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Analytical Method: Sensitive measurement of ortho-Phosphate in groundwater and surface water

Method: Photometric determination with ammonium molybdate, analogous to EPA 365.2+3, APHA 4500-P E and DIN EN ISO 6878

Materials and reagents:
Reagents
Cat. No. 114848         Spectroquant® Phosphate Test
Cat. No. 116754         Water for analysis

Instruments
Cat. No. 173018         Spectroquant® UV/VIS Spectrophotometer Prove 600

Materials
Cat. No. 174011         Rectangular cell 100 mm
Cat. No. SLLGM25NS  Syringe filter holder 0.20 µm pore size
Disposable syringes
Preparation vessel (such as Cat. No. 114901, Flat-bottomed long tubes with screw caps)
Pipette for 20 ml

Measuring range:
0.0025 – 0.5000 mg/l PO4-P

Working instructions:

Sample preparation:
Filter the sample as soon as possible after sampling over a 0.20 µm syringe filter into a clean and dry vessel.

Measurement procedure:
Determine the PO4-P content with the above mentioned test kit.
For measurement in the 100-mm cell, both the sample volume as well as the quantities of reagents PO4-1 and PO4-2 must be quadrupled. This means a sample volume of 20 ml, 20 drops of reagent PO4-1 and 4 level microspoons of reagent PO4-2.
The measurement is carried out against a blank, prepared from water for analysis and the reagents in an analogous manner.

The result can be read off directly.

Note:
The method is analogous to EPA 365.2+3, APHA 4500-P E und DIN EN ISO 6878.

 

Measurement results

Comparison of the Spectroquant® test kit with reference analysis according to DIN EN ISO 6878

 

Groundwater and surface water  ß [mg/l PO4-P]
  Spectroquant®
Phosphate
DIN EN ISO
6878
Lake Starnberger See < 0.0025  < 0.0030 
Lake Wörthsee < 0.0025  < 0.0030
Lake Altmühlsee  0.0126   0.0130
Lake Brombachsee 0.0025  0.0056
Lake Ammersee < 0.0025  < 0.0030
Dam North Rhine-Westfalia < 0.0025  < 0.0030

 

Standard addition

 

Surface water      Addition      Concentration
[mg/l PO4-P]
     Recovery    
Lake 0.0050 0.0055 110 %
Starnberger 0.0100 0.0101 101 %
See 0.0500 0.0516 103 %
  0.1000 0.1005 101 %
 
  0.0050 0.0059 119 %
Lake 0.0100 0.0103 103 %
Wörthsee 0.0500 0.0525 105 %
  0.1000 0.1025 102 %
 
  0.0050 0.0066 131 %
Lake 0.0100 0.0103 103 %
Altmühlsee 0.0500 0.0523 105 %
  0.1000 0.1021 102 %
 
  0.0050 0.0069 137 %
Lake 0.0100 0.0108 108 %
Brombachsee 0.0500 0.0520 104 %
  0.1000 0.1027 103 %
 
  0.0050 0.0061 123 %
Lake 0.0100 0.0106 106 %
Ammersee 0.0500 0.0524 105 %
  0.1000

0.1027

103 %
 
  0.0050 0.0059 119 %
Dam North Rhine- 0.0100 0.0112 112 %
Westfalia 0.0500 0.0532 106 %
  0.1000 0.1056 106 %

 

 

 

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