Standard preparations
Dissolve
USP Salicylamide RSquantitatively in methanol,and mix to obtain a solution having a concentration of 1.0mg 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 |
(1in 5) (3in 20) (1in 10) (1in 20) |
200 150 100 50 |
1.0 0.75 0.5 0.25 |
Procedure
Apply separately 10µLof the
Test preparationand 10µLof each of the
Standard preparationsto a suitable thin-layer chromatographic plate (see
Chromatography á621ñ)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 systemuntil 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 UVlight.Compare the intensities of any secondary spots observed in the chromatogram of the
Test preparationwith 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 preparationdoes not exceed that of the principal spot obtained from
Standard preparation B(1%).