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a) Examine by infrared absorption spectrophotometry (2.2.24), comparing with the spectrum obtained with sodium valproate CRS. If the spectra obtained in the solid state for the substance to be examined and the reference substance show differences, record further spectra using discs prepared by placing 50 õl of a 100 g/l solution in methanol R on a disc of potassium bromide R and evaporating the solvent in vacuo. Use the discs immediately.
b) Examine the chromatograms obtained in the test for related substances. The retention time of the principal peak in the chromatogram obtained with test solution (b) corresponds to that of the principal peak in the chromatogram obtained with reference solution
c) 2 ml of solution S (see Tests) gives reaction (a) of sodium (2.3.1).
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