Dithizone Complex Research Articles

Analytical electrochemical sensing of calcium ions in HCl media in the presence of a dithizone ligand with its biological applications

Using HCl medium, the electrochemical evaluation of different calcium chloride concentrations in the absence and presence of dithizone as a ligand was performed cyclic voltammetrically. The measurements were performed with a prepared 18-carat gold electrode as the working electrode, which was joined with working copper wire and isolated with heat-shrink polymer. The 18 carat Au work electrode exhibit a very useful wave couple at potentials of − 0.15 V on the reduction side and + 0.25 V on the oxidation side, which are very effective to calcium concentration; different pH values were also used to explain the peak couple specific for calcium ion estimation. Thermodynamic parameters for the interaction of calcium ions with the ligand Dithizone were determined, and it was discovered that the calcium metal ions and the ligand Dithizone show strong interaction. Applications were preceded for calcium estimation of different blood serum samples and also molecular docking of calcium –dithizone complex against Viral COVID-19 protein (5GNB) which proving strong bonds of interaction were observed.

Selective extraction-photometric determination of silver (i) with dithizone

A method has been developed for the selective, simple and accelerated extraction-photometric determination of silver, based on the selective extraction of silver (I) from a strongly acidic medium in the presence of iodide ions and dimethylformamide and its complexation with dithizone directly in the organic phase. The apparent molar extinction coefficient of the dithizone complex of silver (I) at a maximum light absorption of 495 nm is 3.46·104. The calibration graph is linear in the range of 0.5-50 mkg of silver (I) in 10 ml of extract. The determination of silver is not interfered with by large amounts of foreign ions in 100,000 multiples within the range of 2-5%. The developed extraction-photometric method for the determination of silver is recommended for the analysis of silver in ores, rocks, industrial waste and other materials with complex chemical composition without separating accompanying elements.

Simple and high-sensitivity colorimetric analysis of cadmium using homogeneous liquid-liquid extraction.

Colorimetric determination with dithizone (diphenylthiocarbazone) is a simple method that has been applied to analyze cadmium (Cd) ions in water. However, determining concentrations close to the environmental standard value (3 μgL-1) using this method is difficult because of its low sensitivity. Herein, we exploited the phase separation phenomenon to generate a small amount of the extraction phase by adding a mixture of 2-propanol and a small amount of chloroform to a water sample, as a pre-concentration method for the Cd(II) ions. The obtained Cd(II)-dithizone complex was successfully extracted into this phase. We then constructed a simple and highly sensitive colorimetric analysis method for the ppb level of Cd(II) using this phase separation technique.

Fast sequential multi element analysis of lead and cadmium in canned food samples using effervescent tablet-assisted switchable solvent based liquid phase microextraction (EA-SS-LPME) coupled with high-resolution continuum source flame atomic absorption spectrometry (HR-CS-FAAS)

An effervescent tablet-assisted switchable solvent based liquid phase microextraction (EA-SS-LPME) was developed for multi-element determination of Pb and Cd in various samples using high-resolution continuum source flame atomic absorption spectrometry (HR-CS-FAAS). The effervescent tablets were used for improving the extraction efficiency. Triethylamine as a hydrophobic solvent was switched to protonated triethylamine carbonate by CO2 and used to extract dithizone complexes from samples. Calibration linearities were obtained from 0.06 to 10.0 mg L−1 (Pb) and 0.02 to 1.50 mg L−1 (Cd). LODs of the proposed method were 0.0195 (Pb) and 0.0068 (Cd). LOQs were 0.0649 mg L−1 (Pb) and 0.0228 mg L−1 (Cd) with %RSDs of 1.25%–1.69% (Pb) and 1.07%–1.64% (Cd). The proposed method was applied for the determination of Pb and Cd in water and canned food samples. The spiked recoveries were 82.3–119.0% (Pb) and 81.7–120.0% (Cd). In addition, the PF was 3.3, with EF at 1.4 (Pb) and 2.6 (Cd) obtained after extraction for under 8 min.

