Radioisotope-induced x-ray fluorescence termination of phenylmercury,methylmercury and inorganic mercury in water after preconcentration on diethylammonium diethyldithiocarbamate-loaded polyurethane foam discs

Polyurethane foam discs (7 mg cm^?2 thick) loaded with diethylammonium diethyldithiocarbamate sob traces of mercury, methylmercury and phenylmercury ions quantitatively from aqueous solution. Matrix effects of the loaded polyurethane sorbent on the final measurement are low. Impurities in the foam do not interfere. The procedure is suitable for 0.3–2 μg cm³ mercury with 25-cm³ samples.     

Preconcentration of phenlymercury,methylmercury and inorganic mercury from natural waters with diethylammonium diethyldithiocarbamate-loaded polyurethane foam

The percentage extraction of organomercurials and inorganic mercury on polyurethane foam loaded with diethylammonium diethyldithiocarbamate is high over a wide pH range, particularly when a plasticizer is added to the foam. Flow rates up to 120 ml min^-1 give quantitative extraction of inorganic mercury. Mercury(II), methylmercury and phenylmercury ions at 1 μg l^-1 levels can be almost quantitatively preconcentrated from tap and saline water, and eluted from the foam with acetone.     

Sequential Extraction-Spectrofluorimetric Determination of Mercury Using Cryptand Ethers

Abstract

A spectrofluorimetric study of the extraction of mercury with 1,2-dichloroethane as an ion-pair formed between the cryptand 2.2.1-mercury complex and the eosinate counter-ion is described.

The detection limit for mercury is 0.7 ng/ml, and the linear working range up to 125 ng/ml of mercury.

The relative standard deviation is found to be 2.0% at the 100 ng/ml level. The proposed method has been tested for the determination of mercury in coal.     

High-performance liquid chromatographic/ion-trap mass spectrometric speciation of aquatic mercury as its pyrrolidinedithiocarbamate complexes

Mercury-pyrrolidinedithiocarbamate complexes are first time used for speciation of aquatic mercury with high-performance liquid chromatographic/ion trap-mass spectrometric method utilizing atmospheric pressure chemical ionization (APCI). The separation of the four mercury species was achieved in less than 5 min with a linear gradient profile of aqueous methanol from 70 up to 100% (v/v) in 4th min, isocratic elution at 100% up to 5th min and followed by a negative gradient to 70% in 6th min. The best separation was achieved on a reverse phase Zorbax Eclipse XDB C18 column (50 mm × 2.1 mm i.d., 1.8 μm particle size). The on-column limits of detection (injection volume 1 μL) were 370 pg for methylmercury (MeHg⁺), 280 pg for ethylmercury (EtHg⁺), 250 pg for phenylmercury (PhHg⁺) and 90 pg for inorganic mercury (Hg²⁺) when the data were collected in selective ion monitoring (SIM) mode. A method of isolation and preconcentration of the mercury species using a “home-made” C18 solid phase extraction (SPE) microcolumns was developed to enhance sensitivity of the method. The preconcentration factor as much as 2500 was achieved with on-column complex formation of mercury-pyrrolidinedithiocarbamate. Methanol (100%) was chosen for elution of preconcentrated mercury species. The method was applied for the determination of mercury species in river water samples.     

Pretreatment of water samples using UV irradiation-peroxodisulfate for the determination of total mercury

Potassium peroxodisulfate (14 g l⁻¹, 25 ml) has been observed to readily oxidize water under UV irradiation (30 W mercury arc tube), even at room temperature. The reaction is complete in 20 min, producing oxygen in stoichiometric amounts. The reaction was applied to pretreatment for the determination of total mercury by cold vapor atomic absorption spectrometry (AAS).The response of mercury(II) chloride by the UV irradiation method was higher than that by the standard permanganate method (95 °C, 2 h). The conversion efficiency of mercury by the UV irradiation method, the standard method and by non-treatment was found to be 100, 93.6 and 85.0%, respectively. The study is also applied to methylmercury, ethylmercury and phenylmercury chlorides.     

