[Derivative spectrophotometric--signal multiplier method and its application to the determination of aspirin in Xiaoer Tuishao Pian].

A Microcomputer was used to process the spectral data measured on a manual spectrophotometer (UV-7520) for the determination of aspirin and acetaminophen in Xiaoer Tuishao Pian, using the derivative spectrophotometric-signal multiplier method. The method is simple and rapid. The mean recovery (%) of aspirin was 99.74 +/- 0.46. Dual wavelength method was used for the determination of acetaminophen and the recovery was 99.54 +/- 0.52%.