The Comparison of Optimum Conditions for Lead (Pb) Analysis Method using DITHIZONE and EDTA Complex in Seaweeds (Eucheuma spinosum)

The comparison of optimum conditions for lead (Pb) analytical method using dithizone and EDTA complexes in Eucheuma Spinosum (Eucheuma Sp.) was measured using a standard addition method, where the standard solution of Pb2+ was added to the sample to reduce noise. Additionally, UV-Vis spectrophotometer was used with dithizone and EDTA complexes in Eucheuma Spinosum, where Pb2+ ions in both complexes were measured. Both complexes were first developed to determine the optimal pH that would measure Pb2+ level in Eucheuma Spinosum. The most favorable pH level for such measurement was pH 8, at which pH activity was most stable, and the most favorable complex was dithizone complex, with a regression value closer to one than that of EDTA complex.

Determination of Cd2+, Cu2+, Mn2+, Pb2+, and Zn2+ in Aqueous Solution after Their Separation and Preconcentation as Metal - Dithizone Complexes on Activated Carbon

A simple and sensitive method for preconcentration and determination of Cd2+, Cu2+, Mn2+, Pb2+ and Zn2+ by flame atomic absorption spectrophotometer was developed. The method is based on the sorption of the studied elements as metal-dithizone complexes (M-DZ) on activated carbon (AC). The effect of various parameters (pH, shaking time, AC amount, ligand concentrations, eluent concentration, and solution volume) on quantitative sorption of metal-dithizone chelates using AC was investigated. The studied elements were eluted from AC simply with HNO3 acid. The results revealed that the optimum pH values for the sorption were 4 for Cu2+, 6 for Zn2+, 8 for Pb2+ and 10 for Cd2+ and Mn2+; shaking time was 10 min for Mn2+ and Pb2+, 30 min for Cu2+ and Zn2+ and 50 min for Cd2+; AC amount was 0.2 g for Zn2+, 0.3 g for Cd2+, 0.5 g for Pb2+, 0.6 g for Mn2+ and 0.8 g for Cu2+; metal: ligand ratio was found to be (1:2 ratio), and eluent concentration used was 1 mol L-1 for Cd2+ and Mn2+, 2 mol L-1 for Zn2+ and 4 mol L-1 for Cu2+ and Pb2+. The method can be applied with a preconcentration factor of 20 for Cd2+, and 40 for Cu2+, Mn2+, Pb2+, and Zn2+. Preconcentration from various water samples showed recovery in the range 95-108 %, confirming the effectiveness and precision of the solid-phase method developed using activated carbon for enrichment of metals examined.

A simple and robust method for radiochemical separation of no-carrier-added 64Cu produced in a research reactor for radiopharmaceutical preparation

Copper-64 is an excellent theranostic radiometal that is gaining renewed attention of the clinical community in the recent times. In order to meet the increasing demand of this radiometal, we have demonstrated the viability of its production via 64Zn (n,p) 64Cu reaction in a nuclear reactor. A semi-automated radiochemical separation module based on selective extraction of 64Cu as dithizonate complex was developed. The maximum available activity at the end of irradiation was ~ 700 MBq. The overall yield of 64Cu after the separation process was >85% and it could be obtained with ~12 GBq/μg specific activity, >99.9% radionuclidic purity and >98% radiochemical purity. The separated 64Cu could be utilized for preparation of a wide variety of radiopharmaceuticals.

Simple and Rapid Device for Mercury Detection Based on The Formation of Mercury(II)-Dithizonate on Polytetrafluoroethylene (PTFE) Membrane

A new analytical device for mercury detection has been developed by doping dithizone on to hydrophobic PTFE (polytetrafluoroethylene) membrane to form a blue dithizone membrane which instantaneously changed to orange color of mercury(II)-dithizonate complex, when this dithizone membrane was contacted to mercury(II) solution. The higher concentration of mercury showed the greater intensity of the orange colour mercury(II)-dithizonate complex. The design and chemicals were optimized to obtain the best performance for mercury measurement. This method is prospective as mercury test kit for simple, low cost, and rapid semi-quantitative method for mercury(II) determination from 1-10 mgL-1 suits for on-site mercury detection and has been applied to cosmetics with satisfactory results.

