Use of graph theory for evaluating the selectivity of flow-injection analysis based on displacement reactions: Determination of alkaline-earth metals in water-ammonia media

摘要

A theory was developed for quantitatively evaluating the selectivity in the determination of metals by the flow-injection technique with spectrophotometric detection. The theory was applied to flow-injection analysis based on the ability of alkaline-earth metals to displace copper(II) ions in the Cu(II)-EDTA-4-(2'-pyridylazo)resorcinol system in water-ammonia solutions. The feasibility of the theory was demonstrated. It was shown how the theory could be used for the selection of justified conditions in the determination of Ca, Sr, and Ba and for the evaluation of the selectivity of the determination. Practical examples of the determination of Ca confirm the usefulness of the approach developed.