Leading into World War II, American scientists scrambled for a way to determine what vitamins, particularly vitamin A, were in food in order to keep US soldiers well-nourished. But state-of-the-art ultraviolet and visible (UV-vis) spectrophotometry, which measures electronic transitions of a wide range of molecules as they absorb light, was cumbersome and expensive.
In July 1941, Arnold Beckman, founder of his eponymous company, introduced his DU UV-vis spectrophotometer. It was the production version of the Model D prototype that he and Howard Cary had first built. It featured a molecular hydrogen lamp, a monochromator made of a Brazilian quartz prism, and a UV-sensitive phototube. Light from the lamp passed through a series of slits and mirrors and separated into the complete visible and UV spectrum at the prism. Once through the sample, the light collected in a phototube for measurement.
The instrument allowed food analysis, but also, of course, much ...
