Radiochemical solvent extraction of Cr(III) using51Cr tracer by 8-hydroxyquinoline and acetylacetone as mixed ligands in chloroform

A radiochemical solvent extraction method has been developed for the determination of Cr(III) using⁵¹Cr tracer. It is based on the complexation of Cr(III) with 8-hydroxyquinoline (oxine) and acetylacetone as mixed ligands at pH 3.8 and extraction in chloroform. Effect of various parameters such as pH, time of equilibration, nature of solvent, quantitative nature, effect of diverse ions has been studied. The method can be used up to 200 ng of Cr.     

Radiochemical solvent extraction of molybdenum/VI/ using99Mo tracer

A radiochemical solvent extraction method has been developed for the micro determination of Mo/VI/ using⁹⁹Mo tracer. It involves removal of^99mTc by ethyl methyl ketone /EMK/ and extraction of Mo with tri-n-butyl phosphate /TBP/ from 5M HCl. Different parameters affecting the extraction such as pH dependence, nature of solvent and interferences due to other radionuclides have been studied. The method can be used up to 2 g of Mo.     

Speciation of arsenite and arsenate by electrothermal AAS following ionic liquid dispersive liquid-liquid microextraction

We have developed a new method for the microextraction and speciation of arsenite and arsenate species. It is based on ionic liquid dispersive liquid liquid microextraction and electrothermal atomic absorption spectrometry. Arsenite is chelated with ammonium pyrrolidinedithiocarbamate at pH 2 and then extracted into the fine droplets of 1-butyl-3-methylimidazolium bis(trifluormethylsulfonyl) imide which acts as the extractant. As(V) remains in the aqueous phase and is then reduced to As(III). The concentration of As(V) can be calculated as the difference between total inorganic As and As(III). The pH values, chelating reagent concentration, types and volumes of extraction and dispersive solvent, and centrifugation time were optimized. At an enrichment factor of 255, the limit of detection and the relative standard deviation for six replicate determinations of 1.0 μg?L^?1 As(III) are 13 ng?L^?1 and 4.9 %, respectively. The method was successfully applied to the determination of As(III) and As(V) in spiked samples of natural water, with relative recoveries in the range of 93.3–102.1 % and 94.5–101.1 %, respectively.

Hollow fiber liquid phase microextraction combined with electrothermal atomic absorption spectrometry for the speciation of arsenic (III) and arsenic (V) in fresh waters and human hair extracts

A new method of hollow fiber liquid phase microextraction (HF-LPME) using ammonium pyrrolidine dithiocarbamate (APDC) as extractant combined with electrothermal atomic absorption spectrometry (ETAAS) using Pd as permanent modifier has been described for the speciation of As(III) and As(V). In a pH range of 3.0-4.0, the complex of As(III)-APDC complex can be extracted using toluene as the extraction solvent leaving As(V) in the aqueous layer. The post extraction organic phase was directly injected into ETAAS for the determination of As(III). To determine total arsenic in the samples, first As(V) was reduced to As(III) by l-cysteine, and then a microextraction method was performed prior to the determination of total arsenic. As(V) assay was based on subtracting As(III) form the total arsenic. All parameters, such as pH of solution, type of organic solvent, the amount of APDC, stirring rate and extraction time, affecting the separation of As(III) from As(V) and the extraction efficiency of As(III) were investigated, and the optimized extraction conditions were established. Under optimized conditions, a detection limit of 0.12 ng mL⁻¹ with enrichment factor of 78 was achieved. The relative standard deviation (R.S.D.) of the method for five replicate determinations of 5 ng mL⁻¹ As(III) was 8%. The developed method was applied to the speciation of As(III) and As(V) in fresh water and human hair extracts, and the recoveries for the spiked samples are 86-109%. In order to validate the developed method, three certified reference materials such as GBW07601 human hair, BW3209 and BW3210 environmental water were analyzed, and the results obtained were in good agreement with the certified values provided.     

