University of North Florida
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Stuart Chalk, Ph.D.
Department of Chemistry
University of North Florida
Phone: 1-904-620-1938
Fax: 1-904-620-3535
Email: schalk@unf.edu
Website: @unf

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J. Sabine Becker

Abbrev:
Becker, J.S.
Other Names:
Johanna Sabine Becker
Address:
Central Department of Analytical Chemistry, Research Centre Juelich, D-52425 Juelich, Germany
Phone:
+49-2461-612698
Fax:
+49-2461-612560

Citations 11

"Mass Spectrometry Of Long-lived Radionuclides"
Spectrochim. Acta B 2003 Volume 58, Issue 10 Pages 1757-1784
Johanna Sabine Becker

Abstract: The capability of determining element concentrations at the trace and ultratrace level and isotope ratios is a main feature of inorganic mass spectrometry. The precise and accurate determination of isotope ratios of long-lived natural and artificial radionuclides is required, e.g. for their environmental monitoring and health control, for studying radionuclide migration, for age dating, for determining isotope ratios of radiogenic elements in the nuclear industry, for quality assurance and determination of the burn-up of fuel material in a nuclear power plant, for reprocessing plants, nuclear material accounting and radioactive waste control. Inorganic mass spectrometry, especially inductively coupled plasma mass spectrometry (ICP-MS) as the most important inorganic mass spectrometric technique today, possesses excellent sensitivity, precision and good accuracy for isotope ratio measurements and practically no restriction with respect to the ionization potential of the element investigated--therefore, thermal ionization mass spectrometry (TIMS), which has been used as the dominant analytical technique for precise isotope ratio measurements of long-lived radionuclides for many decades, is being replaced increasingly by ICP-MS. In the last few years instrumental progress in improving figures of merit for the determination of isotope ratio measurements of long-lived radionuclides in ICP-MS has been achieved by the application of a multiple ion collector device (MC-ICP-MS) and the introduction of the collision cell interface in order to dissociate disturbing argon-based molecular ions, to reduce the kinetic energy of ions and neutralize the disturbing noble gas ions (e.g. of 129Xe+ for the determination of 129I). The review describes the state of the art and the progress of different inorganic mass spectrometric techniques such as ICP-MS, laser ablation ICP-MS vs. TIMS, glow discharge mass spectrometry, secondary ion mass spectrometry, resonance ionization mass spectrometry and accelerator mass spectrometry for the determination of long-lived radionuclides in quite different materials.

"Applications Of Inductively Coupled Plasma Mass Spectrometry And Laser Ablation Inductively Coupled Plasma Mass Spectrometry In Materials Science"
Spectrochim. Acta B 2002 Volume 57, Issue 12 Pages 1805-1820
Johanna Sabine Becker

Abstract: Inductively coupled plasma mass spectrometry (ICP-MS) and laser ablation ICP-MS (LA-ICP-MS) have been applied as the most important inorganic mass spectrometric techniques having multielemental capability for the characterization of solid samples in materials science. ICP-MS is used for the sensitive determination of trace and ultratrace elements in digested solutions of solid samples or of process chemicals (ultrapure water, acids and organic solutions) for the semiconductor industry with detection limits down to sub-picogram per liter levels. Whereas ICP-MS on solid samples (e.g. high-purity ceramics) sometimes requires time-consuming sample preparation for its application in materials science, and the risk of contamination is a serious drawback, a fast, direct determination of trace elements in solid materials without any sample preparation by LA-ICP-MS is possible. The detection limits for the direct analysis of solid samples by LA-ICP-MS have been determined for many elements down to the nanogram per gram range. A deterioration of detection limits was observed for elements where interferences with polyatomic ions occur. The inherent interference problem can often be solved by applying a double-focusing sector field mass spectrometer at higher mass resolution or by collision-induced reactions of polyatomic ions with a collision gas using an ICP-MS fitted with collision cell. The main problem of LA-ICP-MS is quantification if no suitable standard reference materials with a similar matrix composition are available. The calibration problem in LA-ICP-MS can be solved using on-line solution-based calibration, and different procedures, such as external calibration and standard addition, have been discussed with respect to their application in materials science. The application of isotope dilution in solution-based calibration for trace metal determination in small amounts of noble metals has been developed as a new calibration strategy. This review discusses new analytical developments and possible applications of ICP-MS and LA-ICP-MS for the quantitative determination of trace elements and in surface analysis for materials science.

