Analytical Method: Lead in waste water with high concentrations of calcium

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. 114833  Spectroquant® Lead Cell Test
Cat.No. 109717  Spectroquant® Lead Test
Cat.No. 106689  Sodium diethyldithiocarbaminate trihydrate for analysis
Cat.No. 100983  Ethanol for analysis
Cat.No. 109966  Nitric acid 1 mol/l
Cat.No. 109137  Sodium hydroxide solution 1 mol/l
Cat.No. 109535  MColorpHastTM Universal indicator strips pH 0 - 14
Cat.No. 116754  Water for analysis
Cat.No. 114724  Empty cells 16 mm with screw caps
Membranfilter 0.45 μm
Polyethylene syringe, 10 ml, with Luer cone
Thermoreactor
 
Sodium diethyldithiocarbaminate solution10 %:
Dissolve 5 g sodium diethyldithiocarbaminate trihydrate for analysis in 45 ml of water for analysis.
 
Waste water from the metal- and glass-processing industries are normally treated with milk of lime to precipitate metals. However, the resulting high concentrations of Ca2+ tend to interfere with the photometric determination of lead. The procedure described below avoids this type of interference.
 
Sample preparation:
Add 10 drops of a 10 % solution of sodium diethyldithiocarbaminate solution to 10 ml of sample solution, shake and aspirate into a 10 ml-PE syringe. Pass the syringe contents through an membrane filter, wash with 10 ml water for analysis and dispose of the filtrate and wash solution. Pass 5 ml ethanol through the same membrane filter. Collect the ethanolic filtrate in a 16-mm round cell, add 5 drops of nitric acid 1 mol/l and place in the thermoreactor at 100 °C for evaporation to dryness.
Add 5 ml of water for analysis to the residue in the round cell and adjust the pH to the required value of 3 - 6 with sodium hydroxide solution. This can be checked using universal indicator strips. This solution can now be used directly for the determination of lead.
 
Analyse:
Determine with the above mentioned test kits.
 
Calculation:
Lead content in mg/l Pb = analysis value in mg/l Pb x 0.5

Materials

     
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