determination, a stannous chloride solution is added to the test
solution in variable amounts and according to the kind of original
sample. Tests are conducted simultaneously with solutions containing
known amounts of mercury that serve as standards for comparison.
This operation is known as system standardization. Addition of
the reducing reagent leads to the formation of elemental mercury,
which is expelled by aeration, forcing the mercury vapor through
a detector paper lined with an emulsion containing cuprous iodide.
The intensity of the color in the resulting complex (Equation
1) is proportional to the mercury concentration in the original