The absorption spectra of rare earth ions consisting of arrow bands due to electronic transitions within the f n configuration, are affected only slightly by changes in the environment of the metal ion. However, if the strength of the ionic field surrounding the rare earth ions is sufficient to penetrate the shielding of the outer electrons of the ions, some absorption bands may be shifted in wavelength and enhanced in sensitivity. Certain chelating groups, notably the β-diketones and 8-quinolines, are capable of overcoming this difficulty through the formation of an inner-complex compound. These have been used in the determination of one or two REES in mixtures. [1][2][3][4][5][6][7][8] Fleroxacin (1-fluoroethyl-6,8-difluoro-7-(4-methyl-1-piperazinyl)-4-oxo-1,4-dihydro-3-quinoline carboxylic acid) is a fluorinated quinoline antibiotic medicine, which has not been reported as a reagent for the spectrophotometric determination of rare earth elements. In this work, the spectral characteristics of the 4f electron transitions of neodymium, praseodymium, holmium and erbium complexes with Fleroxacin in the presence of CPC were reported. A rapid, selective method for the second-derivative spectrophotometric determination of four components in mixed rare earths is described. Experimental ApparatusA Shimadzu UV-240 spectrophotometer with an OP1-2 spectral processing attachment, which generates the derivative digitally, and 3.0-cm cells were used. The pH values of the solutions were measured with a pHs-2 meter (Analytical Apparatus Plant, Shanghai, China). Reagents and chemicalsA 5.0 × 10 -2 mol dm -3 aqueous solution of Fleroxacin (FLX, Delicacy Chemicals Ltd., Zhejiang Taizhou, China) was prepared by dissolving 1.127 g FLX of 99.85% purity in 100 ml with distilled water. Stock lanthanide solutions (5.0 × 10 -2 mol dm -3 ) were prepared by dissolving an appropriate amount of the oxides with >99.99% purity (Johnson Matthey, Royston, Hertfordshire, UK) in 5.0 ml hydrochloric acid (1 + 1); working solutions were prepared by dilution with water. A standard solution of cetylpyridinium chloride (CPC, 5.0 × 10 -2 mol dm -3 ) was prepared by dissolving 4.475 g of CPC (Fluka) in 250 ml of water.The solution cetyltrimethylammonium bromide (CTMAB, 2.0 × 10 -2 mol dm -3 ) was prepared by dissolving 0.729 g of CTMAB (Shanghai Chemical Reagent Plant, Shanghai, China) in 100 ml of water. A solution of octylphenol poly(ethyleneglycol)ether (TX-100, 5.0% v/v) was prepared by dissolving 5.0 ml of TX-100 (Rohm and Haas, Philadelphia, PA, USA) in 100 ml of water.A solution of dodecylbenzenesulfonic acid sodium salt (DBS, 2.0 × 10 -2 mol dm -3 ) was prepared by dissolving 1.742 g of DBS (Shanghai Chemical Reagent Plant, Shanghai, China) in 250 ml of distilled water. A solution of sodium dodecylsulfonate (SDS, 2.0 × 10 -2 mol dm -3 ) was prepared by dissolving 1.442 g of SDS (Shanghai Chemical Reagent Plant, Shanghai, China) in 250 ml of distilled water. A buffer solution (pH 9.25) was prepared by mixing 100 ml of 1.0 mol dm -3 ammonia and 10...

The matrix effect has a major impact on energy-dispersive X-ray fluorescence analysis (EDXRFA) and is difficult to be evaluated due to that the contents of some low-atomic-number elements cannot be identified by in-situ EDXRFA.Up to today, the fundamental parameter algorithm proposed by Rousseau has been widely applied to correct the matrix effect. Accordingly, determining the matrix and mass attenuation coefficient (μ/ρ) of sample is a key issue for the fundamental parameter algorithm. In present work, the method to deduce μ/ρ by effective atomic number (Z eff ) was studied. First, the relationship between Z eff and coherence to Compton scatting ratio (R) of the incident X-ray was determined by standard samples. Then, we deduce Z eff and their μ/ρ. The value of μ/ρ deduced by our method is in good agreement with that calculated by WinXCOM, and the relative change (Δ) is less than 7%. We also deduced Z eff and their μ/ρ of Chinese national standard soil samples employing our method and good agreement with the calculated values were also obtained. We found that the agreement between experimental values of μ/ρ with theoretical values by WinXCOM still exists when the energy of the incident X-ray is greater than 4 keV, and the Δ is less than 10%. The result indicates that our method may be applied directly to in-situ EDXRFA.

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