Interferences in the quartz tube atomizer during arsenic and antimony determination by hydride generation atomic absorption spectrometry

Interferences of some metals in the determination of arsenic by hydride generation atomic absorption spectrometry utilizing a quartz tube atomizer were studied. The atomizers were coated under vacuum with Ni, Au, Pd and Cr. The arsenic signal was almost totally suppressed by all the metal coatings and thus the interferences from metal ions in the determination of arsenic were attributed both to the carry over of the reaction mixture, as well as interferences in the hydride formation step. Inter-element interferences by arsenic and antimony on each other in the atomizer of the same system were also studied. When arsine and stibine reach the atomizer at the same time they suppress each other's signals. The interference of arsenic on antimony was eliminated by simply separating arsine, which elutes first, from stibine using a simple gas chromatographic column (GC column). However, even when arsine and stibine are separated using the GC column, antimony is deposited in the quartz tube atomizer at the temperatures the quartz tube attains when heated in the air-acetylene flame, suppressing the arsenic signal in subsequent experiments. Therefore, directing of stibine outside of the atomizer, after elution of arsine from the GC column, was suggested for arsenic determination. (C) 2000 Elsevier Science B.V. All rights reserved.