Procedure
Apply 5-µL portions of
Epinephrine standard solution,
Norepinephrine standard solution, and
Test solution to a suitable thin-layer chromatographic plate (see
Chromatography 621) 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 (1 in 10): the
RF value of the principal spot obtained from the
Test solution corresponds to that obtained from the
Epinephrine standard solution. Any spot obtained from the
Test solution is not larger nor more intense than the spot with the same
RF value obtained from the
Norepinephrine standard solution, corresponding to not more than 4.0% of norepinephrine.