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Nitrosamines have been identified as a probable human carcinogen and thus are of high concern in many manufacturing industries and various matrices (for example pharmaceutical, cosmetic and food products, workplace air or potable- and wastewater). This study aims to analyse nine nitrosamines relevant in the field of occupational safety using a gas chromatography-drift tube ion mobility spectrometry (GC-DT-IMS) system. To do this, single nitrosamine standards as well as a standard mix, each at 0.1 g/L, were introduced via liquid injection. A GC-DT-IMS method capable of separating the nitrosamine signals according to retention time (first dimension) and drift time (second dimension) in 10 min was developed. The system shows excellent selectivity as each nitrosamine gives two signals pertaining to monomer and dimer in the second dimension. For the first time, reduced ion mobility values for nitrosamines were determined, ranging from 1.18 to 2.03 cm2s−1V−1. The high selectivity of the GC-DT-IMS method could provide a definite advantage for monitoring nitrosamines in different manufacturing industries and consumer products.

Additive manufacturing (AM) of metals has the potential to provide significant benefits for the construction of future particle accelerators. The combination of low cost manufacturing of complex geometries in combination with efficiency gains from improved linac design enabled by AM may be one way towards future cost-effective green accelerator facilities. As a proof of concept, we present a high-efficiency Z e f f = 280   M Ω / m , 433.632 MHz IH-DTL cavity based on an AM design. In this case, the complex internal drift tube structures with internal cooling channels have been produced from 1.4404 stainless steel and from pure copper using AM. The prototype cavity, as well as stainless steel AM parts have been electroplated with copper. We present results from successful vacuum tests, low level RF measurements of the cavity, as well as the status of preparations for high-power RF tests with a 30 kW pulsed power amplifier. [ABSTRACT FROM AUTHOR]

This mini review focuses on the opportunities provided by current and emerging separation techniques for mass spectrometry metabolomics. The purpose of separation technologies in metabolomics is primarily to reduce complexity of the heterogeneous systems studied, and to provide concentration enrichment by increasing sensitivity towards the quantification of low abundance metabolites. For this reason, a wide variety of separation systems, from column chemistries to solvent compositions and multidimensional separations, have been applied in the field. Multidimensional separations are a common method in both proteomics applications and gas chromatography mass spectrometry, allowing orthogonal separations to further reduce analytical complexity and expand peak capacity. These applications contribute to exponential increases in run times concomitant with first dimension fractionation followed by second dimension separations. Multidimensional liquid chromatography to increase peak capacity in metabolomics, when compared to the potential of running additional samples or replicates and increasing statistical confidence, mean that uptake of these methods has been minimal. In contrast, in the last 15 years there have been significant advances in the resolution and sensitivity of ion mobility spectrometry, to the point where high-resolution separation of analytes based on their collision cross section approaches chromatographic separation, with minimal loss in sensitivity. Additionally, ion mobility separations can be performed on a chromatographic timescale with little reduction in instrument duty cycle. In this review, we compare ion mobility separation to liquid chromatographic separation, highlight the history of the use of ion mobility separations in metabolomics, outline the current state-of-the-art in the field, and discuss the future outlook of the technology. “Where there is one, you’re bound to divide it. Right in two”, James Maynard Keenan.

