Managing transition metal interferences during chemical vapor generation using the hydrolysis products of tetrahydridoborate: a proof-of-concept study

The negative impact of liquid phase interferences of transition metals has plagued chemical vapor generation with tetrahydridoborate since its introduction, which was more than fifty years ago. Herein, the interference from selected transition metal ions in the generation of SbH3 and BiH3 was investigated using the hydrolysis products of NaBH4-hydridoboron intermediates (BH)-as derivatization reagents instead of NaBH4. The BH intermediates were simply generated on-line in a pre-hydrolysis coil of the instrumental set-up. Compared to NaBH4, the use of BH intermediates allowed for significantly improved tolerance to the interference of Ni(ii), Co(ii), and Cu(ii) (tolerance limit of >= 100 mg L-1) for Bi and Sb determination in the absence of any masking agents and in a wide range of acidity. Their applicability to real complex samples was successfully demonstrated by the determination of Sb and Bi in steel and copper standard reference materials. Beyond the analytical application, this work aims to play a part in the comprehension of borohydride chemical behaviour, which is still not completely understood. In this work, the different reactivity of BH4- and its hydrolysis intermediates towards analytical substrates (Sb and, Bi) and interfering metal ions was is studied for (ultra)trace-level quantifications in challenging matrices.

Automated summary

The use of BH intermediates as derivatization reagents significantly improves the tolerance to interference from transition metal ions in the generation of SbH3 and BiH3, and shows high tolerance in a wide range of acidity. The method has been successfully applied to the determination of Sb and Bi in complex samples, providing further understanding of the chemical behavior of borohydrides.