BS ISO 6849:1996

Defines two methods for determining boron in photographic processing wastes. The first method estimates borates by titration of the boric acid-mannitol complex. Alternatively, a spectrophotometric technique utilising methylene blue can be used, in the boron range of 0,1 ml/l to 1,0 mg/l which is the most likely concentration to be found in photographic processing wastes.

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 0,1mg/l and higher. In the range 0,1mg/l to 5mg/l, phosphate is removed by precipitation by lead acetate. In the range 1mg/l to 100mg/l, the sample is diluted 25 times; this eliminates phosphorous interference if the phosphorous concentration is below 500mg/l.

The second and alternative method is a spectrophotometric technique using methylene blue and is useful in the boron range of 0,1ml/l to 1,0mg/l, this being the concentration likely to be encountered in photographic processing wastes.