A modification of the pyroelectric sodium fluoride carrier distillation method for analysis of impurities in plutonium metal is described. The metal is dissolved. Plutonium is precipitated and treated with nitric acid. The slurry obtained is dried and ignited. The resultant low density oxide is mixed with sodium fluoride and pressed into a pellet for arcing. Cobalt is used as the internal standard for densitometric using visual comparisons against prepared standards. The procedural modifications improve reproducibility and sensitivity of most of the elements involved. (auth)

Selective occlusions of straight-chain paraffins in the presence of branched-chain hydrocarbons by naturally occurring zeolites of suitable dimension was reported as early as 1944 by Barrer and Ibbitson. More recently the capacity of synthetic zeolites or molecular sieves to absorb exclusively the straight-chain hydrocarbons from complex hydrocarbon mixtures has found extensive application in the petroleum industry. Under the conditions developed for most sieving operations any normal olefins present are occluded along with the normal paraffins. A supplemental separation technique must be employed to obtain n-paraffins free of olefins.