The liquid crystalline polysiloxane substrate offers unique selectivity when used in capillary column gas chromatography. The separation and identification of priority pollutants along with other compounds is very difficult but important. In particular, the separation of isomeric organic compounds having similar volatilities could not be obtained on capillary columns using conventional stationary phases. The complete separation of ortho, meta, and para isomers of certain disubstituted benzenes as well as polycyclic aromatic compounds was achieved on a capillary column using a liquid crystalline polysiloxane stationary phase. The complete separation of octachlorodibenzodioxin from octachlorodibenzofuran was also obtained on this column which is not possible on columns of identical lengths using conventional stationary phases. The separation of polycyclic aromatic compounds in a complex sample of airborne particulate matter extract on the liquid crystal column is demonstrated.