Estimation of Aldehydes other than Formaldehyde

The method depends on the combination of alkali bisulphites with aldehydes. 

of the solution to be examined, which must not contain more than 0-5% of total aldehyde, are run into 50 c.cs. of a solution of potassium bisulphite containing 12 gms. of KHS03 per litre, placed in a 150-c.c. flask which is then well corked and allowed to stand for 15 minutes. During this time another 50 c.cs. of the potassium bisulphite solution is 

Aldehydes insoluble in water should be dissolved in dilute aqueous alcohol, the concentration of alcohol being kept below 5%. 

Aldehydes (e.g., citral, cinnamic aldehyde, etc.) and certain ketones e.g., acetone) react with hydroxylamine hydrochloride forming oximes with the liberation of hydrochloric acid (Z. a., 1895, 623) which can be titrated in presence of methyl orange. 

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