Elektrothermische atomisierung von quecksilber bei anwesenheit von thiolhaltigen verbindungen

Electrothermal atomisation of mercury in the presence of thiols. Sample stabilisation during the drying step is important for the determination of mercury by electrothermal a.a.s. Addition of complexing agents with thiol groups makes possible the analysis of pure aqueous solutions. Mercury can be determined at concentrations down to 5 × 10^-6% with a reproducibility of 2–10%. Small amounts of acids and salts depress the efficiency of stabilisation, so that separation becomes necessary. The use of a selective ion-exchanger with thiol groups solves the problems of sample storage, separation and stabilisation. The enrichment enhances the sensitivity by two orders of magnitude. Determinations of 2–20 ppb Hg in water, 0.2–2 M HC1 and 0.2–1 M NaCl are reported.     

Determination of Cadmium in Plant Tissues by Electrothermal Atomisation Atomic Absorption Spectrometry with Matrix/Analyte Modification and Smith-Hieftje Background Correction

Abstract

Pressure decomposition in a microwave oven provides a rapid means of sample preparation for plant tissue analyses. The use of delayed atomisation cuvettes, Smith-Hieftje background correction and matrix/analyte modification enables accurate determinations of cadmium concentrations in plant materials to be made. However, care should be taken to restrict the concentrations of modifier used, as too high a concentration may lead to problems with both tube life and over-correction by the Smith-Hieftje background correction system.     

Determination of Low Level Mercury in Organic Samples

Abstract

This report describes work done to develop a method for the determination of low-level mercury in organics from a chemical plant. The method developed is based on heating the sample with phosphoric acid, collecting the atomic mercury produced on a gold-plated Nichrome wire, followed by thermally releasing the mercury through a UV spectrophotometer. The method is useful down to a few ppb mercury.     

Determination of Hg in water and wastewater samples by CV-AAS following on-line preconcentration with silver trap

An online mercury preconcentration and determination system consisting of cold vapor atomic absorption spectrometry (CV-AAS) coupled to a flow injection (FI) method was studied. The method was developed involving the determination of ng/L levels of mercury retained on the silver wool solid sorbent. Experimental conditions such as sample volume, flow rate, stability of the column and effect of foreign ions on the determination of trace amounts of mercury were optimized. The detection limit is 3 ng/L and dynamic range 10–250 ng/L require only 50 mL of sample. The relative standard deviations (RSD) of the determinations are below 4%. The presence of common metal ions, such as K+, Na⁺, Cu²⁺, Pb²⁺, Fe³⁺, Ni²⁺, and Mn²⁺, does not interfere with the measurement of mercury by this method. The method was successfully applied to the determination of mercury in water and wastewater samples.     

Determination of Traces of Mercury (II) and Phenylmercury by Direct Polyurethane foam Thin-Layer Spectrophotometry

Abstract

The determination of mercury and phenylmercury in the ppb concentration range using polyurethane foam (PUF) thin-layer spectrophotometry has been described. Sorption of mercury and phenylmercury into foam parallepiped loaded with diphenylthiocarbazone (dithizone) contributed to considerable improvement in the absorbance value of the colored species, being concentrated about 140 times.

The method allowed the achievement of satisfactory results, the detection limits are 5 and 10 μg per litre for mercury and phenylmercury, respectively, for 100ml sample volume. The average recovery from tap water amounts to 100% for mercury and 96.6% for phenylmercury.     

Detection of silver nanoparticles in parsley by solid sampling high-resolution–continuum source atomic absorption spectrometry

In this work, we present a fast and simple approach for detection of silver nanoparticles (AgNPs) in biological material (parsley) by solid sampling high-resolution–continuum source atomic absorption spectrometry (HR-CS AAS). A novel evaluation strategy was developed in order to distinguish AgNPs from ionic silver and for sizing of AgNPs. For this purpose, atomisation delay was introduced as significant indication of AgNPs, whereas atomisation rates allow distinction of 20-, 60-, and 80-nm AgNPs. Atomisation delays were found to be higher for samples containing silver ions than for samples containing silver nanoparticles. A maximum difference in atomisation delay normalised by the sample weight of 6.27?±?0.96 s mg^?1 was obtained after optimisation of the furnace program of the AAS. For this purpose, a multivariate experimental design was used varying atomisation temperature, atomisation heating rate and pyrolysis temperature. Atomisation rates were calculated as the slope of the first inflection point of the absorbance signals and correlated with the size of the AgNPs in the biological sample. Hence, solid sampling HR-CS AAS was proved to be a promising tool for identifying and distinguishing silver nanoparticles from ionic silver directly in solid biological samples.

