# Commission Regulation (EC) No 152/2009 of 27 January 2009 laying down the methods of sampling and analysis for the official control of feed (Text with EEA relevance), Division 3.4: Luff-Schoorl reagent:

Extent: E+W+S+N.I.

Stirring carefully, pour the citric acid solution (3.4.2) into the sodium carbonate solution (3.4.3). Add the copper sulphate solution (3.4.1) and make up to 1 litre with water. Leave to settle overnight and filter. Check the concentration of the reagent thus obtained (Cu 0,05 mol/litre; Na2 CO3 1 mol/litre). The solution's pH shall be approximately 9,4.

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Source: https://www.legislation.gov.uk/eur/2009/152/annex/III/division/K/division/3/division/3.4 (the official version)
Page: https://openlegislation.uk/eu-regulation-2009-152/annex-III/division-K/division-3/division-3.4
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.