Coupling of a High-Resolution Ambient Pressure Drift Tube Ion Mobility Spectrometer to a Commercial Time-of-flight Mass Spectrometer

Ion mobility spectrometry provides information about molecular structures of ions. Hence, high resolving power allows separation of isomers which is of major interest in several applications. In this work, we couple our high-resolution ion mobility spectrometer (IMS) with a resolving power of R_p?=?100 to a time-of-flight mass spectrometer (TOF-MS). Besides, the benefit of an increased resolving power such an IMS-MS also helps analyzing and understanding the ionization processes in IMS. Usually, the coupling between IMS and TOF-MS is realized by synchronizing data acquisition of the IMS and MS resulting in two-dimensional data containing ion mobility and mass spectra. However, due to peak widths of less than 100 μs in our high-resolution IMS, this technique is not practicable due to significant peak broadening during the ion transfer into the MS and an insufficient data acquisition rate of the MS. Thus, a novel but simple interface between the IMS and MS has been designed which minimizes ion losses, allows recording of ion mobility at full IMS resolving power, and enables a shuttered transmission of ions into the MS. The interface is realized by replacing the Faraday plate used in IMS by a Faraday grid that is shielded by two additional aperture grids. For demonstration, positive product ions of benzene, toluene, and m-xylene in air are investigated. The IMS is equipped with a radioactive ³H source. Besides the well-known product ions M⁺ and M·NO⁺, a dimer ion is also observed for benzene and toluene, consisting of two molecules and three further hydrogen atoms.

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Graphical Abstract ?

     

Determination of homogeneity of standard materials by ion microscopy

Summary Secondary-ion microanalysis is used to investigate the homogeneity (at the microlevel) of a number of standard reference materials. High mass-resolution measurements are accomplished with a CAMECA IMS-300 ion microscope/ion microprobe equipped with an electrostatic analyser. By use of a 5.5-keV¹⁶O₂ ⁺ primary ion beam with approximately 1A intensity the following materials were investigated: NBS-SRM copper-base alloys, low-alloy steels and zinc-base alloys, and Aluminium Péchiney Al-Si-Cu, Al-Cu and Al-Mn alloys. The sampling-constant concept was applied in order to evaluate the applicability of the reference materials for micro-probe analysis, and other microanalytical techniques. The degree of heterogeneity was estimated and the number of replicate analyses required for achieving 5 and 10% precision were calculated. The results show that care must be taken when using these standards for calibration work in SIMS and other microsampling techniques, since heterogeneity on the microscale is proven for a number of elements. The technique was also applied to the determination of the homogeneity of standard samples of boron in zirconium metal from the Bureau of Reference Materials of the EEC.

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Bestimmung der Homogenität von Standardproben durch Ionenmikroskopie

Zusammenfassung Sekundärionenmikroanalyse wurde zur Untersuchung der Homogenität einiger Standardreferenzmaterialien im Mikrobereich verwendet, wobei Messungen mit hoher Massenauflösung mittels einer CAMECA IMS-300 Ionenmikroskop/Ionenmikrosonde durchgeführt wurden, die mit einem elektrostatischen Sektor ausgestattet ist. Nachstehende Materialien wurden unter Verwendung eines 5,5 keV¹⁶O₂ ⁺-Primärionenstrahls mit etwa 1A Intensität untersucht: NBS-SRM Kupferlegierungen, NBS-SRM niedrig legierte Stähle, NBS-SRM Zinklegierungen und Aluminium Péchiney Al-Si-Cu-, Al-Cu- und Al-Mn-Legierungen.Zur Überprüfung der Verwendbarkeit der Referenzmaterialien für Mikrosondenanalysen und andere mikroanalytische Methoden wurde das Sampling-Constant-Konzept angewandt. Nach dem Abschätzen des He-terogenitätsgrades wird die Anzahl der Wiederholungen von Analysen berechnet, die für 5 und 10% Genauigkeit notwendig sind. Da Heterogenität im Mikrobereich für mehrere Elemente erwiesen ist, weisen die Resultate auf die anzuwendende Sorgfalt, soferne diese Standards für Eichungen in SIMS und anderen mikroanalytischen Methoden Verwendung finden sollen. Ebenso wird diese Technik für die Bestimmung der Homogenität von Bor in Standardproben des Bureau of Reference Materials des E. E. C. angewandt.

