Gas-expansion Separators for Vapour Generation Atomic Spectrometric Systems

4 Gas-expansion Separators for Vapour Generation Atomic Spectrometric Systems 

In vapour generation methods for atomic spectrometry, the detection of the analyte is achieved in the gaseous phase the amount of gas produced is normally much larger than separations based on collection in a liquid acceptor stream, and a carrier gas is usually used to assist the efficient separation and transport of the gaseous analyte to the detector 

4 Gas-expansion gas-liquid separators. a modified Vijan-type U-tube separator b. Perkin-Elmer W-configuration separator and c, modified W-configuralion separator with PTFE tube scrubber. G-L, gas-liquid mixture D, to detection system W. to waste pump B. glass beads T, microporous PTFE lube with blocked end O, outer tube with gas outlet. 

Recently, Marshall and van Staden [45] described a gas expansion separator used for FI hydride generation AAS which is separated into two compartments by a cotton gauze membrane. The reaction mixture is allowed to flow on the membrane from the top compartment, where a flow of argon gas is directed parallel to the membrane to sweep the hydrogen and hydrides into a quartz atomizer, while the liquid phase is pumped out from the base of the lower compartment (cf. Sec. 5.5.1). 

5 Schematic diagram of a typical FI manifold with gas-diffusion separation and volume-based sampling. CR. carrier stream S, sample R. reagent for formation of volatile analyte species SP. membrane gas-diffusion separator, A. acceptor stream D, detector and W, waste outlets for donor and acceptor streams. 

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