Diethyldithiocarbamate Complexes Research Articles

Speciation of Cr(III) and Cr(VI) after column solid phase extraction on Amberlite XAD-2010

A speciation procedure for Cr(III) and Cr(VI) based on column solid phase extraction on Amberlite XAD-2010 and flame atomic absorption spectrometry combination. Cr(VI) was quantitatively recovered on Amberlite XAD-2010 resin at pH range of 2.0–3.0 as its diethyldithiocarbamate complex, while the recoveries of Cr(III) was below 5%. The influences of the various parameters including amounts of the reagents, eluent type and its volume, sample volume, etc., on the quantitative recoveries were examined. The interference of matrix and coexistent elements for method were studied. The detection limit (corresponding to three times the standard deviation of the blank) and the enrichment factor for Cr(VI) were found to be 1.28 μg/L and 25, respectively. To verify the accuracy of the method, drinking water certified reference material (CRM-TMDW-500) was analyzed and the results obtained were in good agreement with the certified value. The proposed method has been successfully applied to the speciation of Cr(III) and Cr(VI) in water samples and preconcentration of total chromium in environmental samples.

Reduction enhances yields of nitric oxide trapping by iron–diethyldithiocarbamate complex in biological systems

The mechanism of NO trapping by iron–diethylthiocarbamate complexes was investigated in cultured cells and animal and plant tissues. Contrary to common belief, the NO radicals are trapped by iron–diethylthiocarbamates not only in ferrous but in ferric state also in the biosystems. When DETC was excess over endogenous iron ligands like citrate, ferric DETC complexes were directly observed with EPR spectroscopy at g = 4.3. This was the case when isolated spinach leaves, endothelial cultured cells were incubated in the medium with 2.5 mM DETC or mouse liver was perfused with 100 mM DETC solution. After trapping NO, the nitrosylated Fe–DETC adducts are mostly in diamagnetic ferric state, with only a minor fraction having been reduced to paramagnetic ferrous state by endogenous biological reductants. In actual in vivo trapping experiments with mice, the condition of excess DETC was not met. The substantial quantities of iron in animal tissues were bound to ligands other than DETC, in particular citrate. These non-DETC complexes appear as roughly equal mixtures of ferric and ferrous iron. The presence of NO favors the replacement of non-DETC ligands by DETC. In all biological systems considered here, the nitrosylated Fe–DETC adducts appear as mixture of diamagnetic and paramagnetic states. The diamagnetic ferric nitrosyl complexes may be reduced ex vivo to paramagnetic form by exogenous reductants like dithionite. The trapping yields are significantly enhanced upon exogenous reduction, as proven by NO trapping experiments in plants, cell cultures and mice.

Determination of Lead, Iron, Manganese and Zinc in Sea Water Samples by Atomic Absorption Spectrometry after Preconcentration with Chromosorb 105

A solid phase extraction procedure based a column technique for preconcentration of lead, iron, manganese and zinc from water samples was developed. The analyte ions as its diethyldithiocarbamate complex were retained on a column of Chromosorb 105 from buffered sample solution. Then they were eluted with acetone. The recoveries of lead, iron, manganese and zinc under the optimum working conditions were 100, 97, 100 and 100%, respectively. The relative standard deviations were less than 6%. The method presented was applied for the determination of lead, iron, zinc and manganese in sea water samples.

Semiconductor/porous silica glass nanocomposites via the single-source precursor approach

The utilization of single-source molecular precursor approach to obtain II–VI and IV–VI semiconductors encapsulated in porous Vycor glass (PVG) is described. The procedure is based on the impregnation of cadmium and lead(II) diethyl-dithiocarbamate complexes, Cd(S 2CNEt 2) 2 and Pb(S 2CNEt 2) 2, inside the porous environment of PVG followed by a thermal treatment of the glass. The pyrolysis of the impregnated precursor gives rise to binary semiconductors CdS and PbS, respectively. The impregnation step is driven by interactions between the precursors and active sites located at glass pore surfaces. After completing the impregnation–decomposition cycle, it was found that the active glass sites were regenerated, making new cycles possible. The amount of encapsulated semiconductor increases linearly as a function of the number of cycles. Nanocomposites obtained after 1–10 cycles were prepared and characterized by optical spectroscopy, X-ray diffraction powder and transmission electron microscopy.

