Abstract
Quantitative analysis of solid sample insoluble or difficultly soluble in solvent used in infrared analysis was investigated in a dispersed phase in liquid paraffin. As an example of analysis, a mixture of 1, 5-dinitronaphthalene and 1, 8-dinitronaphthalene obtained after removal of mononitronaphthalene by extracting with carbon disulfide from nitrated naphthalene is determined by using 11.24μ and 11.96μ, respectively, as key bands and the relation between wave heights of these two key bands in the absorption spectrum and the mixed ratio of these two substances was investigated to find a few working functions adjusted in such a way as to give no effect by the difference of the thickness of sample layer, in which an estimating line obtainable by plotting the ratio of content of 1, 5-isomer/1, 8-isomer in ordinate and B/(B-A) (where A=wave height at 11.24μ, and B=wave height at 11.96μ) in abscissa is found to be linear; this working function is simple and useful. By use of this working curve, quantitative analysis of commercial products were carried out. The standard deviation of analytical data of 1, 5-isomer observed by this method, when the content is within the range of 3050%, was about ±2%.
