. Some of the more common substances found include phorone, mesitylene and isophorone. The latter substance is listed as an EPA priority pollutant.