Synthesis hexagonal ß-Ni(OH)2 nanosheets for use in electrochemistry sensors

A new method for the determination of inorganic arsenic species (As(III) and As(V)) was developed by dispersive liquid-liquid microextraction (DLLME) separation and graphite furnace atomic absorption spectrometry (GFAAS) detection. In the pH range of 3–5, As(III) complexes with ammonium pyrrolidinedithiocarbamate (APDC) and then can be extracted into carbon tetrachloride droplets formed by injecting the binary solution of carbon tetrachloride (extraction solvent) and methanol (dispersive solvent) into the sample solution. As(V) is not extracted at the same pH conditions and remained in the aqueous phase. After extraction and phase separation by centrifugation, the enriched As(III) in the sedimented phase was determined by GFAAS. Total inorganic arsenic was determined after reduction of As(V) to As(III) with sodium thiosulfate and potassium iodide, and As(V) was calculated by difference. Under optimized conditions, the detection limits of this method for As(III) were 36 ng L^?1 with an enrichment factor of 45, and the relative standard deviation (R.S.D.%) was 3.1% (n?=?11, c?=?1.0 ng mL^?1). The method has been applied to the speciation of As(III) and As(V) in natural water samples with satisfactory results.     

Radiochemical solvent extraction of Au(III) using thionalide in ethyl methyl ketone/iso buthyl methyl ketone

A radiochemical method for the determination of gold using¹⁹⁸Au, has been developed. It is based on the synergistic extraction of Au(III) with thionalide (TA) in ethyl methyl ketone (EMK) or isobuthyl methyl ketone (IBMK) at pH 5.0.Effect of various parameters such as pH, nature of solvent and interferences due to other radionuclides have been studied. The method can be used up to 25 ng of Au.     

Dispersive Liquid–Liquid Microextraction Combined with Micellar Electrokinetic Chromatography for the Determination of Pesticide in Apple Sample

A fast and reliable dispersive liquid–liquid microextraction method for the determination of three pesticides by micellar electrokinetic chromatography was developed. Several variables that affect the extraction efficiencies, including the type and volume of the extraction solvent and dispersive solvent, extraction time, effect of pH and salt addition, were optimized. Under the optimum conditions, the enrichment factors were obtained in the range of 87 to 95. The extraction recoveries for the target analytes were in the range of 95.0% and 101%, and the relative standard deviation (%) was below 11.3%. The limits of detection at a signal-to-noise ratio of 3 ranged from 50 to 80 ng · mL^?1 with correlation coefficients (r ²) ranging from 0.9958 to 0.9986. The developed method has been successfully applied to the analysis of the three pesticides in apple juice with a satisfactory result.     

Use of less polar organic solvents for the polarographic determination of metals after extraction of their diethyldithiocarbamates

Summary Physico-chemical parameters of various organic solvents, such as conductivity, viscosity, available potential range and phase-separation characteristics, have been evaluated for the use of direct polarographic analysis after liquid-liquid extracxtion. Due to its higher conductivity of 1.16 mS cm^–1 and a wide available potential range of 0.81 –1.72 V vs. Ag/AgCl, a dichloromethane solution containing 0.1 mol/l tetrabutylammonium perchlorate is chosen as the best organic solvent solution for the purpose of this study. Bismuth(III) is extracted into the organic phase and gives well-defined anodic and cathodic waves at –0.12 V and –0.51 V, respectively. A selective polarographic determination of the metal after the dichloromethane extraction has been developed.     

Solvent bar microextraction combined with electrothermal vaporization inductively coupled plasma mass spectrometry for the speciation of inorganic arsenic in water samples

A new method of solvent bar microextraction (SBME) combined with electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS) for the speciation of As(III) and As(V) in water samples was developed. The method is based on the chelation of As(III) and ammonium pyrrolidine dithiocarbamate (APDC) under the selected conditions, and the As(III)-PDC complex could be extracted into the organic phase, while As(V) remained in aqueous solution. The post-extraction organic phase was directly injected into ETV-ICP-MS for determination of As(III) with the use of iridium as permanent chemical modifier. As(V) was reduced to As(III) by L-cysteine and was then subjected to SBME prior to total As determination. The assay of As(V) was based on subtracting As(III) from total As. The factors affecting on the SBME, such as organic solvent, sample pH, chelating reagent concentration, stirring rate and extraction time, and chemical modification of iridium in ETV-ICP-MS have been studied. Under the optimized conditions, the enrichment factor of 220-fold could be achieved in 15 min extraction, the limit of detection (LOD) for As(III) was 0.32 pg mL^− 1, and the relative standard deviation (RSD) was 8.8% (0.1 ng mL^− 1, n = 9). Compared with hollow fiber liquid phase microextraction (HF-LPME), SBME has a higher enrichment factor and faster extraction kinetics. In order to validate the accuracy of the method, a Certified Reference Material of GSBZ50004-88 (No. 200420) water sample was analyzed and the results obtained were in good agreement with the certified values. The developed method was also applied to the speciation of inorganic As in environmental waters with satisfactory results.     

