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
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.
Determine with the above mentioned test kits.
Lead content in mg/l Pb = analysis value in mg/l Pb x 0.5


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