Catalytic solid substrate–room temperature phosphorimetry for the determination of residual perphenazine based on the electronic effect of rhodamine 6G

The rhodamine 6G + ‐perphenazine (Rhod 6G + –PPH) compound is formed in the ester‐exchange reaction between ‐OH of PPH and ‐COOC 2 H 5 of Rhod 6G + . PPH was oxidized to a red compound (PPH') in the presence of K 2 S 2 O 8 . Interestingly, the room temperature phosphorescence (RTP) of Rhod 6G + was quenched because the ‐OH of PPH′ reacted with ‐COOC 2 H 5 of Rhod 6G + –PPH to form Rhod 6G + –PPH’ and PPH, which decreased the π‐electron density (δ) of the carbon atom in the Rhod 6G + –PPH’ conjugated system and enhanced the nonradiation energy loss of the excited Rhod 6G + of the triplet state. The PPH content was directly proportional to the Δ I p of the system. Thus, a new catalytic solid‐substrate room temperature phosphorimetry (SSRTP) method was established for the determination of PPH. The method had high sensitivity (the limit of detection was 0.019 fg/spot, corresponding to a concentration of 4.8 × 10 –14  g/mL; the sampling quantity was 0.40 μL/spot), good selectivity, convenience and speed. The analytical results were in accordance with those of high‐performance liquid chromatography (HPLC). The structures of Rhod 6G + , PPH and Rhod 6G + –PPH were characterized by infrared spectra. The reaction mechanism by which PPH was determined is discussed. Copyright © 2012 John Wiley & Sons, Ltd.