"Classical titrimetric methods"
Classical titrimetric methods such as oxidimetry, complexometry, volumetric precipitation and photometry are used by Lehmann & Voss & Co. in three main areas: magnesia, carbon black and filter aids analytics.
In the field of magnesia analytics complexometry is used to determine Ca2+, Mg2+. Photometry is used to determine the proportion of iron and manganese in magnesium oxide MgO. Chlorid Cl- is determined by means of precipitation titrimetrics with silver nitrate. The activity of magnesium oxide is determined using iodometric titration based on the iodine value.
Carbon black analysis encompasses titrimetric methods; the iodine absorption value of carbon black is determined iodometrically using back titration with a sodium thiosulphate solution.
In the case of filter aids (celite), which mainly consist of silica gel (SiO2) the beer-soluble proportion of Ca2+ and Fe2+ is of interest. The calcium proportion is determined by complexometry with EGTA-solution, the iron proportion is analysed by photometry using 1,10-phenantroline-monohydrate complex.
In the field of magnesia analytics complexometry is used to determine Ca2+, Mg2+. Photometry is used to determine the proportion of iron and manganese in magnesium oxide MgO. Chlorid Cl- is determined by means of precipitation titrimetrics with silver nitrate. The activity of magnesium oxide is determined using iodometric titration based on the iodine value.
Carbon black analysis encompasses titrimetric methods; the iodine absorption value of carbon black is determined iodometrically using back titration with a sodium thiosulphate solution.
In the case of filter aids (celite), which mainly consist of silica gel (SiO2) the beer-soluble proportion of Ca2+ and Fe2+ is of interest. The calcium proportion is determined by complexometry with EGTA-solution, the iron proportion is analysed by photometry using 1,10-phenantroline-monohydrate complex.
| Fundamentals - Oxidimetry |
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Oxidimetric titrations determine the concentrations of substances/ions. Oxidimetric determinations are based on complete redox reactions in which electrons are transferred from a donator ion (or molecule) to an acceptor ion (or molecule): | ||
| Iodometry (e.g. for Cl2, Br2, Cu(I)...) | ||
| 2 S2O32- + I2 | ------> | S4O62- + 2I- |
| (thiosulphate + iodine) | (tetrathionate + iodide) | |
| Bromatometry (e.g. for Sb(III), As(III), Cu(I)...) | ||
| BrO3- + 6 H+ + 6 e | ------> | Br- + 3 H2O |
| Manganometry (e. g. for Ca2+, Fe2+, H2O2, oxalate) | ||
| MnO4- + 8 H+ + 5 e | ------> | Mn2+ + 4 H2O |
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| Fundamentals - Photometry | ||
Photometry involves determining concentrations (mostly of a metal ion complex) by measuring the absorption of a specific wavelength of visible or UV light passing through the sample solution. The reference used is a solution of a known concentration. Photometry is based on the Lambert-Beer law which describes the intensity of radiation passing through a sample. F ex = F * e-k * c * d oder ln(F/F ex) = k * c * d with F = intensity at the beginning F ex = intensity after passing through sample solution k = molar absorption co-efficient (material specific) c = concentration d = thickness of sample solution | ||
