# Fertilisers (Sampling and Analysis) Regulations (Northern Ireland) 1996, Paragraph 7: PROCEDURE


Test sample
7.1 Calcium, magnesium, sodium and sulfur in the form of sulfates are extracted from a test sample of 5 g weighed to within 1 mg. However, when the fertiliser contains more than 15% of sulfur (S) i.e. 37.5% SO3, and more than 18.8% of calcium (Ca) i.e. 26.3% CaO, the extraction of calcium and sulfur is carried out on a test sample of 1 g, weighed to within 1 mg. Place the test sample in a 600 ml beaker.
Preparation of the solution
7.2 Add approximately 400 ml of water and, taking care when the sample contains a significant quantity of carbonates, 50 ml of dilute hydrochloric acid (4.1) a small amount at a time. Bring to the boil and maintain for 30 minutes. Allow to cool, stirring occasionally. Transfer quantitatively into a 500 ml graduated flask. Make up to volume with water, and mix. Pass through a dry filter into a dry container, discarding the initial portion. The extract must be completely clear. Stopper if the filtrate is not used immediately.

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Source: https://www.legislation.gov.uk/nisr/1996/513/schedule/2/part/I/chapter/15./paragraph/7 (the official version)
Page: https://openlegislation.uk/fertilisers-sampling-and-analysis-regulations-northern-ireland-1996/schedule-2/part-I/chapter-15./paragraph-7
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.