Solvent extraction of Co/III/ with 1, 2, 3-benzotriazole into n-butanol

A new and rapid method has been developed for the quantitative extraction of Co/III/ with 1, 2, 3-benzotriazole into n-butanol. The extraction coefficient value of Co/III/ between n-butanol and an aqueous 5% solution of 1, 2, 3-BT in 2M sodium acetate-acetic acid buffer showed a maximum value of E=280 at pH 8.5. The effect of various other parameters on the extraction coefficient of Co/III/ such as solvents, anions, cations etc. has also been studied. The stoichiometry of the metal: reagent determined by the method of substoichiometric extraction and slope-ratio method was found to be 12. The separation factors studied for most of the elements were found to be better than 10³.     

Substoichiometric radiochemical determination of thallium with sodium isopropyl xanthate

A rapid radiochemical method for the determination of thallium(III) has been developed based on the substoichiometric extraction of its 13 complex with sodium isopropyl xanthate into chloroform from pH 9 ammonia buffer. The effect of foreign ions on the extraction was also studied. 10 g amounts of thallium were determined with an average error of 1.9%. The method has been successfully applied for the determination of thallium content present in sphalarite ores collected from Jawar Mines, Rajasthan (India).     

Solvent extraction of cerium/III/ with 1-/2-pyridylazo/-2-naphthol from perchloric acid media

A study on solvent extraction of cerium/III/ ion with 1-/2-pyridylazo/-2-naphthol /PAN or HL/ in chloroform from perchloric acid solution is described. The effect of equilibrium time, the pH of the aqueous phase and the concentration centration of extractant in organic phase on the extraction efficiency of cerium/III/ has been studied. The results show that the mechanism of extraction reaction is 3Ce _/aq/ ³⁺ + 3HL_/o/ CeL_3/o/ + 3H ₊ ^/aq/     

Development of dynamic headspace-liquid phase microextraction method performed in a home-made extraction vessel for extraction and preconcentration of 1,4-dioxane from shampoo

In the present study, a new, simple, rapid, and environmentally friendly headspace-liquid phase microextraction method followed by gas chromatography–flame ionization detection has been developed for the extraction/preconcentration and determination of 1,4-dioxane from shampoo. The developed procedure is performed in a home-made extraction vessel, connected to a glass vial containing sample and extraction solvent. In this method, an aliquot weight of shampoo is mixed with a binary mixture of n-hexane and dichloromethane (50:50, v/v) as the extractant and the target analyte is extracted during a liquid–liquid extraction procedure. Then a home-made extraction vessel containing a few microliters of a collection/extraction solvent is contacted to a glass vial containing the organic phase obtained from the previous step. By heating 1,4-dioxane is vaporized and enriched in a μL volume of the collection/extraction solvent. Then an aliquot volume of the collected phase is injected into the separation system. The effect of several factors which may influence performance of the method, including kind and volume of the extraction solvents used in both steps, extraction temperature, extraction time, and salt addition were evaluated. Under the optimum extraction conditions, limits of detection and quantification for the target analyte were obtained 0.52 and 1.73 μg kg^?1, respectively. Enrichment factor and extraction recovery were 333 and 89 %, respectively. The method precision was evaluated at a concentration of 25 μg kg^?1 and relative standard deviation was less than 6.9 % for intra-day (n = 6) and inter-day (n = 4) precisions. Finally, the proposed method has been successfully applied in analysis of 1,4-dioxane in different shampoo samples.     

Utilization of potassium ethyl xanthate as a substoichiometric reagent for the determination of indium

A sensitive and rapid radiochemical method has been developed for the determination of microgram amounts of indium(III) based on the substoichiometric extraction of its 13 complex with potassium ethyl xanthate from pH 7 ammonia buffer into chloroform. 5–50 g of indium was determined with an average error of 1.56%. The effect of associated species on the extraction was studied.     

Separation and spectrophotometric determination of thorium contained in uranium concentrate

A method for the determination of thorium in uranium concentrate by spectrophotometry with Arsenazo III has been developed. Preliminary solvent extraction procedures were used to eliminate interfering species. Samples were dissolved in nitric, perchloric and sulfuric acid and the uranium extracted from the solution using tri-octylamine. The aqueous layer was evaporated to dryness and the residue re-dissolved with hydrochloric acid, thorium was extracted by tri-n-octyl phosphine oxide and stripped with oxalic acid. For a typical uranium concentrate produced from the phosphate rock of Itataia, Brazil, concentrations of thorium as low as 5 g·g^-1 can be determined.     