Solid-phase extraction–gas chromatography–mass spectrometry using a fullerene sorbent for the determination of inorganic mercury(II), methylmercury(I) and ethylmercury(I) in surface waters at sub-ng/ml levels

A novel, straightforward solid-phase extraction system for the determination of inorganic mercury and organomercury compounds in water is proposed. The analytes, in a buffer medium at pH 4.5, are sorbed as diethyldithiocarbamate complexes on a C 60 fullerene column an subsequently eluted and derivatized with sodium tetra- n-propylborate in ethyl acetate. Following elution, 1 μl of extract is injected into a gas chromatograph–mass spectrometer system. The proposed gas chromatography–mass spectrometry speciation method exhibits a linear range of 4–1 ng/ml, and a detection limit of 1.5 ng/l (sample volume, 50 ml). Its repeatibility, as relative standard deviation (RSD) (from 11 standards containing 50 ng/l for each analyte), is ca. 7%. No interferences from metals ions, such as Zn 2+, Fe 3+, Sb 3+, As 3+, Pb 2+, Ni 2+, Cu 2+, Sn 2+, Co 2+, Mn 2+and Cd 2+ were encountered at concentrations 1000 times higher than those of the mercury compounds. The method was used for the speciation of inorganic mercury, methylmercury and ethylmercury in various types of water including sea and waste water.

Solid-Phase Extraction of Cd(II) as Diethyldithiocarbamate Complex by Polyurethane Foam: Kinetic and Thermodynamic Characterization

ABSTRACTThis paper presents a study about the sorption of the cadmiumdiethyldithiocarbamate [Cd(II)-DDTC] complex onto polyurethane foam (PUF). It was observed that the maximum sorption of Cd(ll) (80 or 150 µgL-1) was verified at pH 6.8 in the presence of 4.5 × 10-5 mol L-1 DDTC. The shaking time needed to achieve the equilibrium was 40min. From these data, a kinetic characterization was performed by applying three models, which revealed that a film-diffusion process was a rate-determining mechanism. Results also indicated that an ether-like solvent extraction was the sorption mechanism. The investigation of many metallic ions as concomitants showed that the sorption by foam is relatively selective and it can be enhanced by using a suitable masking agent or incrementing the foam mass.

Investigations of Cobalt, Nickel, and Copper Diethyldithiocarbamates Using Thermal Lens Spectrometry

Thermal lens spectrometry was used to study the dissociation kinetics of diethyldithiocarbamate complexes of copper(II), cobalt(III), and nickel(II) as a function of pH in the presence of chloride and sulfate ions. It is shown that, as distinct from conventional spectrophotometric and potentiometric measurements, the reversible dissociation of the test complexes and the irreversible oxidation of the ligand can be studied separately (at a level of n × 10–8–n × 10–6 M) using thermal lens spectrometry. Because of work in more dilute solutions and due account of the kinetic features of the systems in question, thermal lens spectrometry provides a higher accuracy of the determination of stability constants for diethyldithiocarbamate complexes of copper(II), cobalt(III), and nickel(II). The adsorption of the diethyldithiocarbamate complexes in question from water–ethanol solutions (1 : 3) on Silasorb C18 silica is studied, and the adsorption constants are determined. The limits of detection of copper(II), cobalt(III), and nickel(II) diethyldithiocarbamates obtained in extraction–thermal-lens determination are n × 10–8 M.

Endogenous superoxide production and the nitrite/nitrate ratio control the concentration of bioavailable free nitric oxide in leaves.

We have quantitatively measured nitric oxide production in the leaves of Arabidopsis thaliana and Vicia faba by adapting ferrous dithiocarbamate spin tapping methods previously used in animal systems. Hydrophobic diethyldithiocarbamate complexes were used to measure NO interacting with membranes, and hydrophilic N-methyl-d-glucamine dithiocarbamate was used to measure NO released into the external solution. Both complexes were able to trap levels of NO, readily detectable by EPR spectroscopy. Basal rates of NO production (in the order of 1 nmol g(-) (1) h(-1)) agreed with previous studies. However, use of methodologies that corrected for the removal of free NO by endogenously produced superoxide resulted in a significant increase in trapped NO (up to 18 nmol g(-) (1) h(-1)). Basal NO production in leaves is therefore much higher than previously thought, but this is masked by significant superoxide production. The effects of nitrite (increased rate) and nitrate (decreased rate) are consistent with a role for nitrate reductase as the source of this basal NO production. However, rates under physiologically achievable nitrite concentrations never approach that reported following pathogen induction of plant nitric-oxide synthase. In Hibiscus rosa sinensis, the addition of exogenous nitrite generated sufficient NO such that EPR could be used to detect its production using endogenous spin traps (forming paramagnetic dinitrosyl iron complexes). Indeed the levels of this nitrosylated iron pool are sufficiently high that they may represent a method of maintaining bioavailable iron levels under conditions of iron starvation, thus explaining the previously observed role of NO in preventing chlorosis under these conditions.

