# The Feedingstuffs (Zootechnical Products) Regulations 1999, Paragraph 2


PRINCIPLE
The sample is extracted with dimethylformamide and the extract is purified on a column of aluminium oxide. A portion of the purified extract containing the nifursol is treated with phenylhydrazine hydrochloride and the resulting phenylhydrazone extracted into toluene. The addition of methylbenzethonium hydroxide to the toluene solution produces a blue colour, the absorbance of which is measured as 515nm.

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Source: https://www.legislation.gov.uk/uksi/1999/1871/schedule/5/part/III/paragraph/2 (the official version)
Page: https://openlegislation.uk/feedingstuffs-zootechnical-products-regulations-1999/schedule-5/part-III/paragraph-2
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.