Source Mass Spectrometer Research Articles

On the measurement of the valve-mixing correction of the changeover valve of a dual-inlet gas source mass spectrometer

One of the most important instrumental correction factors in the measurement of stable isotope ratios from dynamic gas source mass spectrometers is the so-called mixing correction for the changeover valve of the inlet system. Methods for the determination of this parameter are discussed and it is demonstrated that with a particular valve a commonly used technique gives values of the correction factor which are not necessarily applicable to normal operation. A more rigorous procedure is suggested, and details are given of the mixing investigated with argon, carbon dioxide and nitrogen.

Characteristics of a volcano field ionization source mass spectrometer operating at 30 kV accelerating voltage

A volcano ionization source has been coupled to an E x B velocity filter type mass spectrometer. The principal advantages of this instrument are its high efficiency, measured at 10(-5) ions per molecule for toluene (m/z 92), and long source lifetimes of over 200 h. The mass spectrometer is designed primarily to obtain mass profiles from multicomponent samples. These profiles are obtained from untreated urine and blood serum (1 microliter and 0.25 microliter samples), then measured between m/z 50 and 400, and are finally analyzed by computer.

Correlation of excited electronic states of organic ions and mass-spectral fragmentation patterns

In a recent paper, the authors presented a new method of measuring parent-ion-fragmentation rate constants as a function of energy in a mass spectrometer source. Charge-exchange ionization was used to provide nearly monoenergetic excitation. The fragmentation rate constant curves obtained in this way were shown to have an experimental correlation with the photoelectron spectrum (PES) of the compound. A brief argument was presented to explain this observed correlation theoretically. However, the proposed explanation of the effect was incorrect. An alternative explanation of the observed correlation is now proposed. This does not invalidate use of the correlation in assigning the electronic states from which fragmentations occur.

Comment on “Ion Implantation Standards as a Spark Source Mass Spectrometric Surface Analysis Calibration Technique”

Abstract While it is pleasing to note that ion implantation standards are being applied to yet another instrumental method for elemental near-surface analysis, it is unfortunate that the concept of using ion implantation for the manufacture of calibration standards has had to be re-invented. More regrettable than the (surely unintentional) omission to acknowledge earlier work1–6 on the subject though, is the neglect of the authors to provide evidence for their assertion that “the implant dose was measured to an accuracy of better than 5%”. This would be unlikely with the ion current integration mode of dose measurement used by the authors, because significant backscattering of the very much lighter incident 11B+ ion from the Zircaloy target in predominantly neutral form should render the dose calculation more inaccurate than this. Evidence of substantial backscattering is provided by the authors themselves in the form of the measured depth profiles of implanted 11B shown in their Fig. 1, viz., extrapolation of these depth profiles into the vaccum side of the surface provides a means of estimating roughly the dose fractio lost by backscatteing. From the data the extrapolted loss fraction would appear to be not less than 5%. On the basis of other independent more direct experimental evidence7 it would appear that the backscattered fraction should be about 8% (taking the “equivalent” case - same reduced energy ∊ and mass ratio - of 500 keV 24Na+ bombardment of Au, and adjusting it by the proportionality factor A1 ½/Z1 ⅔ of Vukaní and Sigmund8). This same percentage value is also derived from both theoretical and experimental proton backscattering data provided in ref. 83. The fact that the backscattered fraction is virturally independent of dose for low concentrations of implanted 11B precludes detection of this effect by comparison of dose-equivalent ion microprobe signals of 11B used by the authors. Therefore, the statement by the authors that “the accuracy of the standards was verified using an ARL ion microprobe mass analyser (IMMA)” is unsubstantiate. At best, the IMMA measurements provide an indication that implantation-associated dose-dependent re-sputtering of implanted 11B is negligible for the doses used by the authors. But this fortunate state of affairs is attributable solely to the unusually low sputtering yield for the combination boron/Zircaloy. In this connection it is important to point out that for many other combinations the fractional loss by re-sputtering of the implanted ion in the energy region under discussion is in considerable excess of 5% for the doses used by the authors; and this not take into account any possible loss inrease that may be caused by bombardment-induced radiation-enhanced diffusion towards the surface. Calculation of the minimum re-sputtering loss is possible with an algorith developed by gries3,9.

