Cyanides atomic absorption spectrometry

Chattaraj S, Das A. 1991. Indirect determination of free cyanide in industrial waste effluent by atomic absorption spectrometry. Analyst (London) 116(7) 739-741. 

Figure 4.45. Principles of conversion methods in FIA. (a) A manifold in which the analyte (cyanide) in a packed column of copper(II) sulfide is converted to tetracyanocuprate(I), which is detected by atomic absorption spectrometry (AA). b) A system in which the analyte (sulfide) is precipitated by cadmium(II) ions the colloidal precipitate formed passes unhin-. dered through the system and is detected by A A. Excess of cadmium(II) is retained by the ion-exchange column (lEC) and later eluted.

Mercury is analyzed by atomic absorption spectrometry using a graphite furnace or by a mercury analyzer. Cyanide is tested by an ion-specific electrode. 

Single-line FIA system with solid-phase reagents for the indirect determination of cyanide by flame atomic absorption spectrometry. IV injection valve SPR AgX (where X is Cl. Br and D solid-phase reactor. 

Obviously, cyanide cannot be directly measured by flame atomic absorption spectrometry (FAAS), but an indirect approach, as that schematically depicted in Figure 7.16, allows this possibility to be implemented, improving detection limits with regard to those reported previously for flow-based methods. The FIA manifold relies on the formation of soluble metal-cyanide complexes as the sample passes through a small column packed with soUd-phase reagent (SPR). Different SPR have been tested for indirect determination of cyanide using FIA. In all cases the eluted complex is measured by FAAS. Detection limits close to 0.05 mg/1 cyanide have been reported [28]. 

The method is based on insertion of aqueous cyanide solutions into a SPR-packed column. The eluent containing the analyte as a metal-cyanide complex, as a reaction product of solid reagent and cyanide, was measured by flame atomic absorption spectrometry (FAAS). 

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