Synthesis and Thermodynamic Investigation of 4-Amino-6-Hydroxy-2-Mercapto Pyrimidine (AHMP) Complexes with Some Selected Divalent Metal(II) Ions

The synthesis and characterization of zinc(II), cadmium(II), lead(II), mercury(II) and phenylmercury(II) complexes of 4-amino-6-hydroxy-2-mercapto pyrimidine (AHMP) are reported. The stoichiometry of the complexes was found to be 1:2 except for the phenylmercury(II) complex where the ratio is 1:1. Characterization of these complexes was carried out by means of elemental analyses, IR and ¹H NMR measurements. In these complexes the ligand is bonded to the metal through its sulfur atom. The potentiometric results showed the formation of 1:1 and 1:2 complexes and the corresponding stability constants were determined for both Zn(II) and Cd(II) ions. The high insolubility of mercury(II), phenylmercury(II) and lead(II) complexes prevented the determination of their stability constants. The concentration distribution of the complexes in solution was evaluated. The effect of temperature on the dissociation constant of AHMP and the formation constants of both the Zn-AHMP and Cd-AHMP complexes were studied and the thermodynamic parameters were calculated.     

Capillary electrophoretic determination of mercury compounds in different matrixes

Summary Capillary electrophoresis has been used to separate inorganic (Hg²⁺) and organic (methyl-, ethyl-, and phenylmercury) mercury compounds as their cysteine complexes. The optimized electrophoretic separation was performed in fused-silica capillary tubing at 25 kV with 25mm sodium borate buffer (pH 9.3). Identification and quantification of the mercury species at mg L⁻¹ levels was achieved by use of UV detection at 200 nm. The relative standard deviation (n=10) ranged from 0.38 to 0.51% for migration times and from 0.43 to 2.94% for corrected peak areas. Good recovery (>90%) was obtained for all four mercury species in surface waters, and for inorganic mercury and methylmercury in five- to tenfold diluted biofluids (urine, saliva, and cerebrospinal fluid). TheLOQ values obtained were too high to be useful for determination of mercury species in real samples. Presented at Balaton Symposium '01 on High-Performance Separation Methods, Siófok, Hungary, September 2–4, 2001     

Sequential Extraction-Spectrofluorimetric Determination of Lead and Mercury Using Cryptand Ethers

Abstract

A spectrofluorimetric method for the determination of ultratrace amounts of lead and mercury is described based on the sequential extraction of the ternary ion-association complexes formed between the cation, a cryptand as the ligand and eosin as counter ion. A linear working range from the detection limit (9 ng/ml) to 250 ng/ml of lead and 12 ng/ml of mercury was obtained.

The relative standarddeviation was 3.5 % – 2.1 %. We propose that this method could be used routinely to control lead and mercury simultaneous.     

Determination of mercury species in gas condensates by on-line coupled high-performance liquid chromatography and cold-vapor atomic absorption spectrometry

A method for the speciation of mercury in gas condensates is reported. Mercury(II) chloride (HgCl₂), methylmercury chloride (MeHgCl), phenylmercury acetate (PhHgAc) and diphenylmercury (Ph₂Hg) are separated by reversed-phase high-performance liquid chromatography (HPLC) using gradient elution. Prior to the determination, the organic ligands and the matrix were destroyed by oxidation with K₂Cr₂O₇. Mercury is detected with cold-vapor atomic absorption spectrometry (CVAA), where the mercury compounds are reduced to metallic mercury by a treatment with NaBH₄. In a continuous-flow system the concentrations of the reagents used are optimized using a modified simplex algorithm. Detection limits for mercury are at the 10 ng ml^?1 level. Analysis of multi-compound mixtures indicates that chemical reactions between HgCl₂ and Ph₂Hg and between MeHgCl and Ph₂Hg take place. The method developed was applied to the speciation of mercury in gas condensates and did not require use of any solvent extraction or chemical derivatization steps. In the gas condensates, mercury(II) compounds were found to be present at the 100 ng ml^?1 level.     

