The effect of molybdenum(VI) on the production of arsine by the tetrahydroborate(III) reaction

Molybdenum(VI) increases signals in the determination of arsenic after reduction by tetrahydroborate(III). An increase in the signal by up to two-and-a-half fold is observed when arsenic(III) is determined in the presence of sulphuric and hydrochloric acid concentrations of 0.01-0.02M. The enhancement effect disappears at higher acid concentrations and is eliminated by the presence of L-cysteine. Signals from other hydride-forming elements (antimony, bismuth and tin) were reduced in the presence of molybdenum(VI). Reduction of interferences in the hydride-forming reaction from nickel and cobalt is observed, so that the range of tolerance of these elements is extended by one and two orders of magnitude, respectively. The interference reducing effect is not as profound as that observed with L-cysteine.