Hardness

This method is used for the determination of Total Hardness in drinking, surface and saline waters, domestic and industrial wastes, plants and soils. The EPA range of this method is 10 to 400 mg/L as CaCO 3 . However, this method is also applicable to other ranges.

Summary

Magnesium EDTA exchanges Magnesium for Calcium or other cations on an equivalent basis to form a more stable chelate than Magnesium. The free Magnesium reacts with calmagite at pH of 10 to give a red-violet complex measured at 520 nm.

Limitations

Turbid samples must be filtered prior to analysis.