Micro Methods for Determination of 3-Ketosucrose and 3-Ketoglucose

Methods for differential determination of 3-ketosucrose and 3-ketoglucose were established. For determination of 3-ketosucrose, alkaline treatment with 0.1 N NaOH was found to be most effective. In this method, 3-ketosucrose gave a characteristic absorption spectrum with a molar extinction coefficient of 6.5 × 103 m‒1cm‒1 at 340 mμ, while 3-ketoglucose did not show a significant absorption spectrum within a range from 300 to 400 mμ. By mixing with 0.2 m phosphate buffer, pH 7.0, 3-ketoglucose gave a characteristic absorption spectrum with a molar extinction coefficient of 3.8 × 103 m‒1cm‒1 at 310 mμ, while 3-ketosucrose showed little absorbance. From the reduction rate of 2,6-dichloroindophenol with 3-ketoglucose, the ketosugar was determined. 3-Ketosucrose was not able to reduce the reagent at all. The methods established here were not affected by fructose.