# 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 4.9: Amino acid analyser or HPLC equipment with ion exchange column, device for ninhydrin, post column derivatisation and photometric detector.

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

The column is filled with sulfonated polystyrene resins capable of separating the amino acids from each other and from other ninhydrin-positive materials. The flow in the buffer and ninhydrin lines is provided by pumps having a flow stability of ±0,5 % in the period covering both the standard calibration run and the analysis of the sample.
With some amino acid analysers hydrolysis procedures can be used in which the hydrolysate has a sodium concentration of c = 0,8 mol/l and contains all the residual formic acid from the oxidation step. Others do not give a satisfactory separation of certain amino acids if the hydrolysate contains excess formic acid and/or high sodium ion concentrations. In this case the volume of acid is reduced by evaporation to approx. 5 ml after the hydrolysis and prior to pH adjustment. The evaporation shall be performed under vacuum at 40 o C maximum.

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Source: https://www.legislation.gov.uk/eur/2009/152/annex/III/division/F/division/4/division/4.9 (the official version)
Page: https://openlegislation.uk/eu-regulation-2009-152/annex-III/division-F/division-4/division-4.9
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.