Determination of platinum, palladium and rhodium in biological and environmental samples by low temperature electrothermal vaporization inductively coupled plasma atomic emission spectrometry with diethyldithiocarbamate as chemical modifier

A novel method for inductively coupled plasma atomic emission spectrometry (ICP-AES) determination of trace amounts of Pt(II), Pd(II) and Rh(III), based on gaseous compounds introduction into the plasma as their diethyldithiocarbamate complexes by electrothermal vaporization (ETV), was developed. At the temperature of 1100 °C, the trace amounts of Pt, Pd and Rh were vaporized into plasma. The factors affecting the formation of the chelates and their vaporization behaviors, such as ashing temperature and time, vaporization temperature and time, pH and the concentration of chelating reagents were studied in detail. Under the optimized conditions, the limits of detection (LODs) (3 σ) of Pt, Pd and Rh for tested solutions were 5.4, 1.4 and 0.8 ng ml −1, and for actual sample (auto-catalyst NIST SRM 2557) were 0.27, 0.07 and 0.04 μg g −1, respectively. The relative standard deviations (RSDs) for Pt, Pd and Rh were 1.4, 2.6 and 2.4% ( C Pt=0.5 μg ml −1, C Pd,Rh=0.25 μg ml −1, n=7), respectively. The linear ranges of calibration graphs for Pt, Pd and Rh cover three orders of magnitude. Compared with conventional electrothermal vaporization technique, using the reagent of diethyldithiocarbamate as chemical modifier could not only enhance the analytical sensitivities, but also reduce the vaporization temperature. By combination with a separation/preconcentration step, the proposed method had been successfully applied to the analysis of the artificial seawater, tap water and urine with recoveries ranging from 91 to 106%. The two certified reference material meager platinpalladium ore GBW 07293 and auto-catalyst NIST SRM 2557 was also analyzed for validation, and the determined values obtained were in good agreement with the certified values.

Formation of Crystalline Stibnite Bundles of Rods by Thermolysis of an Antimony(III) Diethyldithiocarbamate Complex in Ethylene Glycol.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Formation of crystalline stibnite bundles of rods by thermolysis of an antimony(III) diethyldithiocarbamate complex in ethylene glycol.

A synthesis of novel crystalline stibnite (Sb(2)S(3)) submicrometer-sized rod bundles of straw has been investigated using a wet chemical method via thermal decomposition of an antimony(III) diethyldithiocarbamate complex in ethylene glycol under mild conditions. By carefully controlling the experimental parameters, such as precursor concentration, temperature, and time, flowerlike bunches of rods and straw-shaped crystalline stibnite submicrometer-sized rod bundles are successfully achieved. The possible mechanism is proposed, which reveals that the inherent highly anisotropic layered structure of stibnite and precursor concentration take crucial roles in determining the final morphologies of the products. The high yields, simple reaction apparatus, low manipulating temperature, and newly discovered uniform morphology of the products may mean that this simple method has good potential in related future applications.

Solid phase extraction of Cu(II) as diethyldithiocarbamate (DDTC) complex by polyurethane foam

This paper presents a study about the sorption of copper-diethyldithiocarbamate complex onto polyurethane foam (PUF). It was observed that the maximum sorption of Cu(II) (80 or 150 µg L-1) was verified at pH 6.8 in presence of 4.5 x 10-5 mol L-1 DDTC. The shaking time needed to achieve the equilibrium was 40 minutes. From these data, a kinetic characterization was performed by applying three models, which revealed that a film diffusion process was a rate-determining mechanism. Results also indicated that a ether-like solvent extraction was the sorption mechanism. The investigation of many metallic ions as concomitants showed that the sorption by foam is relatively selective and it can be enhanced by using a suitable masking agent or incrementing the foam mass.

Role of nitric oxide in radiation-induced initiation of mammary tumorigenesis in rats

