Zinc (Total) in Beer Worts
Photometric determination subsequent to acid mineralisation with sulfuric acid and Perhydrol®
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 or
Cat.No. 173632 Spectroquant® Colorimeter Move 100
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. 114566 Spectroquant® Zinc Cell Test
Cat.No. 100861 Spectroquant® Zinc Cell Test
Cat.No. 114832 Spectroquant® Zinc Test*
Cat.No. 100731 Sulfuric acid 95 - 97 % for analysis
Cat.No. 107209 Hydrogen peroxide 30 % (Perhydrol®) for analysis
Cat.No. 105590 Sodium hydroxide solution 32 % for analysis
Cat.No. 109535 MQuant® Universal indicator strips pH 0 - 14
Cat.No. 116754 Water for analysis
*not compatible with Move 100
Sample preparation:
In a 400-mL glass beaker mix 25 mL of wort with 2 mL sulfuric acid 95 - 97 % and 5 mL Perhydrol® for analysis and evaporate to a moist residue on the steambath. Dissolve again the residue into 5-mL Perhydrol® and reevaporate. The resultant oily fluid should be clear and colorless - if not, treat it once again with 5-mL Perhydrol® and, again, evaporate.
Take up the final residue into 15-mL of water for analysis and adjust by dropwise addition of sodium hydroxide solution 32 % to pH 5 - 8. Check by using Universal indicator strips. Transfer to a 25-mL volumetric flask and fill up to volume with water for analysis.
Analysis:
Determine with the above mentioned test kits
Calculation:
Zinc (total) content in mg/l Zn = analysis value in mg/l Zn
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