Spectrophotometric determination of magnesium through adsorption of its oxinate complex on microcrystalline naphthalene

An analytical procedure for spectrophotometric determination of magnesium has been developed. The method is based on adsorption of its oxinate complex under controlled experimental conditions on microcrystalline naphthalene at room temperature. The adsorbed species is then dissolved in dimethylformamide and magnesium is quantified spectrophotometrically at 382 nm. The oxine complex in DMFO has molar absorptivity of 4.1 × 10³ liter mol^?1 cm^?1, while its sensitivity is 5.9 × 10^?3 μg/cm² for 0.001 absorbance. The analytical precision is good, since for 10 replicate analyses at 30 μg of Mg, the relative standard deviation did not exceed 2.5%. The method has been applied toward Mg analysis in reference materials and environmental samples.