Optimisation of a Flow Injection System with a Piezoelectric Quartz Crystal Detector for the Determination of Inorganic Mercury

ABSTRACT

A new method combining flow injection methodology with quartz crystal microbalance (QCM) detection is proposed for inorganic mercury analysis. A modified simplex method is used in order to maximise the observed analytical signals (crystal frequency decrease). Six parameters were optimised: the concentration of the acidic carrier solution, the lengths of the sample loop and mixing coil, and the flow rates of the sample carrier, the reductant stream (SnCl₂), and the carrier of the mercury vapour (N₂). An increase of 18% in the signal of the centroid of the calibration line was achieved, as well as an increase in the sensitivity from 290 Hz μg^? to 313 Hz μg^?. Following the proposed procedure, detection limits of 47 μg L^? of inorganic mercury were found for sample volumes of 0.5 mL.     

Dosage DU Mercure Par Spectroscopy D' Absorption Atomique Sans Flamme

Abstract

A method has been developed whereby low levels of mercury can be determined in biological samples. The sample is burned in an air stream and the mercury vapors are collected in a cold trap and determined by flameless atomic absorption spectroscopy.     

Determinated of Trace Amounts of Mercury by Non-Disperse Atomic Fluorescence Method

Abstract

A rapid and sensitive cold vapor method for the determination of trace mercury by non-disperse atomic fluorescence measurement is proposed. Mercury vapor generated from solution was swept into the nozzle (the funnel type of glass tube) by nitrogen, and the atomic fluorescence (AF) of mercury in the gas mixture was detected by a non-dispersive AF method using a solar-blind photomultiplier. The detection limit obtained was 0.5 ng per 5 ml sample solution.     

Determination of Trace Levels of Mercury in Effluents and Wastewaters

Abstract

Concern about mercury pollution of the environment and the inapplicability of natural water methods necessitated development of a procedure for determining parts per billion mercury in effluents and wastewaters containing large amounts of organic matter. The sample is digested with sulfuric and nitric acids to destroy the organic matter, and the ionic mercury is reduced to the elemental state by stannous ion. Then the digestate is aerated with a stream of air to carry the mercury vapor through a heated line into a quartz cell positioned in an atomic absorption spectrophotometer for measurement. Analyses of effluents and aqueous samples gave good recoveries of added mercury. Effluents, wastewaters, water supplies and aqueous samples secured within manufacturing plants have been analyzed. With minor modification, the procedure has been applied to manufacturing materials such as vinylpyri-dine, latex, sizing, dyes, caustic, and hydro.     

Indirect Mercury Speciation in Biological Tissues by Closed‐Vessel Microwave‐Assisted Digestion and Flow‐Injection Cold‐Vapor Atomic Fluorescence Detection

Abstract

A simple and rapid method based on closed vessel microwave‐assisted extraction was developed to determine total, inorganic mercury and organomercury in biological tissues. Total mercury was extracted using HNO₃:H₂O₂ (4:1) mixture. In a separate subsample, extraction of mercury species was carried out with tetramethylammonium hydroxide (TMAH). The total and inorganic mercury analyses were carried out by flow‐injection cold‐vapor atomic fluorescence spectrometry (FI‐CV‐AFS). The organomercury concentration was calculated by difference. Considering a sample amount of 0.2 g, the detection limits were 4 and 26 ng/g for total and inorganic mercury, respectively. The accuracy of the procedures was checked by analyzing certified reference materials and recovery studies of spiked fish tissues.     

Comparison of the Adsorbed Mercury Screening Method with Cold-Vapor Atomic Absorption Spectrophotometry for Determination of Mercury in Soil

ABSTRACT

A field screening method for the determination of elemental mercury in environmental soil samples involves the thermal desorption of the mercury from the sample onto gold and then the thermal desorption from the gold to a gold-film mercury vapor analyzer. This field screening method contains a large number of conditions that could be optimized for the various types of soils encountered. In this study, the conditions were optimized for the determination of mercury in silty clay materials, and the results were comparable to the cold-vapor atomic absorption spectrophotometric method of determination. This paper discusses the benefits and disadvantages of employing the field screening method and provides the sequence of conditions that must be optimized to employ this method of determination on other soil types.     

Determining Ppb Mercury Concentrations Using a Spark-Source Mass Spectrometer Sample Changer

Abstract

A probe-type sample changer has been added to a spark-source mass spectrometer enabling the rapid determination of ppb levels of mercury by isotope dilution. The technique has also been used for determining Cd, Hg, and Zr in samples of air, water, and urine.     

