CHEMICAL METHODS FOR THE DETERMINATION OF BORON IN REACTOR MATERIALS. PART II. ISOLATION OF BORON BY METHYL BORATE DISTILLATION AND ITS COLORIMETRIC DETERMINATION BY THE CIRCUMIN-TRICHLORACETIC ACID METHOD

Procedures were standardized for the determination of 0.04 to l ppm of boron in uranium and thorium metals and compounds. It consists of distillation of boron as methyl borate, hydrolysis of methyl berate in dilute sodium hydroxide solution, and colorimetric determination of boron using the curcumin- trichloracetic acid method. When excess alkali is used for the hydrolysis of methyl borate, an ion-exchange separation stage is included in the conventional method for the removal of excess alkali as otherwise poorer recoveries of boron are obtained. Details are given for the treatment of different types of samples such as uranium metal, oxide, nitrate solutions, sodium diuranate, uranium tetrafluoride, thorium nitrate, and graphites containing large amounts of fluoride. (auth)