Drift tube is one of the core components of proton transfer reaction mass spectrometer (PTR-MS). Technical innovation of the drift tube is one of the important ways to improve the performance of the instrument. In recent years, focusing drift tube (FDT) has been paid more and more attention because of its high ion utilization ratio. In this work, the design and simulation of a FDT combined with a radio frequency quadrupole and a resistor glass tube was reported. The quadrupole was used to provide an RF focusing field, and the resistor glass tube was used to generate a uniformly distributed DC gradient electric field. Based on the designed 3D structure, the simulation model was built in SIMION 8.1 and the parameters such as the diameter of the quadrupole, the frequency and the voltage amplitude of the RF field were simulated systematically with three kinds of ions (m/z 19, 55 and 100). The results showed that the introduction of the RF field was very effective in reducing the radius of the ion beam, and the rod with larger diameter was beneficial to improve the ion focusing efficiency, especially for the ions with low mass-charge ratio. When the frequency was about 2 MHz, the focusing efficiency was the highest. With the increase of the voltage amplitude, the radius of ion beam decreased rapidly and finally tended to smooth. In addition, more than 85% of the ions could successfully pass through the sampling orifice with a diameter of 1.0 mm, and the transport efficiency was about 28 times higher than that of the traditional drift tube. In this study, structural design, SIMION modeling and ion transmittance of RF quadrupole focusing drift tube (RFQ-FDT) were described in detail, hoping to provide some technical support for follow-up research.

Additive manufacturing (AM) of metals has the potential to provide significant benefits for the construction of future particle accelerators. The combination of low cost manufacturing of complex geometries in combination with efficiency gains from improved linac design enabled by AM may be one way towards future cost-effective green accelerator facilities. As a proof of concept, we present a high-efficiency Zeff=280 MΩ/m, 433.632 MHz IH-DTL cavity based on an AM design. In this case, the complex internal drift tube structures with internal cooling channels have been produced from 1.4404 stainless steel and from pure copper using AM. The prototype cavity, as well as stainless steel AM parts have been electroplated with copper. We present results from successful vacuum tests, low level RF measurements of the cavity, as well as the status of preparations for high-power RF tests with a 30 kW pulsed power amplifier.

The High Luminosity LHC (HL-LHC) program will pose a great challenge for the CMS Muon System. Existing subdetectors, which consist of Drift Tubes (DT), Resistive Plate Chambers (RPC) and Cathode Strip Chambers (CSC), will have to operate at 5 times larger instantaneous luminosity than the designed for, and, consequently, will have to sustain about 10 times the original LHC integrated luminosity. Longevity of DT system will be crucial to ensure a good performance in the CMS barrel region. Assessing DT performance is part of the upgrade program. In this talk will be reported the outcome of the accelerated irradiation studies, carried on at the CERN Gamma Irradiation Facility (GIF++) and recently concluded. These studies allowed to estimate performance of DT up to 3 times HL-LHC, and to plan a strategy to keep the longevity effects under control. [ABSTRACT FROM AUTHOR]

The Antiproton Decelerator (AD) at CERN provides antiproton bunches with a kinetic energy of 5.3 MeV. The Extra-Low ENergy Antiproton ring at CERN, commissioned at the AD in 2018, now supplies a bunch of electron-cooled antiprotons at a fixed energy of 100 keV. The MUSASHI antiproton trap was upgraded by replacing the radio-frequency quadrupole decelerator with a pulsed drift tube to re-accelerate antiprotons and optimize the injection energy into the degrader foils. By increasing the beam energy to 119 keV, a cooled antiproton accumulation efficiency of (26 ± 6) % was achieved. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM or "3D printing") has become a powerful tool for the rapid prototyping and manufacturing of complex part geometries. Especially interesting for the world of particle accelerators is the process of the 3D printing of stainless steel (and copper) parts. We present a first prototype of a 433   M H z IH-type linac cavity with an internal drift tube structure manufactured by metal 3D printing. The prototype cavity has been constructed to act as a proof-of-concept for the technology. In this paper we present the concept of the cavity as well as first results of vacuum testing and materials testing. [ABSTRACT FROM AUTHOR]

