Study on the interaction between palladium(II)-lincomycin chelate and erythrosine by absorption, fluorescence and resonance Rayleigh scattering spectra and its analytical applications.

In pH 5.0-5.4 HAc-NaAc buffer solution, lincomycin (Linco) reacted with Pd(II) to form 1:1 cationic chelate, which could further react with erythrosine (Ery) to form 1:1 ion-association complexes (Pd-Linco)Ery. As a result, not only were the absorption and fluorescence spectra changed, but also the resonance Rayleigh scattering (RRS) intensity was greatly enhanced. These phenomena offered useful means for the determination of Linco by spectrophotometry, fluorescence and RRS methods. The linear range and detection limit of Linco were 0.20-3.00 microg/mL and 0.057 microg/mL, 0.20-4.80 microg/mL and 0.061 microg/mL, 0.05-2.70 microg/mL and 0.015 microg/mL for the spectrophotometric, fluorescence quenching and RRS methods, respectively. Among these, the RRS method obtained the highest sensitivity. Therefore, the optimum reaction conditions and the influences of coexisting substances were investigated using the RRS method. A simple, sensitive and rapid method has been developed for the determination of Linco in either the pharmaceutical form or human body fluids, and the reasons for RRS enhancement are discussed.