NONLINEARITY WITH METAL-METAL LIGAND COMPLEX-REACTIONS IN FLOW-INJECTION SYSTEMS - METAL-THIOCYANATE REACTIONS

The linearity of the standard calibration graph for the spectrophotome tric flow injection determination of chloride, based on its displaceme nt of thiocyanate from mercury(II) thiocyanate and the subsequent reac tion of the thiocyanate with iron(III), was extended by the addition o f nickel(II) and copper(II) to the standard reagent solution. This was done after a theoretical study of the relationship between the amount of metal ion and thiocyanate as ligand in the metal-thiocyanate compl ex reaction systems. The calibration graph was linear between 0 and 12 00 mg l(-1) for standard chloride solutions with r=0.982 (n=12) as opp osed to 0-80 mg l(-1) in the normal procedure.