The spectrophotometric determination of boron in tourmalines

A procedure for the spectrophotometric determination of macro amounts of boron ill tourmaline with azomethine H is described. The used tourmaline concentrate was obtained by magnetic separation and heavy-liquids purification of the schorl zone of pegmatite or granite aplite. The samples of tourmaline were decomposed by fusion with anhydrous sodium carbonate and taken up in dilute hydrochloric acid. The interfering, effects of iron and aluminium were eliminated by masking with an EDTA - NTA solution. After pH adjustment, the boron was reacted with azomethine H and the absorbance of the obtained coloured complex was measured at 415 urn. The results are compared with those obtained by other procedures. The relative error of the determination was less than 3 %.