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Presented at the 8th International Microchemical Symposium, Graz, August 25–30, 1980.     

Vergleichende Untersuchungen der Nachweisempfindlichkeit in der Elektronenstrahl-Mikroanalyse

Zusammenfassung Die Erfassungsgrenzen liegen für die japanische Mikrosonde JEOL-JXA-3 bei den angegebenen Meßbedingungen bei etwas höheren Werten als für das französische Gerät (CAMECA), doch für beide Geräte stets innerhalb einer Zehnerpotenz, so daß von einem signifikanten Unterschied der Empfindlichkeit der beiden Geräte nicht gesprochen werden kann.Die Stromdichte von 1 A/cm² entspricht bei einem Strahldurchmesser von 2m einem Gesamtstrom von 0,03A; dies entspricht dem Arbeitsbereich des französischen Gerätes. Der routinemäßige Arbeitsbereich des JXA-3 liegt bei ungefähr 0,3A Gesamtstrahlstrom, der vom CAMECA-Gerät nur mehr schwer erreicht werden kann. Bei Vergleich der Geräte unter diesen Voraussetzungen unterscheiden sich die Erfassungsgrenzen im Arbeitsbereich, für den die Geräte jeweils ausgelegt sind, nur mehr um einen Faktor von maximal 2. Sie liegen für alle untersuchten Elemente stets im Bereiche von 0,2 bis 2,0 · 10^–13 g.

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Summary The detection limits of the Japanese microsonde JEOL-JXA-3 under the given measuring conditions are somewhat higher than with the French device (CAMECA) though with either appliance they are always within a power of ten, so that there is no significant difference in the sensitivity of the two instruments.At a beam diameter of 2m, the current density of 1 amp/cm² corresponds to a total current of 0.03amp. This corresponds to the operating region of the French appliance. The routine operation range of the JXA-3 lies at approximately 0.3amp. total current, which can be reached only with difficulty by the CAMECA instrument. When comparing these devices under these premises, the detection limits in the working range, for which the individual instruments are designed at times, differ from each other by a factor of 2 (maximum). With all the elements studied, they invariably fell in the range from 0.2 to 2.0 · 10^–13 g.

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Résumé Les limites de dilution correspondent à des valeurs un peu plus élevées pour la microsonde japonaise JEOL-JXA-3 dans les conditions de mesure communiquées que pour l'appareil français (CAMECA); cependant, pour les deux appareils, elles se maintiennent toujours dans les limites d'une puissance de 10, de sorte que l'on ne peut pas parler d'une différence de sensibilité significative entre les deux appareils.La densité de courant de 1 A/cm² correspond, dans le cas d'un diamètre de 2m, à un courant total de 0,03A, pour le domaine de travail de l'appareil français. Celle du JXA-3 se situe habituellement à 0,3A environ du courant total, valeur qui ne peut être atteinte que plus difficilement par l'appareil CAMECA. En comparant les appareils suivant ces points de vue, les limites de dilution dans le domaine opératoire pour lequel chacun des appareils est considéré, ne diffèrent que par un facteur de deux au maximum. Elles se situent toujours pour tous les éléments étudiés dans le domaine de 0,2 à 2,0 · 10^–13 g.

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Vortrag anläßlich des Kolloquiums für metallkundliche Analyse mit besonderer Berücksichtigung der Elektronenstrahl-Mikroanalyse, Wien, 22. Oktober 1964.     

Investigation of surface reactions of metals by quantitative distribution analysis with SIMS

Summary Surface reactions like carburization or nitriding are important in metallurgy to improve the properties of the surface. In the reaction of FeAlSi-alloys with CO at temperatures of about 1223 K carburization and oxidation occur. Quantitative distribution analysis of C, O, Al and Si in a layer of a few micrometers within a concentration range from x% to x /g is necessary to study the reaction and to calculate diffusion coefficients. Analysis was performed by combination of bulk analysis (thermal analysis for C, O), in situ microanalysis (EPMA/SEM) and surface analysis (SIMS). The investigations focussed on the capability of SIMS for quantitative distribution analysis of trace elements in surface zones of metals.For SIMS measurements a CAMECA IMS 3f ion probe analyzer was used 1. In the analysis of Al and Si matrix and sputter effects could be minimized by careful optimization of the chemical surface reaction with O₂ (oxygen-leak) during analysis. For quantification with an accuracy of approximately 30% rel. external standards were used. For the determination of O and C Ar⁺-primary ions were used. Quantification of oxygen was only possible by combination with bulk analysis (integration method). Due to selective sputtering crater bottoms were rough. Therefore in these measurements depth could not be determined with stylus techniques. Depth scale was obtained by comparing with measurements of Al and Si.

