A Colorimetric and Fluorescent Signaling Probe for Assaying Pd in Practical Samples

We developed an optical signaling probe to detect Pd ions in Pd-containing catalyst and drug candidate. The Pd signaling probe (Res-DT) was readily prepared by reacting the versatile fluorochrome resorufin with phenyl chlorodithioformate. In a phosphate-buffered saline solution (pH 7.4) containing sodium dodecyl sulfate (SDS) as a signal-boosting surfactant, Res-DT exhibited a pronounced colorimetric response with a chromogenic yellow to magenta shift, leading to a substantial increase in the fluorescence intensity. The Pd signaling performance of Res-DT was attributed to the Pd-promoted hydrolysis of the dithioate moiety. The probe displayed high selectivity toward Pd ions and remained unaffected by commonly encountered coexisting components. Moreover, the detection limit of Res-DT for Pd ions was 10 nM, and the signaling was achieved within 7 min. Furthermore, to demonstrate the real-world applicability of Res-DT, a Pd assay was performed in Pd-containing catalyst and drug candidate using an office scanner as an easily accessible measurement device. Our results highlight the prospects of Res-DT as a tool to detect Pd ions in various practical samples, with potential applications in catalysis, medicine, and environmental science.