{
  "url": "https://openlegislation.uk/fertilisers-sampling-and-analysis-regulations-northern-ireland-1996/schedule-2/part-I/chapter-8b./paragraph-4",
  "json_url": "https://openlegislation.uk/fertilisers-sampling-and-analysis-regulations-northern-ireland-1996/schedule-2/part-I/chapter-8b./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/8b./paragraph/4",
  "kind": "paragraph",
  "number": "4",
  "heading": "REAGENTS",
  "text": "4.1 Potassium sulfate.\n4.2 Iron powder, reduced with hydrogen (the prescribed quantity of iron must be able to reduce at least 50 mg nitric nitrogen).\n4.3 Potassium nitrate.\n4.4 Ammonium sulfate.\n4.5 Urea.\n4.6 Sulfuric acid, 0.1 M solution.\n4.7 Sodium hydroxide solution 30 g per 100 ml, ammonia free.\n4.8 Sodium or potassium hydroxide, 0.2 M solution, free of carbonates.\n4.9 Sulfuric acid (ρ = 1.84 g/ml).\n4.10 Hydrochloric acid solution: dilute an appropriate volume of hydrochloric acid (ρ = 1.18 g/ml) with an equal volume of water.\n4.11 Glacial acetic acid.\n4.12 Sulfuric acid solution, approximately 30% (W/V) H2SO4.\n4.13 Ferrous sulfate, crystalline FeSO4.7H2O.\n4.14 Sulfuric acid, 0.05 M solution.\n4.15 Octan-l-ol.\n4.16 Potassium carbonate, saturated solution.\n4.17 Sodium or potassium hydroxide, 0.1 M solution.\n4.18 Barium hydroxide, saturated solution.\n4.19 Sodium carbonate solution, 10 g per 100 ml.\n4.20 Hydrochloric acid, 2 M solution.\n4.21 Hydrochloric acid, 0.1 M solution.\n4.22 Urease solution: suspend 0.5 g active urease in 100 ml distilled water. Using 0.1 M hydrochloric acid (4.21), adjust to pH 5.4, measured with pH meter.\n4.23 Xanthydrol solution, 5 g per 100 ml in ethanol or methanol (4.28) (do not use products giving a high proportion of insoluble material). The solution can be kept for 3 months in a carefully stoppered bottle in the dark.\n4.24 Catalyst: copper oxide (CuO), 0.3 to 0.4 g per determination, or an equivalent amount of copper sulfate pentahydrate (0.95 to 1.25 g).\n4.25 Anti-bump granules of pumice stone washed with hydrochloric acid and ignited.\n4.26 Indicator solutions:\n4.26.1 Mixed indicator:\nSolution A: dissolve 1 g methyl red in 37 ml 0.1 M sodium hydroxide solution and make up to 1 litre with water.\nSolution B: dissolve 1 g methylene blue in water and make up to 1 litre. Mix 1 volume of solution A and 2 volumes of solution B. This indicator is violet in acid solution, grey in neutral solution and green in alkaline solution; use 0.5 ml (10 drops) of this indicator.\n4.26.2 Methyl red indicator solution:\nDissolve 0.1 g methyl red in 50 ml 95% ethanol, make up to 100 ml with water and filter if necessary; 4-5 drops of this indicator can be used instead of the previous one.\n4.27 Indicator papers:litmus, bromothymol blue (or other papers sensitive in the range pH 6-8).\n4.28 Ethanol or methanol, 95% (V/V).",
  "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/8b./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."
}