Drift tube is one of the core components of proton transfer reaction mass spectrometer (PTR-MS). Technical innovation of the drift tube is one of the important ways to improve the performance of the instrument. In recent years, focusing drift tube (FDT) has been paid more and more attention because of its high ion utilization ratio. In this work, the design and simulation of a FDT combined with a radio frequency quadrupole and a resistor glass tube was reported. The quadrupole was used to provide an RF focusing field, and the resistor glass tube was used to generate a uniformly distributed DC gradient electric field. Based on the designed 3D structure, the simulation model was built in SIMION 8.1 and the parameters such as the diameter of the quadrupole, the frequency and the voltage amplitude of the RF field were simulated systematically with three kinds of ions (m/z 19, 55 and 100). The results showed that the introduction of the RF field was very effective in reducing the radius of the ion beam, and the rod with larger diameter was beneficial to improve the ion focusing efficiency, especially for the ions with low mass-charge ratio. When the frequency was about 2 MHz, the focusing efficiency was the highest. With the increase of the voltage amplitude, the radius of ion beam decreased rapidly and finally tended to smooth. In addition, more than 85% of the ions could successfully pass through the sampling orifice with a diameter of 1.0 mm, and the transport efficiency was about 28 times higher than that of the traditional drift tube. In this study, structural design, SIMION modeling and ion transmittance of RF quadrupole focusing drift tube (RFQ-FDT) were described in detail, hoping to provide some technical support for follow-up research. [ABSTRACT FROM AUTHOR]

In a previous work, we explored zone broadening and the achievable plate numbers in linear drift tube ion mobility‐mass spectrometry through developing a plate‐height model [1]. On the basis of these findings, the present theoretical study extends the model by exploring peak‐to‐peak resolution and peak capacity in ion mobility separations. The first part provides a critical overview of chromatography‐influenced resolution equations, including refinement of existing formulae. Furthermore, we present exact resolution equations for drift tube ion mobility spectrometry based on first principles. Upon implementing simple modifications, these exact formulae could be readily extended to traveling wave ion mobility separations and to cases when ion mobility spectrometry is coupled to mass spectrometry. The second part focuses on peak capacity. The well‐known assumptions of constant plate number and constant peak width form the basis of existing approximate solutions. To overcome their limitations, an exact peak capacity equation is derived for drift tube ion mobility spectrometry. This exact solution is rooted in a suitable physical model of peak broadening, accounting for the finite injection pulse and subsequent diffusional spreading. By borrowing concepts from the theoretical toolbox of chromatography, we believe that the present study will help in integrating ion mobility spectrometry into the unified language of separation science. [ABSTRACT FROM AUTHOR]

Ion mobility spectrometers (IMS) are able to detect pptV-level concentrations of substances in gasses and in liquids within seconds. Due to the continuous increase in analytical performance and reduction of the instrument size, IMS are established nowadays in a variety of analytical field applications. In order to reduce the manufacturing effort and further enhance their widespread use, we have developed a simple manufacturing process for drift tubes based on a composite material. This composite material consists of alternating layers of metal sheets and insulator material, which are connected to each other in a mechanically stable and gastight manner. Furthermore, this approach allows the production of ion drift tubes in just a few steps from a single piece of material, thus reducing the manufacturing costs and efforts. Here, a drift tube ion mobility spectrometer based on such a composite material is presented. Although its outer dimensions are just 15 mm × 15 mm in cross section and 57 mm in length, it has high resolving power of Rp = 62 and detection limits in the pptV-range, demonstrated for ethanol and 1,2,3-trichloropropane. [ABSTRACT FROM AUTHOR]

Ion‐molecule reaction cross sections between 0.03 and 3 eV can best be inferred from data taken in drift tube mass spectrometers. For the title reactions, the cross sections inferred from drift‐tube measurements in the late 1970s have been accepted as accurate, even though the methods used to infer them made substantial assumptions about the ion velocity distribution functions. Here the Gram‐Charlier method for solving the Boltzmann equation is used to obtain ion distribution functions that are anisotropic, having different average energies parallel and perpendicular to the uniform electrostatic field. The Gram‐Charlier method incorporates skewness, kurtosis, and correlation between the motions parallel and perpendicular to the field. This leads to more accurate ion distribution functions from which more accurate reaction cross sections have been inferred. The results differ by as much as 50% from the generally accepted cross sections that are currently used to model ion‐neutral reactions in the upper atmosphere. Key Points: Drift‐tube measurements of the rate coefficients for the title reactions are reanalyzedThe results indicate that the reaction cross sections previously extracted from the data are in significant errorNew, improved cross sections are inferred from the data for energies between 0.03 and 3 eV [ABSTRACT FROM AUTHOR]

