The interaction between furosemide-palladium (II) chelate and basic triphenylmethane dyes by resonance Rayleigh scattering spectra and resonance non-linear scattering spectra and their analytical applications

Abstract

In pH 4.5–7.0 Britton-Robinson buffer solution, furosemide (FUR) reacted with Pd (II) to form a 1:1 anionic chelate. This chelate could further react with such basic triphenylmethane dyes (BTPMD) as ethyl violet (EV), crystal violet (CV), methyl violet (MV), methyl green (MeG) and brilliant green (BG) to form 1:1 ion-association complexes. This not only resulted in the change of absorption spectra, but also led to the significant enhancement of resonance Rayleigh scattering (RRS), second-order scattering (SOS) and frequency doubling scattering (FDS). The maximum RRS wavelengths were located at 324 nm for the EV, CV and MV system, and 340 nm for the BG and MeG system. The maximum SOS wavelengths were located at 550 nm for the EV, CV, BG and MeG system, and 530 nm for the MV system. The maximum scattering peaks of all the systems were at 392 nm for FDS. The enhanced RRS, SOS and FDS intensities were directly proportional to the concentration of FUR. The detection limits for the different dye systems were 0.3–4.9 ng mL−1 for the RRS method, 3.2–33.1 ng mL−1 for the SOS method and 9.0–85.7 ng mL−1 for the FDS method. These methods could be used for the determination of trace amounts of FUR. The effects of the formation of ternary ion-association complexes on the spectral characteristics and intensities of absorption, RRS, SOS and FDS have been investigated. The optimum conditions of these reactions, the influencing factors and the analytical properties have been tested. The influences of coexisting substances were tested by RRS method and the results showed that this method exhibited a high sensitivity. Based on the aforementioned research, the highly sensitive, simple and rapid methods for the determination of trace amounts of FUR by resonance light scattering technique have been established, which could be applied to the determination of FUR in tablet, injection, human serum and urine samples. The composition and structure of the ternary ion-association complex and the reaction mechanism were discussed.