Nitric oxide (NO) and its reaction products have been shown to cause DNA damage and to be mutagenic. To elucidate whether NO produced by irradiation participates in the initiation of mammary tumorigenesis, we performed experiments using the nitric oxide-specific scavenger Fe 2+-diethyldithiocarbamate complex (Fe(DETC) 2) or a selective inhibitor for inducible nitric oxide synthase (iNOS), S, S ′-(4-phenylene-bis(1,2-ethanedinyl))bis-isothiourea (1,4-PB-ITU). Mother rats at day 21 of lactation were injected simultaneously with diethyldithiocarbamate intraperitoneally and Fe 2+-citrate subcutaneously to form Fe(DETC) 2, in vivo, and then irradiated with 1.5 Gy γ-rays immediately after the injection. An additional injection of chemicals followed twice at 8 and 24 h after the irradiation in the same manner. Both control and treated rats were then implanted with diethylstilbestrol pellets as a tumor promoter. The mammary tumor incidence in the experimental group was significantly reduced to one-fourth of that in the irradiated-alone group as the control. On the other hand, when mother rats took drinking water containing 0.005% 1,4-PB-ITU for 6 days from 3 days prior to irradiation at day 21 of lactation, a low tumor incidence in the iNOS inhibitor-treated groups was observed in the 1-year period. This report is the first to show that the NO derived from iNOS is an important radical for radiation-induced initiation of tumorigenesis of mammary glands in rats.

Automated on-line solvent extraction and AAS-graphite furnace determination of trace metals in difficult matrices

A simple automated on-line extraction system for AAS-graphite furnace determination of trace metals in difficult matrices has been developed. The system uses solvent extraction of aqueous trace metals as diethyldithiocarbamate complexes into methyl isobutyl ketone fed directly to a graphite furnace for AAS determination. It was shown that complete extraction of the metals Cd, Co, Cu, Ni, Pb and Zn was possible under acid conditions at pH below 2. Since such a low pH is often encountered in acid digests of various materials it is possible to extract the metals directly from these digests. The extraction system was tested for Cd, Cu and Pb for a number of reference materials (soil, sediment, plant, animal tissue and bone). The accuracy of the total analytical procedure including the automated extraction was satisfactory and the results agreed well with the certified values within the tabulated standard deviations. By using the developed system tedious and contaminating sample preparation is minimized, and interference from matrix constituents (salts and Fe) is absent. The system is relatively simple to construct utilising general laboratory components, and it has been in service for many years at our laboratories, substantially cutting down laborious manual work and resulting in an increased output and higher quality of the analytical results.

Adducts of Diethyldithiocarbamate Complexes of Zinc(II) and Copper(II) with Piperidine [M(Pip)(Edtc)2] and Their Solvated Forms [M(Pip)(Edtc)2] · L (L = C6H6, C5H5N, C4H9NO): Synthesis, EPR and Solid-State (13C, 15N) CP/MAS NMR Studies

Crystal adducts of diethyldithiocarbamate complexes of zinc(II) and copper(II) with piperidine (Pip) were synthesized, and their solvated forms with the outer-sphere molecules of benzene, pyridine (Py), and morpholine (Mf) were obtained. Adducts with composition [M(Pip)(Edtc)2] · L (L = Py, Mf) were shown to be able, in principle, to give solvated isomers [M(L)(Edtc)2] · Pip with the Pip molecule arranged in the outer sphere. The composition, structure, and properties of the obtained adducts were studied by EPR, high-resolution solid-state 13C, 15N NMR spectroscopy. Solvation of all three adducts with Pip, Mf, and Py was found to result in a substantial increase in the contribution of the trigonal–bipyramidal component to the geometry of a copper coordination pentahedron. In addition, for adducts with Mf and Py, a structural unification of two isomeric forms was observed at the molecular level to yield a qualitatively new (rather than intermediate) state. It was shown that in all solvated forms of the copper(II) adducts, the metal polyhedron is mainly a trigonal bipyramid, while the square–pyramidal contribution is insignificant. Results of (13C, 15N) NMR studies revealed a structural inequivalence of the Edtc–ligands in the zinc adducts under investigation.

Flow injection solid phase extraction with Chromosorb 102: determination of lead in soil and waters by flame atomic absorption spectrometry

A flow-injection, solid-phase extraction, preconcentration method was developed for the determination of lead in soil and water samples by flame atomic absorption spectrometry. Lead, in the form of the diethyldithiocarbamate complex, was retained on a miniature column of Chromosorb 102 from buffered sample solutions. Several parameters governing the efficiency and throughput of the method were evaluated including pH, eluent composition, volume and flow rate. The complex retained from pH 9.0 (ammonium acetate) solutions was eluted with 176 μl of ethanol, at 4.2 ml min −1 into the nebulizer–burner system of the spectrometer. The detection limit was 2 μg l −1 for preconcentration at 2.2 ml min −1 for 120 s. The relative standard deviation (R.S.D.) was less than 4% for concentrations down to 400 μg l −1. The procedure was validated by the analysis of NIST standard reference material 2711 (Montana Soil) which contains lead at a concentration of 1162 μg g −1. Recoveries of spike additions (100–400 μg l −1) to artificial sea water and tap water were quantitative.