Spectrophotometric determination of iron after separation of its 9,10-phenanthrenequinone monoximate on microcrystalline naphthalene

A sensitive and selective spectrophotometric method has been developed for the determination of iron as Fe(II) or Fe(III) using 9,10-phenanthrenequinone monoxime (PQM) as the complexing agent. Fe(II) and Fe(III) react with PQM to form coloured water insoluble complexes which can be adsorbed on microcrystalline naphthalene in the pH ranges 3.7–6.2 and 2.0–8.4, respectively. The solid mass consisting of the metal complex and naphthalene is dissolved in DMF and the metal determined spectrophotometrically by measuring the absorbances Fe(II) at 745 nm and Fe(III) at 425 nm. Beer's law is obeyed over the concentration range 0.5–20.0 g of iron(II) and 20–170.0 g of Fe(III) in 10 ml of DMF solution. The molar absorptivities are 1.333 × 10⁴ 1 · mole^–1 · cm^–1 for Fe(II) and 2.428 × 10³1· mole^–1 · cm^–1 for Fe(III). The precision of determination is better than 1%. The interference of various ions has been studied and the method has been employed for the determination of iron in various standard reference alloys, bears, wines, ferrous gluconate, human hair and environmental samples.     

A study on the solvent extraction of Ag/I/ with 1,2,3-benzotriazole in chloroform

A rapid and selective method has been developed for the substoichiometric extraction of Ag/I/with 1,2,3-benzotriazole /1,2,3-BT/ in chloroform in the presence of versenate. The effect of various parameters such as pH, time of equilibration, solvent, anions, cations, etc., on the extraction coefficient value has been studied. The stoichiometry of the extracted species of 11 /Ag:1,2, 3-BT/ was obtained by the slope ratio method and substoichiometric extraction. Decontamination factors for most elements in the substoichiometric extraction of Ag/I/ were found to be higher than 10⁴.     

Solvent extraction of Fe/III/ with 1,2,3-benzotriazole into n-heptanol

A new and rapid method has been developed for the quantitative extraction of Fe/III/ with 1,2,3-benzotriazole /1,2,3-BT/ into n-heptanol. The extaction coefficient value of Fe/III/ between n-heptanol and an aqueous 1% solution of 1,2,3-BT was found to be better than 99% over the pH range of 7.3 to 8.0 for an equilibration time of 2.0 min. The effect of various other parameters on the extraction coefficient value of Fe/III/ such as solvents, anions and cations etc. has also been studied. The stoichiometry of the metal: reagent determined by the method of substoichiometric extraction and slope-ratio method was found to be 13. Separation factors for most of the elements studied were better than 10³.     

Speciation of very low amounts of arsenic and antimony in waters using dispersive liquid–liquid microextraction and electrothermal atomic absorption spectrometry

A new procedure for the determination of inorganic arsenic (III,V) and antimony (III,V) in water samples by dispersive liquid–liquid micro extraction separation and electrothermal atomic absorption spectrometry (ETAAS) is presented. At pH 1, As(III) and Sb(III) are complexed with ammonium pyrrolidine dithiocarbamate and extracted into the fine droplets formed when mixing carbon tetrachloride (extraction solvent), methanol (disperser solvent) and the sample solution. After extraction, the phases are separated by centrifugation, and As(III) and Sb(III) are determined in the organic phase. As(V) and Sb(V) remain in the aqueous layer. Total inorganic As and Sb are determined after the reduction of the pentavalent forms with sodium thiosulphate. As(V) and Sb(V) are calculated by difference. The detection limits are 0.01 and 0.05 µg L^− 1 for As(III) and Sb(III), respectively, with an enrichment factor of 115. The relative standard deviation is in the 2.9–4.5% range. The procedure has been applied to the speciation of inorganic As and Sb in bottled, tap and sea water samples with satisfactory results.     

Radiochemical solvent extraction of Mn(II) using54Mn tracer

A radiochemical solvent extraction method has been developed for the determination of Mn(II) using⁵⁴Mn tracer. Mn(II) is complexed with 2-thenoyltrifluoroacetone (TTA) at pH 8.5 and extracted in isobutyl methyl ketone (IBMK). Different parameters affecting the extraction, and interferences due to diverse ions have been studied. The method can be used for the determination of Mn in microgram amounts.