Bromine, detection purification

The impurity profile (synthesis related impurities) was actually better for dilevalol than for the parent compound, labetalol, reflecting the benefits of further purification during the DBTA resolution step. Thus, although dilevalol hydrochloride contained traces of DBTA itself, no tertiary amine impurities or brominated dilevalol could be detected—both types of impurity are present at very low levels in labetalol. 

Surprisingly, the bromoperoxidases do not (like other peroxidases) oxidize organic electron donors il9,31) such as o-dianisidine or guaia-col, which are normally used to detect peroxidase activity, and thus enzymic activity easily escapes detection. When bromide or iodide are present in the assay medium HOBr and HOI are formed these reactive species will oxidize, brominate, or iodinate the organic dyes, thus allowing detection. Early in this century similar organic dyes were used to detect peroxidase activity in seaweed tissues and extracts. However, the results were not clearly reproducible. This is understandable since in seaweed variable amounts of iodide and bromide are present. On purification of the bromoperoxidase the halides are removed, resulting in an apparent decrease in or lack of activity. 

Impurities in recoil systems present much the same problem as in any other chemical system. Their presence is perhaps a bit more serious in recoil work, particularly in gas-phase studies. This can be illustrated by a siiecific example. In studying the effect of perdeuteration on product yield from the reaction of carbon-11 with ethane, it was found that the ethylene- C yield tended to be erratic. A standard method of preparation of ethaiie-dg involves the reduction of ethylene-d4 with deuterium. Traces of ethylene remaining are removed by treatment with bromine, a most effective method. The removal of bromine is accomplished by the usual techniques and is continued until its presence can no longer be detected. Under the circumstance in question it meant that the mole fraction of bromine in the mixture was less than 10 . In the same system, ethylene- C was produced at a concentration of about 10 mole fraction. The trace of bromine remaining was sufficient to scavenge part of the labeled ethylene. The problem was readily solved by using another method of purification. 

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