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Abstract: 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 300nm (RRS), 650nm (SOS) and 304nm (FDS). The scattering intensities were proportional to the Ami concentration in a certain range and the detection limits were 7.3ngmL−1 (RRS), 32.9ngmL−1 (SOS) and 79.1ngmL−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. [Copyright &y& Elsevier]

In pH 1.0 acidic medium, 12-Tungstophosphoric acid (TP) reacted with meclofenoxate (MFX) to form an ion-associate complex, which resulted in a significant enhancement of the resonance Rayleigh scattering (RRS) intensity. The RRS intensity at the maximum scattering peak of 374 nm was linear to the concentration of MFX in the range of 0.2-12.0 μg mL-1. Therefore, a novel method for the determination of MFX by RRS method coupled with flow injection analysis (FIA) technique was developed. The method has highly sensitivity and the detection limit (3σ) was 5.6 ng mL-1. The present method was applied to the determination of MFX in pharmaceutical preparations and the results agreed well with those provided by the pharmacopeia. The average recovery of standard addition in capsules was 97.0-103.1%. The proposed method exhibited the satisfactory reproducibility with a relative standard derivation (R.S.D.) of 3.7% for 9 successive determinations of 4.0 μg mL-1 MFX. The maximal sample throughput in the optimized system was 48 h-1. In addition, the optimum experiment condition, the effect of coexisting substance, and influence of FIA variables were investigated in the paper. [ABSTRACT FROM AUTHOR]