title: Study on the ternary system of MoO4 (2-) -enzyme-PdCl2 by resonance Rayleigh scattering, second-order scattering and frequency-doubling scattering spectra and its analytical application.
abstract: In pH 4.0 Britton-Robinson buffer medium, PdCl2 was able to react with enzymes (EZ) such as lysozyme (LYSO) and papain (PAP) to form a coordination complex (EZ-PdCl2 ), which further reacted with MoO4 (2-) to form a ternary complex (MoO4 (2-) -EZ-PdCl2 ). As a result, the absorption and fluorescence spectra changed; new spectra of resonance Rayleigh scattering (RRS), second-order scattering (SOS) and frequency-doubling scattering (FDS) appeared and their intensities were enhanced greatly. The maximum RRS, SOS and FDS wavelengths of two ternary complexes were located at 310, 560 and 350 nm, respectively. The increments of scattering intensity were directly proportional to the concentrations of EZ within certain ranges. The detection limits (3σ) of LYSO and PAP were 4.5 and 14.0 ng/mL (RRS method), 9.6 and 57.8 ng/mL (SOS method), and 5.2 and 106.0 ng/mL (FDS method). Taking the MoO4 (2-) -LYSO-PdCl2 system, which was more sensitive, as an example, the effects of coexisting substances were evaluated. The methods showed excellent selectivity. Accordingly, new rapid, convenient, sensitive and selective scattering methods for the determination of LYSO and PAP were proposed and applied to determine LYSO in egg white with satisfactory results. The reaction mechanism and basis of the enhancement of scattering were discussed.
authors.affiliation: Education Ministry Key Laboratory on Luminescence and Real-Time Analysis, School of Chemistry and Chemical Engineering, Southwest University, 400715, Chongqing, People's Republic of China.
authors.forename: Yaqiong
authors.initials: Y
authors.lastname: Wang
authors.forename: Shaopu
authors.initials: S
authors.lastname: Liu
authors.forename: Zhongfang
authors.initials: Z
authors.lastname: Liu
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Hu
authors.forename: Jiaxing
authors.initials: J
authors.lastname: Xue
authors.forename: Jing
authors.initials: J
authors.lastname: Tian
mesh_terms: D008982:Molybdenum / Q000737:chemistry* / Q000378:metabolism; D009113:Muramidase / Q000032:analysis* / Q000378:metabolism; D010165:Palladium / Q000737:chemistry* / Q000378:metabolism; D010206:Papain / Q000032:analysis* / Q000378:metabolism; D012542:Scattering, Radiation; D013050:Spectrometry, Fluorescence / Q000295:instrumentation; D013056:Spectrophotometry, Ultraviolet / Q000295:instrumentation
chemical_list: C044659:molybdate; D010165:Palladium; D008982:Molybdenum; D009113:Muramidase; D010206:Papain; C008756:palladium chloride