Study on the ternary mixed ligand complex of palladium(II)-aminophylline- fluorescein sodium by resonance Rayleigh scattering, second-order scattering and frequency doubling scattering spectrum and its analytical application

摘要

The interaction between palladium(II)-aminophylline and fluorescein sodium was investigated by resonance Rayleigh scattering, second-order scattering and frequency doubling scattering spectrum. In pH 4.4 Britton-Robinson (BR) buffer medium, aminophylline (Ami) reacted with palladium(II) to form chelate cation([Pd(Ami)]~(2+)), which further reacted with fluorescein sodium (FS) to form ternary mixed ligand complex [Pd(Ami)(FS)_2]. As a result, resonance Rayleigh scattering (RRS), second-order scattering (SOS) and frequency doubling scattering spectrum (FDS) were enhanced. The maximum scattering wavelengths of [Pd(Ami)(FS)_2] were located at 300 nm (RRS), 650 nm (SOS) and 304 nm (FDS). The scattering intensities were proportional to the Ami concentration in a certain range and the detection limits were 7.3 ng mL~(-1) (RRS), 32.9 ng mL~(-1) (SOS) and 79.1 ng mL~(-1) (FDS), respectively. Based on it, the new simple, rapid, and sensitive scattering methods have been proposed to determine Ami in urine and serum samples. Moreover, the formation mechanism of [Pd(Ami)(FS)_2] and the reasons for enhancement of RRS were fully discussed.