Simultaneous Cloud-Point Extraction of Nine Cations from Water Samples and Their Determination by Flame Atomic Absorption Spectrometry

Abstract

Several analytical techniques, such as atomic absorption spectrometry (AAS), inductively coupled plasma atomic emission spectrometry (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS), are available for the determination of trace metals with sufficient sensitivity for most applications. However, the determination of trace metal ions in natural water samples is difficult due to various factors, particularly their low concentration and matrix effects.Preconcentration and separation can solve these problems and lead to a higher confidence level and an easy determination of trace elements by less sensitive, but more accessible instrumentation, such as flame atomic absorption spectrometry (FAAS) Cloud-point extraction (CPE) is related to the conventional LLE, and is used in micellar liquid chromatography (MLC). 7The first applications of phase separation based on the cloudpoint phenomenon refer to the extraction of metal ions forming complexes that are sparingly soluble in water. The efficiency of the process depends on the hydrophobicity of the ligand and of the complex formed, on the apparent equilibrium constants in the micellar medium, and on the formation kinetics of the complex and on the transference between the phases. This type of extraction by the cloud-point method was initially described by Watanabe and coworkers 8 for the preconcentration of Zn(II) using 1-(2-pyridylazo)naphthol (PAN) as a ligand and PONPE 7.5 as an extractant. Later, this methodology was also applied to the determination of different metal ions in different types of samples. 9 Like for all other established LLE methods, the metal ion is required to be in the uncharged chelated form prior to its extraction to the organic phase.The phase separation phenomenon has also been used for the extraction and preconcentration of metal ions after the formation of sparingly water-soluble complexes. 10 U, 11 Er 12 and Gd 13 were determined by spectrophotometry by room temperature phosphorescence; Cu, 14 Cd, 15 Ni and Zn, 16 Ag and Au, 17 by FAAS after CPE using complexing agents. Gold and lead were extracted efficiently without a complexing agent, using a non-ionic surfactant, such as poly oxyethylene nonyl phenyl ether (PONPE 7.5). Gold 18 in the aqueous phase was determined by ICP-MS and in the surfactant phase by a calculation based on mass balances. Lead 19 in the surfactant-rich phase was determined by FAAS after diluting with ethanol. Recently, the determination of trace elements by X-ray fluorescence spectrometry 20 and ultrasonic nebulization ICP-MS using phase separation with a surfactant have been reported. reviewed the use of surfactant-based assemblies in analytical atomic spectrometry. Also, concentration by CPE has been established for a number of trace organic pollutants from an aqueous phase. 22Based on the present work we report on the results obtained in a study of the simultaneous cloud-point preconcentration of Cu 2+ , Mn 2+ , Ni 2+ , Cd 2+ , Fe 3+ , Co 2+ , Zn 2+ , Cr 3+ and Pb 2+ after the formation of a compl...

Application of Internal Standard Method for Several 3d-Transition Metallic Elements in Flame Atomic Absorption Spectrometry Using a Multi-wavelength High-resolution Spectrometer

“…After cooling, the residue was removed with a 5B filter, and then 0.05 dm 3 of the rhodium standard solution (Rd 0.594 gdm -3 ) was added, and finally sample solutions of 10 gdm -3 were prepared by diluting and Rh I 343.489 nm (cross-mark), and in their absorbance ratio (square) in ten-replicate measurements, when using an air-acetylene flame. Fig.…”

“…After cooling, the residue was removed with a 5C filter and the concentration of ruthenium was determined by ICP atomic emission spectrometry with a standard solution of ruthenium. 3 . A stock solution of 1.0-gdm -3 titanium was prepared by dissolving 0.25 g of pure titanium lump (Mitsuwa Chemicals Corp.; 99.9999% purity) with 0.05 dm 3 of 6.0 M-hydrochloric acid on a hot plate completely; it was then diluted with 6.0 M-hydrochloric acid to a volume of 0.25 dm 3 .…”

“…3 . A stock solution of 1.0-gdm -3 titanium was prepared by dissolving 0.25 g of pure titanium lump (Mitsuwa Chemicals Corp.; 99.9999% purity) with 0.05 dm 3 of 6.0 M-hydrochloric acid on a hot plate completely; it was then diluted with 6.0 M-hydrochloric acid to a volume of 0.25 dm 3 . Working solutions for various concentrations of each element were prepared by diluting with deionized water or a hydrochloric acid solution, just before the measurement.…”

“…1 Many scientific papers were published in the actual applications of FAAS, which were associated with various types of separation and preconcentration techniques. [2][3][4][5][6] Especially in steel materials, it is necessary to determine trace impurity elements in them accurately and precisely, because they might affect the mechanical and chemical properties of these materials seriously. 7,8 For this purpose, FAAS has been employed as a referee analytical method; for instance, a JIS standard regarding atomic absorption analysis of iron and steels.…”

The Use of Polyphenolic Compounds from Black Tea for the Solid Phase Extraction and Determination of Trace Iron in Drinking Water

“…Moreover, the preconcentration step increases the sensitivity, enhances the accuracy, and facilitates the calibration of the instrument [3,4]. The most frequently employed methods for preconcentration are solvent extraction [5], solid phase extraction [6], cloud point extraction [7], and membrane filtration [8]. Among the different preconcentration methods, a lot of interest has recently been focused on solid phase extraction, owing to its high enrichment factors and simplicity.…”