Ultrasonic-enhanced preconcentration of trace Pb(II) using hydrophobic, lighter-than-water ionic liquid microextraction combined with solidification of the aqueous solution prior to detection by graphite furnace atomic absorption spectrometry in human fluids

Herein, we adopted a hydrophobic, lighter-than-water phosphonium-based ionic liquid (LTWP-IL) for preconcentration of trace Pb(II)-dithizone complexes prior to detection by graphite furnace atomic absorption spectrometry (GFAAS) in human fluids. Because the solvent injected into GFAAS contained LTWP-IL phase, the routine pyrolysis temperature such as 300–400 °C was not appropriate for LTWP-IL, and the optimized pyrolysis and atomization temperatures of Pb(II) were 800 °C and 1800 °C, respectively. The hydrophobic LTWP-IL floats on the surface of the aqueous phase after centrifugation, which allows for convenient and complete collection after solidification of the aqueous phase (HLILM-SAP), and thus overcomes the prominent disadvantage of conventional heavier-than-water ionic liquids-based microextraction. Ultrasound was used to disperse hydrophobic LTWP-IL in the absence of a dispersive solvent. Several operational parameters were optimized using a one-factor-at-a-time approach: LTWP-IL extractant, 30 μL; chelating agent, 0.3% dithizone; ultrasonic time, 5 min; solution pH = 6.0; solidification at −20 °C, 60 min and back extractant, 200 μL of 0.5 mol L−1 HNO3. Under optimized conditions, limits of detection were as low as 0.014–0.018 μg L−1 and enrichment factors reached >43-fold in urine and blood samples. Inter- and intra-day precisions had relative standard deviations of 3.77–6.79%. Trueness was evaluated by determining four certified reference materials of Pb(II) resulting in recovery values of 95–103%. Overall, the HLILM-SAP-GFAAS method is convenient, efficient and robust, making it suitable for rapid and accurate analysis of trace Pb(П) in complex biological fluids.

Determination of Au(III) and Ag(I) in Carbonaceous Shales and Pyrites by Stripping Voltammetry

Techniques of stripping voltammetry (SV) determination of silver and gold in pyrites and carbonaceous matter are developed. The problem of quantitative transfer of the analytes into the solution is solved. For this purpose, the ore matrix of carbonaceous shales was decomposed by mineral acids in autoclaves at high pressures. The element to be determined from the sample matrix was separated by extraction. Ag(I) ions from the solutions were extracted in the form of a dithizonate complex in CCl4. Au(III) ions were extracted by diethyl ether. The extracts were decomposed thermally. The dry residue was dissolved in the background electrolyte, and the element was determined by the SV method. The graphite electrode (GE) impregnated with polyethylene was used as a working electrode in the SV determination of silver. The SV determination of gold was carried out using a GE modified by bismuth. The limits of detection (LOD) of Ag(I) and Au(III) contents were equal to 0.016 mg L−1 and 0.0086 mg L−1, respectively. The results of SV determination of gold and silver in standard samples, pyrites, and carbonaceous shales were presented. The silver content in the pyrite was 13.6 g t−1, and in carbon shale it was 0.34 g t−1. The concentration of gold in the pyrite of the Kirovsko–Kryklinskaya ore zone was 1.15 g t−1, while in carbonaceous shales it was 2.66 g t−1. The obtained data were consistent with the data of atomic emission spectroscopy (AES) and inductively-coupled plasma mass spectrometry (ICP–MS). The error of determination of elements by stripping voltammetry was calculated as ranging from 10 to 6 g t−1 (less than 12%) in pyrite and carbonaceous material when determining the silver content, and from 1 to 3 g t−1 (less than 22%) when determining the gold content in pyrite and carbonaceous matter.

White-light emissive upconversion nanoparticles for visual and colorimetric determination of the pesticide thiram.

The authors describethe use of white-light emitting upconversion nanoparticles (WL-UCNPs) for visual detection of thepesticide thiram. The method is demonstrated to undergo a better discernable color change upon target binding. The WL-UCNPs are modified with the lead(II)-dithizone complex which acts as the energy acceptor and recognition unit. This leads to quenching of theblue (475nm) and green (545nm) emissions of theWL-UCNPs, while the red emission (650nm) remains unaffected. Upon addition of thiram, the quenched emissions are recovered, with a linear signal increase in the range from 2nM to 20nM of thiramand a limit of detection of 0.26nM. The nanoprobe was further integrated into a test paper for visual detection. The concentration-dependent color change that varies from red to cyan and bluish violet and then to white can be visually distinguished. Graphical abstract Schematic presentation of a white-light emissive upconversion nanoparticle based test paper for color-discernable detection of thepesticide thiram. The test stripe exhibits a concentration-dependent color variation spanning from red, cyan, to bluish violet, and at last to white.

