I came to Detroit, Michigan in Aug 1963 from Cairo, Egypt, as Chief of Hematology, in the Department of Medicine, Wayne State University School of Medicine. Soon after my arrival in Detroit, I got a call from Walter Slavin from PerkinElmer. He informed me that he would like to send me a commercial made Atomic Absorption spectrophometer which could be used for assay of zinc in the plasma. He also told me that the instrument is very simple to use and that I should be able to assay many samples simultaneously, thus saving a lot of my time. Additionally this instrument will be a gift from PerkinElmer. The price of this instrument was approximately $40,000. All this made me very happy and I accepted his offer. The instrument arrived and we set it up in our laboratory. Although I was able to assay zinc in normal saline, I could not assay zinc in plasma. The protein in the plasma and other substances interfered with the aspiration of samples. This disappointed me immensely and I called Walter Slavin. He told me that he sent the instrument for me to develop a method for assaying of zinc in biological samples. This turned out to be a real challenge but we finally succeeded and published a detailed procedure by which one could assay zinc in biological samples. We published our method in 1965.
Unbelievably this method is being used all over the world even now, fifty years later.