Flow injection potentiometry of primary and interfering ion with a gold complex ion-exchange membrane

A gold(I) organic complex in the perchlorate form was incorporated in plasticized poly(vinyl chloride) (PVC) membranes and the potentiometric response towards perchlorate (primary ion) and permanganate (interfering ion) was studied. Membranes with 2:1 and 1:2 (w/w) plasticizer to PVC ratio were selected for the determination of primary and interfering ions, respectively. In the selected flow injection conditions, a linear relationship between peak height and log c were obtained between 1×10−2 and 2×10−5 mol l−1 perchlorate and 1×10−3–1×10−5 mol l−1 permanganate. Good reproducibilities and excellent selectivity coefficients towards many common ions were obtained. The methods proposed were applied satisfactorily to the determination of perchlorate in water and of permanganate in pharmaceutical preparations. Permanganate can be directly determined even in the presence of a high amount of manganese dioxide.