Abstract
An improved curcumin method has been developed using a 20% (v/v) 2-ethyl-1, 3-hexanediol, a boron complexing agent, in diisobutyl ketone as an extracting solvent. Boron in the upper, organic solvent is converted to rosocyanin complex by the addition of glacial acetic acid-curcumin solution (0.375%) and concentrated sulfuric acid in this order. The concentrate is diluted with 95% ethanol and spectrophotometrically read at 550 nm vs. ethanol. Beer's law is obeyed over the concentration range of 0.02 (cell : 5cm) -10 (cell : 1cm) mg B/l, and relative standard deviations for blank and 1 mg B/l solutions are ca. 2 and 0.9%, respectively. The improved curcumin method eliminates inconvenient time limits and the interferences of hardening agents, iron (III), fluoride and nitrate. This method with or without alkali fusion as a pretreatment was applied to the determination of boron in industrial waste water, disposal plant sewage, river water and sea water. The results obtained by this method were in good agreement with those obtained by a modified curcumin method and ICP-atomic emission spectrophotometry. When boron in a sample solution such as industrial waste water exists in the chemical form of fluoroborate, etc., the pretreatment of alkali fusion followed by this method must be carried out.
