The determination of ethanol in official drug preparations. Part II. An evaluation of multiple internal reflectance infrared spectrophotometry

Abstract

The use of multiple internal reflectance spectrophotometry for the determination of ethanol in official drug preparations is evaluated. A rectilinear relationship is obtained between ethanol concentration and the absorbance difference of two ethanol bands at 1045 and 1080 cm^–1, and this is used to determine the ethanol concentration of drug preparations, either directly or after distillation. The results are reasonably accurate and precise, although in certain cases interference from other ingredients affects the results obtained by the direct method.