Direct determination of rare earth impurities in lanthanum oxide by fluorination assisted electrothermal vaporization inductively coupled plasma atomic emission spectrometry with slurry sampling

Slurry sample introduction with electrothermal vaporization (ETV) has been applied to inductively coupled plasma atomic emission spectrometry (ICP-AES ) for the direct determination of rare earth impurities in lanthanum oxide. A polytetrafluoroethylene (PTFE) emulsion was used as fluorinating reagent to form volatile fluorides rather than refractory carbides of rare earth e lements (REEs). The flow path of carrier gas between the graphite furnace d evice and the ICP torch was improved, and the main factors affecting the an alytical signals, such as the flow rate of carrier gas and auxiliary carrie r gas, matrix concentration, exposure time, vaporization temperature and va porization time, were studied systematically. Under the optimum operating c onditions, the detection limits (DL) for 14 REEs were obtained in the range of 2 ng ml(-1) (Yb) to 130 ng ml(-1) (Ce), and the relative standard devia tion (RSD) is less than 5%. The recommended approach has been applied to di rectly analyse lanthanum oxide without any chemical pretreatment.