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 differenti al oscillopolarographic detection is described for the determination of tel lurium, based on its activation effect on the slow Pd(II)-catalyzed reactio n of sodium hypophosphite and methyl red in hydrochloric acid medium at 100 degrees C. Methyl red exhibited a sensitive 2.5-order differential polarog raphic wave at -0.35 V (Vs. SCE) in the supporting electrolyte of pH 5.0 ac etate buffer solution and was chosen as the indicating component for the in direct 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 d etection limit was 0.007 ng mL(-1). Possible interferences by co-existing s ubstances were examined. The new method has been used to analyze trace tell urium 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.