THE ZINC CONTENT OF SOME FOOD PRODUCTS

Abstract

The fact that zinc is a normal constituent of the ash of many foodstuffs has been largely overlooked.The papers by Lechartier and Bellamy,l Mendel and Bradley,2 Javillier,3 and Weitzel,4 while establishing the presence of the "white metal" in various animal and vegetable tissues, did not greatly stimulate work along this line owing to the fact that the methods used by these investigators were too laborious to be applicable for routine determinations.The need for a process by which it is possible to determine amounts of less than I mg. of zinc expeditiously and with a fair degree of accuracy, is, therefore, keenly felt.The turbidimetric method recently suggested by Breyer5 undoubtedly fulfills these requirements, and after a few trials, its use was decided upon for the purpose of this investigation.The method as used by myself was devised primarily for the determination of zinc in cow's milk.For this reason, the precipitations of the zinc sulfide were made from solutions of the chloride, instead of the sulfate, as usual, because, owing to the preponderance of calcium in the ash of milk, there seemed to be some danger of losing zinc through occlu'sion in the calcium sulfate from which the sulfate solution would have to be filtered off.The precipitation of zinc sulfide from a chloride solution, and its 1 Lechartier,