A specific method for the determination of trace concentrations of tetramethyl- and tetraethyllead vapours in air
A method is described for the specific determination of tetraalkyllead vapour in air. The atmosphere under test is passed through a solution of iodine monochloride in hydrochloric acid, which converts the tetraalkyllead compounds into their dialkyllead ionic forms.
A procedure is given in which dialkyllead species are preferentially extracted as dithizonates from the buffered sample solution in the presence of ethylene-diaminetetraacetic acid, which complexes any inorganic lead compounds that may be present. The dialkyllead dithizonates are then decomposed by shaking with a nitric acid-hydrogen peroxide solution and the concentration of lead in the resulting solution is determined by atomic-absorption spectrophotometry, using a carbon furnace for atomisation.
The method has a limit of detection of 7 ng of lead in the sample. When expressed as a concentration of tetraalkyllead in air the detection limit is 0·2 µg m–3 for a 10-min sampling period and 0·04 µg m–3 for 1-h sampling period.