An absorption apparatus for the micro-determination of certain volatile substances

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Abstract
A method is given for the micro-determination of bromide, using the special absorption apparatus already descr. [see B. A. 10(9) entry 20717]. The bromide ion is oxidized in the outer chamber by a suitable acid dichromate solution, the liberated Br being received in 1 ml. of 20% KI in the central chamber and detd. iodometrically, the whole procedure being conducted at room temp., without aeration or distillation. For standard KBr solutions the coeff. of variation for a single determination of 800 7 Br was found to be 0.6%; with 80, 8 and 2 7 Br it was 1.8,1.5 and 4.0% respectively. Small quantities of bromide added to blood and urine are quantitatively recoverable. The method is independent of chloride. Iodide can be removed if present by a simple preliminary procedure. The application of the method to the determination of bromide in normal blood (1 ml.) and urine is descr. Bromide in the normal whole blood of 8 students varied between 227 and 572 [gamma] Br%. The mean value was 372 Br%. For urine the mean concn. was 572 7%. The av. Br/Cl ratio (expressed as equivs.) for urine was 1/2150. For whole blood this ratio was 1/1950 (assuming 292 mg. Cl%). After a single therapeutic dose of bromide, this can be determined conveniently in finger blood (0.2 ml.).