# Fertilisers (Sampling and Analysis) Regulations (Northern Ireland) 1996, Paragraph 4: REAGENT


4.1 2% citric acid solution (20 g per litre), prepared from citric acid monohydrate.
Note:
Verify the concentration of this citric acid solution by titrating 10 ml with a 0.1 M sodium hydroxide standard solution using phenolphthalein as an indicator. If the concentration is correct, the titre should be 28.55 ml.

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Source: https://www.legislation.gov.uk/nisr/1996/513/schedule/2/part/I/chapter/9c./paragraph/4 (the official version)
Page: https://openlegislation.uk/fertilisers-sampling-and-analysis-regulations-northern-ireland-1996/schedule-2/part-I/chapter-9c./paragraph-4
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.