Ion-pair extraction and spectrophotometric determination of potassium using dibenzo-18-crown-6 and bromothymol blue

Escobar, R.; Lamoneda, Concepción; Pablos, Fernando; Guiraúm, Alfonso

doi:10.1039/an9891400533

Cited by 15 publications

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“…However, the cation extraction properties of the macrocyclic ethers with different side groups of various types were examined for their extractive abilities [11,12,27,28]. The spectrophotometric methods for solvent extraction of an ion association complex and an anionic dye have been commonly used [22][23][24]29,30]. Since a large anion is easily extracted into low dielectric constant solvents, the picrate anion was widely used as the counter ion [2,27,[31][32][33].…”

Section: Introductionmentioning

confidence: 99%

Synthesis of some 3-phenyl chromenone-crown ethers and equilibrium studies on complexation with ion-pair extraction of sodium and potassium dyes

Çakır

2004

Dyes and Pigments

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Section: Introductionmentioning

confidence: 99%

Synthesis of some 3-phenyl chromenone-crown ethers and equilibrium studies on complexation with ion-pair extraction of sodium and potassium dyes

Çakır

2004

Dyes and Pigments

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“…In the extraction of an alkali metal ion, M + , with a crown ether, L, and a sulfonephthalein (e.g. bromcresol green, BCG) from water into an immiscible organic solvent, the absorbance of the extracted ion pair, LM + BCG - , in the visible region is a measure of M + originally present in the aqueous phase. − It, therefore, is of interest to estimate the sultone content of the organic phase in such extractions.…”

Section: Introductionmentioning

confidence: 99%

Stability of the γ-Sultone Form of Bromcresol Green in the Organic Phase from Partitioning of the Dye between Water and Benzene

2001

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In this study, bromcresol green, BCG, was partitioned between benzene and buffered aqueous solutions, pH 3.12 to 3.92. The colorless γ-sultone form of the dye in the organic phase was determined spectrophotometrically upon back-extracting into aqueous phosphate buffer at pH 6.7. The yellow monoanion (quinoid) form, BCG -, in the benzene phase prior to back-extraction was found to be practically negligible (e1 × 10 -6 mol dm -3 ). From the above, the equilibrium constant of the reaction (BCG -) w + (H + ) w a (sultone) organic is 373 ( 42 mol -1 dm 3 . Lithium chloride and/or 18-crown-6 only slightly increased the extractability of BCG under the experimental conditions.

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“…Although the extraction properties of crown ether complexes have been widely studied, 2-9 their applications to the determination of metal ions are still rather limited. [10][11][12][13][14][15][16][17] The application of highly molar absorbance anionic dyes or counter anions with large molar absorptivities could lead to a sensitive method for trace metal determinations.In this paper, we report a simple and sensitive method for the quantitative extraction of the 18C6-Ba-RB ternary complex into dichloromethane, followed by spectrophotometric measurements at 565 nm. …”

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confidence: 99%

Extraction—Spectrophotometric Determination of Trace Amounts of Barium by 18-Crown-6 and Rose Bengal

Parham

Fazeli

2000

ANAL. SCI.

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Liquid-liquid extraction methods for the separation and determination of barium are limited. Macrocyclic crown ethers are well known as selective ligands for various ions. 1 Some such complexes can be extracted from aqueous solutions into an organic phase. Although the extraction properties of crown ether complexes have been widely studied, 2-9 their applications to the determination of metal ions are still rather limited. [10][11][12][13][14][15][16][17] The application of highly molar absorbance anionic dyes or counter anions with large molar absorptivities could lead to a sensitive method for trace metal determinations.In this paper, we report a simple and sensitive method for the quantitative extraction of the 18C6-Ba-RB ternary complex into dichloromethane, followed by spectrophotometric measurements at 565 nm. Experimental Reagents and chemicalsAll of the chemicals used were of the highest purity available, and were used without further purification. Double-distilled deionized water was used throughout.Stock solutions of barium (1000 µg ml -1 ), Rose Bengal (2.0 × 10 -4 M) and 18-crown-6 (4.0 × 10 -3 M) were prepared. ApparatusThe absorption spectra were recorded on a UV-240 spectrophotometer (Shimadzu). A Model 550S spectrophotometer (Perkin-Elmer) was used for absorbance measurements. ProcedureAfter an aliquot of a sample containing 0.83 -47 µg ml -1 of barium was placed in a 10 ml volumetric flask, 4 ml of Rose Bengal solution (2.0 × 10 -4 M) and 4 ml of 18C6 solution (4.0 × 10 -3 M) were added; the solution was then diluted to the mark with distilled water. The solution was transferred into a 50 ml separatory funnel and 8 ml of dichloromethane was added. The solution was shaken vigorously for 1 min. After the phases were allowed to separate, the organic phase was separated, and its absorbance was measured at 565 nm against a reagent blank. Results and DiscussionSince Ba 2+ ion forms a fairly stable 1:1 complex with 18C6 in aqueous solution, 1 the application of an anionic dyestuff as a counter ion was expected to result in a sensitive and useful method for a trace barium ion determination.In preliminary experiments, it was found that the counter anion plays an important role in the formation of a stable ternary complex; among the dyestuffs examined (Alizarin Yellow R (AYR), Methyl Orange (MO), Rose Bengal (RB)), the best results were obtained with Rose Bengal (the molar absorptivities of extracted complexes were: εRB = 1.69 × 10 5 , εMO = 1.34 × 10 2 , εAYR = 23). Many ternary complexes which are extractable into organic solvents, such as chloroform, carbon tetrachloride and 1,2-dichloromethane, are reported using Rose Bengal as a counter ion. 18 The formula of the complex was determined by Job's method, and the results show a mole ratio of 1:1:1 for 18C6:Ba:RB. Effect of variablesThe influence of the pH on the extraction of the 18C6-Ba-RB complex was studied over the pH range 2 -12; the results are shown in Fig. 1. As can be seen, the maximum extraction of the barium complex occurs within the pH range...

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Ion-pair extraction and spectrophotometric determination of potassium using dibenzo-18-crown-6 and bromothymol blue

Cited by 15 publications

References 0 publications

Synthesis of some 3-phenyl chromenone-crown ethers and equilibrium studies on complexation with ion-pair extraction of sodium and potassium dyes

Synthesis of some 3-phenyl chromenone-crown ethers and equilibrium studies on complexation with ion-pair extraction of sodium and potassium dyes

Stability of the γ-Sultone Form of Bromcresol Green in the Organic Phase from Partitioning of the Dye between Water and Benzene

Extraction—Spectrophotometric Determination of Trace Amounts of Barium by 18-Crown-6 and Rose Bengal

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