Application Notes: Reflectometry – Glucose in Jam

Reflectometric determination after reaction with glucose oxidase and peroxidase


Cat. No. 116720 Reflectoquant® Glucose Test
Cat. No. 117246 Reflectometer RQflex® 20

This application note pertains to RQflex® 20 and all discontinued instruments (RQflex® 10, RQflex® plus)

Sample preparation:

Weigh exactly 0,5 g of sample into a beaker and add 100 ml distilled water. Mix thoroughly.
Transfer 1 ml of this solution into a 25-ml volumetric flask and make up to 25 ml by adding distilled water.

RQflex® 20 Reflectoquant®
RQflex® 20 Reflectoquant®


Press the reflectometer START key and simultaneously place the test strip into the prepared sample solution (15-30 °C) for 15 seconds, ensuring that both reaction zones are immersed. Remove the strip and allow excess liquid to run off via the long edge of the strip on to an absorbent paper towel.

Wait 60 seconds and then measure the strip in the reflectometer. The value [mg/l] will be stored automatically. (Please refer to the RQflex® operating instructions and the package insert of the Reflectoquant® Glucose Test.)


Glucose content [mg/kg] = Measured value [mg/l] x 5000

Results - comparison with enzymatic method:

Sample Reflectoquant® [g/kg] Enzymatic [g/kg]
Apricot jam 177 180
Sour cherry jam 197 194
Cherry jelly 213 201


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