Study of the absorption spectra of 4f electron transitions of the neodymium complex with 8-hydroxyquinoline and octylphenol poly(ethylene glycol)ether and its analytical application

Quanjie

et al. 2001

Analyst

Ciprofloxacin (CPFX) is proposed as a reagent for the derivative spectrophotometric determination of praseodymium in mixed rare earths. The absorption spectra of 4f electron transitions of the praseodymium complex with CPFX was studied by normal and derivative spectrophotometry. The stoichiometry of the praseodymium-CPFX complex was calculated by the molar ratio and continuous variations methods. A ratio of Pr to CPFX of 1:3 was found. The absorption bands of the 4f electron transitions of the complex were enhanced markedly. Using the third derivative spectrum. Beer's law was obeyed up to 35 microg cm(-3) of praseodymium. The relative standard deviation is 0.62% for 14 microg cm(-3) of praseodymium. The detection and quantification limits were 0.17 and 0.56 microg cm(-3) of praseodymium, respectively. A method for the direct determination of praseodymium in mixtures of rare earths with good accuracy and selectivity is described.

Section: Introductionmentioning

confidence: 99%

Study of the absorption spectra of the 4f electron transitions of the praseodymium complex with ciprofloxacin and its analytical application

Quanjie

et al. 2001

Analyst

“…Many kinds of rare earth-metallochromic reagent-surfactant systems have been reported, but few of them can enhance the amplitude of the absorption bands for the 4f electron transitions and thus be useful for the determination of individual rare earths [8][9][10]. Methyl thymol blue (MTB) and cetyltrimethylammonium bromide (CTAB) or cetylpyridinium bromide (CPB) have been proposed for the thirdderivative spectrophotometric determination of samarium only in the presence of the middle and heavier rare earth elements [11], although these ternary complexes halve not been used for the determination of neodymium in the presence of other rare earths.…”

Section: Introductionmentioning

confidence: 99%

Fourth-derivative spectrophotometric determination of neodymium in mixed rare earths with methyl thymol blue and cetylpyridinium chloride

1994

Mikrochim Acta

Abstract.A sensitive and selective method is described for the determination of neodymium in mixed rare earths using fourth-derivative spectrophotometry. The method is based on the absorption spectra of 4f electron transitions of the complex of neodymium with methyl thymol blue and cetylpyridinium chloride. The influence of various instrumental parameters and reaction conditions for maximum colour development are investigated. The calibration curve is linear over the range 0-3.5 #g m1-1 neodymium. The relative standard deviation for determination of 1.4 #g m1-1 neodymium (n = 7) is 1.6%. The detection limit (signal-to-noise ratio = 3) is 0.2 #g m1-1.Key words: derivative spectrophotometry, neodymium, methyl thymol blue, cetylpyridinium chloride.The determination of individual rare earth elements in their mixtures based on the absorption bands of their 4f electron transitions has long been of interest [1][2][3][4][5][6][7]. Many kinds of rare earth-metallochromic reagent-surfactant systems have been reported, but few of them can enhance the amplitude of the absorption bands for the 4f electron transitions and thus be useful for the determination of individual rare earths [8][9][10]. Methyl thymol blue (MTB) and cetyltrimethylammonium bromide (CTAB) or cetylpyridinium bromide (CPB) have been proposed for the thirdderivative spectrophotometric determination of samarium only in the presence of the middle and heavier rare earth elements [11], although these ternary complexes halve not been used for the determination of neodymium in the presence of other rare earths. This paper reports the fourth-derivative spectrophotometric determination of neodymium in mixed rare earths, based on the 4f electron transition absorption bands of neodymium at 587 nm, in which the Nd-MTB-CPC complex is greatly

“…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.…”

mentioning

confidence: 99%

Visible Absorption Spectra of the 4f Electron Transitions of Neodymium, Praseodymium, Holmium and Erbium Complexes with Fleroxacin and Their Analytical Application

et al. 2002

ANAL. SCI.

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...