ISO/R 849:1968

Phosphoric acid for industrial use — Determination of iron content — 2,2'- Bipyridyl spectrophotometric method
Applicable to products having Fe contents of more than 0.001 % (m/m). Preliminary hydrolysis of polyphophate acids by prolonged boiling in the presence of hydrochloric acid. Reduction of iron(III) by means of hydroxylammonium chloride. Formation of the iron(II)-2,2'-dipyridyl complex in the presence of ammonium acetate at pH of 3.1 and a temperature of 75 °C (under the test conditions the phosphate ions do not interfere). Spectrophotometric measurement of the coloured complex at a wavelength of about 522 nm.
SDO:
ISO
Language:
English
ICS Codes:
71.060.30
Status:
Withdrawn
Publish date:
1968-09-30
Standard Number:
ISO/R 849:1968