Solid-liquid Separation after Liquid-liquid Extraction. Sped:rophotometric Determination of Magnesium after Extraction of Its Oxinate with Melted Naphthalene

A new method by "solid-liquid separation after liquid-liquid extraction" was proposed for the spectrophotometric determination of trace amount of magnesium. This method is based on the formation of a yellow chelate (oxinate) which is quantitatively extractable by melted naphthalene in the pH range of 10-12. The extract of oxinate in naphthalene is not soluble in ethyl alcohol, benzene or chloroform, but is soluble in methyl alcohol. The optical absorbancy at 375 nm was measured against the reagent blank and the Beer's law was obeyed with 5-120 μg of magnesium in 25 m1 of methyl alcohol. The chelate in methyl alcohol solution is very stable for a long time