Differential reflectance spectrophotometry-I High-reflectance method for determination of micro amounts of substances resolved on thin plates.

The basic principles of differential high-reflectance spectroscopy are discussed from the standpoint of the determination of substances resolved on chromatoplates. Results obtained with the use of two systems, nickel dimethylglyoximate or copper neocuproinate adsorbed on cellulose, are used as illustrations. A graphical method for selecting the optimum concentration range for analysis and for determining the maximum accuracy attainable is also outlined. When contrasted with the conventional method of measuring reflectance, the technique promises substantially increased accuracy over a wider concentration range and seems particularly suited to the analysis of trace amounts of material.