Reply to W.H. Gries' comments on “Ion Implantation Standards as a Spark Source Mass Spectrometric Surface Analysis Calibration Technique.” Anal. Lett. 12(A10), 1123 (1979)

Reply to W.H. Gries' comments on “Ion Implantation Standards as a Spark Source Mass Spectrometric Surface Analysis Calibration Technique.” Anal. Lett. 12(A10), 1123 (1979)

The relationship between purity and mechanical (Knoop hardness) or electrical (room resistivity) properties of single crystals and polycrystals of β rhombehedral boron

During a wider study of the correlation between the purity and the physical properties of β rhombohedral boron, Knoop hardness and room resistivity measurements were performed on samples prepared by different methods (chemical vapour deposition (CVD) and fusion) and precisely analysed with a spark source mass spectrometer. We systematically measured the hardness (taking into account the surface state, the load, the anisotropy and the grain size) to determine small hardness variations within the range of 10%. Hardness HK 200 (kg mm −2) increases regularly with the impurity content C (ppm) according to the equation HK 200 = 0.015 λC + 2320 where λ = 1 for the molten samples and λ = 6.2 for the CVD samples; the different slopes are probably due to a different impurity distribution: the logarithm of the room resistivity ρ (MΩ cm) increases linearly with the purity according to the equation log 10 ρ = (0.6 −1.1) × 10 −4 C for samples of grain size 5–500μm; the Knoop hardness and resistivity are anisotropic in single crystals.

Incidence of Cocaine Metabolites in Urine Specimens from Medical Examiners' Cases

Isobutane CIMS is useful for determining the molecular weight of morphine and its derivatives, as well as for identifying labile acyl substituents on morphine's O-6 position. Furthermore, this technique will provide information relating to the presence or absence of pi-bonding on the C-7 carbon. The spectra of morphine derivatives can be further simplified by employing ethylenediamine as a reagent gas. This approach proves useful for eliciting or confirming molecular weight information from the CI spectrum. In our laboratory extended use of ethylenediamine has been accomplished without any deleterious effect on the mass spectrometer's source or its vacuum system. The utility of isobutane and ethylenediamine CI rests with its ability to supply the analyst with structure elucidation data that may be used to complement more detailed information extractable from either EI or CE spectra. This aspect of mass spectrometry is especially useful when one is dealing with an unknown member of a particular class of organic compounds.

Ion Implantation Standards as a Spark Source Mass Spectrometric Surface Analysis Calibration Technique: The Analysis of B in Irradiated Zircaloy-2

Abstract Ion implantation standards were used to calibrate a spark source mass spectrometer (SSMS) near surface region analytical method. Standards were prepared by ion implanting 11B+ at 100 keV into Zircaloy-2 at doses in the 3 × 1015 to 3 × 1016 11B atoms/cm2 range. The analytical method was predicated on the idea that both standards and samples could be sparked in a SSMS under essentially identical and reproducible conditions. Calibration plots gave linear log-log results for plots of 11B+/122Sn+ versus B concentration in the standards. Calibration plots were determined on the basis of 5 to 6 replicate determinations for 3 different implant standard concentration levels. A series of irradiated Zircaloy-2 cladding samples were analyzed and shown to contain not more than 0.06 μg/cm2 total B in the near surface region.

The Structures of the [2M–1]+ ions formed from benzene in a high pressure mass spectrometer source

AbstractThe ionic species [C12H11]+ has been formed by ion‐molecule reactions in benzene at high pressure (˜0.5 Torr). This ion has been shown to be stable for at least 10−5 s and its structure has been inferred by a study of its unimolecular and collision induced fragmentations in both the first and second field free regions of the ZAB‐2F mass spectrometer.

