Paragraph 3.2 Reagents
Northern Ireland Not yet in force
Formaldehyde solution: the strength of the commercially available solution should be checked as follows: mix 3 ml formaldehyde solution with 50 ml 1N sodium hydroxide solution and 25 ml hydrogen peroxide solution (20 volumes). Heat on a steam bath until effervescence stops. Cool, and titrate with 1N hydrochloric acid using phenolphthalein indicator. Carry out a blank titration using 3 ml water in place of the formaldehyde.
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1 ml of 1N sodium hydroxide ≡ 0.0300 g formaldehyde
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strength of formaldehyde solution ≡
where:
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B = blank titre; and
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T = sample titre.
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