"Inorganic Trace Analysis By Mass Spectrometry"
Spectrochim. Acta B 1998 Volume 53, Issue 11 Pages 1475-1506
Johanna Sabine Becker* and Hans-Joachim Dietze

Abstract: Mass spectrometric methods for the trace analysis of inorganic materials with their ability to provide a very sensitive multielemental analysis have been established for the determination of trace and ultratrace elements in high-purity materials (metals, semiconductors and insulators), in different technical samples (e.g. alloys, pure chemicals, ceramics, thin films, ion-implanted semiconductors), in environmental samples (waters, soils, biological and medical materials) and geological samples. Whereas such techniques as spark source mass spectrometry (SSMS), laser ionization mass spectrometry (LIMS), laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), glow discharge mass spectrometry (GDMS), secondary ion mass spectrometry (SIMS) and inductively coupled plasma mass spectrometry (ICP-MS) have multielemental capability, other methods such as thermal ionization mass spectrometry (TIMS), accelerator mass spectrometry (AMS) and resonance ionization mass spectrometry (RIMS) have been used for sensitive mono- or oligoelemental ultratrace analysis (and precise determination of isotopic ratios) in solid samples. The limits of detection for chemical elements using these mass spectrometric techniques are in the low ng g-1 concentration range. The quantification of the analytical results of mass spectrometric methods is sometimes difficult due to a lack of matrix-fitted multielement standard reference materials (SRMs) for many solid samples. Therefore, owing to the simple quantification procedure of the aqueous solution, inductively coupled plasma mass spectrometry (ICP-MS) is being increasingly used for the characterization of solid samples after sample dissolution. ICP-MS is often combined with special sample introduction equipment (e.g. flow injection, hydride generation, high performance liquid chromatography (HPLC) or electrothermal vaporization) or an off-line matrix separation and enrichment of trace impurities (especially for characterization of high-purity materials and environmental samples) is used in order to improve the detection limits of trace elements. Furthermore, the determination of chemical elements in the trace and ultratrace concentration range is often difficult and can be disturbed through mass interferences of analyte ions by molecular ions at the same nominal mass. By applying double-focusing sector field mass spectrometry at the required mass resolution-by the mass spectrometric separation of molecular ions from the analyte ions-it is often possible to overcome these interference problems. Commercial instrumental equipment, the capability (detection limits, accuracy, precision) and the analytical application fields of mass spectrometric methods for the determination of trace and ultratrace elements and for surface analysis are discussed.
Inorganic compounds Mass spectrometry Review

"Ultratrace Determination Of Uranium And Plutonium By Nano-volume Flow Injection Double-focusing Sector Field Inductively Coupled Plasma Mass Spectrometry (nFI-ICP-SFMS)"
J. Anal. At. Spectrom. 2005 Volume 20, Issue 1 Pages 17-21
Dirk Schaumlöffel, Pierre Giusti, Myroslav V. Zoriy, Carola Pickhardt, Joanna Szpunar, Ryszard obiski and J. Sabine Becker

Abstract: A sensitive analytical procedure based on nano-volume flow injection (FI) and inductively coupled plasma double-focusing sector field mass spectrometry (ICP-SFMS) was developed for the ultratrace determination of uranium and plutonium. A 54 nL sample was injected by means of a nanovolume injector into a continuous flow of carrier liquid at 7 µL min-1 prior to ICP-SFMS. The absolute detection limits were 9.1 x 10^-17 g (3.8 x 10^-19 mol, ? 230000 238U atoms) and 1.5 x 10^-17 g (6 x 10^-200 mol, ?38000 242Pu atoms) for uranium and plutonium, respectively. The method was validated for the determination of the uranium isotope ratios by the analysis of a certified isotope reference material (NIST U350). The analysis of a contaminated urine sample showed the enriched uranium to be the origin of contamination. Another application concerned the determination of plutonium at the subfemtomolar level in water with a detection limit down to the ag mL -1 range (6 x 1018 g mL-1).

