http://rms.scu.ac.ir/files/articles/journals/abstract/th-hazardous.pdf2010125103160.pdf

An optical chemical sensor for thorium (iv) determination based on thorin

Speciation analysis of mercury contaminants in water samples by RP-HPLC after solid phase extraction on modified C18 extraction disks with 1,3-bis(2-cyanobenzene)triazene

A facile, rapid and sensitive spectrophotometric method for the determination of trace amounts of UO2(II) and Th(IV) ions in aqueous samples was performed, based on complexation reaction between metal ion and 4-chloro-N-(2,6-dimethylphenyl)-2-hydroxy-5-sulfamoylbenzamide (xipamide). The important analytical parameters and their effects on the reported system were investigated. UO2(II) and Th(IV) react with xipamide in the ratio 1:1 and 1:2 (metal:ligand) in the pH range 7 and 8 to form a complex with an absorption maximum 445 and 325 nm, respectively. The reaction was extremely rapid at room temperature, and the absorbance value remains unchanged for at least 24 h. The apparent stability constants (log βn) and the free energies change (ΔG*) of formation of the complexes were calculated using the results of mole ratio and continuous variation methods. Beer's law was obeyed in range 0.2–3.6 μg/mL for UO2(II) and 0.1–4.8 μg/mL for Th(IV). For more accurate analysis, Ringbom optimum concentration range was found from 0.3–3.4 μg/mL for UO2(II) and 0.2–4.2 μg/mL for Th(IV). The apparent molar absorptivity, Sandell sensitivity, detection and quantification limits were also calculated. The interference effect of some anions and cations was also tested. The method was applied to the determination of UO2(II) and Th(IV) in water samples.

Optimized and validated spectrophotometric methods for the determination of trace amounts of uranium and thorium using 4-chloro-N-(2,6-dimethylphenyl)-2-hydroxy-5-sulfamoylbenzamide

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.

https://journals.sagepub.com/doi/pdf/10.4137/ACI.S5949

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

A rapid and sensitive spectrophotometric method has been developed for the determination of Th 4+ ions using tetra butyl 2,2′-bipyridine-5,5′-diylbis(methylene) diphosphonate (L) as a chemosensor. The selective complexation of L was examined with various f -metal ions like Th 4+ , U 6+ and Ln's(III) ions and other selected metal ions (from s, p, and d-block elements). The chemosensor L selectively portrayed a naked-eye detectable colour change from colourless to pink with an appearance of a new charge transfer band at 320 nm and 525 nm. No noticeable spectral and colour changes of L were observed with other tested metal ions. This confirms high selectivity of L towards Th 4+ ions. The Job’s plot delineated the formation of a host–guest complex between L and Th 4+ in 1:1 binding stoichiometry. The binding constant for the complexation of L-Th 4+ was calculated from Benesi–Hildebrand (BH) plot and was found to be 6 × 10 3  M −1 . The complexing ability L with Th 4+ was supported by 31 P NMR, FT-IR, UV-DRS, vibrating sample magnetometery and mass spectral data. The limit of detection (LOD) and limit of quantification (LOQ) of L for the analysis of Th 4+ was calculated to be 2.02 μM and 6.1 μM, respectively. Finally, the chemosensor L was successfully applied for the quantification of Th 4+ contents present in monazite sand, gas mantels and different water samples.

Development of highly selective chemosensor for thorium estimation

A new highly sensitive and selective chromogenic reagent, 2-(2,5-disulfonic-4-methoxyphenylazo)-7-(2-hydroxyl-5-carboxylphenylazo)-1,8-dihydroxynaphthalene-3,6-disulfonic acid (1), was synthesized and applied to the spectrophotometric determination of trace thorium. In 5 mL of a 6 M perchloric acid medium, which greatly increases the selectivity, thorium reacts with 1 to form a 1: 2 green complex, having a sensitive absorption peak at 670 nm. Under optimal conditions, Beer’s law is obeyed over the range from 0 to 0.8 μg/mL Th(IV) and the apparent molar absorptivity is 2.09 × 105 L/mol cm. It is found that, uranium(VI), Ti(IV), heavy rare earths, and most of other common metal ions do not interfere. The method has been tested on the determination of thorium in food samples with satisfactory results.

Spectrophotometric determination of thorium in food using 2-(2,5-disulfonic-4-methoxyphenylazo)-7-(2-hydroxyl-5-carboxylphenylazo)-1,8-dihydroxynaphthalene-3,6-disulfonic acid

A new and very sensitive and selective chromogenic reagent, 2-methylthiophenyldiazoaminoa-zobenzene (MTDAA), was synthesized and studied in detail for the determination of trace mercury(II) in water samples. The method is based on the color reaction between MTDAA and mercury(II). It was found that mercury(II) reacts with MTDAA in Na2B4O7-NaOH buffer solution (pH = 10.0) to form 1 : 2 red complexes; these show maximum absorption at 520 nm. Beer’s law is obeyed in 0–15 µg of mercury(II) in 25 mL of solution. The apparent molar absorptivity of the complex is 1.33 × 105 L/(mol cm); its limit of quantification, limit of detection, and relative standard deviation are 0.75 ng/mL, 0.27 ng/mL, and 1.0%, respectively, giving better sensitivity. The influence of the reaction variables and the effect of interfering ions are reported; most of the metal ions in water samples can be tolerated in considerable amounts. Only a few ions can interfere with the determination of trace mercury(II), but these can be eliminated by prior extraction. The proposed method is sensitive, simple, and rapid. It has been applied to the determination of trace mercury(II) in water samples with satisfactory results.

https://rd.springer.com/content/pdf/10.1007%2Fs10809-005-0149-z.pdf

M. Tian

Papers

Spectrophotometric determination of thorium in food using 2-(2,5-disulfonic-4-methoxyphenylazo)-7-(2-hydroxyl-5-carboxylphenylazo)-1,8-dihydroxynaphthalene-3,6-disulfonic acid

The Color Reaction of Mercury(II) with the New Reagent 2-Methylthiophenyldiazoaminoazobenzene and Its Application