FOR MAGNESIUM SULFATE INTENDED FOR USE IN PREPARING PARENTERAL DOSAGE FORMS
Rinse all glassware used in this test with Dilute hydrochloric acid
Dilute hydrochloric acid
Dilute 1 mL of hydrochloric acid to 1000 mL with water, and mix.
Ammonium acetate solution
Transfer 250 g of ammonium acetate to a 500-mL volumetric flask, dissolve in and dilute with water to volume, and mix.
Ascorbic acid solution
Transfer 1.34 g of ascorbic acid to a 100-mL volumetric flask, dissolve in and dilute with water to volume, and mix. Use this solution on the day prepared.
Transfer 380 mg of 3-(2-pyridyl)-5,6-di-(2-furyl)-1,2,4-triazine-5¢,5¢¢-disulfonic acid, disodium salt to a 100-mL volumetric flask, dissolve in Ammonium acetate solution, shaking by mechanical means if necessary, dilute with Ammonium acetate solution to volume, and mix. Use this solution on the day prepared.
Standard iron solution
Transfer 5.0 mL of Standard Iron Solution to a 50-mL volumetric flask, dilute with Dilute hydrochloric acid to volume, and mix. This solution contains 1.0 µg of iron per mL.
To three separate 50-mL volumetric flasks transfer 2.0, 5.0, and 10.0 mL of Standard iron solution, and dilute each to 35 mL with Dilute hydrochloric acid. These solutions contain 2.0, 5.0, and 10.0 µg of iron, respectively.
Transfer 10.0 g of Magnesium Sulfate to a 50-mL volumetric flask, add Dilute hydrochloric acid to 35 mL, and sonicate, if necessary, to achieve complete dissolution.
Transfer 35 mL of Dilute hydrochloric acid to a 50-mL volumetric flask.
To each of the flasks containing the Standard preparations, the Test preparation, and the Blank, add 5 mL of Ascorbic acid solution and 5 mL of Color reagent. Dilute each solution with Dilute hydrochloric acid to volume, mix, and allow to stand for 10 minutes. Concomitantly determine the absorbances of the solutions from the Standard preparations and the Test preparation at the wavelength of maximum absorbance at about 594 nm, with a suitable spectrophotometer, using the solution from the Blank to set the instrument to zero. Plot the absorbance values of the solutions from the Standard preparations versus their iron contents, in µg per 50-mL volumetric flask, and draw the straight line best fitting the three plotted points. From the graph so obtained determine the iron content, C, in µg per 50-mL volumetric flask, of the solution from the Test preparation. Calculate the content, in ppm, of iron in the portion of Magnesium Sulfate taken by multiplying C by 0.1: the limit is 0.5 µg per g.