{
  "url": "https://openlegislation.uk/fertilisers-sampling-and-analysis-regulations-northern-ireland-1996/schedule-2/part-I/chapter-22./paragraph-4",
  "json_url": "https://openlegislation.uk/fertilisers-sampling-and-analysis-regulations-northern-ireland-1996/schedule-2/part-I/chapter-22./paragraph-4.json",
  "legislation": "nisr/1996/513",
  "legislation_title": "Fertilisers (Sampling and Analysis) Regulations (Northern Ireland) 1996",
  "legislation_url": "https://openlegislation.uk/fertilisers-sampling-and-analysis-regulations-northern-ireland-1996",
  "path": "schedule/2/part/I/chapter/22./paragraph/4",
  "kind": "paragraph",
  "number": "4",
  "heading": "REAGENTS",
  "text": "Standard 0.05 M solution of magnesium:\n4.1 4.1.1 Dissolve 1.232 g of magnesium sulfate (MgSO47H2O) in the 0.5 M hydrochloric acid solution (4.11) and make up to 100 ml with the same acid.\nor:\n4.1.2 Weigh out 2.016 g of magnesium oxide, previously calcined to remove all traces of carbonation. Place it in a beaker with 100 ml of water.\nStir in approximately 120 ml of approximately 1 M hydrochloric acid (4.12).\nAfter dissolution, transfer quantitatively into a graduated 1 litre flask. Make up to volume and mix.\n1 ml of these solutions should contain 1.216 mg of Mg ( = 2.016 mg of MgO).\nThe laboratory is responsible for testing the strength of this standard solution.\n0.05 M solution of EDTA\n4.2 Weigh out 18.61 g of the dihydrated disodium salt of ethylenediaminetetraacetic (C10H14Na2O82H2O), place it in a 1000 ml beaker and dissolve in 600 to 800 ml of water. Transfer the solution quantitatively into a graduated 1 litre flask. Make up the volume and mix. Check this solution with the standard solution (4.1) by taking a sample of 20 ml of the latter and by titration according to the analytical procedure described at 7.2.\n0.05 molar standard solution of calcium\n4.3 Weigh out 5.004 g of dry calcium carbonate. Place it in a beaker with 100 ml of water. Progressively stir in 120 ml of approximately 1 M hydrochloric acid (4.12).\nBring to the boil in order to drive off the carbon dioxide, cool, transfer quantitatively into a graduated one-litre flask, make up the volume with water and mix. Check this solution against the EDTA solution (4.2) following analytical procedure (8.3). 1 ml of this solution should contain 2.004 mg of Ca ( = 2.804 mg of CaO) and should correspond to 1 ml of the 0.05 M EDTA solution (4.2).\nCalcium indicator\n4.4 Carefully mix in a mortar one gram of calcein with 100 g of sodium chloride. Use 10 mg of this mixture. This indicator changes colour from green to orange. Titration must be carried out until an orange colour free from green tinges is obtained.\nCalcon carbonic acid indicator\n4.5 Dissolve 400 mg of calcon carbonic acid in 100 ml of methanol. This solution may only be kept for approximately four weeks. Use three drops of this solution. The indicator changes colour from red to blue. Titration must be carried out until a blue colour free from red tinges is obtained.\nEriochrome black-T indicator\n4.6 Dissolve 300 mg of Eriochrome black-T in a mixture of 25 ml of propan-l-ol and 15 ml of triethanolamine. This solution may only be kept for approximately four weeks. Use three drops of this solution. This indicator changes colour from red to blue and titration must be carried out until a blue colour free from red tinges is obtained. It changes colour only when magnesium is present. If necessary add one millilitre of the standard solution (4.1).\nWhen both calcium and magnesium are present the EDTA first forms a complex with the calcium and then the magnesium. In that case the two elements are determined concurrently.\nPotassium cyanide solution\n4.7 Aqueous solution of KCN at 2%. (CAUTION: potassium cyanide is extremely poisonous, take suitable precautions and do not pipette by mouth. See also 10.7).\nSolution of potassium hydroxide and potassium cyanide\n4.8 Dissolve 280 g of KOH and 66 g of KCN in water, make up the volume to one litre and mix.\nBuffer solution, pH 10.5\n4.9 In a 500 ml graduated flask, dissolve 33 g of ammonium chloride in 200 ml of water, add 250 ml of ammonia (ρ = 0.91), make up the volume with water and mix. Check the pH of the solution regularly.\nDiluted hydrochloric acid\n4.10 One volume of hydrochloric acid (ρ = 1.18 g/ml) plus one volume of water.\n4.11 Hydrochloric acid solution approximately 0.5 M.\n4.12 Hydrochloric acid solution approximately 1 M.\n4.13 Sodium hydroxide solution 5 M.",
  "extent": null,
  "status": null,
  "version": "current",
  "annotations": [],
  "outstanding_effects": [],
  "provenance": {
    "source": "legislation.gov.uk",
    "source_url": "https://www.legislation.gov.uk/nisr/1996/513/schedule/2/part/I/chapter/22./paragraph/4",
    "retrieved_at": "2026-10-29T02:32:40.012993+00:00"
  },
  "licence": "Open Government Licence v3.0",
  "licence_url": "https://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/",
  "attribution": "Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives."
}