Improvement of the detection limit for determination of 129I in sediments by quadrupole inductively coupled plasma mass spectrometer with collision cell

The previously developed sample introduction device for the hot extraction of iodine from environmental samples (soils or sediments) and on-line introduction of analyte via the gas phase in quadrupole inductively coupled plasma mass spectrometry with hexapole collision cell (ICP-CC-QMS) was equipped with a cooling finger, which allowed intermediate iodine enrichment and improved the detection limits for I-129 down to 0.4 pg g(-1) without any additional sample preparation. A mixture of oxygen and helium as reaction gases in the hexapole collision cell was used for reducing the disturbing background intensity of Xe-129(+). Oxygen was also used as the carrier gas for iodine thermal desorption and transport into the ICP-CC-MS. The developed analytical method was applied for I-129 determination at the ultra-trace level and for isotope ratio measurements of I-129/I-127 down to 10(-7) in contaminated sediments and in SRM 4357 (Ocean Sediment Environment Radioactivity Standard). The measured I-129/I-127 ratio of 5.3x10(-7) corresponded to the expected value of 4.45x10(-7) reported for this sediment in the certificate

Copper, zinc, phosphorus and sulfur distribution in thin section of rat brain tissues measured by laser ablation inductively coupled plasma mass spectrometry: possibility for small-size tumor analysis

A microanalytical method using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) was developed to measure element distribution in rat brain tissues for the detection of a small-size tumor. The stereotaxically guided tumor was implanted by injecting 5 mu l of 10(3) F98 cells into the right Caudatus putamen of a male F344 Fisher rat brain hemisphere. The second non-treated rat brain hemisphere is used as control tissue. Tumor investigation of adjacent slices is carried out by LA-ICP-MS and, in addition, autoradiographically with a tritiated ligand (H-3-PK11195) of the peripheral benzodiazepine-receptor, which is not expressed in the brain under normal, physiological conditions but during tumor development. Ion intensities of Cu-63(+), Zn-64(+), P-31(+) and S-32(+) in the rat brain section (thickness: 20 mm; analyzed area 12 mm by 6 mm) containing the local tumor and control area were measured by scanning with a focused laser beam at wavelength 213 nm, diameter of laser crater 50 mu m and laser power density 3.10(9) W cm(-2), in a cooled laser ablation chamber coupled to a double-focusing sector field ICP-MS. The quantitative determination of element distribution in a thin slice of the rat brain tissue was carried out using matrix-matched laboratory standards. The mass spectrometric analysis yielded an inhomogeneous distribution for Cu, Zn, S and P in the analyzed rat brain sections. For Cu and Zn a deficiency in and around the tumor region in comparison with the control brain tissue of the second hemisphere was found. The detection limits for distribution analysis of Zn and Cu measured by LA-ICP-MS are in the ng g(-1) range. The capability and the limits of LA-ICP-MS will be studied for the imaging of element distribution in thin cross sections of brain tissues in order to create a new diagnostic method for the borders of small-size tumors

Metal Imaging on Surface of Mirco- and Nanoelectronic Devices by Laser Ablation Inductively Coupled Plasma Mass Spectrometry and Possibility to Measure at Nanometer Range

An analytical mass spectrometric method for the elemental analysis of nano-bioelectronic devices involved in bioengineering research was developed and applied for measurements of selected metals (Au, Ti, Pt, Cr, etc.) on interdigitated electrode array chips (IDA-chip). An imaging laser ablation inductively coupled plasma mass spectrometric (LA-ICP-MS) procedure was used to map the elements of interest on the surface of the analyzed sample. The obtained images of metals were in a good agreement and corresponded to the micro- and nanofabricated metal electrode pattern. For the analysis at nanometer resolution scale a NF-LA-ICP-MS (NF-near-field) procedure was applied, which utilize thin Ag needle to enhance laser beam energy and improve spatial resolution of the method. The results show a approximately 100x enhancement of analyte signal, when the needle was positioned in the "near-field region" to the sample surface and the laser shot was performed. In addition, mass spectrometric studies of reproducibly for five separated NF-LA shots in different places of analyzed sample yielded an RSD of the measurement of 16%

LA-ICP-MS studies of cross section of NiCrAlY-based coatings on high-temperature alloys

A microlocal analytical technique using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) was developed to investigate elemental diffusion at the interface of NiCrAlY-based coatings on high-temperature alloys. The surface of the cross section of alloyed sample was scanned with a focused laser beam (diameter of laser crater, 25 mu m; wavelength, 213 nm; laser power density, 10(11) W cm(-2)), and the laser ablation system was coupled to a double-focusing sector field ICP-MS. The capabilities of LA-ICP-MS using "linescan'' and "single point'' mode at laser energies of 2 and 4 mJ were compared. Alloy certified reference material (CRM) BAM-328-1 (BAM-Bundesanstalt fur Materialprufung, Berlin, Germany) with a similar matrix composition to the samples investigated was employed to determine the relative sensitivity coefficients (RSCs) of chemical elements to quantify the analytical data. The RSCs of analytes measured by LA-ICP-MS in alloy CRM vary between 0.2 and 2. In addition, other calibration procedures involving calibration curves and solution-based calibration were considered. LA-ICP-MS was used to study the lateral element distribution on NiCrAlY-based alloy and coating after oxidation in air (300, 1000, 5000, 15 000 hours) at a temperature of 980 degrees C, whereby an increasing loss of aluminium due to diffusion from coating into the high-temperature base alloy was observed. Furthermore, the diffusion of several substrate alloying elements (e.g., Co, Ta, Mo, W) into the coating after annealing was found, which could be the reason for the alteration of mechanical properties (high-temperature stability) or oxidation performance or both