Development of Cellulosic Paper-Based Test Strips for Mercury(II) Determination in Aqueous Solution.

Titration method (dropping-on method) was introduced as an efficient approach for determining the mercury ion (Hg2+) concentration in aqueous solution by using fabricated cellulosic paper-based test strips. In this study, dithizone used as a recognition reagent was physically loaded on cellulosic paper-based test strips for Hg2+ selective recognition. The sensing mechanism was established on the spectral absorption rate of the coordination compound that was formed by dithizone and Hg2+ under strong acidic conditions. The calibration curve was obtained by the absorbency of Hg2+-dithizone complexes from different Hg2+ concentration solutions, and the correlation coefficient (R2) reached 0.9971. The detection range of the test trip for Hg2+ was obtained at 0.1 μg/mL to 30 μg/mL. Moreover, these superior cellulosic paper-based test strips have a rapid color-forming time (1.5 min) and low volume demand (3.7 μL samples at 0.0127 g/L dithizone recognition concentration). This portable paper-based test strip can give potential applications for field screening or on-site semiquantitative analysis.

Young leaf protection from cadmium accumulation and regulation of nitrilotriacetic acid in tall fescue (Festuca arundinacea) and Kentucky bluegrass (Poa pratensis)

Phytoextraction efficiency of cadmium (Cd) contaminated soil mainly depended upon the mechanism of plants in absorption, translocation, distribution, and detoxification of Cd. A pot experiment was designed to investigate Cd distribution and accumulation among the different leaves of tall fescue (Festuca arundinacea) and Kentucky bluegrass (Poa pratensis) and its regulation by Nitrilotriacetic acid (NTA), a biodegradable chelating agent. The results showed that Cd concentrations in the senescent and dead leaves were 3.2 and 5.3 fold of that in the emerging leaves of tall fescue, and 19.3 and 25.1 fold of that in the emerging leaves of Kentucky bluegrass, respectively. The lower Cd concentrations were maintained in the emerging and mature leaves to avoid Cd toxicity. In the emerging and mature leaves, Cd was mainly accumulated in the vascular bundles and epidermis. No Cd dithizonate color was observed in the mesophyll tissues of Kentucky bluegrass and only minor Cd was observed in the mesophyll tissues of tall fescue. In the senescent leaves, Cd dithizonate complexes were located in the protoplasts and cell walls of all leaf tissues. NTA greatly promoted Cd translocation and distribution to the senescent and dead leaves of tall fescue, but no significant effect was observed in Kentucky bluegrass. Our results indicate that a young leaf protection mechanism might be involved in their Cd hypertolerance. The Cd preferential accumulation could lead a novel phytoextraction strategy by the continuously harvesting the senescent and dead leaves of tall fescue and Kentucky bluegrass.

Application of MALDI-TOFMS Combined with Partial Least Square Regression for the Determination of Mercury and Copper in Canned Tuna, Using Dithizone as the Complexing Agent and Ag(I) as Internal Standard

In this work, a procedure for the determination of mercury and copper in canned tuna samples is presented, based on the extraction of their respective dithizone complexes and quantification by conventional MALDI-TOFMS with the aid of partial least square regression (PLS2). Methanolic dithizone solution (1 ml, 0.01% m/v) containing Ag(I) as internal standard was added to the calibration solutions and to the acid-digested samples (5 ml, pH 3); copper, mercury, and silver complexes were extracted to cyclohexane (1.5 ml), and after evaporation, the residues were re-constituted in acetone (100 μl). The samples were prepared by dried droplet crystallization with α-cyano-4-hydroxycinnamic acid. The experimental and MALDI-TOFMS instrument operating conditions were set up under criteria of as high as possible detectability and repeatability. When univariate calibration was carried out using the most intense ion of Cu or Hg complex normalized by internal standard, determination seemed feasible yet precision of the results was poor. Taking baseline-corrected spectra in m/z range 560–725, PLS2 model was constructed for the prediction of two elements with the method quantification limits 63 μg kg−1 for Cu and 75 μg kg−1 for Hg, respectively. For different brands of canned tuna, the results obtained by MALDI-TOFMS combined with PLS2 and by ICP-MS were in good agreement. The proposed procedure is an attractive alternative for the determination of trace metals in foods because of the procedural simplicity, micro-scale dimension, high speed of data acquisition/processing, and the cost of instrument operation lower as compared to any atomic spectrometry technique.

