Abstract
In our previous study 1 dealing with determinations of bromide in blood and in. cerebrospinal fluid it was pointed out that with the colorimetric procedure of Hauptmann 2 one cannot recover the actual amount of bromide in blood serum. According to Wuth's assumption the precipitates of blood proteins retain a certain amount of bromide. 3 However, with another method 4 for the bromide determination in which, like Wuth, we also used protein-free filtrates, we were always able to recover the total amount of bromide dissolved in various specimens of blood serum.
Having inferred from these findings that proteins are not essentially responsible for the loss of bromide, we tried out in vitro the effect of various blood components on the bromide determination: Dissolving, respectively, uric acid, creatinine, urea, glucose, amino-acids (glycine), lactic acid, potassium sulfate, sodium carbonate, magnesium-ammonium phosphate, potassium iodide and sodium chloride in aqueous solutions of sodium bromide, we found that only sodium chloride influenced the results obtained with Hauptmann's colorimetric determination of bromide: The more sodium chloride added, the lighter became the color, and the less bromide was found.
On the basis of this observation we attempted to modify Hauptmann's procedure, so as to eliminate the error arising from the presence of sodium chloride. The principle of our modification consists in equalizing (as nearly as possible) the NaCl concentration in the blood serum, spinal fluid and standard before carrying out the color reaction (due to formation of gold bromide). For that purpose we used, instead of distilled water, salt solutions for the dilution of the blood serum and for the preparation of the standard.
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