M. E. Brown
Jan 1, 1961
Citations
1
Influential Citations
129
Citations
Quality indicators
Journal
Diabetes
Abstract
This communication is concerned with a chemical method for the determination of blood sugar by an "ultra" micro technic on blood volumes as little as o.oi to 0.03 ml. The need for such a method and its development occurred during experiments on small diabetic animals (guinea pigs) when difficulties were encountered in collecting as little as 0.05 to 0.1 ml. of blood. Although the literature abounds in reports on technics for micro blood sugar determinations, no copper reduction method has yet been reported to be applicable to these small quantities of blood."'* This method follows that originally described by Folin and "Wu, with two important modifications, namely, a twentyfold reduction in the amount of crystalline copper sulfate used to prepare the alkaline copper solution, and a replacement of the phosphomolybdic acid by a solution of neocuproine. The use of 2,2'-diquinoline (cuproine) for the detection of the cuprous ion was described by Hoste in 1950.* Later reports by Smith, Gahler and others showed that 2,9-dimethyl-i,io-phenanthroline (neocuproine) was highly specific for the cuprous ion, and that the presence of fifty-six other metallic ions, including the cupric ion, did not interfere in the reaction of neocuproine with cuprous ion." It was further shown that the final color was very stable over a pH range of 3 to 10, and that the presence of chloride, tartrate, citrate, acetate, phosphate and several other negative radicals did not interfere with the final color development. The availability of the water soluble neocuproine hydrochloride salt suggested that it might serve as a replacement for the various "molybdic acids" used in the copper reduction sugar methods. In order to validate the use of an "ultra" micro blood sugar technic, comparison with the macro Folin-Wu blood sugar method was made. Reagents: (A) Alkaline dilute copper solution. Dissolve 40 gm. of anhydrous sodium carbo-