"Application Of Double-focusing Sector Field ICP Mass Spectrometry With Shielded Torch Using Different Nebulizers For Ultratrace And Precise Isotope Analysis Of Long-lived Radionuclides -Invited Lecture"
J. Anal. At. Spectrom. 1999 Volume 14, Issue 9 Pages 1493-1500
J. Sabine Becker and Hans-Joachim Dietze

Abstract: The capability of double-focusing sector field ICP-MS with a plasma-shielded torch using different nebulizers (a Meinhard nebulizer with a Scott-type spray chamber with a solution uptake rate of 1 mL min-1; a MicroMist microconcentric nebulizer used with a minicyclonic spray chamber with a solution uptake rate of 0.085 mL min-1; an ultrasonic nebulizer with a solution uptake rate of 2 mL min-1; and a direct injection high-efficiency nebulizer with a solution uptake rate of 0.085 mL min-1) for the introduction of radioactive sample solutions into the ICP was investigated. The total amount of analyte for each long-lived radionuclide (Ra-226, Th-230, Np-237, U-238, Pu-239 and Am-241; concentration of each was 1 ng L-1 in the aqueous solution) using different nebulizers was 5 pg for the Meinhard nebulizer, 0.4 pg for the MicroMist microconcentric nebulizer and 10 pg for the ultrasonic nebulizer. The application of the shielded torch yielded an increase in sensitivity for all these nebulizers of up to a factor of 5 compared with the original configuration without a shielded torch. Sensitivities of about 2000 MHz ppm-1 were measured for the radionuclides investigated (except for Ra-226) using the MicroMist microconcentric nebulizer with a shielded torch. The detection limits were in the sub-pg L-1 range and the precision ranged from 1 to 2% RSD (n=5) for the 1 ng L-1 concentration level (0.4 pg sample size). A further increase in sensitivity for long-lived radionuclides of nearly one order of magnitude in comparison with the MicroMist microconcentric nebulizer was observed using ultrasonic nebulization, but the amount of analyte required was significantly higher (by a factor of 25). In contrast, the direct injection high-efficiency nebulizer (DIHEN) in double-focusing sector field ICP-MS (DF-ICP-MS) with a shielded torch resulted in a decrease in sensitivity in comparison with the unshielded torch because of a higher water load due to the direct injection of aqueous solution into the plasma. At low solution uptake rates (down to several µl min-1), the uranium solutions were analyzed by DIHEN-ICP-MS using a double-focusing sector field instrument with higher sensitivity than quadrupole-based ICP-MS. Flow injection was used for sample introduction to measure small sample volumes of radioactive waste solutions (20 µl). The determination of Np-237 at a concentration of 10 ng L-1 by flow injection DF-ICP-MS was possible with a precision of 2.0% (RSD, n=5). In order to avoid mass spectral interferences and matrix effects long-lived radionuclides (e.g., of U, Th and Tc-99) were separated from the radioactive waste matrix by liquid-liquid extraction or ion exchange. The methods developed for the precise determination of the concentration and isotopic ratios of long-lived radionuclides were applied to aqueous standard solutions and radioactive wastes by double-focusing sector field ICP-MS. The precision of Pu isotopic analysis by double-focusing ICP-MS with a shielded torch was 0.2, 2 and 14% for 1000, 100 and 10 pg L-1 (amount of analyte: 500, 50 and 5 fg), respectively.

