An isotope dilution method for environmental lead determinations

A method is described for the use of 212Pb to measure overall recovery in lead analysis. Other modifications of published procedures are also outlined. Most difficulties occur with samples containing small amounts (<10μg) of Pb. In addition to low recovery factors, spectra are often obscured by the presence of dithizone oxidation product: a procedure for dealing with this is given. Data for two typical samples are shown in tables. These results are for two low volume air samples: they clearly illustrate the low recovery factors found in these cases. In samples containing larger amounts of Pb, chemical yields were higher and usually between 90 and 100%. (T.G.)