{
  "url": "https://openlegislation.uk/fertilisers-sampling-and-analysis-regulations-northern-ireland-1996/schedule-2/part-I/chapter-3a./paragraph-4",
  "json_url": "https://openlegislation.uk/fertilisers-sampling-and-analysis-regulations-northern-ireland-1996/schedule-2/part-I/chapter-3a./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/3a./paragraph/4",
  "kind": "paragraph",
  "number": "4",
  "heading": "REAGENTS",
  "text": "4.1 Hydrochloric acid solution, 50% (V/V): dilute an appropriate volume of hydrochloric acid (ρ = 1.18 g/ml) with an equal volume of water.\n4.2 Sulfuric acid, 0.05 M solution.\n4.3 Sodium or potassium hydroxide, 0.1 M solution, carbonate free.\n4.4 Sulfuric acid solution, approximately 30% H2SO4 (W/V), ammonia free.\n4.5 Powdered iron reduced in hydrogen. (The prescribed quantity of iron must be able to reduce at least 0.05 g nitrate nitrogen.)\n4.6 Sodium hydroxide solution, 30 g per 100 ml, ammonia free.\n4.7 Indicator solutions:\nMixed indicator:\n4.7.1 Solution 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.\nThis indicator is violet in acid solution, grey in neutral solution and green in alkaline solution; use 0.5 ml (10 drops).\nMethyl red indicator solution:\n4.7.2 Dissolve 0.1 g methyl red in 50 ml 95% ethanol, make up to 100 ml with water and filter if necessary.\nThis indicator may be used (4-5 drops) instead of the preceding one.\n4.8 Anti-bump granules of pumice stone, washed in hydrochloric acid and ignited.\n4.9 Sodium nitrate.",
  "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/3a./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."
}