DETERMINATION OF TRACE AMOUNTS OF MOLYBDENUM IN WATERS WITH CARMINIC ACID BY ION-EXCHANGE SPECTROFLUOROMETRY

A spectrofluorimetric method for the determination of trace amounts of molybdenum was developed, based on ion-exchange spectrofluorimetry (I EF). Molybdenum reacts with carminic acid to give a red fluorescent co mplex, which was fixed on a dextran-type anion-exchange gel. The fluor escence of the gel, packed on a 1-mm quartz cell, was measured directl y using a solid-surface attachment. The applicable concentration range was from 1.0 to 15.0 mu g.l(-1), with a relative standard deviation o f 1.4 % and a detection limit of 0.3 mu g.l(-1). The method was applie d to the determination of molybdenum in natural waters. This method is more sensitive and selective than that using carminic acid alone.