Determination of Sb using microwave induced plasma atomic emission spectrometry after preconcentration in a cryogenic trap

This paper describes a system in which antimony hydride generation with a preconcentration step in a cryogenic trap is combined with detection using MIP-AES. The MIP operates at atmospheric pressure with a forward power of 30 - 180 Watt, using a TM010 cavity (Beenakker resonator), equipped with a tangential flow torch design, which allows the use of metal-loaded helium or other molecular gases as carrier gas and argon as internal plasma gas. The plasma emission was observed end-on. Antimony hydride was generated batchwise in aqueous medium, preconcentrated in a liquid nitrogen cryogenic trap and then evaporated by electrical heating into the plasma discharge. The optimum working conditions were at 217.6 nm with a forward power of 130 Watt, a plasma gas flow rate of 335 ml/min of argon, a carrier gas flow rate of 134 ml min-1 of helium, a NaBH4 concentration of 0.50 % and acetic acid concentration of 0.87 M. Under these conditions a detection limit of 9 ng of Sb(III) in a total sample volume of 100 ml was achieved. This is about 100-times lower than the corresponding continuous hydride generation. The proposed method has been successfully applied to the determination of Sb in environmental samples.