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A new method of efficient rotating gold-film glassy-carbon electrode preparation prior to the determination of As(III) and As(V) in seawater by anodic stripping voltammetry (ASV) is described. Factors affecting sensitivity and precision including pH, deposition time and potential, rotation and scan rate, and the nature of working electrode were investigated. Electroinactive As(V) was reduced to As(III)...
Mass spectrometry was used to detect transfer of deuterium from labeled reagents to arsines following hydride-generation reactions. The arsine gases liberated from the reactions of arsenite, arsenate, methylarsonic acid, and dimethylarsinic acid with HCl and NaBD 4 in H 2 O, or with DCl and NaBH 4 in D 2 O, were examined. Differences in the mode of deuterium incorporation...
An anion exchange HPLC-ICP-MS procedure allowing the simultaneous multielemental speciation analysis of arsenic, selenium, antimony and tellurium has been developed. Four arsenic species (As III , As V , monomethylarsonic acid and dimethylarsinic acid), two selenium species (Se IV and Se VI ) may be determined in a single run as well as one antimony (Sb V )...
A flow injection procedure for the separation and pre-concentration of inorganic arsenic based on the complexation with ammonium diethyl dithiophosphate (DDTP) and sorption on a C-18 bonded silica gel minicolumn is proposed. During the sample injection by a time-based fashion, the As 3+ -DDTP complex is stripped from the solution and retained in the column. Arsenic(V) and other ions that...
In this study a special sequential extraction method is proposed to discriminate between arsenic adsorbed and co-precipitated in precipitates arising mainly from iron hydroxides or bound in low solubility mineral phases. Synthetic iron hydroxide precipitates were prepared to investigate the influence of the amount of arsenate, of the manganese additionally added and of the valence state of arsenic...
A sample solution containing less than 0.5 μg of As was adjusted to pH 2. As in the solution was collected on activated carbon (AC) as molybdoarsenate. The AC was directly introduced as an AC suspension into a graphite furnace atomizer, and the concentration of As was determined by atomic absorption spectrometry (AAS). This method is relatively free from interference caused by coexisting ions. The...
Arsenic compounds were determined in six reference materials of biological origin. None of them has yet been certified for arsenic compounds but some are in the process of certification; for most of these reference materials indicative literature values are available. Eight commonly used arsenic standards were used for quantification using a recently developed hyphenated speciation system comprising...
A rapid and sensitive sorbent extraction hydride generation-flow injection analysis atomic absorption spectrometric (HG-FIAS-AAS) method is described for the determination of As(III) and As(V) based upon online preconcentration on a microcolumn packed with activated alumina. In the present procedure these arsenicals are complexed with quinolin-8-ol-5-sulphonic acid from neutral solutions in the flow...
This review deals with liquid phase separation of major arsenic and selenium species followed by element specific detection. It concerns papers published since 1980 and describing only currently used methods that were or could be applied to As and Se speciation in environmental matrices. Methods performances are compared on the basis of efficiency, rapidity, absolute and concentration detection limits...
An automated system with a C 18 bonded silica gel packed minicolumn is proposed for spectrophotometric detection of arsenic using flow-injection hydride generation following sorbent extraction preconcentration. Complexes formed between arsenic(III) and ammonium diethyl dithiophosphate (ADDP) are retained on a C 18 sorbent. The eluted As-DDP complexes are merged with a 1.5%...
The effects on the absorbance signals obtained using HG-AAS of variations in concentrations of the reaction medium (hydrochloric acid), the reducing agent [sodium tetrahydroborate(III); NaBH 4 ], the pre-reducing agent (l-cysteine), and the contact time (between l-cysteine and arsenic-containing solutions) for the arsines generated from solutions of arsenite, arsenate, monomethylarsonic acid...
The kinetic of the oxidation of trivalent arsenic was investigated in synthetic as well as in natural samples of a tin mill seepage water. The influence of ferric ions and solid MnO 2 on the process was studied. To determine the time dependence of the concentrations of the arsenic species, a series of samples were taken sequentially and analysed by coupling of ionchromatographic separation...
Mineralization procedures for arsenic and selenium analysis are usually limited to wet digestion methods owing to high volatility of these analytes. On the other hand, variable amounts of silicon in some types of samples imply elaborated mineralization procedures to liberate analytes which may be retained in an insoluble residue. Consequently, methods for such material generally include an hydrofluoric...
A precise, accurate automatic preconcentration method for the determination of total arsenic at the ng g -1 level in wheat flour is proposed. The sensitivity of the method can be increased by a factor of 20 by precipitating As(V) from 10 ml of digested sample using a weakly acid silver solution. The Ag 3 AsO 4 precipitate is dissolved with 0.5 ml of 6 M ammonia and the...
Determination of arsenate based on its conversion to molybdoarsenate heteropoly anions followed by potentiometric titration is described. The titration is realized on the ion-pairing principle using cetylpyridinium chloride (or an analogous titrant containing a lipophilic cation), and is monitored by a carbon paste electrode, although other liquid-polymeric membrane-based electrodes can also be used...
The presence of arsenic in groundwater above the maximum permissible limit of 50 μg l -1 has threatened the health of more than 50 million people in Bangladesh and neighboring India. We report here the development of an inexpensive anodic stripping voltammetric (ASV) technique for routine measurement and speciation of arsenic in groundwater. The measurements are validated by more expensive...
For countries such as Bangladesh with a significant groundwater arsenic problem, there is an urgent need for the arsenic-contaminated wells to be identified as soon as possible and for appropriate action to be taken. This will involve the testing of a large number of wells, potentially up to 11 million in Bangladesh alone. Field-test kits offer the only practical way forward in the timescale required...
This paper describes a robust and sensitive method for the determination of arsenic species in seawater by ion-exclusion liquid chromatography (LC) combined with inductively coupled plasma mass spectrometry (ICP-MS) using reaction cell and hydride generation (HG) techniques. A good separation of arsenite, arsenate, and monomethylarsonic acid was achieved using an ion-exclusion column packed with a...
This review deals with environmental origin, occurrence, episodes, and impact on human health of arsenic. Arsenic, a metalloid occurs naturally, being the 20th most abundant element in the earth's crust, and is a component of more than 245 minerals. These are mostly ores containing sulfide, along with copper, nickel, lead, cobalt, or other metals. Arsenic and its compounds are mobile in the environment...
There are several U.S. EPA approved methodologies for the determination of arsenic in ground water. Such technologies are lab-based, time intensive and can lead to a large capital cost for multi-sample analysis. In light of the number of sites found to contain arsenic at levels higher than the maximum contaminant level (MCL), on-site screening and monitoring systems are an attractive alternative....
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