Cumulative yields of stable and long-lived isotopes of ruthenium and palladium in neutron-induced fission

The relative cumulative yields of nine stable and long-lived isotopes of ruthenium and palladium (masses 101 to 110) produced in the thermal neutron fission of 233U and in the thermal and epicadmium neutron fission of 235U and 239Pu have been measured using a solid source mass spectrometer and isotope dilution techniques. Absolute yields of these isotopes for the thermal neutron fission of 233U, 235U, and 239Pu are obtained using normalization procedures. These yields provide the first experimentally determined yields of the palladium masses 105, 106, 107, 108, and 110.In the thermal fission of 233U and 235U the ruthenium isotope yields obtained are in general agreement with previously determined values, although discrepancies exist of the order of 10% at masses 103, 104, and 106 for thermal fission of 235U.A plot of the ruthenium and palladium isotope mass yields together with the previously determined yields for the cadmium and tin isotopes indicate a significant depression in the mass yield curve at masses 111 and 114 for 233U and 235U thermal fission, respectively. In the 235U epicadmium fission, yields at even mass numbers are relatively higher than those at odd numbers, resulting in a zigzag yield curve in the 101 to 110 mass region.

A rotating-electrode system for improved reproducibility in spark source mass spectrometry

A modified electrode configuration in a spark source mass spectrometer improves the reproducibility of analytical results. The system consists of vertically mounted cylindrical electrodes facing each other, one of which is rotating. No rotary feedthrough is needed as coupling between a small magnet inside the source and one (driven by a motor) outside allows rotation. Hence the vacuum inside the source can be kept low (less than 10-6 Pa approximately=10-8 Torr). Relative standard deviations do not exceed 6% for highly inhomogeneous powder mixtures. Moreover, higher and more stable transmissions are obtained, while short-circuiting between low-melting point materials is greatly reduced.

The isotopic composition of tellurium

The isotopic composition of tellurium in meteoritic and terrestrial materials was measured using a solid source mass spectrometer. The relative isotope abundances for terrestrial tellurium are 0.00284, 0.07701, 0.02687, 0.14250, 0.21122, 0.56073 and 0.93753 for 120Te, 122Te, 123Te, 124Te, 125Te, 126Te, 128Te relative to 130Te, respectively. Apart from linear mass fractionation these data are in agreement with other published data. Tellurium is unique in that it is the only element which possesses three s-only process nuclides. A comparison of the isotopic composition of 8 meteorites with the terrestrial data did not reveal any evidence of rapid and slow neutron capture process anomalies.

Variations in mass spectral fragmentation produced by active sites in a mass spectrometer source

Variations in mass spectral fragmentation produced by active sites in a mass spectrometer source

The interpretation of the mass spectrum of an ornithine-containing lipid fromThiobacillus thiooxidans

The electron impact mass spectrum of a previously identified ornithine-containing lipid from Thiobacillus thiooxidans has been interpreted using exact mass measurements, low and high energy ionization, and defocused metastable studies. The spectrum, which did not contain a molecular ion for the intact lipid, was consistent with cyclization of the ornithine zwitterionic moiety with elimination of water to give 3[3'-(11,12-methylene-2-hydroxyoctadecanoxy)hexadecanylamine]-2-piperidone. Production of this sufficiently volatile species for mass spectral analysis was accomplished by gentle pyrolysis in the mass spectrometer source. The spectrum can be understood to arise by three primary decompositions which serve to separate the two fatty acid constituents. The remainder of the spectrum is consistent with the expected fragmentations of these constituents.

A Survey of British Container Glass Using Spark Source Mass Spectrometry with Electrical Detection

A procedure is described for the analysis of container glass using a spark source mass spectrometer fitted with electrical detection. The analyses show that small glass fragments can be classified as either window glass or container glass by an examination and comparison of the elemental composition. The most important elements for this purpose are iron, magnesium and arsenic with in addition, manganese, zirconium and rubidium. The elemental composition of container glass is shown to be reasonably constant over a period of several months. Also the elemental composition within a container is shown to be constant.

The isotopic and elemental abundance of ytterbium in meteorites and terrestrial samples

The isotopic composition of ytterbium in meteoritic and terrestrial materials was measured using a solid source mass spectrometer. Isotopic abundances of meteoritic and terrestrial Yb agree within experimental errors. The relative isotope abundances for reagent Yb are 0.00429, 0.0964, 0.4512, 0.6887, 0.5075 and 0.3997 for the 168Yb, 170Yb, 171Yb, 172Yb, 173Yb and 176Yb relative to 174Yb respectively. Apart from linear mass fractionation, these data are in agreement with other published data. The concentration of Yb in 21 stony meteorites was determined using the isotope dilution method. In general, the agreement between this work and other published data is excellent.