Imaging of Copper, Zinc and other Elements in Thin Section of Human Brain Samples (Hippocampus) by Laser Ablation Inductively Coupled Plasma Mass Spectrometry

Laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) was used to produce images of element distribution in 20-microm thin sections of human brain tissue. The sample surface was scanned (raster area approximately 80 mm(2)) with a focused laser beam (wavelength 213 nm, diameter of laser crater 50 microm, and laser power density 3 x 10(9) W cm(-2)) in a cooled laser ablation chamber developed for these measurements. The laser ablation system was coupled to a double-focusing sector field ICPMS. Ion intensities of 31P+, 32S+, 56Fe+, 63Cu+, 64Zn+, 232Th+, and 238U+ were measured within the area of interest of the human brain tissue (hippocampus) by LA-ICPMS. The quantitative determination of copper, zinc, uranium, and thorium distribution in thin slices of the human hippocampus was performed using matrix-matched laboratory standards. In addition, a new arrangement in solution-based calibration using a micronebulizer, which was inserted directly into the laser ablation chamber, was applied for validation of synthetic laboratory standard. The mass spectrometric analysis yielded an inhomogeneous distribution (layered structure) for P, S, Cu, and Zn in thin brain sections of the hippocampus. In contrast, Th and U are more homogeneously distributed at a low-concentration level with detection limits in the low-nanogram per gram range. The unique analytical capability and the limits of LA-ICPMS will be demonstrated for the imaging of element distribution in thin cross sections of brain tissue from the hippocampus. LA-ICPMS provides new information on the spatial element distribution of the layered structure in thin sections of brain tissues from the hippocampus

Imaging of elements in thin cross sections of human brain samples by LA-ICP-MS: A study on reproducibility

Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) developed for the imaging of elements in thin cross sections of biological tissues was investigated with respect to its reproducibility. A commercial laser ablation system was coupled to a double-focusing sector field ICP-SFMS. Five neighboring sections from the same human brain tissue were cut to a thickness of 20 mu m and scanned (raster area similar to 1 cm(2)) with a focused laser beam (wavelength 266 nm, diameter of laser crater 50 mu m, and laser power density 1 x 10(9) W cm(-2)). The obtained 2D images of adjacent sections were compared with each other. For all adjacent slices of human brain tissue, similar spatial distributions of the elements of interest (C, Cu and Zn) were found. The calibration of analytical data (e.g., Cu and Zn) was performed using a matrix-matched standard prepared synthetically. The reproducibility of the developed method was quantified as the relative standard deviation of the concentration of elements in the same regions in tissue analyzed for five adjacent sections. Using this approach, three different zones (A, B and C) were selected in the scanned sample. The following values were obtained for reproducibility in these zones: 5.4-6.5% for the C-13(+) measurements, 5.8-8.2% for Cu concentrations and 5.1-6.7% for Zn concentrations. (C) 2007 Elsevier BN. All rights reserved

Possibility of nano-local element analysis by near-field laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS): New experimental arrangement and first application

A near-field laser ablation inductively coupled plasma mass spectrometric (NF-LA-ICP-MS) procedure was created for element analysis in the nm resolution range. The method utilizes a well-known near-field effect in order to enhance the incident light energy on the thin tip of a Ag needle during the laser ablation process. A robust needle etching procedure was developed to produce the thin needles with a tip diameter in the range of hundreds of nm. An experimental arrangement was constructed to control the "sample-to-tip" distance via the measurements of tunnel current between the needle and sample surface. The NF-LA-ICP-MS technique thus developed was applied to analyze thin Au films deposited onto a Si substrate. The observed craters ranged from 500 nm to about 1 mu m in diameter and were dependent on the needle used as well as on the "sample-to-tip" distance. These results were also confirmed by mass spectrometric measurements of the Au sample. Theoretical calculations performed showed that using the developed NF-LA-ICP-MS arrangement a detection efficiency of 2.7 x 10(-5) cps per ablated Au atom can be achieved. (C) 2008 Elsevier B.V. All rights reserved

Reduction of UH+ formation for U-236/U-238 isotope ratio measurements at ultratrace level in double focusing sector field ICP-MS using D2O as solvent

The main factors affecting the accurate and precise determination of U-236 using ICP-MS are instrumental background, the isobaric interference of U-235 H+ molecular ion on U-236(+) analyte ions, and the presence of U-238(+) and U-235(+) peak tails. An optimized analytical method for attenuating the influence of these factors on uranium isotope ratio measurements at ultratrace level of environmental samples has been developed. In order to reduce (UH+)-U-235 formation, D2O (heavy water) is used as a solvent for the dissolution and dilution of uranium samples. Abundance sensitivity was improved by use of medium mass resolution (m/Deltam = 4450) in comparison with low mass resolution in double-focusing sector field ICP-MS (ICP-SFMS). For solution introduction the performances of several different sample introduction systems (Meinhard, Aridus and ultrasonic nebulizer) were studied. It has been shown, that for all nebulization systems, a diminution in UH+/U+ is observed in D2O as compared with H2O as solvent. Optimum results were obtained in ICP-SFMS for a desolvating microconcentric nebulizer system (Aridus) with a minimum hydride formation rate of 9 X 10(-7) and a limit for U-236/U-238 isotopic ratio measurements of 3 - 5 x 10(-7). A comparison was performed of three commercially available sector field ICP-MS devices, with good agreement found between single collector and multiple collector ICP-MS (MC-ICP-MS)