The determination of magnesium in plasma and urine

Magnesium can be determined on the same sample as for calcium, following a fifty-fold dilution with lanthanum chloride. 

Working standard. Dilute the Mg 2mg% solution fifty-fold with lanthanum diluent. 

Take an appropriate volume of serum and dilute fifty-fold with lanthanum diluent. For magnesium in urine dilute with lanthanum diluent so that the concentration is about 2 mg/lOOml. 

Haemolysis of the sample will cause a significant increase in plasma magnesium level. Lanthanum is added to samples and standard for convenience so that calcium and magnesium determinations may be made on each sample. 

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