2.7.2. Solution B
Stock impurity solution. An accurately weighed 7.2 mg of USP
4-epianhydrotetracycline RS, in triplicate, was transferred into
a 100 mL volumetric flask, dissolved in 50 mL of the diluent;
the flask was then completed to mark with the diluent. Three
individual solutions were prepared by diluting 10.0 mL of each
solution to 100 mL with diluent.