This method is used for the determination of boron in aqueous solutions and extracts. It is applicable to many ranges.
Boron is complexed with Azomethine-H to form a colored compound measured at 420nm. The absorbance is directly proportional to the boron concentration.
Some cations (e.g. calcium, magnesium, aluminum) can interfere. EDTA is added online to complex these ions. Colored vitamin or food digests could also interfere.