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Untersuchung von Oberflächenreaktionen von Metallen durch Quantitative Verteilungsanalyse mit SIMS

Zusammenfassung In der Metallurgie werden Oberflächenreaktionen wie Carburierung oder Nitrierung zur Verbesserung der Oberflächeneigenschaften verwendet. Bei der Reaktion von FeAlSi-Legierungen mit CO bei Temperaturen von ca. 1223 K tritt Carburierung und Oxidation auf. Zum Studium der Reaktion und zur Berechnung der Diffusionskoeffizienten ist eine quantitative Verteilungsanalyse von C, O, Al und Si in einer Schicht von einigen Mikrometern und einem Konzentrationsbereich von x% bis x g/g notwendig. Die Untersuchungen wurden mit einer Kombination von Durchschnittsanalyse (thermische Verfahren für C, O), in situ Mikroanalyse (ESMA/REM) und Oberflächenanalyse (SIMS) durchgeführt. Es wurden insbesondere die Möglichkeiten von SIMS für die quantitative Verteilungsanalyse von Spurenelementen in Metalloberflächen untersucht.Die SIMS-Analysen wurden mit einer CAMECA IMS 3f-Ionensonde durchgeführt 1. Bei der Analyse von Al und Si konnten Matrix und Sputtereffekte durch sorgfältige Optimierung der chemischen Oberflächenreaktion mit O₂ (oxygen-leak) während der Analyse minimiert werden. Die Quantifizierung erfolgte mit einer Richtigkeit von ca. 30% rel. unter Verwendung von externen Standards.Für die Bestimmung von O und C wurde mit Ar⁺-Primärionen gesputtert. Die Quantifizierung für Sauerstoff war nur durch Kombination mit der Durchschnittsanalyse (Integrationsmethode) möglich. Die Tiefenskala konnte bei diesen Messungen nicht direkt mit Oberflächenprofilometrie Methoden bestimmt werden, da der Kraterboden durch selektives Sputtern sehr rauh war. Die Tiefe wurde daher durch Normierung auf die Al und Si-Messungen bestimmt.

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Symbols used for Analytical Conditions PI primary ions - i _P primary ions current - d _Z crater depth - d _A diameter of analyzed area - PO₂ pressure in sample chamber if oxygen leak was used     

Simulation of Electric Potentials and Ion Motion in Planar Electrode Structures for Lossless Ion Manipulations (SLIM)

We report a conceptual study and computational evaluation of novel planar electrode structures for lossless ion manipulations (SLIM). Planar electrode SLIM components were designed that allow for flexible ion confinement, transport, and storage using a combination of radio frequency (rf) and DC fields. Effective potentials can be generated that provide near ideal regions for confining and manipulating ions in the presence of a gas. Ion trajectory simulations using SIMION 8.1 demonstrated the capability for lossless ion motion in these devices over a wide m/z range and a range of electric fields at low pressures (e.g., a few Torr). More complex ion manipulations (e.g., turning ions by 90^o and dynamically switching selected ion species into orthogonal channels) are also shown feasible. The performance of SLIM devices at ~4 Torr pressure for performing ion mobility-based separations (IMS) is computationally evaluated and compared with initial experimental results, and both are also shown to agree closely with experimental and theoretical IMS performance for a conventional drift tube design. Graphical Abstract

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The spectrophotometric determination of palladium with 2,2'-diquinolylketone-2″-pyridylhydrazone

Summary A method for the spectrophotometric determination of traces of palladium with 2,2'-diquinolylketone-2"-pyridylhydrazone is described. Experimental parameters were evaluated and a study of diverse ion tolerance carried out. Beer's law was obeyed and the molar absorptivity at 624 nm was 1.95×10⁴.