"Determination Of Long-lived Radionuclides By Inductively Coupled Plasma Quadrupole Mass Spectrometry Using Different Nebulizers"
J. Anal. At. Spectrom. 1999 Volume 14, Issue 6 Pages 933-937
J. Sabine Becker, Rajiv S. Soman, Karen L. Sutton, Joseph A. Caruso and Hans-Joachim Dietze

Abstract: Different nebulizers (cross-flow, ultrasonic and two microconcentric nebulizers) were used for sample introduction of radioactive solutions into a quadrupole-based inductively coupled plasma mass spectrometer (ICP-QMS). The best sensitivity (from 420 to 850 MHz, which is about one order of magnitude higher in comparison with the crossflow nebulizer) for long-lived radionuclides (Ra-226, Th-230, Np-237, U-238 and Am-241) was observed using the ultrasonic nebulizer. However, using the ultrasonic nebulizer, a significantly higher sample size (26-fold) in comparison with the micronebulizers is required. Sample introduction by micronebulization with a small sample size in the low picogram range is the method of choice for the determination of long-lived radionuclides. The precision of determination of a 10 ng L-1 concentration was in the low-% range (and sub-% range) for all measurements using different nebulizer types. The detection limits for the determination of long-lived radionuclides in aqueous solutions applying the different nebulizers were 0.01-0.6 ng L-1. The flow injection analysis approach was optimized for isotope dilution analysis of Th-232 (using 20 µl of 5 µg L-1 Th-230) by ICP-QMS. The isotopic abundance ratios of Th-230-Th-232 isotope mixtures (Th-230/Th-232 = 0.01, 0.001 and 0.0001) were determined using a microconcentric nebulizer and 1 µg L-1 Th solutions with a relative external standard deviation of long-term stability measurements (over 20 h) of 0.17, 0.62 and 2.66%, respectively.

"Inorganic Mass Spectrometric Methods For Trace, Ultratrace, Isotope, And Surface Analysis"
Int. J. Mass Spectrom. 2000 Volume 197, Issue 1-3 Pages 1-35
J. Sabine Becker and Hans-Joachim Dietze

Abstract: Inorganic mass spectrometric methods are widely used for multielemental determination at the trace and ultratrace level for isotope ratio measurements and surface analysis (depth profiling, imaging) in quite different materials (e.g. conducting, semiconducting, and nonconducting solid samples; technical, environmental, biological, geological, and water samples). The capability of spark source mass spectrometry (SSMS), laser ionization mass spectrometry (LIMS), glow discharge mass spectrometry (GDMS), laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), secondary ion mass spectrometry (SIMS), sputtered neutral mass spectrometry (SNMS), and inductively coupled plasma mass spectrometry (ICP-MS) have been applied as the most important mass spectrometric techniques with their multielemental capability for the characterization of solid and aqueous samples. The detection limits for the direct analysis of solid samples by inorganic solid mass spectrometry were determined up to sub ng g-1 and for aqueous solutions by ICP-MS up to sub-pg L-l. This article discusses the most important inorganic mass spectrometric techniques and their application for quantitative determination of trace element, isotope ratio measurements, and in-surface analysis.

"Precise Isotope Ratio Measurements For Uranium, Thorium And Plutonium By Quadrupole-based Inductively Coupled Plasma Mass Spectrometry"
Fresenius J. Anal. Chem. 1999 Volume 364, Issue 5 Pages 482-488
J. S. Becker and Hans-Joachim Dietze

