|
Sodium Phosphates Rectal Solution
»Sodium Phosphates Rectal Solution is a solution of Dibasic Sodium Phosphate and Monobasic Sodium Phosphate,or Dibasic Sodium Phosphate and Phosphoric Acid,in Purified Water.It contains,in each 100mL,not less than 5.4g and not more than 6.6g of dibasic sodium phosphate (Na2HPO4·7H2O),and not less than 14.4g and not more than 17.6g of monobasic sodium phosphate (NaH2PO4·H2O).
Packaging and storage—
Preserve in tight,single-unit containers,at controlled room temperature.
Specific gravity á841ñ:
between 1.112and 1.136.
pHá791ñ:
between 5.0and 5.8.
Assay—
Pipet 5.0mLof Rectal Solution into a 250-mLbeaker,and add 15.0mLof 0.5Nsodium hydroxide VSand 95mLof water.Titrate the excess base potentiometrically with 0.5Nhydrochloric acid VSto the first inflection point,at a pHof about 9.2.Record the volume (A),in mL,of 0.5Nhydrochloric acid consumed.Continue the titration to the second inflection point,at a pHof about 4.4,and record the total volume (B),in mL,of 0.5Nhydrochloric acid required in the titration.Each mLof the volume (15.0-A)of 0.5Nhydrochloric acid is equivalent to 69.0mg of monobasic sodium phosphate (NaH2PO4·H2O).Each mLof the volume (B-15.0)of 0.5Nhydrochloric acid is equivalent to 134.0mg of dibasic sodium phosphate (Na2HPO4·7H2O).
Auxiliary Information—
Staff Liaison:Elena Gonikberg,Ph.D.,Scientist
Expert Committee:(PA4)Pharmaceutical Analysis 4
USP28–NF23Page 1792
Pharmacopeial Forum:Volume No.27(1)Page 1816
Phone Number:1-301-816-8251
|