Determination Of Volatile Elements Research Articles

A review of reflux systems using cold finger for sample preparation in the determination of volatile elements

The present paper presents advantages, limitations and applications of a reflux system (cold finger) employed for sample preparation during determination of volatile elements. Also other techniques employed for sample preparation in the determination of volatile elements are discussed and compared. A list of ten papers published reporting use of cold finger as reflux system are being cited and discussed.

Transverse heated filter atomizer: optimization of design and heating mode

The use of a transverse heated filter atomizer (THFA) in the atomic absorption determination of volatile elements provides a substantial reduction of matrix interferences without application of chemical modifiers. The analytical effects are obtained because of a large surface, which is provided by the collector, and vapor filtration through the heated graphite. In the THFA, the heating of both the filter and collector occurs due to energy transfer from the external tube, which can be affected by characteristics of both the design and heating mode. The complicated design of the atomizer makes its analytical characteristics a priori vulnerable to random deviation of its physical characteristics or experimental conditions. Nevertheless, these negative effects can be reduced if the design and heating mode provide high and stable temperatures of the analytical zone during sample vaporization and vapor transport. The attempt to fulfill these requirements was undertaken, and the model of heat exchange between the THFA components was developed in order to improve the design and operation parameters. The final system of differential equations was solved using MATLAB software. According to theory, the reduction of filter length, increase of mass and heat capacity of the collector, provision of uniform distribution of the sample on the substrate, and low temperature of the atomizer before the vaporization step results in the required analytical properties. The theoretical recommendations were examined experimentally. The modification of the THFA according to the theoretical findings provided complete atomization for direct determination of Pb, as tetraethyl lead in organic medium, and Cd and Pb in a urine matrix. Analytical signals for Pb in both organic and inorganic matrices were found to be reproducible with RSD of 4–6% in 20 randomly selected THFA tubes. Application of the theory to the commercial transverse heated graphite atomizer with a platform (THGA) and comparison of both atomizers showed that the delayed vaporization in the THFA has a similar nature to that in the THGA in the presence of chemical modifiers.

Determination of volatile elements in biological materials by isotopic dilution ETV-ICP-MS after dissolution with tetramethylammonium hydroxide or acid digestion

Isotopic dilution for the determination of Ag, Cd, Hg, Pb and Tl in biological materials by ETV-ICP-MS is proposed. The sample was simply dissolved with tetramethylammonium hydroxide (TMAH) or acid digested in a microwave furnace, with an on line matrix separation. When the dissolution was employed, Ir was used as a chemical modifier for Hg and Pb and Pd was used for Cd and Tl. No modifier was used for Ag. The pyrolysis temperatures were taken from pyrolysis temperature curves. The on line preconcentration was performed in a flow injection system with solenoid valves and was based on the analyte complexation with ammonium diethyldithiophosphate and sorption of the complexes on C 18 bonded to silica gel in a minicolumn. For the digested sample submitted to the analyte preconcentration procedure, a modifier, Ir, was only used for Hg. For the other analytes, since a low pyrolysis temperature, 300°C, was employed, no modifier was added. The isotopic dilution calibration was applied to two certified materials, bovine liver and dog fish muscle, dissolved with TMAH or acid digested, and to another two certified materials, corn bran and rice flour, acid digested and submitted to analyte preconcentration. The obtained concentration values agree with the certified ones, showing that this calibration procedure leads to accurate results in the determination of low concentrations of volatile elements. Due to simplicity, the dissolution with TMAH is very attractive.

Iridium Modifier for Determination of Selenium by Graphite Furnace Atomic Absorption Spectrometry

ABSTRACT The behaviour of thermally reduced or electrodeposited iridium modifier in graphite furnace atomic absorption spectrometry (GFAAS) for the determination of selenium was investigated. The performance of modification for standard solution of selenium as well as in the presence of chloride containing matrix (e.g. sea water) was examined. It was found that the graphite material plays a significant role in the determination of volatile elements by the formation of graphite intercalation compounds. Those compounds are responsible for the long-term performance of stabilisation of selenium in chloride containing solutions.

Reductive coprecipitation as a separation method for the determination of gold, palladium, platinum, rhodium, silver, selenium and tellurium in geological samples by graphite furnace atomic absorption spectrometry

A method for the separation of Au, Pd, Pt, Rh, Ag, Te and Se from geological samples at trace levels is presented. The elements are separated from the matrix after dissolution by reductive coprecipitation using mercury as a collector and tin(II) chloride as a reductant. The efficiency of coprecipitation is studied by varying the acidity of the solutions and the amount of collector. The analyte elements are determined by graphite furnace atomic absorption spectrometry. In the determination of volatile elements (Te, Au and Ag), matrix modification with iridium is used. Selenium is determined with a mixed matrix modifier containing ascorbic acid and iridium. The method is tested by analysing geochemical reference samples.

Reducing the effects of the sample chemical composition on the results of the atomic absorption determination of volatile elements using a metallic atomizer in an oxidizing atmosphere

Reducing the effects of the sample chemical composition on the results of the atomic absorption determination of volatile elements using a metallic atomizer in an oxidizing atmosphere

Communication. Determination of volatile elements by carbon furnance atomic-emission spectrometry

Communication. Determination of volatile elements by carbon furnance atomic-emission spectrometry