EN ISO 7887:2011

Foreword
1 Scope
2 Normative references
3 Terms and definitions
4 Method A: Visual examination
5 Method B: Determination of the true colour using optical
  instruments
6 Method C: Determination of true colour using optical
  instruments for determination of absorbance at
  wavelength lambda = 410 nm
7 Method D: Visual method for the determination of the
  colour in natural water
8 Test report
Annex A (informative) - Quality control
Annex B (informative) - Precision data
Bibliography

ISO 7887:2011 specifies four different methods, designated A to D, for the examination of colour.The previously most employed method for assessment of water colour in water treatment plants, limnological surveys, etc. was based on the hexachloroplatinate scale. Methods C and D are harmonized with this traditional procedure.Method A involves examination of apparent colour by visually observing a water sample in a bottle. This gives only preliminary information, for example for use in field work. Only the apparent colour can be reported.Method B involves determination of the true colour of a water sample using optical apparatus and is applicable to raw and potable water and to industrial water of low colour. A subclause on interferences is included.Method C involves determination of the true colour of a water sample using optical apparatus for comparison with hexachloroplatinate concentration at wavelength, λ = 410 nm. A subclause on interferences is included.Method D involves determination of colour by visual comparison with hexachloroplatinate standard solutions and can be applied to raw and drinking water. A subclause on interferences is included.Methods A and B are appropriate if the colour hue of the sample differs from the hue of the matching solution.When stating the result, the procedure used (methods A to D) is also recorded.