Identification
A:
The
Assay preparation,prepared as directed in the
Assay,exhibits an absorption maximum at about 313nm when tested as directed for
Procedurein the
Assay.
B:
Add 0.3mLof alkaline mercuric-potassium iodide TSto 5mLof Injection:a reddish-brown color develops.
C:
Evaporate 50mLof Injection on a steam bath to a volume of about 0.3mL,and add 0.3mLof ammonium hydroxide.Cool,and add slowly,with mixing,a well-cooled mixture of 1mLof nitric acid and 1.2mLof water.Allow to stand for 24to 48hours,and pass through a sintered-glass filter.To the filtrate add 0.5mLof dibasic sodium phosphate TS:a yellow precipitate is formed,and it dissolves in an excess of 6Nammonium hydroxide.
Assay
Ammonium hydroxide diluent
Dilute 40mLof ammonium hydroxide with water to 1000mL.Store in a plastic bottle.
Sodium sulfate solution
Dissolve 1g of sodium sulfate in water to make 100mL.
Molybdenum stock solution
Transfer about 1.84g of previously assayed Ammonium Molybdate,accurately weighed,to a 1000-mLvolumetric flask,dilute with Ammonium hydroxide diluentto volume,and mix.This solution contains the equivalent of 1000µg of molybdenum per mL.
Standard preparations
Transfer 0,1.0,2.0,3.0,and 4.0mL,respectively,of Molybdenum stock solutionto separate 100-mLvolumetric flasks,and to the respective flasks add 5.0,4.0,3.0,2.0,and 1.0mLof Ammonium hydroxide diluent.To each flask add 10mLof Sodium sulfate solution,dilute with water to volume,and mix.These Standard preparationscontain,respectively,0,10,20,30,and 40µg of molybdenum per mL.
Assay preparation
Transfer an accurately measured volume of Injection,equivalent to about 500µg of molybdenum,to a 25-mLvolumetric flask,add 1.25mLof Ammonium hydroxide diluentand 2.5mLof Sodium sulfate solution,dilute with water to volume,and mix.
Procedure
Concomitantly determine the absorbances of the
Standard preparationsand the
Assay preparationat the molybdenum emission line of 313.3nm with a suitable atomic absorption spectrophotometer (see
Spectrophotometry and Light-scattering á851ñ)equipped with a molybdenum hollow-cathode lamp and a nitrous oxideacetylene reducing flame,using water as the blank.Plot the absorbances of the
Standard preparationsversus concentration,in µg per mL,of molybdenum,and draw the straight line best fitting the five plotted points.From the graph so obtained,determine the concentration,in µg per mL,of molybdenum in the
Assay preparation.Calculate the quantity,in µg,of molybdenum (Mo)in each mLof the Injection taken by the formula:
25C/V,
in which
Cis the concentration,in µg per mL,of molybdenum in the
Assay preparation;and
Vis the volume,in mL,of Injection taken.