A candidate reference method for the determination of magnesium in serum.

A candidate reference method for the determination of magnesium in serum (analytical range 0.5 to 2.0 mmol/l) by flame atomic absorption spectrometry was commissioned. The relative standard deviation of the 4 replicates of each value ranged from 0.18 to 1.07%, and the standard error of the mean ranged from 0.63 to 8.34 mumol/l. In the analysis of 3 different standard solutions (prepared by weighing the analyte), which was performed in each of three different experiments the values recorded by the candidate reference method deviated by -0.15, 0.44 and 0.24%, respectively. The reference method value did not differ significantly from the definitive value. As the method seems to be as reliable as comparable reference methods for the determination of sodium, potassium or calcium, tests of transferability should now be undertaken.