DETERMINATION OF CHLORIDE-IONS BY REACTION WITH MERCURY THIOCYANATE IN THE ABSENCE OF IRON(III) USING A UV-PHOTOMETRIC, FLOW-INJECTION METHOD

The absorbance at 254 nm of a previously undocumented complex, which forms when chloride and mercury thiocyanate are mixed in aqueous solution, provides the basis for a new technique for the determination of chloride ions in water, Performance of this new technique is compared to that of the widely applied method described by Utsumi, in which Fe-III is included as a reagent and the absorbance of the absorbing species, Fe(SCN)2+, is measured at 450 nm, A single-line flow injection (FI) system was employed for studies of the Cl-Hg(SCN)(2) system at 254 nm, A logarithmic response was obtained for chloride concentrations in the range of 0-2000 mu g ml(-1) without the need for sample dilution, The detection limit of the system was determined to be 0.16 mu g ml(-1), Sulfate, magnesium, and calcium ions do not interfere with chloride ion determination, Bromide and iodide ions interfere significantly in the determination of Cl- over the concentration ranges of 10-100 mu g ml(-1) of interferent.