A method is described for the direct reading spectrometric determination of zinc, copper and lead in plant material. The metals to be determined are separated by dithizone extraction from a solution of 1 gram of the plant material. The excitation source consists of an interrupted d c. arc struck between a graphite counter electrode and a rotating graphite-sodium carbonate disc, on to which a chloroform solution of the metal dithizonates is sprayed. Spectrum line emission measurements are made by means of a medium dispersion quartz prism spectrograph with direct reading attachment A series of plant material samples has been analysed by the method and the standard deviations of the results obtained from the mean of two arcings in each of ten replicate analyses were found to be 5.1% for zinc, 7.3% for copper and 6.1% for lead.
A. Strasheim and D. J. Eve, "Direct Reading Spectrometric Determination of Zinc, Copper and Lead in Plant Material," Appl. Spectrosc. 14, 97-100 (1960)