Investigations into biovolatilization of metal(loid)s in the environment by using GC-ICP-TOF-MS

A cryo-trapping GC-ICP-TOFMS method for the determination of volatile metal(loid) compounds (VOMs) in gases containing large amounts Of CO2 and CH4 has been developed. Continuous internal standards (as nebulized indium. or rhodium solution) added to the GC outlet are useful tools to identify plasma instabilities through elution of matrix gases. NaOH cartridges are efficient scavengers for CO2, so that less blockage and more reliable measurements of VOMs are possible using -196 degreesC as a cryo-trapping temperature. During this pre-concentration step, care has to be taken concerning the species' integrity if acidic compounds such as SbH3 have to be determined. Anaerobic fermentors can be used to generate at least six different VOMs in the lab in order to study bio-volatilization processes. The use of the ICP-TOFMS as a detector for the cryotrapping GC was shown to be beneficial because many different isotopes can be measured at the same time. Furthermore, the isotope ratios of individual VOMs can be measured with a precision of more than 0.5%, which is only limited by the counting statistics. However, it is not yet clear if this precision is good enough to identify isotopic fractionation of metal(loid)s through bio-volatilization processes.