Highly selective solid-state sensor for iodide based on the combined use of platinum (IV) phthalocyanine and solidified pyridinium ionic liquid

Solid-state iodide-selective electrodes based on the commercial screen-printed electrodes modified with readily available low-melting ionic material (ionic liquid solidifying at room temperature), such as N-cetylpyridinium bromide, CPBr, and a specially synthesized metallo-complex, namely, platinum (IV) phthalocyanine, PctPtCl2, are obtained. For comparison, PVC-membrane ion-selective electrodes (ISE) based on the same compounds and solid-state ISEs with other solid matrices (N-cetylpyridinium chloride, 1,3-dicetylimidazolium iodide) are studied. Plasticized PVC-membrane ISEs exhibit normal selectivity corresponding to the Hofmeister series: interfering effect of large hydrophobic ions (perchlorate, dodecyl sulfate, etc.) is significant. Incorporation of PctPtCl2 metallo-complex into plasticized membranes improves selectivity to a certain extent, but not dramatically. At the same time, the CPBr-based solid-state ISEs demonstrate high selectivity toward iodide even in the presence of hydrophobic anions: the interfering effect of perchlorate and dodecyl sulfate decreases by 3 and 6 orders of magnitude, respectively. The introduction of the metallo-complex into the matrix improves selectivity even more significantly. The CPBr-PctPtCl2-based solid-state sensor demonstrates a reversible and reproducible response to iodide. The electrode function slope S = − (54 ± 1) mV/dec, Cmin = 1.9 × 10−5 M, response time is 5–10 s.