DETERMINATION OF AS, CD, AND PB IN EPICUTICULAR WAXES OF PINE AND SPRUCE NEEDLES BY ETAAS

Waxes were separated from needles by chloroform washing, drying and di ssolving the residue in tetrahydrofuran (THF). Both a THF solution of the wax and an aqueous solution of the Pd-Mg matrix modifier were samp led directly into the graphite tube. The reaction conditions were opti mised for the wax concentration of 45 mg ml(-1) in THF and the Pd:Mg r atio of 1:1 in the matrix modifier. The atomisation and charring tempe ratures for As, Cd and Pb were the same as those recommended for analy sis of aqueous solutions except the charring temperature of Cd takes 2 00 degrees C lower. The characteristic masses for As (26 pg), Cd (0.5 pg) and pb (9 pg) are also comparable to published data. The parameter s of calibration curves were identical for all three elements dissolve d either in clear THF or in the wax solution. Elemental concentrations were found to range from 0.1 to 1.0 mg g(-1), increasing with needle age for As, Pb but not Cd.