Cobalt ion-enhanced photochemical vapor generation of tellurium (IV) in mixed acid medium for its sensitive detection by atomic fluorescence spectrometry
A method of cobalt ion assisted enhancement of photochemical vapor generation-atomic fluorescence spectrometry (PVG-AFS) was proposed for sensitive determination of ultratrace tellurium (IV). With a mixure of 5% (v/v) formic acid and 20% (v/v) acetic acid as the reaction medium, more than 13-fold improvement in AFS intensity for Te(IV) was achieved simply by adding 1 mg L-1 Co2+ as a homogenous catalyst. Its possible reaction mechanism was proposed with the characterized results of GC-MS and electron paramagnetic resonance (EPR). Under optimal conditions, a limit of detection (LOD) for Te(IV) was 0.06 g L-1, with relative standard deviation (RSD) of 1.3% (10 µg L−1 Te, 7 times). The accuracy and utility of this methodology were validated by analysis of real water samples, with satisfactory recoveries of 91-108%.