Cadmium Assisted Photochemical Vapor Generation of Tungsten for ICPMS detection

Efficient photochemical vapor generation (PVG) of tungsten has been achieved for the first time using a 19W thin film flow-through photoreactor. The volatile product (most probably tungsten hexacarbonyl) was generated using a flow injection mode and 40% (v/v) formic acid as the reaction medium. An inductively coupled plasma mass spectrometer was utilized for ultrasensitive detection. The addition of Cd2+ as sensitizer was critical, enhancing the overall PVG efficiency some 30,000-fold. At an optimal irradiation time of 19 s, a 6.1-fold enhancement factor and an overall PVG efficiency of 43% were determined from a comparison of response to direct solution nebulization when using a sample flow rate of 2 mL min–1 and 500 mg L–1 Cd2+ as sensitizer. A limit of detection of 0.9 ng L–1 and repeatability (RSD) of 2% at 100 ng L–1 were achieved. Interferences from inorganic acids (HNO3, HCl, H2SO4 and HF) were investigated with respect to analytical application to real samples. The accuracy and practical feasibili...