Catalytic determination of ultra trace amounts of tellurium by 2.5-order differential oscillopolarography.

A highly sensitive and selective catalytic method with 2.5-order differential oscillopolarographic detection is described for the determination of tellurium, based on its activation effect on the slow Pd(II)-catalyzed reaction of sodium hypophosphite and methyl red in hydrochloric acid medium at 100 degrees C. Methyl red exhibited a sensitive 2.5-order differential polarographic wave at -0.35 V (vs. SCE) in the supporting electrolyte of pH 5.0 acetate buffer solution and was chosen as the indicating component for the indirect determination of tellurium. A calibration curve of tellurium in the range of 0.02-2.0 ng mL(-1) was obtained by the fixed-time procedure. The detection limit was 0.007 ng mL(-1). Possible interferences by co-existing substances were examined. The new method has been used to analyze trace tellurium in organs of white mice with satisfactory results. RSD was 0.54% to 2.10%, recovery 98.4% to 95.7%. The mechanism is also discussed.