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Second‐order Scattering and Frequency Doubling Scattering Spectra of Thallium(III)‐Methotrexate System and Its Analytical Application
Author(s) -
XI CunXian,
LIU ZhongFang,
HU XiaoLi,
LIU ShaoPu,
DUAN Hui
Publication year - 2008
Publication title -
chinese journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.28
H-Index - 41
eISSN - 1614-7065
pISSN - 1001-604X
DOI - 10.1002/cjoc.200890292
Subject(s) - chemistry , cndo/2 , scattering , spectral line , analytical chemistry (journal) , thallium , buffer solution , inorganic chemistry , chromatography , optics , molecule , quantum mechanics , organic chemistry , physics
In pH 4.9 Britton‐Robinson buffer solution, methotrexate (MTX) reacted with thallium(III) to form a 3:1 chelate. This resulted in great enhancement of second‐order scattering (SOS) spectra and frequency doubling scattering (FDS) spectra and appearance of new SOS and FDS spectra. Their maximum wavelengths were located at 520 and 390 nm, respectively. The increments of scattering intensities (Δ I ) were directly proportional to the concentrations of MTX in the ranges of 0.022–2.0 µg·mL −1 (SOS method) and 0.008–2.5 µg·mL −1 (FDS method). The methods exhibited high sensitivities. The detection limits for MTX were 7.4 ng·mL −1 (SOS method) and 2.3 ng·mL −1 (FDS method), respectively. The optimum conditions of the reaction, the influencing factors and the effects of coexisting substances were investigated. A highly sensitive, simple and fast method for the determination of MTX has been developed. The method can be applied satisfactorily to the determination of MTX in human serum samples. In this work, the charge distribution of MTX was calculated by a CNDO quantum chemistry method. In addition, the reaction mechanism was discussed.