Diazonium-based ion-imprinted polymer/clay nanocomposite for the selective extraction of lead (II) ions in aqueous media

Ion imprinted polymer/montmorillonite clay nanocomposite (MMT/IIP) was prepared by the combination of diazonium salt chemistry and photopolymerization process, and used for the selective removal of Pb(II). Toward this end, clay was ion exchanged with dimethylaminobenzenediazonium (DMA) to facilitate incorporation of hydrogen donating sites to the aluminosilicate layers. Upon irradiation of the mixture of the intercalated clay, acrylamide, bisacrylamide and Pb(II)–dithizone complex in the presence of benzophenone in DMSO, the copolymerization initiated by the free radicals formed by the hydrogen abstraction of photoexcited benzophenone from the dimethylamino groups of the intercalated clay. The resulting ion imprinted network nanocomposite and the precursors pristine and diazonium cation intercalated clays were thoroughly characterized by detailed FT-IR, XPS, XRD and SEM. Particularly, XRD analysis brought strong supporting evidence for high exfoliation of the clay upon photopolymerization, whereas XPS permitted to demonstrate that the final nanocomposite has polyacrylamide-rich surface. The adsorption and recognition properties of MMT/IIP for Pb(II) were evaluated using atomic absorption technique. The adsorption capacity was found to be as high as 301mg/g after about 30min contact time, and the relative selectivity coefficients to Zn2+ and Fe3+ were 9.2 and 93, respectively. Compared with non-imprinted clay/polymer nanocomposites, the MMT/IIP exhibited much higher affinity for Pb(II) therefore stressing the importance of the artificial receptor sites within the nanocomposite. Altogether, the results are consistent with an MMT/IIP nanocomposite that is specific to lead II. This work demonstrates for the first time the potential of aryldiazonium chemistry combined with photopolymerization for the fabrication of high performance clay/ion imprinted nanocomposites for the removal of toxic heavy metals.

Naked magnetite nanoparticles for both clean-up and solid-phase extraction-trace determination of mercury

A new solid-phase extraction method was developed for trace determination of Hg(II) by using a small amount of naked magnetite nanoparticles as an adsorbent. The magnetite nanoparticles were characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The adsorbed Hg(II)-dithizone complex was eluted with 1.0 mL aliquot of an acidic 1-propanol solution prior to electrothermal atomic absorption spectrometry. A huge positive effect was found on the mercury adsorption by ionic strength. Under optimized condition, a linear calibration curve was obtained for mercury in the range of 0.2–50 ng mL−1 with relative standard deviation in the range of 0.5–2.0%. The limit of detection and enrichment factor were 0.01 ng mL−1 and 98.3, respectively. The effects of coexisting ions were studied extensively, and a new clean-up procedure was used to remove the matrix effects by using a simple sample pretreatment step using a little amount of magnetite nanoparticles. The method was successfully applied to the determination of Hg(II) in different water and human urine samples and a commercial sodium nitrate.

Spectrophotometric determination of dithizone–mercury complex by solid phase microextraction in micropipette tip syringe packed with activated carbon xerogel

A new simple miniaturized solid phase microextraction system in a syringe was developed for mercury (Hg) preconcentration of in water samples based on the adsorption of its dithizone complex on a microcolumn. The syringe system contains a micropipette tip packed with activated carbon xerogel. The influence of acidity, eluting agents, amount of adsorbent, complex stability and interfering ions was studied in detail. The complex retained on activated carbon xerogel in the micropipette tip–syringe system could be eluted using ethanol and the concentration was determined by visible spectrophotometry.The method showed good linearity in the range of 30–280μgL−1, with a limit of detection of 7.6μgL−1. The relative standard deviation (RSD%) for six replicate measurements of 280μgL−1 of Hg2+ ion was 1.36%.The proposed method was successfully applied to quantitative determination of Hg2+ in ground water and mineral water with satisfactory results.

