This article reports detailed procedures: 1) to decrease organic contaminat
ion of samples in the laboratory; 2) to extract sewage sludge with methylen
e chloride; and 3) to fractionate extracts by silica-gel thin layer chromat
ography (TLC) into fractions enriched in alkanes,aromatic hydrocarbons, ket
ones, alcohols and fatty acids, eluting either hexane or methylene chloride
.