Sucrose, colorimetric determination

The formaldehyde formed in a periodate reaction is determined gravimet-rically with Dimedon, or colorimetrically with chromotropic acid, after the excess oxidant is destroyed with ethylene glycol, stannous chloride, sodium arsenite, or sodium bisulfite 221), The formic acid is generally titrated directly. Titration to pH 6.0 will measure all the formic acid present. Titration to higher alkalinities will usually measure any formic acid bound as an ester 222) but also other acidic products the end-point may be indefinite. Sucrose will give 80 to 90 % of the theoretical formic acid, and maltose and lactose similarly low values. Both formaldehyde and formic acid are attacked only extremely slowly by periodate, but light apparently accelerates an oxidation to carbon dioxide and water 223),... 

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