DEVELOPMENT OF NONDESTRUCTIVE METHODS FOR THE DETERMINATION OF AIRBORNE POLLUTANTS IN PINE NEEDLES - IDENTIFICATION OF TRACE CONSTITUENTS IN RADIATA PINE EPICUTICULAR WAX

In an attempt to develop non-destructive workup procedures for monitoring lipophilic pollutants in the air by analysis of pine needle epicuticular wax, a project was undertaken to identify substances that interfere with the normal gas-chromatographic quantitations. Epicuticular wax was extracted from needles of radiata pine and processed to remove the bulk estolides and resin and fatty acids. Fractionation of the residue on a silica gel column gave three fractions, representing less than 0.2% of the wax. The fractions contained a mixture of natural products and anthropogenic chemicals. Among the natural products were sesquiterpenes, comprising mainly amorphene, cadinenes, germacrene and cadalene; bisnor-, nor- and diterpene hydrocarbons; methyl esters of resin acids; and 9,10-secodehydroabietanes of unknown ring-A structure. Some of these compounds have not been reported from pine needle epicuticular wax previously. Anthropogenic chemicals identified include polycyclic aromatic hydrocarbons. The organochlorine compounds of environmental importance were hexachlorocyclohexanes (including lindane), hexachlorobenzene, pentachloroanisole, chlordanes, dieldrin, p,p'-DDE, p,p'-DDT, and penta-, hexa- and heptachlorobiphenyls. The organochlorine compounds were present at concentration orders of magnitude lower than the interfering compounds, and therefore had to be identified using gas chromatography-mass spectrometry methods. By identifying the interfering compounds, non-destructive work-up procedures could be developed in order to retain the integrity of all of the anthropogenic compounds contributing to environmental pollution.