2.3. Standard preparation
The stock solution of Lead, Copper and Zinc were prepared by
dissolving in a liter volumetric flask 24.62, 1.63 and 1.60 g of
Lead nitrate, Copper sulfate and Zinc chloride respectively
with 68% of nitric acid. The mixture was shaken and the flask
made up to the 1 L mark with the nitric acid for each metal.
Calibration solutions of the target metal ions were prepared
from the standard stock by serial dilution.