Abstract
A novel flow injection system is presented for monitoring sodium ion in brine based on a catalytic decomposition of a chelate-type chromoionophore with highly concentrated sodium ions. Bis (1, 4, 7, 10, 13-pentaoxa-16-aza-cyclooctadecane-N-carbodithioato) cobalt (II)(Co-A18CC) was newly synthesized and examined as a chelate-type chromoionophore. The catalytic decomposition of Co-A18CC was highly specific for sodium ion. Various analytical parameters of the reverse-mode FIA for monitoring sodium ion were investigated, and optimal conditions and a manifold configuration were established. A linear calibration was obtained for sodium ion in the range of 0-5 mol dm-3 (Relation coefficient: 0.996). Minor components of brine, such as magnesium, bromide, sulfate and carbonate, did not interfere with the decomposition reaction. Artificial brine samples were examined for the purpose of applying the FIA method to the monitoring of the brine process, resulting in a satisfactory performance for within-a-day monitoring.
