Thorium In Water Samples Research Articles

Moving window partial least squares after orthogonal signal correction as a coupling method for determination of uranium and thorium by ultrasound‐assisted emulsification microextraction

AbstractThis study, a fast, simple, and efficient ultrasound‐assisted emulsification microextraction coupled with orthogonal signal correction‐moving window partial least squares (OSC‐MWPLS) was successfully used to preconcentration and simultaneous spectrophotometric determination of uranium and thorium in water samples. Response surface methodology based on a Box‐Behnken design was used to optimize the extraction conditions. The analysis of variance and some statistical tests such as lack‐of‐fit and coefficient of determination (R2) showed good fit of the experimental data with the second‐order polynomial model. Under the optimum conditions, the calibration graphs were linear in the range of 10.0 to 230.0 and 10.0 to 250.0 ng mL−1 with detection limits of 3.11 and 3.56 ng mL−1 (3Sb/m) for uranium and thorium, respectively. The preconcentration factor of this method for uranium and thorium reached 192. Repeatability (intra‐day) and reproducibility (inter‐day) were obtained 1.23% and 2.18% for uranium and 1.34% and 1.95% for thorium, respectively. The OSC was used for preprocessing of data matrices, and also MWPLS regression has been proposed for the selection of informative spectral intervals. In this paper, ultrasound‐assisted emulsification microextraction coupled with OSC‐MWPLS method was presented for the first time. The root mean square error of prediction for uranium and thorium with PLS, OSC‐PLS, and OSC‐MWPLS were 11.755, 10.335 and 5.301, 5.399 and 0.974, 0.986 ng mL−1, respectively. The results indicated that practical and environmentally friendly proposed method could be successfully used to the simultaneous determination of uranium and thorium in different environmental water samples.

Synthesis of UiO-66-OH zirconium metal-organic framework and its application for selective extraction and trace determination of thorium in water samples by spectrophotometry

In this study, a zirconium-based metal-organic framework (Zr-MOF), named UiO-66-OH, was synthesized by the solvo-thermal method and characterized by Fourier transform-infrared spectroscopy (FTIR), powder X-ray diffraction (PXRD), and scanning electron microscopy (SEM). This Zr-MOF was then employed as a sorbent for selective extraction and preconcentration of thorium ions after their complexation with 2‑(2,4‑dihydroxyphenyl)‑3,5,7‑trihydroxychromen‑4‑one (morin) from environmental water samples prior to its spectrophotometrical determination. The experimental parameters affecting extraction, such as pH of sample solution, amount of Zr-MOF, type and volume of eluting solvent, adsorption and desorption time, and concentration of complexing agent were evaluated and optimized. Under the optimized conditions, an enrichment factor of 250 was achieved. The limit of detection was calculated to be 0.35μg·L−1 with a linear range between 10 and 2000μg·L−1of thorium. The maximum sorption capacity of MOF toward thorium was found to be 47.5mg·g−1. The proposed procedure was successfully applied to the analysis of real water samples.

Flotation-assisted homogeneous liquid–liquid microextraction for determination of thorium in water samples by inductively coupled plasma–mass spectrometry and Box–Behnken design

ABSTRACTA fast, simple, and efficient method for extraction, preconcentration, and determination of thorium in water samples with acceptable recoveries based on flotation-assisted homogenous liquid–liquid microextraction combined with inductively coupled plasma–mass spectrometry (ICP-MS) is presented. Various parameters affecting the extraction efficiency were optimized by Box–Behnken design. Under the optimum conditions (concentration of dimethyl vinyl phosphonate = 2.4 × 10–4 mol/L, pH = 6.5, n-heptane = 150 μL, and acetonitrile = 0.5 mL), the calibration graph was linear in the range of 10.0–400.0 ng/L for thorium. The limit of detection of this method was 2.62 ng/L, and the enrichment factor was estimated to be 136 for thorium.

A NOVEL METHOD FOR THE DETERMINATION OF TRACE THORIUM BY DISPERSIVE LIQUID-LIQUID MICROEXTRACTION BASED ON SOLIDIFICATION OF FLOATING ORGANIC DROP

In this study, dispersive liquid-liquid microextraction based on the solidification of floating organic droplets was used for the preconcentration and determination of thorium in the water samples. In this method, acetone and 1-undecanol were used as disperser and extraction solvents, respectively, and the ligand 1-(2-thenoyl)-3,3,3-trifluoracetone reagent (TTA) and Aliquat 336 was used as a chelating agent and an ion-paring reagent, for the extraction of thorium, respectively. Inductively coupled plasma-optical emission spectrometry was applied for the quantitation of the analyte after preconcentration. The effect of various factors, such as the extraction and disperser solvent, sample pH, concentration of TTA and concentration of aliquat336 were investigated. Under the optimum conditions, the calibration graph was linear within the thorium content range of 1.0-250 µg L-1 with a detection limit of 0.2 µg L-1. The method was also successfully applied for the determination of thorium in the different water samples.

