DETERMINATION OF GERMANIUM SPECIES BY HYDRIDE GENERATION INDUCTIVELY COUPLED ARGON PLASMA MASS-SPECTROMETRY

Inorganic and methylated germanium species were determined at sub parts per trillion levels by a combination of hydride generation and inductively coupled argon plasma mass spectrometry (ICP-MS). The germanium species in solution were reduced to the corresponding hydrides by sodium tetrahydroborate, transferred with a helium gas stream, and trapped in a liquid nitrogen cooled U-trap. The hydrides were evaporated and introduced into the ICP torch, and the ion count at m/z = 74 was monitored. The reduction efficiencies for methylated germanium species in a malic acid matrix were more than 97%. The absolute detection limits were 0.08 pg of Ge for inorganic germanium (Ge(i)), 0.1 pg of Ge for monomethylgermanium (MMGe) and dimethylgermanium (DMGe), and 0.09 pg of Ge for trimethyl-germanium (TMGe). The dynamic ranges of the detection span 4 orders of magnitude. The proposed method was applied to natural waters and wastewaters, and Ge(i), MMGe and DMGe were detected in all of the samples studied.