With recent advances in ionization sources and instrumentation, ion mobility spectrometers (IMS) have transformed from a detector for chemical warfare agents and explosives to a widely used tool in analytical and bioanalytical applications. This increasing measurement task complexity requires higher and higher analytical performance and especially ultra-high resolution. In this review, we will discuss the currently used ion mobility spectrometers able to reach such ultra-high resolution, defined here as a resolving power greater than 200. These instruments are drift tube IMS, traveling wave IMS, trapped IMS, and field asymmetric or differential IMS. The basic operating principles and the resulting effects of experimental parameters on resolving power are explained and compared between the different instruments. This allows understanding the current limitations of resolving power and how ion mobility spectrometers may progress in the future. [ABSTRACT FROM AUTHOR]

The strong synergy arising from coupling two orthogonal analytical techniques such as ion mobility and mass spectrometry can be used to separate complex mixtures and determine structural information of analytes in the gas phase. A tandem study is performed using two systems with different gases and pressures to ascertain gas-phase conformations of homopolymer ions. Aside from spherical and stretched configurations, intermediate configurations formed by a multiply charged globule and a "bead-on-a-string" appendix are confirmed for polyethylene-glycol (PEG), polycaprolactone (PCL), and polydimethylsiloxane (PDMS). These intermediate configurations are shown to be ubiquitous for all charge states and masses present. For each charge state, configurations evolve in two distinctive patterns: an inverse evolution which occurs as an elementary charge attached to the polymer leaves the larger globule and incorporates itself into the appendage, and a forward evolution which reduces the globule without relinquishing a charge while leaving the appendix relatively constant. Forward evolutions are confirmed to form self-similar family shapes that transcend charge states for all polymers. Identical structural changes occur at the same mass over charge regardless of the system, gas or pressure strongly suggesting that conformations are only contingent on number of charges and chain length, and start arranging once the ion is at least partially ejected from the droplet, supporting a charge extrusion mechanism. Configurational changes are smoother for PDMS which is attributed to the larger steric hindrance caused by protruding pendant groups. This study has implications in the study of the configurational space of more complex homopolymers and heteropolymers. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Powerful options by coupling two meter drift tube to two meter time-of-flight tube. • High mass resolution readily identifies an ion (e.g. charge state, oligomer size). • Mobility-selected ions are readily identified by isotope pattern. • Ion selection with high mass resolution aids in interpretation of mobility data. Abstract A new instrument combining a two meter long ion mobility drift tube fabricated of resistive glass with a high-resolution time-of-flight (TOF) mass spectrometer is presented and new features are discussed in detail. Ions are formed by electrospray ionization. An ion gate positioned at the exit of the drift tube allows analysis of mobility-selected ions. A quadrupole mass filter and a collision cell are located between the drift tube and the TOF analyzer, an arrangement which allows collision-induced dissociation experiments of mass-selected and/or mobility-selected ions. The ability of the TOF spectrometer to resolve isotopologues differing by 1 Da in mass even for multiply charged ions opens up exceptional possibilities for ion selection and mobility analysis. The unique combination of instrument attributes including gentle ion production and analysis, the first principles measurement of cross sections, and high mobility (R∼100) and mass (R>20k) resolving powers allows for the analysis of a broad range of analytes including amino acid oligomer clusters (e.g. Phe 97), peptides, and proteins. [ABSTRACT FROM AUTHOR]

The influence of the Earth’s gravitational field on a weakly relativistic electron involved in the process of generation of microwave radiation is evaluated. It is shown that such exposure leads to the generation of a second harmonic. [ABSTRACT FROM AUTHOR]