Determination of halides by microwave induced plasma and stabilized capacitive plasma atomic emission spectrometry after on-line continuous halogen generation.

This paper describes a comparative study of the microwave induced plasma (MIP) and the stabilized capacitive plasma (SCP) for halide determinations. The MIP is generated in a Beenakker cavity TM(010) using a tangential flow torch and the SCP consists of a 27.12 MHz discharge sustained in a liquid-cooled, fused silica tube surrounded by two annular electrodes.

Serum and tissue selenium contents related to renal disease and colon cancer as determined by electrothermal atomic absorption spectrometry.

Microwave digestion with nitric acid and hydrogen peroxide was applied to the determination of selenium in biological tissues by Electrothermal Atomic Absorption Spectrometry (ETAAS). Validation of this method is presented in terms of adequate recovery of selenium from standard reference materials and the method is applied to carcinogen human colon tissue. Ultramicrofiltration was used to study selenium protein binding and its fractionation and speciation in blood serum.

Selenium speciation by coupling vesicle mediated HPLC with off-line ETAAS and on-line focused microwave digestion HG-AAS detection.

A novel High Performance Liquid Chromatography (HPLC) method for the separation of selenium species with specific detection by off-line Electrothermal Atomization Atomic Absorption Spectrometry (ETAAS) or on-line focused microwave digestion (MW) Hydride Generation Atomic Absorption Spectrometry (HG-AAS) is described. Vesicular mobile phases of the cationic surfactant didodecyldimethylammonium bromide (DDAB) have been evaluated for the liquid chromatographic separation of inorganic selenium (selenite and selenate) and different selenoaminoacids (selenocystine, selenomethionine and selenoethionine) on a C(18) reversed-phase column modified by DDAB molecules. The effects of different parameters (pH, buffer and vesicle concentrations) of the mobile phase on the retention times have been determined.

Sb(III) and Sb(V) separation and analytical speciation by a continuous tandem on-line separation device in connection with inductively coupled plasma atomic emission spectrometry.

A sensitive, precise and automated non-chromatographic method for Sb(III) and Sb(V) analytical speciation based on a continuous tandem on-line separation device in connection with inductively coupled plasma-atomic emission (ICP-AES) detection is proposed. Two on-line successive separation steps are included into this method: a continuous liquid-liquid extraction of Sb(III) with ammonium pyrrolidine dithiocarbamate (APDC) into methylisobuthylketone (MIBK), followed by direct stibine generation from the organic phase. Both separation steps are carried out in a continuous mode and on-line with the ICP-AES detector.

Aluminium and silicon speciation in human serum by lon-exchange high-performance liquid chromatography-electrothermal atomic absorption spectrometry and gel electrophoresis.

Speciation of aluminium and silicon in serum was studied by a reliable and sensitive high-performance liquid chromatographic-electrothermal atomic absorption spectrometric (HPLC-ETAAS) hybrid method, based on the use of a polymeric anion-exchange column (Protein-Pak DEAE-5PW). This polymer-based column minimizes the risk of aluminium losses and of silicon contamination from the column during separation. The results obtained were compared with the results of previous studies carried out using different, complementary techniques including ultramicrofiltration, gel filtration and silica-based column for HPLC.

Beyond total element analysis of biological systems with atomic spectrometric techniques.

One of the fundamental limitations of atomic methods in biological analysis is their inability to distinguish individual physico-chemical forms of the metal. After a brief overview of 'hot' trace elements and atomic techniques used for total element analysis in bioanalytical work, the importance and main challenges of speciation of toxic metals in biological systems is addressed. The main analytical problems of speciation and present techniques/analytical strategies to tackle this problem are highlighted.

On-line preconcentration of inorganic mercury and methylmercury in sea-water by sorbent-extraction and total mercury determination by cold vapour atomic absorption spectrometry.

A comparative study of three mercury chelate forming reagents [diethyldithiocarbamate, pyrrolidin-1-yldithioformate and diphenylthiocarbazone (dithizone)] has been carried out for the preconcentration of ultratrace amounts of inorganic mercury and methylmercury in silica C(18) minicolumns as the solid sorbent. Sample flow injection in-line sorbent extraction was coupled with continuous cold vapour atomic absorption spectrometry (CVAAS) for detection. Results showed the superiority of the carbamate type reagents over the dithizone for the on-line formation and preconcentration of the corresponding mercury chelates.

Surfactant-based ordered media in analytical atomic spectrometry.

During the last 10 years or so we have witnessed an enormous growth of interest and applications of surfactant-based ordered media in analytical chemistry. However, their use in analytical atomic spectroscopy (AAS) has been rather scarce and often controversial. The utilization of surfactants in this latter field is discussed here along two main lines: one refers to the favourable manipulation of physical properties of the sample solutions (Part A) while the other, demonstrated very recently, refers to the adequate manipulation of chemical reactions and/or interactions of analytes in solution by resorting to surfactants use (Part B).

Determination of arsenic by inductively-coupled plasma atomic emission spectrometry enhanced by hydride generation from organized media.

A method is described for the determination of arsenic, which combines a continuous flow hydride generation technique with an inductively coupled plasma atomic emission detection system. Some atomic absorption preliminary studies are described as well. Arsine is generated with NaBH(4) from a didodecyldimethylammonium bromide (DDBA) vesicular medium.

Serum analysis for potassium ions using a fibre optic sensor.