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Spektrophotometrische Palladiumbestimmung mit 2,2-Dichinolylketon-2 -Pyridylhydrazon

Zusammenfassung Die spektrophotometrische Bestimmung von Palladiumspuren mit 2,2'-Dichinolylketon-2"-Pyridylhydrazon wurde beschrieben. Die experimentellen Parameter wurden angegeben. Die Toleranz der Methode gegenüber verschiedenen Fremdionen wurde bestimmt. Das Beersche Gesetz ist gültig; die molare Extinktion beträgt 1,95×10⁴ bei 624 nm.

     

Electrochemically controlled solid-phase micro-extraction of proline using a nanostructured film of polypyrrole, and its determination by ion mobility spectrometry

We report on a fast, simple and accurate method for the determination of proline in urine samples by employing a nanostructured film of conducting polypyrrole for electrochemically controlled solid-phase microextraction, and ion mobility spectrometry (IMS) for detection. This method has the advantages of simple sample preparation and a sensitivity of IMS to proline that is higher than that for other amino acids. The calibration curve is linear in the range of 0.5–60 μg L^?1 (4–521 nmol L^?1), and the detection limit is 0.2 μg L^?1. The electrochemical potentials for uptake and release were optimized. The method was successfully applied to the clean-up and quantitation of trace amounts of proline in urine samples.

Determination of boron in silicon by SIMS with the matrix ion species ratio method

Summary In quantitative SIMS, the oxygen content of the sample surface proves to be a very important analytical parameter. The matrix ion species ratio method (MISR) was used to investigate the influence of the presence of oxygen on the determination of boron in silicon. By analysing standard samples at conditions of different oxygen coverage, the relation between the sensitivity of boron and the oxygen content of the sample surface, as indexed by the SiO⁺/Si³⁺ matrix ion species ratio, was established. The influence of the primary ion current density on this relation was investigated. The MISR procedure proves to be a suitable method to perform quantitative determinations (relative error < 10%) in conditions of changing oxygen content on the sample surface.

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Bestimmung von Bor in Silicium durch SIMS mit der Matrix Ion Species Ratio Method

     

A Simple Analytical Model for Predicting the Detectable Ion Current in Ion Mobility Spectrometry Using Corona Discharge Ionization Sources

Corona discharge ionization sources are often used in ion mobility spectrometers (IMS) when a non-radioactive ion source with high ion currents is required. Typically, the corona discharge is followed by a reaction region where analyte ions are formed from the reactant ions. In this work, we present a simple yet sufficiently accurate model for predicting the ion current available at the end of this reaction region when operating at reduced pressure as in High Kinetic Energy Ion Mobility Spectrometers (HiKE-IMS) or most IMS-MS instruments. It yields excellent qualitative agreement with measurement results and is even able to calculate the ion current within an error of 15%. Additional interesting findings of this model are the ion current at the end of the reaction region being independent from the ion current generated by the corona discharge and the ion current in High Kinetic Energy Ion Mobility Spectrometers (HiKE-IMS) growing quadratically when scaling down the length of the reaction region.

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Graphical Abstract ?

     

Multilayer thin-film coatings based on chromium nitride and aluminum nitride: Comparative depth profiling by secondary ion mass spectrometry and glow-discharge optical emission spectrometry

Round-robin characterization is reported on the sputter depth profiling of CrN/AlN multilayer thin-film coatings on nickel alloy by secondary ion mass spectrometry (SIMS) and glow-discharge optical emission spectrometry (GD-OES). It is demonstrated that a CAMECA SIMS 4550 Depth Profiler operated with 3 keV O ₂ ⁺ primary ions provides the best depth resolution and sensitivity. The key factor is sample rotation, which suppresses the negative influence of the surface topography (initial and ion-induced) on the depth profile characteristics.     

Ion fractions of matrix elements and impurities in GaAs bombarded by O2+ primary ions

Summary Useful ion yields Y of secondary ion mass spectrometry (SIMS) analyses were measured for GaAs bombarded with O ₂ ⁺ primary ions at normal incidence. The useful ion yields of several analytes were found to decrease with increasing ionisation potentialE _i of the analytes far less drastically than reported in the literature. For valuesE _i lower than 8 eV only a slight decrease of Y with increasing ionisation potential is observed. The saturation of the useful ion yields at lower values of the ionisation potential is interpreted to result from very high ion fractions. If an ion fraction of unity is assumed for Ga the ion fractions of impurities withE _i lower than 8 eV would exceed 40%. For analytes withE _i higher than 8 eV the ion fraction decreases rapidly with increasing ionisation potential. A value of 8×10^–4 is estimated for the matrix element As (E _i= 9.81 eV).

