Application Notes: Reflectometry – Glucose in Fermentation Solutions

Reflectometric determination after reaction with glucose oxidase and peroxidase


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

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

Sample preparation

Dilute the sample in a suitable way by adding distilled water, e.g. transfer 1 ml (exactly) of sample solution to a 100-ml volumetric flask and make up to 100 ml with distilled water (diltution factor 100).

Glucose in fermentation solutions


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.)




Results – comparison with enzymatic method

Sample Reflectoquant® [g/L] Enzymatic [g/l]
Nutrient solution 1 3480 3420
Nutritent solution 2 6400 6140
Fermentation solution 1 5080 5226
Fermentation solution 2 1660 1669
Fermentation solution 3 3080 2950
Fermentation solution 4 1160 1153
Fermentation solution 5 4100 4045
Fermentation solution 6 1170 1193