A low consumption air-segmented sequential injection vapor generation system for the determination of mercury by atomic absorption spectrometry

A sequential injection system for the determination of mercury by vapor gen eration atomic absorption spectrometry (VGAAS) using tetrahydoborate reduct ant was developed, characterized by prevention of sample and reagent mixing in the holding coil using small air segments and initiation of the vapor g eneration in a flow-through gas-liquid separator. Extremely small volumes o f reductant of 15-30 mu l (0.2-1.0% NaBH4) and sample acidity as low as 0.0 5 mol 1(-1) HCl were sufficient for achieving performance similar to how in jection (FI) VGAAS systems. A sample throughput of 90 h(-1) was achieved wi th 400 mu l samples with a precision of 2.0% RSD at 10 mu g l(-1) Hg, and a detection limit of 0.1 mu g l(-1) (3 sigma). Reagent consumption was reduc ed by a factor of 25 in comparison to the FI-VGAAS system. Good agreement w ith the certified value was obtained for the determination of mercury in se awater in a standard reference sample. (C) 1999 Elsevier Science B.V. All r ights reserved.