The characteristic spectra of azomethine-H (R) and the B-R complex were surveyed in detail. The behaviors for R and its complex with boron are diffe- rentiated by extraction with TBP in the presence of diphenplguanidine. It is confirmed that a complex formed between boron and R is present and the molar ratio is 1:2. This. method has been applied to the determination of boron in tourma- line after the interfering ions were separated by 2, 2, 4-trmethylpentanediol- 1,3。