This method is used for the determination of magnesium in drinking and surface waters, domestic and industrial wastes, plants and soils. This method is applicable across several ranges.


Magnesium reacts with calmagite (in the blue alkaline form) to produce a pink color which is measured at 520 nm.


Potassium cyanide is added to prevent interference by heavy metals by forming metallic complexes. Calcium interference is eliminated by preferential binding with EDTA. The following concentrations of ions may be present without significant interference: Calcium, 200 mg/L; Copper, 4 mg/L; Iron (II), 10 mg/L; Zinc, 4 mg/L; Phosphorus, 250 mg/L.


System Method # Range(s)
Flow System A291  1.5 to 75 mg/l
Astoria 2 A291 1.5 to 75 mg/l