抄録
Coprecipitation with magnesium hydroxide was applied for a preconcentration method of iron and manganese in drinking waters. Both of iron and manganese were quantitatively concentrated through the coprecipitation with over 65mg per liter of magnesium hydroxide at the pH value of 10.7 or above. Half a milliliter of 10% magnesium sulfate solution was added to 100ml of sample solution in a beaker, and then 6N sodium hydroxide solution was added dropwise, under vigorous stirring with a glass rod, until the sample solution became cloudy. The precipitate was gathered either by centrifugation or by decantation after standing overnight, and dissolved into a 2ml aliquot of 6N hydrochloric acid by heating on a hotplate for 10min. The acid solutions thus obtained were measured up to 20ml with water and applied for atomic absorption spectrometry. The coefficients of variation were 1.32 and 3.75% with iron (0.15mg/l) and manganese (0.08mg/l) respectively in groud water. Coexistence of chelating substances such as polyphosphate or EDTA with concentrations over 20mg/l caused negative errors.
