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Biomedical subjects

Frank Vanhaecke

Publications and source records attributed to Frank Vanhaecke.

10 recordsLinked to original sources
PubMed2005

Combustive approach for measuring total volatile phosphorus content in landfill gas.

A technique was developed to measure the total gaseous phosphorus content in biogas. The amount of air needed for a neutral to oxidising flame was mixed with the biogas. The gas mixture was burnt in a closed quartz burner and the combustion gasses were bubbled through a nitric acid solution. The phosphate content in the bubbling liquid was determined with sector field ICP-MS. The technique was validated in the lab with phosphine. Afterwards the set-up was installed on a landfill. The total gaseous phosphorus content in the landfill gas, measured with the combustive technique, ranged from 1.65 to 4.44 microg P/m3. At the same time the phosphine concentration in the landfill gas was determined gas chromatographically (GC). The phosphine (PH3) content measured with GC ranged from 7.6 to 16.7 microg PH3-P/m3. Since the phosphine-P content (GC) was consistently higher than the total gaseous phosphorus content (burner/ICP-MS), the hypothesised presence of highly toxic gaseous phosphorus compounds other than phosphine could not be demonstrated.

Chromatography, Gas↗
PubMed2004

Hyphenated techniques for speciation of Se in in vitro gastrointestinal digests of Saccharomyces cerevisiae.

A method was developed allowing the separation, detection and identification of Se species extracted from yeast supplements during simulated digestion processes. The in vitro gastric and intestinal digests were studied for their Se compounds by successive high-performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICP-MS) and high-performance liquid chromatography-electrospray tandem mass spectrometry (HPLC-ES-MS-MS) analyses. The conditions for the separation were chosen as to be compatible with both ICP-MS and ES-MS-MS detection. HPLC-ICP-MS was used to screen the extracts for their Se content. By means of HPLC-ES-MS-MS, the compounds extracted were identified on-line according to their retention time, m/ z of the molecular ion and the presence of typical product ions. From these results, it was clear that the main compound extracted by both gastric and intestinal fluid was Se-methionine, which was also the main Se compound extracted by proteolytic digestion from the yeast supplements. Two other minor compounds could be identified as Se-cystine and Se(O)-methionine, a degradation product of Se-methionine.

Chromatography, High Pressure Liquid↗
PubMed2004

Validated measurements of the uranium isotopic signature in human urine samples using magnetic sector-field inductively coupled plasma mass spectrometry.

Increased interest in measuring uranium isotope ratios in environmental samples (biological materials, soils, dust particles, water) has come from the necessity to assess the health impact of the use of depleted uranium (DU) based ammunitions during recent military conflicts (e.g., Gulf war, Kosovo) and from the need to identify nondeclared nuclear activities (nuclear safeguards). In this context, very important decisions can arise which have to be based on measurement data of nondisputable uncertainty. The present study describes the certification to 2.5% (k = 2) relative combined uncertainty of n(235U)/n(238U) at ultralow uranium levels (approximately 5-20 pg g(-1)) in human urine samples. After sample decomposition and matrix separation, the isotope ratios were measured by means of a single-detector magnetic sector-field inductively coupled plasma mass spectrometry instrument fitted with an ultrasonic nebulizer. Correction for mass discrimination effects was obtained by means of the certified isotopic reference material IRMM-184. The analytical procedure developed was validated in three complementary ways. First, all major sources of uncertainty were identified and propagated together following the ISO/GUM guidelines. Second, this quality was controlled with a matrix matching NUSIMEP-3 sample (approximately 0.06-0.7% difference from certified). Third, the instrumental part of the procedure was proven to be reproducible from the confirmation of the results obtained for three samples remeasured 7 months later (approximately 1.5% difference). The results obtained for 33 individuals indicated that none seemed to have been exposed to contamination by DU.

Humans↗
PubMed2003

Determination of ultra-trace amounts of Fe in AgNO3 solutions by means of isotope dilution analysis applying an inductively coupled plasma mass spectrometer equipped with a dynamic reaction cell.

The development of an ICP-MS method for the determination of ultra-trace amounts of Fe in AgNO(3) solutions using isotope dilution for calibration is described. AgNO(3) solutions are used as raw materials in the production of traditional photographic materials, and it is known that contamination with metal traces can influence the quality of the films thus produced. After adding an appropriate amount of an (54)Fe-enriched spike and permitting isotopic equilibration to take place, Ag was selectively removed from the solutions by precipitation as AgBr. Although to some extent, co-precipitation of Fe is possible under the given circumstances, an incomplete recovery of the analyte element did not affect the accuracy of the results, owing to the use of isotope dilution for calibration. NH(3) was used as a reaction gas in a quadrupole-based ICP-MS instrument, equipped with a dynamic reaction cell (DRC), providing interference-free measurement of the (54)Fe/(56)Fe ratio. The limit of detection (LOD) obtained using this procedure was approximately 0.01 micro g g(-1). This is an excellent value in comparison with the detection limit obtained with the more traditional approach: sample dilution and external calibration with a Fe standard solution (LOD ~1 micro g g(-1)). To validate the method, recovery experiments were carried out. In all instances, a quantitative recovery was established. Finally, the method was applied to the analysis of AgNO(3) solutions. A large variation in Fe concentration was observed. Depending on the Fe content in the samples, relative standard deviations typically ranged between 1 and 14%.

