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Analytical Method: Gold in electroplating baths/cyanidic

Instruments and Reagents:

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

Cat.No. 114946  Rectangular cells 10 mm and/or

Cat.No. 114947  Rectangular cells 20 mm and/or

Cat.No. 114944  Rectangular cells 50 mm
Cat.No. 114821  Spectroquant® Gold Test
Cat.No. 100317  Hydrochloric acid 37 % for analysis
Cat.No. 100456  Nitric acid 65 % for analysis
Cat.No. 107209  Wasserstoffperoxid 30 % (Perhydrol®) for analysis
Cat.No. 116754  Water for analysis
 
Hints:
In cyanide baths which contain brighteners at high levels, the gold is bound into a complex - compound, from which it must be liberated before determination. For this reason pretreatment of the sample is necessary.
When the cyanide bath is free of brighteners, sample preparation is unnecessary, since the oxidants in the SQ Gold will produce the reactive Au(III) form.
 
Sample preparation:
In a beaker mix 1 ml of sample with 5 ml Perhydrol® 30 % and 5 ml nitric acid 65 % and evaporate cautiously to about 2 ml on the heating plate (fume cupboard !). Add 2 ml hydrochloric acid 37 % and evaporate once more to about 1 ml.
Treat the residue with 1 ml hydrochloric acid 37 % and 10 ml water for analysis, transfer to a 1000-ml volumetric flask, fill up to the mark with water for analysis, and mix well.
 
Analysis:
Determine with the above mentioned test kit.
 
Calculation:
Gold content in g/l Au = analysis value in mg/l Au

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