ISO 11436:1993

The principle of the method specified is dissolving a test portion in hydrochloric and nitric acids, decomposing resistant boron compounds (e.g. boron nitrides) by fuming the sample solution with phosphoric and sulfuric acids at not less than 290 °C, forming the boron curcumin complex in a buffered acetic acid and sulfuric acid medium, and measuring the absorbance of the test solution in a molecular absorption spectrometer at 543 nm. Applies to nickel and nickel alloys having a total boron content in the range of 4 g/t to 240 g/t.