DETERMINATION OF CHLORINATED PESTICIDES AND PCB IN PINE NEEDLES - IMPROVED METHOD FOR THE MONITORING OF AIRBORNE ORGANOCHLORINE POLLUTANTS

A method to determine organochlorine pollutants in pine needles is des cribed. Fresh, whole needles have been extracted for 48 h in dichlorom ethane to obtain the epicuticular wax fraction. The remainder has been cut into small pieces and again extracted with dichloromethane to obt ain the internal lipids. Prior to gas chromatography, both the wax and the internal lipid extracts have been fractionated on two columns: fi rst a silica gel/silica gel:sulphuric acid 2:1 column with dichloromet hane as eluent and then a nitrophenyl silica column with hexane as elu ent. Three fractions have been collected, fraction 1 containing hexach lorobenzene (HCB), fraction 2 containing polychlorinated biphenyls (PC B) and 1,1-dichloro-2,2-bis(4-chlorophenyl)ethene (DDE), and fraction 3 containing the remaining, more polar, organochlorine pesticides. For some pine species, the nitrophenyl silica column has been combined wi th a short aminopropyl silica column to obtain chromatograms of the PC B fraction free from negative peaks. The precision is in the range of 4-12% relative standard deviation, and the overall recovery is around 65-90%.