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


EDTA buffer solution
4.1 Place in a 500 ml volumetric flask containing 300 ml of water:
— 75 g of ammonium acetate (NH4OOCCH3);
— 10 g of disodium salt of ethylene diamine tetraacetic acid (Na2EDTA);
— 40 ml of acetic acid (CH3COOH, ρ = 1.05 g/ml).
Make up to volume with water and mix thoroughly. The pH of the solution, checked by means of a glass electrode, must be 4.8 ± 0.1.
Azomethine-H solution
4.2 Place in a 200 ml volumetric flask
— 10 ml of the buffer solution (4.1);
— 400 mg of azomethine-H (C17H12NNaO8S2);
— 2 g of ascorbic acid (C6H8O6).
Make up to volume and mix thoroughly. Do not prepare large quantities of this reagent as it is stable for only a few days.
Boron calibration solutions
4.3 Boron stock solution (100 μg/ml)
4.3.1 Dissolve 0.5719 g of boric acid (H3BO3) in water in a 1000 ml volumnetric flask. Make up to volume with water and mix thoroughly. Transfer to a plastic bottle for storage in a refrigerator.
Boron working solution (10 μg/ml)
4.3.2 Place 50 ml of stock solution (4.3.1) in a 500 ml volumetric flask. Make up to volume with water and mix thoroughly.

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Source: https://www.legislation.gov.uk/nisr/1996/513/schedule/2/part/I/chapter/25e./paragraph/4 (the official version)
Page: https://openlegislation.uk/fertilisers-sampling-and-analysis-regulations-northern-ireland-1996/schedule-2/part-I/chapter-25e./paragraph-4
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.