Preliminary studies on flow-injection in situ trapping of volatile species of gold in graphite furnace and atomic absorption spectrometric determination

Volatile species of gold in acidified medium were generated at room temperature by the reduction of NaBH4 using a flow injection vapor generation (FI-VG) system, and trapped in situ on the graphite furnace inner wall to get ETAAS detection. Reaction coil inner-wall and inside of the gas–liquid separator were conditioned by passing through a liquid containing micro amounts of Pd(II) and sodium diethyldithiocarbamate (DDTC) and NaBH4. The FI manifold design, the precondition of the FI-VG system and the effect of temperature parameters for ETAAS are discussed. Optimization of the FI and chemical parameters, such as effect of sample acidity, effect of sodium tetrahydroborate concentration, effects of the flow rates for sample, reagent and carrier gas, effects of HCl and DDTC concentration in rinsing solution were investigated. A detection limit of 0.8 ng/ml (3σ) was obtained with a 40 s trapping time and a sampling frequency of 50/h. The precision of 2.2% R.S.D. (n=11) was obtained at 50 ng/ml level. The method was used for the determination of gold in ore sample digest solution. The recoveries of gold in ore sample digest dilute solution by spiking of 25 ng/ml gold were 90–106%. The results obtained were in good agreement with those obtained from direct ETAAS.