Determination of palladium in gasoline by neutron activation analysis and automated column extraction

Palladium in gasoline was determined by means of neutron activation analysis (NAA) and selective sorbent extraction. Unleaded gasoline consistent with DIN EN 228, RON 95 was irradiated at a thermal neutron flux of phith = 1.68 x 10(13)s(-1)cm(-2) and an epithermal neutron flux of 3.32 x 10(11)s(-1)cm(-2) for t(irr) = 12 h. The irradiated gasoline was digested with nitric acid and palladium was then separated as N,N-diethyl-N'-benzoylthiourea complex by an automated column pre-concentration procedure. The eluate of 50 microL was dried on a filter paper and the 88.03 keV photons resulting from the decay of 109Pd were detected in a low level HPGe spectrometer with an efficiency of 35.5%. Severe interferences with other matrix constituents, especially 82Br could be overcome and the detection limit for palladium was improved to 3.4 ng/L at a confidence level of 90%. Although the analytical procedure applied yielded the lowest detection limit for palladium obtained in gasoline up to now, no indications for the presence of palladium were found.