Micelle Mediated Preconcentration of Mercury in pH Controlled Mode for Trace Analysis

A micell-mediated phase separation method for preconcentration of ultra-trace quantities of mercury as a prior step to its determination by UV-Vis spectrophotometry has been developed. The method is based on Hg(II)-dithizone complex formation in alkaline aqueous solution, and extraction of this Hg(II)-dithizone secondary complex into the surfactant-rich phase of the non-ionic surfactant octylphenoxypolyethoxyethanol (Triton X-114). This cloud point method of extraction was carried out at 54 ◦C and the surfactant- rich phase containing analyte was dissolved in 250 µL of ethanol with pH 8. The obtained solution was introduced into a micro quartz cell and the analyte was determined by UV-Vis spectrophotometry. Complexation and cloud point extraction of the mercury in alkaline solution markedly facilitate the phase-separation process, lower the temperature of the cloud point, enhances the complex to background absorption ratio and eliminates the interference of Cu 2+ , Al 3+ and Fe 3+ . Under the optimal extraction and reaction conditions, detection limits, relative standard deviations and linear calibration graphs were, 0.9 ng/mL, lower than 2% and 3.0-250.0 ng/mL respectively. This detection limit is 15 times lower than one obtained by using the same method but at acidic media. The method was applied to the determination of Mercury in soft water and physiology serum samples.

Mercury(II) determination in commercial cosmetics and local Thai traditional medicines by flow injection spectrophotometry.

The proposed method was developed for the enhancement of sensitivity for Hg(II) determination using dithizone by adding SDS in the presence of ascorbic acid in sulphuric acid medium. The method was based on the reaction between Hg(II) and 1,5-diphenylthiocarbazone (dithizone), in the presence of sodium dodecyl sulphate (SDS) as an anionic surfactant (to avoid solvent extraction) and ascorbic acid in a slightly acidic medium resulting in a soluble orange coloured Hg(II)-dithizone complex which gave the maximum absorption at 490 nm. No extraction system was required in this method. Under the optimum conditions, a linear calibration graph was obtained over the concentration range of 0.05-1.50 μg mL(-1). The method was characterized by a limit of detection (LOD, defined as 3σ) and limit of quantification (LOQ, defined as 10σ) of 0.03 and 0.14 μg mL(-1), respectively. The relative standard deviations for replicate injection were 1.32 and 0.78% (n = 11) for 0.05 and 0.20 μg mL(-1) of Hg(II) standard solutions, respectively. The developed method has been satisfactorily applied for Hg(II) determination in commercial cosmetics and local Thai traditional medicines. Results obtained by the proposed method are compared favourably with those analysed by ICP-MS. Enhancement of sensitivity and rapidity for Hg(II) assay by FIA could be achieved by adding SDS in ascorbic acid. The method would be useful for routine analysis of Hg(II) in real samples.

Zn(II)-concentration dependent Raman spectra in the dithizone complex on gold nanoparticle surfaces in environmental water samples

After the formation of dithizone with metal ion complexes, a selective Raman detection method for the Zn2+ ions in aqueous solutions was developed by observing the intensity change of the ring mode peaks at ∼1585cm−1 on gold nanoparticles (AuNPs). At high concentrations of Zn2+ ions, the conformation of the dithizone complex may have different orientations on AuNPs to yield the spectral changes at ca. ∼510 and ∼1585cm−1. The concentration dependent spectra changes indicated that a detection limit would be in the submicromolar region of Zn2+ ions. The other ions of Mg2+, K+, Fe3+, Hg2+, Co2+, Fe2+, Pb2+, Cu2+, Ni2+, Cr3+, NH4+, Cd2+, Na+, Ca2+, and Mn2+ at micromolar concentrations of 1μM did not produce such spectral changes. The detection limit based on the Raman band intensities was estimated to be as low as 500nM of Zn2+ ion in aqueous solutions. The three real samples of tap, river, and seawater were tested under the interference of the commonly existing interfering ions. Despite the presence of highly concentrated Na, Ca, Mg, and K, our interfacial spectroscopic methodology of Zn2+ determination could be applied in the environmental water samples.