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Ionenausbeuten von Matrixelementen und Dotierstoffen in GaAs unter O ₂ ⁺ -Primärionenbeschuß

     

Intensités des Transitions Électroniques de [PdCl4]2− Intensities of Electronic Transitions of [PdCl4]2−

The oscillator strengths of the symmetry-forbidden transitions of the ion [PdCl₄]^2– were calculated by a method based on the evaluation of the MO of the distorted ion. It is not very likely that the transition to¹ B _1g (a _1g (d _z ²)b _1g ) state, weak, mainlyz polarized, explains the band that appears as a shoulder observed towards 30 000 cm^–1 in the absorption spectrum. If this band is specific of the ion [PdCl₄]^2–, the assignment to the forbidden charge-transfer transition,¹ A _1g ¹ B _2g , is more plausible.

     

The mass spectral fragmentation of copper(II) complexes of cyclic β-diketones

Summary Electron impact mass spectra of several bis(2-trifluoroacetylcycloalkanonato) copper(II) and bis(2-acetylcycloalkanonato) copper(II) chelates, in which the cyclic -diketonate moiety comprises five-, six-, seven-, and eight-membered ring systems, have been recorded. Compared with other copper(II) chelates of acyclic -diketonates, the present series of copper(II) cyclic -diketonates exhibited more pronounced intramolecular reduction reactions accompanied by a remarkably facile hydrogen migration resulting in the formation of the [LCu^(I)-H]⁺ ion as the base peak in all complexes investigated. The proposed fragmentation pathways leading to the formation of a number of important copper-containing daughter ions have been confirmed by metastable scanning of the corresponding parent ion spectra using the defocusing technique.

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Massenspektroskopische Fragmentierung von Kupfer(II)-Komplexen cyclischer -Diketone

Zusammenfassung Es wurden die EI-Massenspektren einiger Bis(2-trifluoracetylcycloalkanato)kupfer(II)-und Bis(2-acetylcycloalkanato)kupfer(II)-Chelate mit fünf-, sechs-, sieben- und achtgliedrigen cyclischen -Diketonat-Liganden gemessen. Im Vergleich zu anderen Kupfer(II)-Chelaten mit offenkettigen -Diketonaten zeigen die cyclischen Komplexe eine ausgeprägte Neigung zu intramolekularen Reduktionsreaktionen, die von einer bemerkenswert leicht erfolgenden Wasserstoffwanderung begleitet sind; dies führt zur Bildung von [LCu^(I)-H]⁺ als Basispeak für alle untersuchten Komplexe. Die vorgeschlagenen Fragmentierungswege, die zur Bildung einer Reihe wichtiger kupferhaltiger Tochterionen führen, wurden durch Untersuchung der entsprechenden metastabilen Mutterionen mittels der Defokussierungsmethode überprüft.

     

Potentiometric determination of the activity of fluoride ion in aqueous solutions at high pressure and high temperature

Summary A fluoride membrane electrode is described for the determination of the activity of fluoride ion in aqueous solutions at high pressure and elevated temperature. An Ag/AgCl electrode is used as a reference. The cell described has a linear potential at temperatures up to 200 °C and pressures up to 1 kbar. The interference of OH^– is only noticeable at fluoride concentration c_f– 10^–5 m in the temperature region between 175 °C and 200 °C.

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Potentiometrische Bestimmung der Aktivität des Fluorid-Ions in wäßrigen Lösungen bei hohem Druck und hoher Temperatur

     

Determining urea levels in dialysis human serum by means of headspace solid phase microextraction coupled with ion mobility spectrometry and on the basis of nanostructured polypyrrole film

A simple and sensitive headspace (HS) solid phase microextraction (SPME) coupled with ion mobility spectrometry (IMS) method is presented for analysis of urea in dialysis human serum samples. A dodecylbenzenesulfonate-doped polypyrrole coating was used as a fiber for SPME. The HS-SPME–IMS method exhibits good repeatability (relative standard deviation of 3 % or less), simplicity, and good sensitivity. The influence of various analytical parameters such as pH, ionic strength, extraction time and temperature was investigated and the parameters were optimized. The calibration graph was linear in the range from 5 to 50 μg mL^?1, and the detection limit was 2 μg mL^?1. The method was applied successfully for determination of urea in human serum and with acceptable recovery (more than 98 %). Finally, a standard addition calibration method was applied to the HS-SPME-IMS method for the analysis of human serum samples before and at the end of dialysis. The proposed method appears to be suitable for the analysis of urea in serum samples as it is not time-consuming and requires only small quantities of the sample without any derivatization process.

