Preconcentration, determination and speciation of iron by solid-phase extraction using dimethyl (E)-2-[(Z)-1-acetyl)-2-hydroxy-1-propenyl]-2-butenedioate

A new sensitive and selective procedure for speciation of trace dissolved Fe(III) and Fe(II), using modified octadecyl silica membrane disks and determination by flame atomic absorption spectrometry was developed. A ML3 complex is formed between the ligand and Fe(III) responsible for extraction of metal ion on the disk. Various factors influencing the separation of iron were investigated and the optimized operation conditions were established. Under optimum conditions, an enrichment factor of 166 was obtained for Fe3+ ions. The calibration graph using the preconcentration system for Fe3+ was linear between 40.0 and 1000.0 μg L-1

A liquid membrane system containing dibenzyldiaza-18-crown-6 for selective and efficient transport of silver ions

594-597Dibenzyldiaza-18-crown-6 has been used as a highly efficient and selective carrier for uphill transport of silver ion through a chloroform bulk liquid membrane, in the presence of picrate ion as a suitable counter anion. The selectivity and efficienci of Ag+ transport from aqueous solutions containing other cations such as Tl+, Mg2+, Ca2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+, Cd +, Pb2+, Hg2+ and Cr3+ have been investigated. The liquid membrane system is used for the recovery of silver ion from a developed radiological film and a silver solder sample

<span style="font-size:15.0pt;mso-bidi-font-size: 11.0pt;font-family:"Times New Roman";mso-fareast-font-family:"Times New Roman"; mso-ansi-language:EN-GB;mso-fareast-language:EN-US;mso-bidi-language:HI; mso-bidi-font-weight:bold" lang="EN-GB">Highly selective transport of Pb²⁺ ion through a liquid membrane containing 1, 4, 8, 11-tetraazacyclotetradecane as a carrier</span>

409-413Tetraaza-14-crown-4 has been used as a highly selective and efficient carrier for the uphill transport of Pb2+ ion through a chloroform bulk liquid membrane. By using pyrophosphate as a metal ion acceptor in the receiving phase, the amount of Pb2+ transported across the liquid membrane after 90 min is found to be 95 ± 2.6 %. The selectivity and efficiency of lead ion transported from aqueous solution containing equimolar mixtures of Cu2+, Hg2+, Ca2+, Mg2+, K+, Na+, Ni2+, Zn2+, Fe3+, Ag+ and Cd2+are also investigated. The proposed system reveals not only an improved selectivity for Pb2+ ion transport, but also a much lower transport time. </span

A new cloud point microextraction method for preconcentration and determination of copper in water samples

338-343<span style="font-size:11.0pt;font-family: " times="" new="" roman";mso-fareast-font-family:"times="" roman";mso-bidi-font-family:="" mangal;mso-ansi-language:en-gb;mso-fareast-language:en-us;mso-bidi-language:="" hi"="" lang="EN-GB">A simple and practical preconcentration method using ultrasound-assisted cloud point extraction for determination of Cu(II) in various water samples has been developed. 2-mercaptopyrdin-n-oxide as a complexing agent and Triton X-114 as a surfactant are used in proposed method. After phase separation, the surfactant-rich phase is diluted with methanolic nitric acid and determined by flame atomic absorption spectroscopy. The variables parameters affecting the complexation and extraction steps are optimized. Under optimum conditions, the detection limit of 2.2 ng mL-1 is obtained for Cu(II) ions. The method is successfully applied to the determination of Cu(II) in drinking and mineral water samples. </span

Optimization of Auxiliary Solvent Demulsification Microextraction for Determination of Cyanide in Environmental Water and Biological Samples by Microvolume UV-Vis Spectrophotometry

A new, simple, rapid and efficient solvent terminated-auxiliary solvent-dispersive liquid-liquid microextraction (ST-AS-DLLME) technique for determination of cyanide ions by microvolume UV-Vis spectrophotometry was developed. Effective parameters on the extraction and absorbance of cyanide were optimized using two optimization methods: fractional factorial design (FFD) and central composite design (CCD). Zinc(II) tetraphenylporphyrine (ZnTPP) was used as a selective cyanide receptor agent. Methyl isobutyl ketone (MIBK), ethanol and 1-butanol were used as extraction solvent, dispersive solvent and demulsifier solvent, respectively. The method shows very good selectivity in presence of other species. The analytical curve was linear in the range of 4.0-130 &#181;g L-1 with a limit of detection of 1.0 &#181;g L-1. Relative standard deviation (RSD) of the method for ten replicate measurements of 100 &#181;g L-1 of cyanide was 1.1%. The method was successfully applied for determination of cyanide in natural water and plasma samples with good spike recoveries