The effect of mM concentrations of K(3)[Fe(CN)(6)], Fe(III), Mo(VI), KSCN and KMnO(4) on the generation of BiH(3) by the reaction of 0.2-10 microg ml(-1) Bi(III) with 0.2 M tetrahydroborate(III) at 1 M acidity (HCl or HNO(3)) was investigated. Chemical vapour generation (CVG) of BiH(3) was investigated by atomic absorption spectrometry using a continuous flow reaction system (CF-CVG-AAS) and different mixing sequences and reagent reaction times. Gas chromatography-mass spectrometry (GC-MS) was employed in batch generation experiments with NaBD(4). In the absence of additives, the formation of Bi(0) at high concentrations of Bi(III) caused rollover of calibration curves and limited the linear range to less than 1 microg ml(-1) Bi(III). In the presence of additives, the formation of Bi(0) was not observed and the linear range was increased to 5 microg ml(-1) of Bi(III) while rollover was completely removed. GC-MS experiments indicated that the presence of additives did not affect the direct transfer of H from boron to bismuth. Experiments with CF-CVG-AAS and different mixing sequences and reagent reaction times suggest that additives act by preventing the formation of Bi(0) through the formation of reaction intermediates which evolve towards the formation of BiH(3) at elevated Bi(III)/NaBH(4) ratios.