The Direct Estimation of True Blood Sugar.

Abstract

Blood sugar values obtained by Somogyi's 1 fermentation technique very probably represent the true sugar of blood. This procedure, while the standard for comparison, is somewhat laborious, requiring 2 determinations for one result. It has been found that blood filtrates prepared by precipitation with acid mercuric sulphate followed by neutralization with barium carbonate and removal of the mercury with zinc give true sugar values as judged by the fermentation procedure. Barium carbonate possesses an advantage as a neutralizing agent in that it not only removes the sulphate from solution but automatically adjusts the pH to a uniformly definite value at which reducing non-sugars are efficiently precipitated by the mercury.

Method: 5 cc. of blood (1 vol.) are laked in 50 cc. of water (10 vol.) and 5 cc. (1 vol.) of acid mercuric sulphate (30% HgSO₄ in 10% H₂SO₄) added, with shaking, from a burette. The flask is stoppered and thoroughly shaken to break up the gel. 9-10 gm. of dry precipitated barium carbonate are added, the flask is rotated for a few seconds until most of the CO₂ has escaped, and then stoppered and shaken. Carbon dioxide is released until no further pressure develops in the flask and the mixture reacts neutral to litmus paper. If neutralization does not take place promptly, add 1-2 gm. additional barium carbonate. The mixture is poured upon a rapid filter. The filtrate (about 22 cc.) is treated with one drop of saturated sodium sulphate (to remove traces of barium) a pinch of zinc dust. and the flask shaken for a second or two. Zinc is filtered off and the sugar determined by the Shaffer-Hartmann method using an unpublished modification of the reagent by Dr. Somogyi.