This is a complete test kit, containing all necessary reagents and accessories to carry out total hardness tests on the spot. The Microtest TH 10 Total Hardness Kit can determine Total Hardness levels within a water source in increments of 10mg/l or 10ppm.
The recommended measuring range is 20 to 200 mg/L (2 - 20 drops @ 10 mg/L) for 5 mL of sample volume. This range can be extended by taking a smaller or larger water sample. For a 2.5 mL sample the measuring range is 20 to 400 mg/L and for a 10 mL sample the range is 5 to 100 mg/L.
- Buffer/Indicator - 15ml
- Titration Solution - 15ml
- Test Tube - 10ml
- Instructions for use
Shelf Life: 2 years.
Complexometric Titration: At pH = 10, earth alkali metals (calcium, magnesium and strontium) form a pink coloured complex with certain indicator dyes (e.g. eriochrome black T, calmagite). On adding EDTA (ethylenediamine tetraacetic acid), these metals prefer to complex with EDTA, and release the indicator dye.
As the uncomplexed dye exhibits a blue colour, the titration endpoint is indicated by a sudden colour change from pink to blue. The amount of EDTA added is directly proportional to the concentration of Ca2+, Mg2+ and Sr2+ ions.
Results are expressed as calcium carbonate CaCO3.
Interferences: Other metals like Al, Fe, Mn or Cu interfere by complexing the indicator dye and not releasing it any more.