Test solution: 20mg per mL,in 0.6Nhydrochloric acid.

Epinephrine standard solution— Dilute with methanol an accurately measured volume of a solution of USP Epinephrine Bitartrate RSin formic acid containing about 364mg per mLto obtain a solution having a concentration of about 20mg per mL.

Norepinephrine standard solution— Dilute with methanol an accurately measured volume of a solution of USP Norepinephrine Bitartrate RSin formic acid containing 16mg per mLto obtain a solution having a known concentration of 1.6mg per mL.

Test solution— Dissolve 200mg of Epinephrine in 1.0mLof formic acid,and dilute with methanol to 10.0mL,and mix.

Procedure— Apply 5-µLportions of Epinephrine standard solution,Norepinephrine standard solution,and Test solutionto a suitable thin-layer chromatographic plate (see Chromatography á621ñ)coated with a 0.25-mm layer of chromatographic silica gel mixture.Allow the spots to dry,and develop the chromatogram in an unsaturated tank using a solvent system consisting of a mixture of n-butanol,water,and formic acid (7:2:1)until the solvent front has moved about three-fourths of the length of the plate.Remove the plate from the developing chamber,mark the solvent front,and allow the solvent to evaporate in warm circulating air.Spray with Folin-Ciocalteu Phenol TS,followed by sodium carbonate solution (1in 10):the RFvalue of the principal spot obtained from the Test solutioncorresponds to that obtained from the Epinephrine standard solution.Any spot obtained from the Test solutionis not larger nor more intense than the spot with the same RFvalue obtained from the Norepinephrine standard solution,corresponding to not more than 4.0%of norepinephrine.