The colorimetric determination of molybdenum in soils and sediments by zinc dithiol

Abstract

A method is presented for determining molybdenum in soils, sediments and rocks. The sample is decomposed by fusion with potassium hydrogen sulphate and the molybdenum is taken into solution with hydrochloric acid. Interference by iron is prevented by reduction to the iron(II) state and the reaction with copper by adding potassium iodide. Tungsten interference is suppressed by careful control of the time allowed for complex formation.

The molybdenum-dithiol complex is extracted into light petroleum and determined either by visual comparison or spectrophotometry.