Analytical Method: Platinum in water and wastewater

Instruments:
Cat.No. 173016  Spectroquant® VIS Spectrophotometer Prove 100 or
Cat.No. 173017  Spectroquant® UV/VIS Spectrophotometer Prove 300 or
Cat.No. 173018  Spectroquant® UV/VIS Spectrophotometer Prove 600 or
Cat.No. 109748  Spectroquant® Photometer NOVA 30 or
Cat.No. 109751  Spectroquant® Photometer NOVA 60

Reagents and accessories:
Cat.No. 104873  Potassium dihydrogen phosphate for analysis
Cat.No. 105590  Sodium hydroxide solution 32 % for analysis
Cat.No. 107243  1,2-Phenylendiamine for analysis
Cat.No. 106146  Isobutylmethylketone for analysis
Cat.No. 106649  Sodium sulfate, anhydrous for analysis
Cat.No. 109533  MColorpHastTM pH-indicator strips pH 0 - 6
Cat.No. 109137  Sodium hydroxide solution 1 mol/l
Cat.No. 109072  Sulfuric acid 0.5 mol/l
Cat.No. 116754  Water for analysis
Cat.No. 114724  Empty cells 16 mm with screw caps
Thermoreactor
 
Reagent 1:
Dissolve 2.0 g 1,2-phenylendiamine in 50 ml water for analysis under light warming (water bath) - this solution turns yellow under air and light influence, for this prepare stock only for 1 - 2 days.
 
Reagenz 2:
Dissolve 13.6 g potassium dihydrogen phosphate in about 500 ml water for analysis and adjust the pH-value to 6.5 by sodium hydroxide solution 32 % at the pH-meter and then fill up to 1 l with water for analysis.
 
Reaction:
Platinum(II,IV) reacts with 1,2-phenylendiamine in a neutral medium to a blue complex, which forms slowly at room temperature within 3 - 5 min when heated up.
 
Measurement range:
Method no. 134
0.10 - 1.25 mg/l Pt at cell length 10 mm and 690 nm
 
Analysis:
In an empty round cell test tube mix 5.0 ml of the weakly acidic sample solution with 1.0 ml of the reagent 1 as well as 0.50 ml of reagent 2. Check the pH-value with pH-indicator strips (set point pH 6.5; correction with NaOH 1 mol/l or H2SO4 resp.). Close the cell and heat it in the thermoreactor to 100 °C for 5 minutes. Afterwards let the sample cool down at ambient temperature (no cooling with ice water!). For extraction of the platinum complex add 5.0 ml isobuthylmethylketone for analysis to the tube, close and shake for 1 min. Separate the organic phase, dry it with sodium sulfate for analysis and then determine against a blank sample.
The blank reading can be obtained in the same way using 5 ml of water instead of sample solution.
 
Measurement:
In the photometers Prove 100, Prove 300, Prove 600, Pharo 100, Pahro 300 and NOVA 60 the method is stored.
The measurement select method no. 134 on the instrument.
 
Interferences:
According to the literature mentioned below, noble metals, Cu, Hg and Ca interfere.

 
Literature:
Golla, E.D. - G.H. Ayres: Talanta 20, 199-210 (1973)

Materials

     
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