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


4.1 Sulfuric acid, concentrated (ρ = 1.84 g/ml).
4.2 Sodium hydroxide solution, 30 g per 100 ml, ammonia free.
4.3 Sulfuric acid, 0.05 M solution. } for variant (a) (see page 21)
4.4 Sodium or potassium hydroxide, 0.1 M solution, carbonate free. } for variant (a) (see page 21)
4.5 Sulfuric acid, 0.1 M solution. } for variant (b) (see page 21)
4.6 Sodium or potassium hydroxide, 0.2 M solution, carbonate free.} for variant (b) (see page 21)
4.7 Sulfuric acid, 0.25 M solution. } for variant (c) (see page 21)
4.8 Sodium or potassium hydroxide, 0.5 M solution, carbonate free. } for variant (c) (see page 21)
4.9 Indicator solutions:
Mixed indicator:
4.9.1 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 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:
4.9.2. 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.
4.10 Anti-bump granules of pumice stone, washed in hydrochloric acid and ignited.
4.11 Urea.

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Source: https://www.legislation.gov.uk/nisr/1996/513/schedule/2/part/I/chapter/5./paragraph/4 (the official version)
Page: https://openlegislation.uk/fertilisers-sampling-and-analysis-regulations-northern-ireland-1996/schedule-2/part-I/chapter-5./paragraph-4
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.