Standard preparations
Dissolve
USP Salicylamide RS quantitatively in methanol, and mix to obtain a solution having a concentration of 1.0 mg per mL. Dilute quantitatively with methanol to obtain
Standard preparations, designated by letter, having the following compositions:
Standard preparation |
Dilution |
Concentration (µg RS per mL) |
Percentage (%, for comparison with test specimen) |
A
B
C
D |
(1 in 5) (3 in 20) (1 in 10) (1 in 20) |
200 150 100 50 |
1.0 0.75 0.5 0.25 |
Procedure
Apply separately 10 µL of the
Test preparation and 10 µL of each of the
Standard preparations to a suitable thin-layer chromatographic plate (see
Chromatography 621) coated with a 0.25-mm layer of chromatographic silica gel mixture, and dry the spots with the aid of a current of air. Place the plate in a suitable chromatographic chamber, and develop the chromatograms with the
Developing solvent system 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, allow the plate to dry, and locate the spots under short-wavelength UV light. Compare the intensities of any secondary spots observed in the chromatogram of the
Test preparation with those of the principal spots in the chromatograms of the
Standard preparations: the total of the intensities of all secondary spots obtained from the
Test preparation does not exceed that of the principal spot obtained from
Standard preparation B (1%).