3-Mercaptopropyltrimethoxysilane coated capillary micro-extraction coupled to capillary electrophoresis for the determination of methylmercury, phenylmercury and mercury in biological sample

A simple method for the separation of methylmercury, phenylmercury and mercury(II) in biological sample was developed. The novel method was targeted on extraction of mercury species using a 3-mercaptopropyltrimethoxysilane coated capillary, and determined by capillary electrophoresis with ultraviolet absorption detection. The effects of pH, sample volume and flow rate, eluent volume and flow rate on the efficiency of micro-extraction were investigated. Under the optimized conditions, the detection limits (S/N?=?3) of MeHg, PhHg and Hg²⁺ were 0.012, 0.007 and 0.003 µg mL^?1, respectively. The precisions (RSDs) of the peak area and the migration time for five replicate injections of the three species after capillary micro-extraction were 6.4%, 8.3%, 5.3% and 1.2%, 1.3%, 1.8%, respectively. The method was successfully applied to the determination of mercury species in biological sample.     

Phase Systems and Post-Column Dithizone Reaction Detection for the Analysis of Organo-Mercurials by HPLC

Abstract

The suitability of HPLC (normal and reversed phase adsorption) with UV or post-column reaction detection for the analysis of organomercurials was investigated systematically. The separation of organomercurials is best carried out on a reversed phase system with a C-8 bonded phase material as the stationary phase and acetonitrile-aqueous sodium bromide mixtures as the mobile phase.

The precision and detection limit of the method and the efficiency of the extraction procedure were established. For the alkylmercury compounds the lowest limit of detection (80ppb) was obtained with the dithizone reaction detection and for the phenylmercury compounds with UV detection (60ppb). A chromatogram of a spiked fish (2ppmHg) and a river water sample (50ppbHg) is shown.     

Effect of HC1 Concentration on the Distribution Factors of Iron and Mercury in Foam Separation

Abstract

A recycling batch foam separation apparatus has been used for the measurement of the distribution factors, Γ/c, of the anionic metal chloro complexes of iron and mercury with the cationic surfactant, hexadecyltri-methylammonium bromide. As a function of HC1 concentration, optimum values in distribution factors occur at roughly 0.3N HC1 for Hg and roughly 8N HC1 for Fe. Separations are thus possible by control of HC1 concentration.     

Chemical speciation of mercury in natural waters

Improved sensitivity of the cold-vapour atomic absorption method for mercury can be obtained by equilibrating the reduced sample with a small volume of air at 90°C. An automated system has been developed that has a detection limit of 1 ng Hg l^-1. By changing the reducing conditions three species of mercury can be differentiated and determined, inorganic mercury, arylmercury compounds such as phenylmercury(II) chloride, and alkylmercury compounds such as methylmercury(II) chloride. Speciation of mercury in natural waters is possible.     

Determination of Organic and Inorganic Mercury Species as Emetine Dithiocarbamate Complexes by High-Performance Liquid Chromatography with Electrogenerated Tris(2,2′-bipyridine)ruthenium(III) Chemiluminescence Detection

A sensitive method for simultaneous determination of organic and inorganic mercury species has been developed and is presented in this study. The method is based on complex formation of mercury species with the emetine dithiocarbamate (emetine-CS₂) ligand, HPLC separation, and tris(2,2′-bipyridine)ruthenium(III) chemiluminescence detection. The complexation reactions of the mercury species and emetine-CS₂ ligand occurred instantaneously upon the addition of emetine-CS₂ solution to the solution containing the mercury species. The complete separation of these complexes was achieved using an ODS column with 20 mM NaH₂PO₄-acetonitrile (52:48, v/v) containing 30 mM NaClO₄ as an ion-pair reagent. The calibration graphs of these complexes were linear in the range from 1–100 µg/L. The detection limits were 0.27 µg/L, 0.33 µg/L, 0.39 µg/L, and 0.17 µg/L for methylmercury, ethylmercury, phenylmercury, and the mercury ion, respectively, at a signal-to-noise ratio of 3. The developed technique was validated by analyzing certified reference materials, CRM7402-a (cod fish, NMIJ) and CE464 (tuna fish, ERM), in combination with sonication-assisted acid leaching and liquid-liquid extraction. The emetine-CS₂ ligand has been used for extraction, separation, and detection of mercury species. The results determined using the proposed method were in good agreement with the values of the certified reference materials. The MeHg⁺ and EtHg⁺ recoveries for the spiked samples were found to be almost 100%.     