A fibre optic potassium ion sensor has been developed based on reflectance measurements of the pH-dependent chromogenic crown ether 'Takagi reagent' immobilized on the non-ionic polymeric resin Amberlite XAD2. The sensor response is in the 1.5-100 mM range with a detection limit of 0.

Determination of bromide by low power surfatron microwave induced plasma after bromine continuous generation.

A simple continuous flow generation of volatile bromine is described for the determination of low concentrations of the elements by atmospheric-pressure argon microwave induced plasma (MIP) surfatron. Bromine is continuously generated by mixing the bromide with sulphuric acid and hypochlorite solutions. The bromine vapor is separated from the aqueous phase by a gas-liquid separator and is desiccated by passing it through concentrated sulphuric acid.

High performance liquid chromatography methods for studying protein binding of aluminium in human serum in the absence and in the presence of desferrioxamine.

Ion-exchange high performance liquid chromatography of serum proteins was combined with aluminium determination by electrothermal-atomisation-atomic-absorption spectroscopy and fluorimetry for studying the distribution of aluminium in human serum in the absence and in the presence of desferrioxamine. Aluminium was eluted as a single peak in the same fraction as transferrin. However, following the addition of desferrioxamine most of the aluminium was liberated from transferrin and become attached to the chelator.

[Serum aluminum and normal kidney function: effect of age and environmental exposure to aluminum].

The first cases of aluminium (Al) toxicity were reported in metal workers with apparent normal renal function. Although safety in industry has had a great improvement over the last decades, it is reasonable to think that Al workers might have a higher daily Al exposure than normal population. Therefore the aim of this study was to investigate the serum Al levels in volunteers with normal renal function, having different jobs, including people working in the main Al factory in our area.

The complexation of Cr(III) and Cr(VI) with flavones in micellar media and its use for the spectrophotometric determination of chromium.

The complexation of chromium by different flavonoid dyes in micellar media has been studied, in particular the reaction between chromium and quercetin. Micellar effects, the reaction pathway proposed and the application of the method to the determination of Cr(VI) and Cr(VI) + Cr(III) mixtures are discussed.

[Influence of the degree of saturation of iron stores on the gastrointestinal absorption of aluminum].

The possible influence of iron metabolism in the regulation of aluminum gastrointestinal absorption in male Wistar rats has been studied. Three groups were considered: Fe overloaded Group 1; Fe normal Group 2; Fe depleted Group 3. All groups were exposed during 45 days to 40 mg of Al(OH)3 investigating the concentration of Al in serum and urine throughout the experiment and also the Al in brain at the end of that period.

Dye-surfactant interactions: a review.

The present state of knowledge of the mechanisms of dye-surfactant interactions for "normal" aqueous micelles is surveyed. The nature of the forces which lead to the binding of dye molecules in micelles, the influence of the cationic, anionic or non-ionic character of a surfactant on the absorption and/or fluorescence behaviour (below and above the critical micelle concentration), ion-association processes and the influence of additives on these processes are discussed. Some discussion along these lines on related systems (reverse micelles, vesicles, polyelectrolytes) is included.

Extractive fluorimetric determination of ultratraces of lead with cryptand 2.2.2 and eosin.

A new speetrofluorimetric method for determination of ultratraces of lead is based on solvent extraction into chloroform of the ion-pair formed between the positively-charged cryptate of lead with cryptand 2.2.2 and the eosinate anion.

Analytical application of the complexation of Nb(V) with bromopyrogallol red in micellar media.

A spectrophotometric method for the détermination of trace amounts of Nb(V) based on the formation of a ternary complex with Bromopyrogallol Red (L) and cetylpyridinium bromide (CPB) in 1M hydrochloric acid/15% dimethylformamide medium has been developed. The ternary 1:2:2 Nb-L-CPB complex is formed. The absorbance maximum is at 645 nm, the molar absorptivity being (4.

Assessing the benefit of changing aluminium hydroxide schedule on anaemia and serum phosphorus control.

Convincing evidence exists concerning aluminium hydroxide (A1 (OH)3) absorption and risk of toxicity. Over recent years our aim has been to reduce exposure to this risk. In this study we evaluated the effect of changing our A1 (OH)3 prescription policy, reducing its intake by stopping the breakfast dose, separating the iron intake from the binder's influence, and tailoring the A1 (OH)3 dose according to the protein intake patterns.

Extractive fluorimetric determination of ultratraces of lead with 18-crown-6 and eosin.

A highly sensitive and selective spectrofluorimetric procedure for the determination of lead in the range 0.003-0.5 ppm, based on solvent extraction of the ion-pair formed between the eosinate anion and the cationic complex of Pb(2+) with 18-crown-6, has been developed.

Extraction-spectrophotometric determination of niobium with dibenzo-18-crown-6 and thiocyanate.

A method is described for the direct spectrophotometric determination of micro-amounts of niobium by extraction into a benzene solution of dibenzo-18-crown-6 (L) from 3M hydrochloric acid containing potassium thiocyanate. The molar absorptivity of the extracted complex is 3.85 +/- 0.

Ion-pair extraction and fluorimetric determination of potassium with 18-crown-6 and eosin.

A highly sensitive and selective fluorimetric determination of potassium is proposed, based on solvent extraction of the ion-pair formed between a large anion and the cationic complex of K(+) with a crown ether. Sensitivity is achieved by selection of a highly fluorescent counter-ion of the fluorescein group (eosin). A linear working range from 0.