Application Notes: Reflectometry – Phosphate in Nutrient Solutions for Plant Growing

Reflectometric determination using phosphomolybdenum blue method

Reagents:

Cat. No. 116978 Reflectoquant® Phosphate Test
Cat. No. 117246 Reflectometer RQflex® 20

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


Sample preparation:

The sample can be analyzed in its original form.

 

RQflex® 20 Reflectoquant®
RQflex® 20 Reflectoquant®

Analysis:
Rinse the test vessel with the pretreated sample solution and fill to the 5-ml mark. Add 10 drops of reagent PO4-1 and swirl. Press START button and simultaneously immerse both reaction zones of the test strip in the sample solution (15 - 35 °C) for approx. 2 seconds. Allow excess liquid to run off via the long edge of the strip on to an absorbent paper towel.

Wait 90 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® Phosphate Test.)


Results – comparison with photometric methods:

Sample pH value Reflectoquant® [mg/l] Photometric 1* [mg/l] Photometric 2** [mg/l]
1 7.0 13 15 15
2 5.7 60 64 97
3 5.9 70 77 88
4 6.5 7 8 11
5 7.0 < 5 0.6 0.9
6 4.6 175 198 201

* Spectroquant® Phosphate Cell Test, Cat. No. 114729
** flow injection analysis

 Materials

     
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