Speciation of inorganic lead and ionic alkyllead compounds by GC/MS in prescreened rainwaters

A simple and novel screening method for lead compounds in environmental waters is proposed. The analytes, in an acetic medium, are sorbed on a C60 fullerene column as diethyldithiocarbamate complexes and subsequently eluted with isobutyl methyl ketone (IBMK), the lead being determined by flame atomic absorption spectrometry. The screening method acts as filter and indicates whether the target analytes are present above or below the detection limit of the method (0.5 ng/mL), giving no false positives. Positive samples were speciated by GC/MS, using a flow system similar to that of the screening method. Lead(II) and ionic di- and trialkyllead are derivatized with a Grignard reagent. Both methods use similar chemical and flow variables except for the eluent, IBMK in the screening method and n-hexane in the speciation method. The GC/MS speciation method is very sensitive; it exhibits a linear range of 0.02-5 ng/mL, and detection limits of 1-4 ng/L are achieved. Also, its repeatibility, as RSD, is less than 6%. The method was applied to the speciation of Pb2+ and di- and trialkyllead in positive prescreened rainwater samples from three different urban areas.

Separation and determination of Ni(II), Co(II) and Cu(II) by RP-HPLC with hexadecyltrimethylammonium bromide/n-propanol mobile phases

The effect of the presence of a cationic surfactant, hexadecyltrimethylammonium bromide (CTAB), and a short chain alcohol,n-propanol, in the mobile phase on the chromatographic retention of Co(II), Ni(II) and Cu(II) diethylammonium diethyldithiocarbamate complexes, has been studied. A simple isocratic reversephase method for the determination of the metals is proposed, using a mobile phase of composition CTAB 0.03 M/n-propanol 45 %v/v. Detection limits at pg levels were obtained for all solutes. The method was applied to the determination of the complexes in tap water samples at three different concentrations, with recoveries close to 100%. In order to evaluate the interaction between the metal complexes and the aggregates formed, the values of solute binding constants are calculated.

Simultaneous determination of trace amounts of multielements in metallic materials

Separation and determination methods were studied for the simultaneous determination of trace amounts of multielements in metallic materials.In the first study, the separation and determination of trace Ti, Zr, Mo, Sn and Hf in Ni were studied.Ti, Zr, Mo, Sn and Hf were separated from Ni by extracting into benzene with N-benzoyl-N-phenylhydroxylamine(BPA)and subsequently back-extracted into nitric acid for the determination by ICP-AES or ICP-MS.In the second study, the separation and determination of Cu, As, Sb, Pb and Bi in Ni and that of Cu, Ag and Cd in Zn were studied.Trace amounts of these elements were separated from Ni or Zn by extraction into xylene as diethyldithiocarbamate complexes using diethylammonium diethyldithiocarbamate(DDDC), and then back-extracted into nitric acid for the determination by ICP-AES or ICP-MS.In the third study, the method of anion-exchange separation was studied.Trace amounts of Fe, Cu, Zn, Ga, Mo, Cd, In and Sn were separated from Ni by adsorption on an anion-exchange resin column as their chloro complexes in hydrochloric acid media, and then eluted with nitric acid, followed by determinations with ICP-AES or ICP-MS.As a result, sub μg g-1 levels of multielements in Ni or Zn could be successfully determined by the proposed methods.

RPECVD thin cadmium, copper and zinc sulphide films

The thin cadmium, copper and zinc sulphide films were first synthesized by remote plasma enhance chemical vapor deposition at low pressure (10 -3 -10 -1 Torr) and low temperatures (373-773 K). The volatile mixed ligand complex of cadmium diethyldithiocarbamate with 1,10-phenantroline Cd(S 2 CN(C 2 H 5 ) 2 ) 2 .C 12 H 8 N 2 - (I), copper diethyldithiocarbamate complex Cu(S 2 CN(C 2 H 5 ) 2 ) 2 - (II), mixture of cadmium diethyldithiocarbamate complex with 1,10-phenantroline Cd(S 2 CN(C 2 H 5 ) 2 ) 2 .C 12 H 8 N 2 and heterometallic Cd(S 2 CN(C 2 H 5 ) 2 ) 2 Cul complex (III)with ready-made Cd-S-Cu fragments and mixture of cadmium/zinc (30%) diethyldithiocarbamate complex with 2,2' bipyridyl Cd/Zn(S 2 CN(C 2 H 5 ) 2 ) 2 .C 10 H 8 N 2 (IV) were used as single-source precursors. Helium was used both for selective plasma excitation of dithiocarbamate molecules and as carrier gas. The growth rates, refractive index, optical transmittance, crystalline structure and phase composition of cadmium, copper and zinc sulphide layers were investigated.