Which reducing agent use in silicate analysis in water?
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Chemicals required for spectrophotometric analysis of Silica present in water samples.
Ammonium Molybdate ( Ligand)
Oxalic Acid
ANSA (Reducing agent)
Ammonium Molybdate forms yellow silicomolybdic acid with absorption maxiama at wavelength 410nm having molar extinction coefficient of 1500 l/mol/cm with limit of detection upto 0.0001 mol/lit.
Along with Silica, phosphates present in water also react with Ammonium Molybdate forming yellow phospho molybdic polyacid absorbing at same wavelenth as of silica.
While measuring silica, the interference due to yellow phospho complex has to be minimized, Upon addition of Oxalic acid, it selectively breaks down the yellow phospho complex. Similarly sulphuric acid is added while measuring the concentration of phosphate to minimize the interference of yellow silicomolybdic acid.
Lastly reducing agents such as ANSA, 1 amino 2 naphtol 4 sulphonic acid is added to redue silicomolybdic acid (in both silica and phosphateanalysis) to molybdenum blue complex, exhibiting absorption maxima at 810nm, molar extinction coefficient of 40,000 l/mol/cm so that concentration as low as 20ppb can be measured accurately.
hope helps ☺️☺️☺️
Ammonium Molybdate ( Ligand)
Oxalic Acid
ANSA (Reducing agent)
Ammonium Molybdate forms yellow silicomolybdic acid with absorption maxiama at wavelength 410nm having molar extinction coefficient of 1500 l/mol/cm with limit of detection upto 0.0001 mol/lit.
Along with Silica, phosphates present in water also react with Ammonium Molybdate forming yellow phospho molybdic polyacid absorbing at same wavelenth as of silica.
While measuring silica, the interference due to yellow phospho complex has to be minimized, Upon addition of Oxalic acid, it selectively breaks down the yellow phospho complex. Similarly sulphuric acid is added while measuring the concentration of phosphate to minimize the interference of yellow silicomolybdic acid.
Lastly reducing agents such as ANSA, 1 amino 2 naphtol 4 sulphonic acid is added to redue silicomolybdic acid (in both silica and phosphateanalysis) to molybdenum blue complex, exhibiting absorption maxima at 810nm, molar extinction coefficient of 40,000 l/mol/cm so that concentration as low as 20ppb can be measured accurately.
hope helps ☺️☺️☺️
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