Gravimetric Determination of Mercury(II) and Vanadium(IV) with Benzoylacetanilide

Abstract

Gravimetric methods for the determinations of mercury(II) and vanadium(IV) with benzoylacetanilide have been described. These metals have been separated from commonly associated ions and a procedure for the determination of vanadium content of steel has been developed. By these methods, 14 to 50 mg. of mercury and 5 to 20 mg. of vanadium have been estimated with relative standard deviations of 0.18% and 0.10%, respectively.     

Semiquantitative and Quantitative Determination of Trace Amount of Phosphate Ion in Water Using Polyurethane Foam Thin -Layer Colorimetry

Abstract

A simple, sensitive and fast method for the colorimetric determination of phosphate ion in water is described.

The method is based on spectrophotometric measurement of the blue molybdoantimony phosphoric acid species sorbed in a polyurethane foam thin-layer for quantitative determination of phosphate ion, or the visual color comparison technique for rapid semiquantitative determination.

The detection limit for the quantitative procedure is 5 μg/1 and for semiquantitative procedure 20 μg/1 for sample volumes of 100 ml and 25 ml, respectively.     

An Electrochemical Flow Cell For The Detection Of Metal Complexes

Abstract

An electrochemical flow cell has been developed using reticulated vitreous carbon (RVC) coated with a thin film of mercury. The flow cell and electrode components are inexpensive and easily constructed. Reproducible results have been obtained for concentrations as low as 100 ppb. Peak currents were dependent on flow rate, electrode size, and mercury deposition time. Oxygen interference was reduced by nitrogen purging to enable analysis of sub-ppm metal concentrations. The cell was tested as a detector for metal complexes eluated from a modified gel permeation chromatographic column.     

Elucidation of Mercury Ion Binding Property of a New Aryl Amide Type Podand by Electrochemical and Fluorescence Measurements

Abstract

A new aryl amide type podand (AAP), 1,8-bis(o-amidophenoxy)-3,6-dioxaoctane, was synthesized and its mercury ion binding property was elucidated by electrochemical and fluorescence measurements. The effects of supporting electrolyte, pH and scan rate on the electroreduction of AAP and on cyclic voltommogram of mercury ion were investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). It was observed that the complex formation between AAP and mercury ion exhibited pH-dependent behavior in different electrolyte solutions. Elucidation of such properties makes the AAP intriguing candidates as a modifying agent in sensor application for determination of mercury ion in mixture of aqueous solution.     

GC-MS Analysis of Organic Vapours Emitted from Polyurethane Foam Insulation

Abstract

The vapours emitted by rigid polyurethane foam at 40° and 80° in dry and in humid (90% RH) air were trapped with a Tenax TA sampling tube and, after thermal desorption, analyzed by high resolution gas chromatography – mass spectrometry. The chromatograms obtained demonstrate a certain characteristic pattern. The qualitative composition of the effluent mixture is basically independent of both temperature and humidity of the foam. Over seventy compounds were identified as polyurethane foam off-gases. Among them the most numerous are hydrocarbons. The most abundant is the blowing agent, trichlorofluoromethane. The most interesting are cyclic acetals, aldehydes, cyclic ethers, alcohols, chloroform and chlorobenzene. The headspace concentration of the majority of them is below 10mg/m³, there are, however, several compounds with the concentration exceeding 100mg/m³.     

Crystal structures of organomercury(II) derivatives of cyclohexanone and benzaldehyde thiosemicarbazones

The crystal and molecular structures of the organomercury(II) complexes [Hg(C₆H₅)(chtsc)], 1, and [Hg(C₆H₅C₅H₄N)(btsc)], 2, obtained from the reaction of phenylmercury(II) acetate with cyclohexanone thiosemicarbazone (Hchtsc) and that of [2-(pyridin-2′-yl)]phenyl]mercury(II) acetate with benzaldehyde thiosemicarbazone (Hbtsc), respectively, are described. Both 1 and 2 are monoclinic, space group C2/c. Complex 1 has a distorted T-shaped geometry {C-Hg-S, 161.91(10)°} and 2 can be considered to have a distorted seesaw geometry {C-Hg-S, 171.2(10)°}. In both complexes the ligands act as bidentate chelating anions bonding through azomethine N¹ and thiolato S atoms.