Application Notes: Reflectometry – Glucose in Red and White Wine

Reflectometric determination after reaction with glucose oxidase and peroxidase

Reagents:

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

Transfer 1 ml of wine into a 100-ml volumetric flask and make up to 100 ml volume with distilled water (dilution factor 100).

Glucose in red and white wine

Analysis

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.)

Calculation

 

Results – comparison with enzymatic method:

Sample Dilution factor Reflectoquant® [g/L] Enzymatic [g/l]
1 50 2.0 2.1
2 100 5.9 6.0
3 50 0.9 1.1
4 50 0.8 1.1
5 50 0.8 0.7
6 100 5.1 4.9
7 50 0.1 0.1
8 100 6.8 6.7

Materials