Assay
Sodium chloride solution
Dissolve 1.8g of sodium chloride in water,dilute with water to 2000mL,and mix.
Manganese stock solution
Transfer 1.000g of manganese to a 1000-mLvolumetric flask,dissolve in 20mLof nitric acid,dilute with 0.1Nhydrochloric acid to volume,and mix.This solution contains 1000µg of manganese per mL.Store in a polyethylene bottle.
Standard preparations
Pipet 10mLof the Manganese stock solutioninto a 500-mLvolumetric flask,dilute with water to volume,and mix.Transfer 4.0,5.0,and 6.0mL,respectively,of this solution to separate 50-mLvolumetric flasks,containing 10mLof Sodium chloride solution,dilute the contents of each flask with water to volume,and mix.These Standard preparationscontain,respectively,1.6,2.0,and 2.4µg of manganese per mL.
Assay preparation
Transfer an accurately measured volume of Injection,equivalent to about 1mg of manganese,to a 100-mLvolumetric flask,dilute with water to volume,and mix.Pipet 10mLof this solution into a 50-mLvolumetric flask.From the labeled amount of sodium chloride,if any,in the Injection,calculate the amount,in mg,of sodium chloride in the initial dilution,and add sufficient Sodium chloride solutionto bring the total sodium chloride content in this flask to 9mg.Dilute with water to volume,and mix.
Procedure
Concomitantly determine the absorbances of the
Standard preparationsand the
Assay preparationat the manganese emission line of 279nm,with a suitable atomic absorption spectrophotometer (see
Spectrophotometry and Light-scattering á851ñ)equipped with a manganese hollow-cathode lamp and an airacetylene flame,using a dilution of
Sodium chloride solution(1:5)as the blank.Plot the absorbances of the
Standard preparationsversus concentration,in µg per mL,of manganese,and draw the straight line best fitting the three plotted points.From the graph so obtained,determine the concentration,in µg per mL,of manganese in the
Assay preparation.Calculate the quantity,in mg,of manganese in each mLof the Injection taken by the formula:
0.5C/V,
in which
Cis the concentration,in µg per mL,of manganese in the
Assay preparation;and
Vis the volume,in mL,of Injection taken.