The methods most commonly employed to determine active ingredient content in solid drug formulations involve dissolution of the sample. While these methods are capable of accurate and precise performance, the sample preparation required limits their use in quality-control applications to an occasional sample. There is a need for nondestructive methods capable of rapidly determining the active ingredient content in drug formulations. Spectroscopic methods of analysis have the potential for making the determinations with little or no sample preparation; hence these methods might be applied as at-line product quality monitors. We have investigated the use of diffuse reflectance infrared and Raman spectroscopies for the determination of bucindolol content in solid drug formulations. In experiments on formulations containing 0 to 100 mg of the active ingredient, the standard error of prediction with the use of either spectroscopic method was about 2.0 mg. The Raman spectroscopic method involved virtually no sample preparation, and the spectroscopic data can be collected rapidly; hence Raman spectroscopy shows very good potential as an at-line quality control monitor.
T. M. Niemczyk, M. Delgado-Lopez, F. S. Allen, J. T. Clay, and D. L. Arneberg, "Quantitative Assay of Bucindolol in Gel Capsules Using Infrared and Raman Spectroscopy," Appl. Spectrosc. 52, 513-518 (1998)