Mass spectrometry of graphite intercalation compounds of binary fluorides of xenon, xenon oxide tetrafluoride and arsenic pentafluoride

Thermal decomposition of the intercalates of XeF 6, XeF 4, XeOF 4 and AsF 5 in graphite has been studied using a molecular beam source mass spectrometer. The product of the hydrolysis of the intercalate of XeF 6 has also been examined. The species liberated at low temperatures (T < 150°C) may be either the ones originally intercalated (XeOF 4, AsF 5) or the next lower oxidation state (XeF 4 from XeF 6, and XeF 2 from XeF 4. At higher temperatures (200-400°C) the intercalated XeF 4, XeF 2 or XeF 4 attack the graphite lattice, and evolve large quantities of xenon, and subsequently fluorocarbons and/or carbonyl fluoride. In contrast, the intercalate of AsF 5 evolves AsF 5 as the dominant gas over most of the temperature range, with a much lower degree of fluorination of the graphite lattice. The hydrolysis product of the XeF 6 intercalate was similar to the intercalate of XeF 4, but the evidence indicates that the hydrolysis proceeded well beyond XeOF 4. The extent of attack upon the graphite lattice correlates well with the oxidizing or fluorinating ability of the intercalated compound.

The Field Within a Commercial EI/FI Source of a Mass Spectrometer

Abstract A novel method for the calculation of the potential distribution in a mass spectrometer source is presented. It consists in solving a Green integral equation and applies both to the FI and EI mode of a CEC 21-110 C mass spectrometer source.

A radioautographic study of the hepatic uptake of circulating carcinoembryonic antigen by the mouse.

Conference Article| February 01 1977 A Radioautographic Study of the Hepatic Uptake of Circulating Carcinoembryonic Antigen by the Mouse PETER THOMAS; PETER THOMAS 1Chester Beatty Research Institute, Institute of Cancer Research, Royal Cancer Hospital, Fulham Road, London SW3 6JB, U.K. Search for other works by this author on: This Site PubMed Google Scholar MICHAEL S. C. BIRBECK; MICHAEL S. C. BIRBECK 2Chester Beatty Research Institute, Institute of Cancer Research, Royal Cancer Hospital, Fulham Road, London SW3 6JB, U.K. Search for other works by this author on: This Site PubMed Google Scholar PATRICIA CARTWRIGHT PATRICIA CARTWRIGHT 3Chester Beatty Research Institute, Institute of Cancer Research, Royal Cancer Hospital, Fulham Road, London SW3 6JB, U.K. Search for other works by this author on: This Site PubMed Google Scholar Biochem Soc Trans (1977) 5 (1): 312–313. https://doi.org/10.1042/bst0050312 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Facebook Twitter LinkedIn MailTo Cite Icon Cite Get Permissions Citation PETER THOMAS, MICHAEL S. C. BIRBECK, PATRICIA CARTWRIGHT; A Radioautographic Study of the Hepatic Uptake of Circulating Carcinoembryonic Antigen by the Mouse. Biochem Soc Trans 1 February 1977; 5 (1): 312–313. doi: https://doi.org/10.1042/bst0050312 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll JournalsBiochemical Society Transactions Search Advanced Search This content is only available as a PDF. © 1977 Biochemical Society1977 Article PDF first page preview Close Modal You do not currently have access to this content.

Photoemission in the second positive system of molecular nitrogen in the Earth's dayglow

The results are presented of analyses of 3371-A profiles measured by the visible airglow experiment reported by Hayes et al. (1973). The measured emission rate profiles are presented as functions of the O and N2 densities determined simultaneously by means of an open source mass spectrometer. The experimental methods used are discussed along with the obtained results. The experimental data are compared with theoretical predictions. It is found that the 3371-A emission depends greatly on the O/N2 concentration ratio.