A Simple Colorimetric Method for Carotenoid Pigments

For the studies on the production of the carotenoid pigment by the mould belonging to the genus Neurospora, a new, simple and rapid colorimetric apparatus was designed. The principle was as follows; a sample was compared with standard potassium bichromate a long solution in path comparator equipped with a special mixed color liquid filter. This gave about :four times exacter values than by ordinary comparator. (The extinction of E=0.007_??_0.0035 could be discriminated by this apparatus.) This method is profitable for the cases of using easily volatile solvents, of analyzing many samples, of having no accurate colorimeter, and especially of treating the samples contaminated with other coloring substance, which makes the colorimetric comparison of the sample with standard solution very hard. The carotenoid pigments produced by the mould were separated by the chromatography into four parts, and the ratio between carotene and others was determined.