A new tetrafluoroborate liquid membrane electrode for selective determination of boron

Summary The construction and performance characteristics of a new liquid membrane electrode selective for BF^– ₄ ion are described. The electrode incorporates nitron-tetrafluoroborate ion-pair complex in nitrobenzene as a liquid membrane. The electrode shows a rapid Nernstian response for BF ₄ ^– ion over the concentration range of 10^–1 to 10^–5 M and the potential is almost independent of the pH over the range of 3–9. The selectivity coefficient values obtained for 21 different anions and cations show no significant interference. The electrode is satisfactorily used for the determination of 0.5–500 g/ml of boron after conversion to BF ₄ ^– . The average recovery is 98.8% and the mean standard deviation being 2.1%.

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Neue Tetrafluoborat-Flüssigmembranelektrode zur selektiven Bestimmung von Bor

Zusammenfassung Der Aufbau und die Charakteristiken einer für BF ₄ ^– selektiven Elektrode werden beschrieben. Die Elektrode enthält den Nitron-Tetrafluoborat-Ionenpaar-komplex in Nitrobenzol als flüssige Membran. Nernstsches Verhalten ergibt sich über einen Konzentrationsbereich von 10^–1 bis 10^–5 M BF ₄ ^– . Das Potential ist fast pH-unabhängig im Bereich von 3 bis 9. Aus den Selektivitätskoeffizienten von 21 verschiedenen Anionen und Kationen ergeben sich keine signifikanten Störungen. Die beschriebene Elektrode kann mit guten Ergebnissen zur Bestimmung von 0,5 bis 500g/ml Bor nach Umsetzung zu BF ₄ ^– ₄ eingesetzt werden. Die durchschnittliche Wiederfindungsrate beträgt 98,8%, die mittlere Standardabweichung 2,1%.

     

Recent improvements of the ion analyzer and typical examples of applications

Improvements of a CAMECA IMS 300 ion microanalyzer are described: ion source, resolution, ion detector and counting system. Comparison with the performances of an electron microprobe is presented. Examples of application are given.     

Fluordiazadiphosphetidine, 15. Mitt.: Die Reaktionen von Hexafluordiazadiphosphetidinen mit Fluorwasserstoff

The reaction of fluorodiazadiphosphetidines with dry hydrogenfluoride has been studied thoroughly. Depending on the nature of the substitutents on the nitrogen atom this reaction can take two different courses: a) yielding the octafluoro-1,3,2⁶,4⁶-diazoniadiphosphatetidines¹; b) forming the corresponding amine-phosphoruspentafluoride-adducts, which are enabled for various further reactions. A scheme of possible reactions has been established.

     

Spatial Ion Peak Compression and its Utility in Ion Mobility Spectrometry

A novel concept for ion spatial peak compression is described, and discussed primarily in the context of ion mobility spectrometry (IMS). Using theoretical and numerical methods, the effects of using non-constant (e.g., linearly varying) electric fields on ion distributions (e.g., an ion mobility peak) is evaluated both in the physical and temporal domains. The application of a linearly decreasing electric field in conjunction with conventional drift field arrangements is shown to lead to a reduction in IMS physical peak width. When multiple ion packets (i.e., peaks) in a selected mobility window are simultaneously subjected to such fields, there is ion packet compression (i.e., a reduction in peak widths for all species). This peak compression occurs with only a modest reduction of resolution, which can be quickly recovered as ions drift in a constant field after the compression event. Compression also yields a significant increase in peak intensities. Ion mobility peak compression can be particularly useful for mitigating diffusion-driven peak broadening over very long path length separations (e.g., in cyclic multi-pass arrangements), and for achieving higher S/N and IMS resolution over a selected mobility range.

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Graphical Abstract ?