Spectrophotometric Determination of Magnesium(II) with m-Acetylchlorophosphonazo

The optimum conditions of spectrophotometric determination of Mg(II) with m-acetylchlorophosphonazo (CPAmA) were studied.In a medium of pH 10.5 NH3-NH4Cl, the maximum absorption peak of Mg (II)-CPAmA complex is located at 610 nm.At this wavelength, Beer's law is obeyed over the range of 0-1.5 µg/mL of Mg(II) and the apparent molar absorptivity of the complex is 2.99 × 10 4 L mol -1 cm -1 .Detection limit of the method is 7.71 ng/mL.When the proposed method was used to determine magnesium in serums, the determined results were in good agreement with those obtained by atomic absorption spectrometry.The recovery of the standard addition for the determination of serum sample by the present method was 97.59-99.71% and the relative standard deviation for eleven replicate determinations was 1.36-3.47%.The analytical results were satisfactory.