The specified volume of each sample was poured into a beaker and evaporated on a hot plate to 50 ml volume and
then transferred to a clean dry planchet. The samples were evaporated to dryness on hot plate. The residues were
transferred onto to a clean, dry and previously weighed planchet and the difference between the mass of empty
planchet and that of the empty planchet plus residue gives the mass of the residue. The residues were uniformly
spread on the planchet by dropping a few drops of ethanol. The residues were allowed to dry and then covered with
Mylar film ready for counting.