Abstract: Precise long-term measurements of uranium and thorium isotope ratios was carried out in 1 wg/L solutions using a quadrupole inductively coupled plasma mass spectrometer (ICP-QMS). The isotopic ratios of uranium (235U/ 238U = 1, 0.02 and 0.00725) were determined using a cross-flow nebulizer (CFN, at solution uptake rate of 1 mL/min) and a low-flow microconcentric nebulizer (MCN, at solution uptake rate of 0.2 mL/min) over 20 h. For 1 wg/L uranium solution (235U/238U = 1) relative external standard deviations (RESDs) of 0.05% and 0.044% using CFN and MCN, respectively, can be achieved. Additional short term isotope ratio measurements using a direct injection high-efficiency nebulizer (DIHEN) of 1 wg/L uranium solution (235U/238U = 1) at a solution uptake rate of 0.1 mL/min yielded an RSD of 0.06-0.08%. The sensitivity of solution introduction by DIHEN for uranium, thorium and plutonium (145 MHz/ppm, 150 MHz/ppm and 177 MHz/ppm, respectively) increased significantly compared to CFN and MCN and the solution uptake rate can be reduced to 1 wL/ min in DIHEN-ICP-MS. Isotope ratio measurements at an ultralow concentration level (e.g. determination of 240Pu/ 239Pu isotope ratio in a 10 ng/L Pu waste solution) were carried out for the characterization of radioactive waste and environmental samples.
Thorium-232 Uranium Waste Mass spectrometry Mass spectrometry Isotope ratio

"Determination Of Selenium In Biological Samples Using ICP-QMS"
Atom. Spectrosc. 2000 Volume 21, Issue 5 Pages 149-155
Boulyga, S.;Dombovari, J.;Becker, J.S.;Dietze, H.J.

Abstract: A method for the determination of selenium traces in plant tissue samples is described. Freeze-dried and homogenized biological samples mere decomposed with HNO3, HF and H2O2 by using closed-vessel microwave digestion under temperature and pressure control. NIST SRM 1577b Bovine Liver and NIST SRM 1547 Peach Leaves reference materials were investigated to optimize the analytical procedure. Selenium concentrations were measured with quadrupole-based inductively coupled plasma mass spectrometry (ICP-QMS) using external calibration and the isotope dilution method. A special solution introduction device combining pneumatic nebulization with hydride generation in the thin liquid film on the walls of the minicyclonic spray chamber was employed for sample introduction into the ICP-MS, which allowed the sensitivity for Se to be increased by up to one order of magnitude without increasing the memory effects. SRMs were doped with different amounts (0, 0.1, 0.2, 0.5 and 1.0 µg/g) of enriched Se-78 spike (98.58% of Se-78) before digestion to study the method performance and selenium losses during sample preparation. For a given matrix selenium losses were reproducible as follows: 9.9±1.6% for Bovine Liver SRM, 15.8±3.6% for Peach Leaves SRM and 20.0±4.5% for the real plant tissue samples. The detection limit for selenium calculated for solid plant tissue was 0.2 µg/g (3s -criteria, m/z=82, digestion 1:1000) using conventional pneumatic nebulization for solution introduction and 0.03 µg/g for a combination of pneumatic nebulization with hydride generation. Applying the method developed, a large number of plant tissue samples were analyzed to study selenium behavior and accumulation in the environment.
Selenium NIST 1577 NIST 1547 Mass spectrometry Reference material Volatile generation

"Ultratrace And Isotope Analysis Of Long-lived Radionuclides By Inductively Coupled Plasma Quadrupole Mass Spectrometry Using A Direct Injection High Efficiency Nebulizer"
Anal. Chem. 1999 Volume 71, Issue 15 Pages 3077-3084
Johanna Sabine Becker, Hans-Joachim Dietze, John A. McLean, and Akbar Montaser

