may be diluted quantitatively with water, if necessary, to yield solutions of suitable concentrations adaptable to the linear or working range of the instrument.
Concomitantly determine the absorbances of the Standard preparations
and the Assay preparation
at the zinc emission line of 213.8 nm with a suitable atomic absorption spectrophotometer (see Spectrophotometry and Light-scattering 851
) equipped with a zinc hollow-cathode lamp and an airacetylene flame, using water as the blank. Plot the absorbances of the Standard preparations
versus concentration, in µg per mL, of zinc, and draw the straight line best fitting the three plotted points. From the graph so obtained, determine the concentration, in µg per mL, of zinc in the Assay preparation
. Determine the concentration, in mg per mL, of Zn in the Injection taken by the formula:
5C / V,
in which C
is the concentration, in µg per mL, of zinc in the Assay preparation
; and V
is the volume, in mL, of Injection taken.