Application of hollow cylindrical wheat stem for electromembrane extraction of thorium in water samples

In this study, wheat stem was used for electromembrane extraction (EME) for the first time. The EME technique involved the use of a wheat stem whose channel was filled with 3M HCl, immersed in 10mL of an aqueous sample solution. Thorium migrated from aqueous samples, through a thin layer of 1-octanol and 5%v/v Di-(2-ethylhexyl) phosphate (DEHP) immobilized in the pores of a porous stem, and into an acceptor phase solution present inside the lumen of the stem. The pH of donor and acceptor phases, extraction time, voltage, and stirring speed were optimized. At the optimum conditions, an enrichment factor of 50 and a limit of detection of 0.29ngmL−1 was obtained for thorium. The developed procedure was then applied to the extraction and determination of thorium in water samples and in reference material.

Preconcentration procedure using vortex-assisted liquid–liquid microextraction for the fast determination of trace levels of thorium in water samples

A new simple and rapid vortex-assisted liquid–liquid microextraction method was applied for the determination of thorium in water samples. In this method, chloroform used as extraction solvent was directly injected into the water sample solution. The extraction solvent was dispersed into the aqueous phase under vigorously shaking with the vortex. After centrifuging, the fine droplets of extractant phase were settled to the bottom of the conical-bottom centrifuge tube. The effect of different experimental parameters on the performance of the method were studied and discussed. Under the optimum conditions, the detection limit for Th(IV) was 7.5 ng mL−1. The precision of the method, evaluated as the relative standard deviation obtained by analyzing of 10 replicates, was 2.8 %. The practical applicability of the developed method was examined using natural water and monazite sand samples.

A multisyringe flow injection method for the determination of thorium in water samples using spectrophotometric detection

A fast and simple multisyringe flow injection analysis (MSFIA) method for routine determination of thorium in water samples was developed. The methodology was based on the complexation reaction of thorium with arsenazo (III) at pH 2.0. Thorium concentrations were spectrophotometrically detected at 665 nm. Under optimal conditions, Beer’s law was obeyed over the range from 0.2 to 4.5 μg mL−1 thorium, a 3σ detection limit of 0.05 μg mL−1, and a 10σ quantification limit of 0.2 μg mL−1 were obtained. The relative standard deviations (RSD, %) at 0.5, 2.5 and 4.5 μg mL−1 was 2.8, 1.5 and 0.8%, respectively (n = 10). It was found that most of the common metal ions and anions did not interfere with the thorium determination. The proposed method was successfully applied to its analysis in various water samples.

Thorium determination in aqueous solutions after separation by ion-exchange and liquid extraction

The concentration of thorium in aqueous samples has been determined by means of alpha-spectroscopy and UV–Vis photometry after chemical separation and pre-concentration of the actinide by cation exchange and liquid-liquid extraction using Chelex-100 resin and 30%TBP in dodecan, respectively. Method calibration was performed using thorium standard solutions and resulted in a high chemical recovery for cation exchange and liquid extraction. Regarding, the effect of physicochemical parameters (e.g., pH, salinity, competitive cations, and colloidal species) on the separation recovery of thorium from aqueous solutions by cation exchange has also been investigated. The investigation was performed to evaluate the applicability of cation exchange and liquid extraction as separation and pre-concentration methods prior to the quantitative analysis of thorium in water samples, and has shown that the method could be successfully applied to waters with relatively low-salinity and metal ion contamination.

Floatation-spectrophotometric Determination of Thorium, Using Complex Formation with Eriochrome Cyanine R.

A novel and sensitive floatation-spectrophotometric method is presented for determination of trace amounts of thorium in water samples. The method is based on the ion-associated formation between thorium, Eriochrome cyanine R and Brij-35 at pH = 4 media. The complex was floated in the interface of the aqueous phase and n-hexane by vigorous shaking. After removing the aqueous phase the floated particles were dissolved in methanol and the absorbance was measured at 607 nm. The influence of different important parameters such as Eriochrome cyanine R and surfactants concentration, pH, volume of n-hexane, standing time and interfering ions were evaluated. Under optimized conditions the calibration graph was linear in the range of 6–230 ng mL−1 of thorium with a correlation coefficient of 0.9985. The limit of detections (LOD), based on signal to noise ratio (S/N) of 3 was 1.7 ng mL−1. The relative standard deviations for determination of 150 and 30 ng ml−1 of thorium were 3.26 and 4.41%, respectively (n = 10). The method showed a good linearity, recoveries, as well as some advantages such as sensitivity, simplicity, affordability and a high feasibility. The method was successfully applied to determine thorium in different water and urine samples.