Direct μ-flow injection isotope dilution ICP-MS for the determination of heavy metals in oil samples.

The determination of trace elements in oil samples and their products is of high interest as their presence significantly affects refinery processes and the environment by possible impact of their combustion products. In this context, inductively coupled plasma mass spectrometry (ICP-MS) plays an important role due to its outstanding analytical properties in the quantification of trace elements. In this work, we present the accurate and precise determination of selected heavy metals in oil samples by making use of the combination of μ-flow direct injection and isotope dilution ICP-MS (ICP-IDMS).

Sulfur trace determination in petroleum products by isotope dilution ICP-MS using direct injection by thermal vaporization (TV-ICP-IDMS).

An accurate, sensitive, and fast method for direct determination of total sulfur in petroleum products after thermal vaporization of an isotope-diluted sample was developed by using ICP-MS. (34)S-labelled dibenzothiophene spike was used for the isotope dilution step. The isotope-diluted sample was injected into a thermal vaporizer which was directly connected by a heated transfer line to the plasma torch.

Development of a species-unspecific isotope dilution GC-ICPMS method for possible routine quantification of sulfur species in petroleum products.

Inductively coupled plasma mass spectrometry (ICPMS) hyphenated with capillary gas chromatography was applied for sulfur multispecies determination in petroleum products by species-unspecific isotope dilution mass spectrometry (IDMS). To guarantee a stable and continuous addition of the spike into the GC-ICPMS system, a special dosing unit was designed and synthesis of a (34)S-labeled dimethyldisulfide spike from (34)S-enriched elemental sulfur in the milligram range was developed. The sample was mixed with an internal standard for spike mass flow calibration.

Development of a species-specific isotope dilution GC-ICP-MS method for the determination of thiophene derivates in petroleum products.

A species-specific isotope dilution technique for accurate determination of sulfur species in low- and high-boiling petroleum products was developed by coupling capillary gas chromatography with quadrupole ICP-MS (GC-ICP-IDMS). For the isotope dilution step 34S-labeled thiophene, dibenzothiophene, and mixed dibenzothiophene/4-methyldibenzothiophene spike compounds were synthesized on the milligram scale from elemental 34S-enriched sulfur. Thiophene was determined in gasoline, 'sulfur-free' gasoline, and naphtha.

Development of an accurate, sensitive, and robust isotope dilution laser ablation ICP-MS method for simultaneous multi-element analysis (chlorine, sulfur, and heavy metals) in coal samples.

A method for the direct multi-element determination of Cl, S, Hg, Pb, Cd, U, Br, Cr, Cu, Fe, and Zn in powdered coal samples has been developed by applying inductively coupled plasma isotope dilution mass spectrometry (ICP-IDMS) with laser-assisted introduction into the plasma. A sector-field ICP-MS with a mass resolution of 4,000 and a high-ablation rate laser ablation system provided significantly better sensitivity, detection limits, and accuracy compared to a conventional laser ablation system coupled with a quadrupole ICP-MS. The sensitivity ranges from about 590 cps for (35)Cl+ to more than 6 x 10(5) cps for (238)U+ for 1 microg of trace element per gram of coal sample.

Determination of extremely low (236)U/(238)U isotope ratios in environmental samples by sector-field inductively coupled plasma mass spectrometry using high-efficiency sample introduction.

A method by inductively coupled plasma mass spectrometry (ICP-MS) was developed which allows the measurement of (236)U at concentration ranges down to 3 x 10(-14)g g(-1) and extremely low (236)U/(238)U isotope ratios in soil samples of 10(-7). By using the high-efficiency solution introduction system APEX in connection with a sector-field ICP-MS a sensitivity of more than 5,000 counts fg(-1) uranium was achieved. The use of an aerosol desolvating unit reduced the formation rate of uranium hydride ions UH(+)/U(+) down to a level of 10(-6).

Simultaneous multi-species determination of trimethyllead, monomethylmercury and three butyltin compounds by species-specific isotope dilution GC-ICP-MS in biological samples.

An accurate and sensitive multi-species species-specific isotope dilution GC-ICP-MS method was developed for the simultaneous determination of trimethyllead (Me3Pb+), monomethylmercury (MeHg+) and the three butyltin species Bu3Sn+, Bu2Sn2+, and BuSn3+ in biological samples. The method was validated by three biological reference materials (CRM 477, mussel tissue certified for butyltins; CRM 463, tuna fish certified for MeHg+; DORM 2, dogfish muscle certified for MeHg+). Under certain conditions, and with minor modifications of the sample pretreatment procedure, this method could also be transferred to environmental samples such as sediments, as demonstrated by analyzing sediment reference material BCR 646 (freshwater sediment, certified for butyltins).

Direct determination of platinum group elements and their distributions in geological and environmental samples at the ng g(-1) level using LA-ICP-IDMS.

Laser ablation inductively coupled plasma isotope dilution mass spectrometry (LA-ICP-IDMS) was applied to the direct and simultaneous determination of the platinum group elements (PGEs) Pt, Pd, Ru, and Ir in geological and environmental samples. A special laser ablation system with high ablation rates was used, along with sector field ICP-MS. Special attention was paid to deriving the distributions of PGEs in the pulverized samples.

Isotope dilution ICP-MS with laser-assisted sample introduction for direct determination of sulfur in petroleum products.

Inductively coupled plasma isotope dilution mass spectrometry (ICP-IDMS) with direct laser-assisted introduction of isotope-diluted samples into the plasma, using a laser ablation system with high ablation rates, was developed for accurate sulfur determinations in different petroleum products such as 'sulfur-free' premium gasoline, diesel fuel, and heating oil. Two certified gas oil reference materials were analyzed for method validation. Two different 34S-enriched spike compounds, namely, elementary sulfur dissolved in xylene and dibenzothiophene in hexane, were synthesized and tested for their usefulness in this isotope dilution technique.

