A NEW METHOD FOR THE VOLTAMMETRIC DETERMINATION OF MOLYBDENUM(VI) USING CARBON-PASTE ELECTRODES MODIFIED IN-SITU WITH CETYLTRIMETHYLAMMONIUM BROMIDE

Molybdenum(VI) is determined by anodic stripping voltammetry using a c arbon paste electrode modified in situ with cetyltrimethylammonium bro mide (CTAB). The preconcentration of molybdenum is performed by adsorp tion and reduction of ion-pairs of cetyltrimethylammonium and molybden um(VI) oxalate at a potential of -0.4 V vs. the saturated calomel elec trode (SCE). The supporting electrolyte contains 0.01 M oxalic acid an d 0.075 mM CTAB. Differential pulse anodic stripping voltammetry explo iting the reoxidation signal is used for the determination of trace le vels of molybdenum(VI). Linearity between current and concentration ex ists for a range of 0.5-500 mu g l(-1) Mo with proper preconcentration times; the limit of detection (calculated as 3 sigma) is 0.04 mu g l( -1) with an accumulation period of 10 min.