The assay of tropane derivatives in formulations by second derivative ultraviolet spectrophotometry.
The development of a second order derivative spectrophotometric assay of atropine, hyoscine and benztropine in formulations is described. The assay involves the extraction into 1,2-dichloroethane of the tetraphenylborate salt of the alkaloids precipitated from pH 6 solution by an excess of sodium tetraphenylboron and measurement of the amplitude near 273 nm to its shorter wavelength satellite in the second derivative spectrum. The second derivative amplitude gives a more precise determination of the alkaloids than absorbance. A two-point bracketing standardization of the amplitude is required owing to a small but significant intercept in the calibration data. The procedures are sufficiently sensitive and precise for the batch and unit-dose assay of tablets of atropine sulphate (0.6 mg) hyoscine hydrobromide (0.3 mg) and benztropine mesylate (2 mg), and for the assay of atropine sulphate injection (0.4 mg ml-1) and tincture of belladonna.
D001285:Atropine / Q000032:analysis; D001590:Benztropine / Q000032:analysis; D006863:Hydrogen-Ion Concentration; D012601:Scopolamine / Q000032:analysis; D013056:Spectrophotometry, Ultraviolet; D014326:Tropanes / Q000032:analysis*
D014326:Tropanes; D001590:Benztropine; D001285:Atropine; D012601:Scopolamine