Species-specific GC/ICP-IDMS for trimethyllead determinations in biological and environmental samples.

An accurate and sensitive species-specific isotope dilution GC/ICPMS method was developed for the determination of trimethyllead (Me3Pb+) in biological and environmental samples. A trimethyllead spike was synthesized from 206Pb-enriched metallic lead by reaction of lead halide with methyllithium and subsequent formation of trimethyllead iodide. The isotopic composition of the spike solution was determined by GC/ICPMS after derivatization with tetraethylborate, and its concentration was determined by reverse isotope dilution analysis.

Application of SEC-ICP-MS for comparative analyses of metal-containing species in cancerous and healthy human thyroid samples.

Size exclusion chromatography (SEC) was coupled on-line to inductively coupled plasma mass spectrometry (ICP-MS) for speciation study of trace metals in cancerous thyroid tissues in comparison to healthy thyroids aimed to estimation of changes in metalloprotein speciation in pathological tissue. The study showed a presence of species binding Cu, Zn, Cd and Pb in healthy thyroid tissue with a good reproducibility of chromatographic results, whereas the same species could not be detected in cancerous tissues. Thus, remarkable differences with respect to metal-binding species were revealed between healthy and pathological thyroid samples, pointing out a completely different distribution of trace metals in cancerous tissues.

Accurate determination of sulfur in gasoline and related fuel samples using isotope dilution ICP-MS with direct sample injection and microwave-assisted digestion.

Inductively coupled plasma isotope-dilution mass spectrometry (ICP-IDMS) with direct injection of isotope-diluted samples into the plasma, using a direct injection high-efficiency nebulizer (DIHEN), was applied for accurate sulfur determinations in sulfur-free premium gasoline, gas oil, diesel fuel, and heating oil. For direct injection a micro-emulsion consisting of the corresponding organic sample and an aqueous 34S-enriched spike solution with additions of tetrahydronaphthalene and Triton X-100, was prepared. The ICP-MS parameters were optimized with respect to high sulfur ion intensities, low mass-bias values, and high precision of 32S/34S ratio measurements.

Isotope-dilution ICP-MS for trace element determination and speciation: from a reference method to a routine method?

This critical review discusses the conditions under which inductively coupled plasma-isotope dilution mass spectrometry (ICP-IDMS) is suitable as a routine method for trace element and element-speciation analysis. It can, in general, be concluded that ICP-IDMS has high potential for routine analysis of trace elements if the accuracy of results is of predominant analytical importance. Hyphenated techniques with ICP-IDMS suffer both from lack of commercially available isotope-labeled spike compounds for species-specific isotope dilution and from the more complicated system set-up required for species-unspecific ICP-IDMS analysis.

Application of isotope-dilution laser ablation ICP-MS for direct determination of Pu concentrations in soils at pg g(-1) levels.

The methods available for determination of environmental contamination by plutonium at ultra-trace levels require labor-consuming sample preparation including matrix removal and plutonium extraction in both nuclear spectroscopy and mass spectrometry. In this work, laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) was applied for direct analysis of Pu in soil and sediment samples. Application of a LINA-Spark-Atomizer system (a modified laser ablation system providing high ablation rates) coupled with a sector-field ICP-MS resulted in detection limits as low as 3x10(-13) g g(-1) for Pu isotopes in soil samples containing uranium at a concentration of a few microg g(-1).

Multi-element trace determinations in pure alkaline earth fluoride powders by high-resolution ICP-MS using wet-chemical sample preparation and laser ablation.

Four alternative analytical procedures for the determination of ten important trace impurities (Mg, Cr, Fe, Cu, Zn, Sr, Zr, Cd, Ba, and Pb) in pure alkaline earth fluoride powders were applied using high-resolution inductively coupled plasma mass spectrometry (ICP-MS). Two procedures are based on a wet-chemical microwave digestion with boric acid and quantification by the standard addition technique and isotope dilution mass spectrometry (IDMS), respectively. In addition, analyses are also performed by laser ablation as a direct solid sampling technique applying matrix-matched external calibration as well as isotope dilution of the powdered sample.

Determination of siloxanes, silicon, and platinum in tissues of women with silicone gel-filled implants.

Silicone [poly(dimethylsiloxane)] gel used in breast implants has been known to migrate through intact silicone elastomer shells, resulting in the clinically observable "gel bleed" on the implant surface. Although silicon concentrations in capsular tissues of women with silicone prostheses have been measured with element-specific silicon analyses, no silicone-specific investigation of these tissues has been performed as yet.A combination of element-specific inductively coupled plasma high-resolution isotope dilution mass spectrometry (ICP-HR-IDMS) and species-specific gas chromatography coupled mass spectrometry (GC-MS) was used to analyze silicon, platinum, and siloxanes in prosthesis capsule, muscle, and fat tissues of women (n=3) who had silicone gel-filled breast implants and in breast tissue of non-augmented women (n=3) as controls.

Characterization and quantification of metallothionein isoforms by capillary electrophoresis-inductively coupled plasma-isotope-dilution mass spectrometry.

In a new approach to the characterization and quantification of metallothionein isoforms an on-line isotope-dilution method in combination with the coupling of capillary electrophoresis (CE) to an inductively coupled plasma-sector field mass spectrometer (ICP-SFMS) is reported. Metallothionein (MT) isoforms are separated by CE and the elements Cu, Zn, Cd, and S are detected simultaneously by use of ICP-SFMS in the medium resolution mode. On-line isotope dilution is performed by continuous introduction of an isotopically enriched, species-unspecific spike solution after the separation step.