Arsenic, antimony, selenium and tin

Kusaka et al. [760] generated the gaseous hydrides of antimony(III), arsenic(III) and tin by sodium borohydride reduction. The hydrides were swept from solution onto a Porapak Q colurrm where they were separated and detected at a gold gas-porous electrode by measurement of the respective electro-oxidation currents. Detection limits for 5ml samples 

Most of the detectors commonly used for gas chromatography have been applied to the detection of the hydrides, among them the thermal conductivity, flame ionisation and the electron c ture detector [761]. 

Cutter et al. [763] have described a method for the simultaneous determination of inorganic arsenic and antimony species in non saline waters using selective hydride generation with gas chromatography-photoionisation detection. 

These workers showed that dissolved arsenic and antimony in natural waters can exist in the bivalent and pentavalent oxidation states, and the biochemical and geochemical reactivities of these elements are dependent upon their chemical forms. They developed a method for the simultaneous determination of arsenic (III) + antimony (III + V) + antimony (III + V) that uses selective hydride generation, liquid nitrogen cooled trapping, and gas chromatography-photoionisation detection. The detection limit for arsenic is lOpmol L while that for antimony is 3.3pmol Lprecision (as relative standard deviation) for both elements is better than 3%. 

The application of gas chromatography to the determination of selenium in non saline waters is also discussed in Table 15.20. 

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Gas-phase spectrophotometric method was proposed for the determination of arsenic in tap water after the conversion into hydride, its collection in a trap cooled by liquid N2 and subsequent evaporation at 80°C in a flow of N2. The recovery of 73-86.7% As was reported. Simultaneous determination of arsenic, antimony, selenium and tin was accomplished. 

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