# Fertilisers (Sampling and Analysis) Regulations (Northern Ireland) 1996, Paragraph 2: PRINCIPLE


The sample is suspended in acid solution with a clarifying agent and filtered. The urea content of the filtrate is determined after the addition of 4-dimethylaminobenzaldehyde (4-DMAB) by measuring the absorbance at 435 nm.

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