1 Scope
This International Standard specifies two methods for the determination of boron in photographic processing wastes. The first method is the estimation of borates by titration of the boric acid-mannitol complex, which is a stronger acid than the boric acid from which it is formed. It is suitable for boron concentrations of 0,1 mg/l and higher. In the range 0,1 mg/l to 5 mg/l, phosphate is removed by precipitation by lead acetate. In the range 1 mg/l to 100 mg/l, the sample is diluted 25 times; this eliminates phosphorous interference if the phosphorous concentration is below 500 mg/l.
The second and alternative method is a spectrophotometric technique using methylene blue and is useful in the boron range of 0,1 ml/l to 1,0 mg/l, this being the concentration likely to be encountered in photographic processing wastes.