Journal Article↗
PubMed2003

Overcoming spectral overlap in isotopic analysis via single- and multi-collector ICP-mass spectrometry.

For isotope ratio applications where an internal isotope ratio precision >0.05-0.1% relative standard deviation suffices, single-collector inductively coupled plasma mass spectrometry (ICPMS) is fit-for-purpose, but for detecting more subtle variations in the natural isotopic composition of a target element, only multi-collector ICPMS (MC-ICPMS) can compete with thermal ionization mass spectrometry (TIMS). While as a result of the extensive sample preparation (analyte isolation) preceding TIMS and the "softer" ionization in vacuum, spectral interferences only seldom occur with this technique, their occurrence is recognized to be the most important drawback of ICPMS. This paper discusses high mass resolution and chemical resolution in a collision or dynamic reaction cell as powerful and versatile means to overcome spectral overlap and illustrates how their introduction has led to a substantial extension of the application range of ICPMS for isotope ratio applications. High mass resolution is the most elegant and straightforward way to overcome the problem of spectral overlap. Offering the possibility to operate the mass analyzer at a higher mass resolution, while at the same time preserving the flat-topped or trapezoidal peak shape required for highly precise isotope ratio measurements, was a challenge for the manufacturers of MC-ICPMS instrumentation. It will be discussed how these apparently contradicting requirements could be fulfilled simultaneously and an overview of the current situation will be given. Chemical resolution in a collision or dynamic reaction cell is an alternative to high mass resolution for overcoming spectral overlap. Real-life examples will be given to illustrate how also this approach can be used to advantage in isotope ratio work. Despite the greater flexibility and straightforwardness of high mass resolution, some situations will be discussed where chemical resolution is to be preferred. Finally, some desires as to future instrumentation are formulated.

Journal Article↗
PubMed2003

Detection of metals in proteins by means of polyacrylamide gel electrophoresis and laser ablation-inductively coupled plasma-mass spectrometry: application to selenium.

The capabilities of laser ablation-inductively coupled plasma-mass spectrometry for the detection of trace elements in a gel after gel electrophoresis were systematically studied. Figures of merit, such as limit of detection, linearity, and repeatability, were evaluated for various elements (Li, V, Cr, Mn, Ni, Cu, Zn, As, Se, Mo, Pd, Ag, Cd, Pt, Tl, Pb). Two ablation strategies were followed: single hole drilling, relevant for ablation of spots after two-dimensional (2-D) separations, and ablation with translation, i.e., on a line, relevant for one-dimensional (1-D) separations. This technique was applied to the detection of selenoproteins in red blood cells extracts after a 1-D separation (sodium dodecyl sulfate-polyacrylamide gel electrophoresis) and the detection of selenium-containing proteins in yeast after 2-D electrophoresis (2-DE). The detection procedure was further improved by using the dynamic reaction cell technology, which allowed the removal of the Ar_2(+) interference and hence the use of the most abundant Se isotope, (80)Se. Reaction gases were compared (methane, carbon monoxide, ammonia, oxygen and the combination of argon (collision gas) and hydrogen (reaction gas)). In each instance, the reaction cell parameters were optimized in order to obtain the lowest detection limit for Se (as (80)Se(+), (82)Se(+) or (77)Se(+); and as (80)Se(16)O(+), (82)Se(16)O(+) or (77)Se(16)O(+) with O(2) as the reaction gas). Carbon monoxide was found to offer the best performance. The detection limit with the use of DRC and He as transport gas was 0.07 microg Se g(-1) gel with single hole drilling and 0.15 microg Se g(-1) gel for ablation with translation.

Animals↗
PubMed2002

Electrothermal vaporisation ICP-mass spectrometry (ETV-ICP-MS) for the determination and speciation of trace elements in solid samples - A review of real-life applications from the author's lab.

The use of electrothermal vaporisation (ETV) from a graphite furnace as a means of sample introduction in inductively coupled plasma mass spectrometry (ICP-MS) permits the direct analysis of solid samples. A multi-step furnace temperature programme is used to separate the vaporisation of the target element(s) and of the matrix components from one another. Sometimes, a chemical modifier is used to enable a higher thermal pre-treatment temperature, by avoiding premature analyte losses (stabilisation) or promoting the selective volatilisation of matrix components. In almost all instances, accurate results can be obtained via external calibration or single standard addition using an aqueous standard solution. Absolute limits of detection are typically ~1 pg, which corresponds to 1 ng/g for a typical sample mass of 1 mg. Real-life applications carried out in the author's lab are used to illustrate the utility of this approach. These applications aim at trace element determination in industrial and environmental materials. The industrial materials analysed include different types of plastics - Carilon, polyethylene, poly(ethyleneterephtalate) and polyamide - and photo- and thermographic materials. As samples from environmental origin, plant material, animal tissue and sediments were investigated. Some applications aimed at a multi-element determination, while in other, the content of a single, but often challenging, element (e.g., Si or S) had to be measured. ETV-ICP-MS was also used in elemental speciation studies. Separation of Se-containing proteins was accomplished using polyacrylamide gel electrophoresis (PAGE). Subsequent quantification of the Se content in the protein spots was carried out using ETV-ICP-MS. As the volatilisation of methylmercury and inorganic mercury could be separated from one another with respect to time, no chromatographic or electrophoretic separation procedure was required, but ETV-ICP-MS as such sufficed for Hg speciation in fish tissue.

Mass Spectrometry↗