1967 Volume 87 Issue 7 Pages 850-856
An analytical curve fitting technique, the least square method, is described and applied to infrared spectrophotometric analysis of caffeine, ethoxybenzamide and dibenzoylthiamine in mixed pharmaceutical preparations. These components were extracted from the pharmaceutical preparations with chloroform, and the transmittance of the chloroform solution was determined at six points of 5.86, 8.70, 8.90, 9.15, 10.23, and 11.13 μ. The conversion of transmittance into absorbance and the calculation by the least square method were carried out by an electronic computer (NEAC 2206). Interferences of the component, which has absorbances at the selected wavelengths, were eliminated by regarding the ratio of these absorbances as constants. This method provides a rapid quantitative analysis of the complex mixtures, can be applied to a wide variety of samples, and is useful as a rapid industrial analysis.
