ISO 2886:1973

Acetaldehyde for industrial use — Determination of iron content — 2,2′- Bipyridyl photometric method

The principle consists in the evaporation to dryness of a test portion and dissolution of the residue in hydrochloric acid. Reduction of iron(III) by means of hydroxylammonium chloride. Formation of the iron(II)- 2,2′-dipyridyl complex. Photometric measurement of the coloured complex at a wavelength of about 522 nm. Specifies the use of a spectrophotometer or photoelectric absorptionmeter. As an alternative it is permitted to employ a visual method comparing the test solution with a series of reference solutions. Has also been approved by the IUPAC.