Characterization of petroleum-contaminated soils by thin-layer chromatography with flame ionization detection

Petroleum hydrocarbons from 20 soils from refineries or other industrial si tes were extracted with a mixture Of chloroform and methanol (I:1, v/v), an d the extracts were analyzed by thin layer chromatography with flame ioniza tion detection (TLC/FID). The TLC/FID procedure has been used widely in bio logical and medical research but generally has been underutilized in enviro nmental chemistry The analysis method involved spotting a small volume of s ample extract (typically I to 3 mu l) on ten silica-coated quartz rods, and chromatographically separating constituents in the spots using solvent sys tems of increasing polarities (hexane, toluene, smd dichloromethane + metha nol). We achieved complete separation of saturated hydrocarbons, aromatic h ydrocarbons, resins, and asphaltenes from the hydrocarbon-contaminated soil s with this method. Analysis of the separated constituents by TLC/FID also allowed quantification of aromatic and aliphatic hydrocarbons without inter ference from soil biogenic lipids. A simplified version of the method permi tted excellent separation of aliphatics + aromatics (forming a single peak) from resins and asphaltenes. The procedure Is rapid (complete analysis of ten samples in about 1 h after extraction). Thus, the method seems well sui ted for synoptic surveys or screening and characterizing numerous samples p rior to using more detailed and costly analyses.