Effets du Platine Sur Les Conditions D'Atomisation de Differents Elements Metalliques en Spectrophotometrie D'Absorption Atomique Sans Flamme

Abstract

L'addition de très faibles concentrations de platine(IV) à des solutions de différents éléments métalliques (Na, Mn, Fe, Co, Ni, Cu, Zn, Ag, Cd, Pb) modifie l'atomisation de ces éléments en spectrophotométrie d'absorption atomique sans flamme. Deux effets sont observés : une évolution de la forme des massifs d'absorption associée à des variations de sensibilité et un accroissement des températures d'atomisation des métaux.     

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.     

Electrospray ionization mass spectrometric study of mercury complexes of N-heterocyclic carbenes derived from 1,2,4-triazolium salt precursors

By mixing 1,2,4-triazolium salts (precursors of N-heterocyclic carbenes 1–6) with mercury acetate, a number of complexes have been obtained under electrospray ionization condition. Carbenes 1 and 2 contain one carbene center; therefore, they are able to bond only one mercury cation. Carbenes 3–5 contain two carbene centers; therefore, they can bond two mercury cations. Mercury complexes of 1–5 always contain an acetate anion attached to a mercury cation. Carbene 6 also contains two carbene centers; however, its structure allows formation of a complex containing mercury bonded simultaneously to both centers, therefore, the complex that does not contain an acetate anion. The MS/MS spectra taken for complexes of carbenes 1–5 have shown formation of a cation corresponding to N1 substituent (adamantyl or benzyl), and those of complexes of carbenes 3–5 (doubly charged ions) have also shown the respective complementary partner ions. Mercury complex of 2 has yielded some other interesting fragmentation pathways, e.g. a loss of the HHgOOCCH₃ molecule. The fragmentation pathway of the mercury complexes of 6 was found to be complicated.     

Determination of Vanadium in Tissues By Atomic Absorption Spectrophotometry

Abstract

A simple and sensitive method for the determination of vanadium in tissues was established by using atomic absorption spectrophotometry with graphite furnace atomisation. The proposed method includes formation of a chelate-complex by reacting vanadium with pyrrolidine dithiocarbamate (PDCA), extracting the chelate with xylene and measurement of the extract using atomic absorption spectrometry. The recoveries of added vanadium in various rat tissues were 96.7 and 109.3%, within 8.6% of the coefficient variation. The sensitivity of this method is 10 – 50 times higher than previous methods, the detection limit is 0.01 μg/g.     

Trace Level Analysis of Mercury Using Urease in Combination with an Ammonia Gas Sensitive Semiconductor Structure

Abstract

A method for the determination of mercury(II) ions at trace levels is described. The method is based on the profound inhibitory effect of mercury on the enzyme urease. The activity of the enzyme was determined by the rate of ammonia produced from urea as followed by an ammonia gas sensitive iridium thin metalfilm-oxide-semiconductor (IrTMOS) structure. Two systems were investigated. For the initial urease activity studies, a simple microcell was used. Also, a test plate, containing dry reagent strips with all necessary chemicals was developed, making the analytical procedure very simple to perform. The test volume applied was 2 μl and the sensitivity to standards of mercury(II) ions is at least 0.005 μM (1.0 ng/ml). One sample could be analyzed in less than 8 minutes. Furthermore, the kinetics of sensor response versus enzyme activity is discussed.     

Determination of Alkylmercury Compounds in Lake Sediments by Steam Distillation-Flameless Atomic Absorption

Abstract

Organic mercury compounds in lake sediments were separated into dialkyl- and monoalkylmercury fractions by steam distillation and subsequently quantified by flameless atomic absorption. The method recovered nearly all CH₃HgCH₃ and CH₃HgCl added to diverse sediments. Parameters influencing the efficacy of the procedure, i.e., Hg concentration, sample size and distillation time, were evaluated.     

Behavior of Mercury Vapor Upon Irradiation by a Mercury Lamp in an Inert Gas

Abstract

The behavior of mercury vapor during irradiation by a mercury lamp is investigated. Using the flameless atomic absorption technique for mercury determination, it was found that when mercury vapor in an inert gas is irradiated by a mercury lamp, the atomic absorption signal of mercury is decreased rapidly and the signal may be restored by heating to 70°C. These phenomena indicate that the irradiation products of mercury vapor in the quartz tube are deposited on the tube, and are dissociated into the mono-atomic state of mercury upon heating.