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


4.1 Glacial acetic acid.
4.2 Ammonia solution: dilute one volume of ammonia (ρ = 0.88 g/ml) with 3 volumes of water.
4.3 Ammoniacal silver solution, according to Tollens, freshly prepared: mix 500 ml silver nitrate solution (10 g per 100 ml) with 500 ml ammonia solution (4.2).
Do not expose unnecessarily to light, heat or air.
Safety precaution: when handling ammoniacal silver nitrate solution, safety goggles must be worn.
4.4 Concentrated sulfuric acid (ρ = 1.84 g/ml).
4.5 Potassium sulfate.
4.6 Copper oxide (CuO), 0.3-0.4 g for each determination or an equivalent quantity of copper sulfate pentahydrate (0.95-1.25 g) for each determination.
4.7 Sodium hydroxide solution, 30 g per 100 ml, ammonia free.
4.8 Sulfuric acid, 0.05 M solution.
4.9 Sodium or potassium hydroxide, 0.1 M solution.
4.10 Indicator solutions:
Mixed indicator:
4.10.1 Solution A: dissolve 1 g methyl red in 37 ml 0.1 M sodium hydroxide solution and make up to 1 litre with water.
Solution B: dissolve 1 g methylene blue in water and make up to 1 litre. Mix 1 volume of A with 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).
Methyl red indicator:
4.10.2 Dissolve 0.1 g methyl red in 50 ml 95% ethanol, make up to 100 ml with water. Filter if necessary. This indicator (4 to 5 drops) may be used instead of the preceding one.
4.11 Anti-bump granules of pumice stone, washed in hydrochloric acid and ignited.
4.12 Potassium thiocyanate.

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Source: https://www.legislation.gov.uk/nisr/1996/513/schedule/2/part/I/chapter/6./paragraph/4 (the official version)
Page: https://openlegislation.uk/fertilisers-sampling-and-analysis-regulations-northern-ireland-1996/schedule-2/part-I/chapter-6./paragraph-4
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.