Abstract: The direct injection high efficiency nebulizer (DIHEN) was explored for the ultrasensitive determination of long-lived radionuclides (226Ra, 230Th, 237Np, 238U, 239Pu, and 241Am) and for precise isotope analysis by inductively coupled plasma mass spectrometry (ICPMS). The DIHEN was used at low solution uptake rates (1-100 µL/min) without a spray chamber. Optimal sensitivity (e.g., 238U, 230 MHz/ppm; 230Th, 190 MHz/ppm; and 239Pu, 184 MHz/ppm) was achieved at low nebulizer gas flow rates (0.16 L/min), high radiofrequency power (1450 W), and low solution uptake rates (100 µL/min). The optimum parameters varied slightly for the two DIHENs tested. The detection limits of long-lived radionuclides in aqueous solutions varied from 0.012 to 0.11 ng/L. The sensitivity of the DIHEN was improved by a factor of 3 to 5 compared with that of a microconcentric nebulizer (MicroMist used with a minicyclonic spray chamber at a solution uptake rate of 85 µL/min) and a factor of 1.5 to 4 compared with that of a conventional nebulizer (cross-flow used with a Scott type spray chamber at a solution uptake rate of 1 mL/min). The precision of the DIHEN ranged from 0.5 to 1.7% relative standard deviation (N = 3) for all measurements at the 10 ng/L concentration. level (~3 pg sample size). The sensitivity decreased to 10 MHz/ppm at a solution uptake rate of 1 µL/min. The precision was ~5% relative standard deviation at a sample size of 30 fg for each long-lived radionuclide by the DIHEN-ICPMS method. The oxide to atom ratios were <0.05 (except ThO+/Th+ ) and decreased under the optimum conditions in the following sequence: ThO+/Th+ > UO+/U+ > NpO+/Np+ > PuO+/Pu+ > AmO+/Am+ > RaO+/Ra+. Atomic and oxide ions were used as analyte ions for ultratrace and isotope analyzes of long-lived radionuclides in environmental and radioactive waste samples. The anal. methods developed were applied to the determination of long-lived radionuclides and isotope ratio measurements in different radioactive waste and environmental samples using the DIHEN in combination with quadrupole ICPMS. For instance, the 240Pu/239Pu isotope ratio was measured in a radioactive waste sample at a plutonium concentration. of 12 ng/L. This demonstrates a main advantage of DIHEN-ICPMS compared with α-spectrometry, which cannot be used to selectively determine 239Pu and 240Pu because of similar α energies (5.244 and 5.255 MeV, respectively).
Precision

"Determination Of Phosphorus In Small Amounts Of Protein Samples By ICP-MS"
Anal. Bioanal. Chem. 2003 Volume 375, Issue 4 Pages 561-566
J. Sabine Becker, Sergei F. Boulyga, Carola Pickhardt, J. Becker, Stefan Buddrus, Michael Przybylski

Abstract: Inductively coupled plasma mass spectrometry (ICP-MS) is used for phosphorus determination in protein samples. A small amount of solid protein sample (down to 1 µg) or digest (1-10 µL) protein solution was denatured in nitric acid and hydrogen peroxide by closed-microvessel microwave digestion. Phosphorus determination was performed with an optimized analytical method using a double-focusing sector field inductively coupled plasma mass spectrometer (ICP-SFMS) and quadrupole-based ICP-MS (ICP-QMS). For quality control of phosphorus determination a certified reference material (CRM), single cell proteins (BCR 273) with a high phosphorus content of 26.8±0.4 mg g-1, was analyzed. For studies on phosphorus determination in proteins while reducing the sample amount as low as possible the homogeneity of CRM BCR 273 was investigated. Relative standard deviation and measurement accuracy in ICP-QMS was within 2%, 3.5%, 11% and 12% when using CRM BCR 273 sample weights of 40 mg, 5 mg, 1 mg and 0.3 mg, respectively. The lowest possible sample weight for an accurate phosphorus analysis in protein samples by ICP-MS is discussed. The analytical method developed was applied for the analysis of homogeneous protein samples in very low amounts [1-100 µg of solid protein sample, e.g. β-casein or down to 1 µL of protein or digest in solution (e.g., tau protein)]. A further reduction of the diluted protein solution volume was achieved by the application of flow injection in ICP-SFMS, which is discussed with reference to real protein digests after protein separation using 2D gel electrophoresis. The detection limits for phosphorus in biological samples were determined by ICP-SFMS down to the ng g-1 level. The present work discusses the figure of merit for the determination of phosphorus in a small amount of protein sample with ICP-SFMS in comparison to ICP-QMS.
Phosphorus