A colorimetric determination of boron in biological materials.

Abstract

To measure sodium mercaptoundecahydrododecaborate Na2B12H11SH, used for B neutron-capture therapy, a colorimetric method with curcumine for determining B in biological materials was developed. Biological samples such as the [mouse] tumor, surrounding tissues and blood plasma were ashed gently using the radiofrequency combustion system with excited O2 plasma. Urine samples [human] were not ashed but usually required dilution with water. After oxidative degradation with KMnO4 B in the degradation products was extracted with chloroform containing 2-ethyl-1,3-hexanediol. B in the chloroform extract was converted into the B-curcumine complex by adding an acetic acid solution of curcumine, followed by concentrated sulfuric acid. After dilution with 95% (vol/vol) ethanol, the absorbancy of the solution at 554 nm based on the complex was measured by spectrophotometry. The linear dynamic range for the assay was 0.5-20 .mu.g of B/sample solution. Compared with the 1,1''-dianthrimide method the present method is simple and safe, and is sensitive enough to be useful for the determination of B in biological materials.