Exploring Complex Mixtures by Cyclic Ion Mobility High-Resolution Mass Spectrometry: Application Toward Petroleum.

The in-depth isomeric and isobaric description of ultra-complex organic mixtures remains one of the most challenging analytical tasks. In the last two decades, ion mobility coupled to high-performance mass spectrometry added an additional structural dimension. Despite tremendous instrumental improvements, commercial devices are still limited in ion mobility and mass spectrometric resolving power and struggle to resolve isobaric species and complex isomeric patterns. To overcome these limitations, we explored the capabilities of cyclic ion mobility high-resolution mass spectrometry with special emphasis on petrochemical applications. We could show that quadrupole-selected ion mobility mass spectrometry gives closer insights into the isomeric distribution. In combination with slicing the specific parts of the ion mobility dimension, isobaric interferences could be drastically removed. Collision-induced dissociation (CID) allowed separating structural groups of polycyclic aromatic hydrocarbons and heterocycles (PAH/PASH), deploying up to 10 passes in the cyclic ion mobility device. Finally, we introduce a data processing workflow to resolve the 3.4 mDa SH4/C3 mass split by combining ion mobility and mass spectrometric resolving power. Cyclic ion mobility with the intelligent design of experiments and processing routines will be a powerful approach addressing the isobaric and isomeric complexity of ultra-complex mixtures.

Application of a novel cyclic ion mobility-mass spectrometer to the analysis of synthetic polymers: A preliminary evaluation.

RATIONALE: Mass spectrometry (MS) is often employed in the characterisation of synthetic polymers. As polymer architecture becomes more complex, ion mobility (IM) is increasingly being coupled with MS to provide an additional dimension of separation, along with structural information. In this study, we explore the use of a novel cyclic ion mobility (cIM) mass spectrometer for the analysis of a co-polymer sample. METHODS: A solution of poly(ethylene glycol)-poly(propylene glycol) random co-polymer (PEG-ran-PPG) was used as a representative polymer sample. The solution was infused into a cIM-enabled quadrupole time-of-flight mass spectrometer. An m/z region of interest, selected using the quadrupole, was passed around the cIM device multiple times. Subsequently, regions of an arrival time distribution were 'sliced' and subjected to tandem mass spectrometric (MS/MS) analysis. RESULTS: Typical, multiply charged series were observed for the polymer under electrospray ionisation. Multiple passes of the cIM device resulted in the separation of otherwise-overlapping charge states within a narrow m/z window (~3 m/z units), allowing individual selection of ions. These isolated ions were then subjected to post-mobility fragmentation resulting in clean, high-resolution product ion spectra, with a significant reduction in interference. CONCLUSIONS: Scalable IM separation (IMS), brought about by passing ions multiple times around the cIM device, was demonstrated to provide increased IM resolution for ions in the selected m/z window. After multiple passes, deconvoluted high-resolution MS/MS product ion spectra were successfully acquired for ions that previously had interfering overlapping species present.

Isolation of Crude Oil Peaks Differing by m/z ∼0.1 via Tandem Mass Spectrometry Using a Cyclic Ion Mobility-Mass Spectrometer.

Mass spectrometry is widely used in studying the structures of compounds present in crude oil. In this study, a novel mass spectrometer incorporating a cyclic ion mobility separator was used to obtain tandem mass spectra of crude oil compounds in a narrow mass-to-charge ratio (m/z) window. Isolation of specific peaks was performed by combining quadrupole and ion mobility separation. As a result, peaks differing by an m/z value of 0.1 could be isolated. Tandem mass spectrometry with collision-induced dissociation was successfully performed to study the chemical structures of the isolated ions. A series of ions ranging from m/z 374 to m/z 384, differing by two hydrogen atoms but with the same number of carbons, were isolated and tandem mass spectra were obtained. The higher m/z precursor ions produced smaller fragment ions; this is explained by the reduced aromaticity owing to an increased number of hydrogen atoms. The ions at m/z 388 and 374, differing by a CH2 group, produced very similar fragmentation patterns. Overall, the data obtained from this study clearly demonstrate that the novel cyclic ion mobility-mass spectrometer is a powerful instrument that can provide tandem mass spectra of individual compounds constituting complex mixtures such as crude oils.

Elucidating molecular structures of nonalkylated and short-chain alkyl (n < 5, (CH2)n) aromatic compounds in crude oils by a combination of ion mobility and ultrahigh-resolution mass spectrometries and theoretical collisional cross-section calculations.

Ultrahigh-resolution mass spectrometry has allowed the determination of elemental formulas of the compounds comprising crude oils. However, elucidating molecular structures remains an analytical challenge. Herein, we propose and demonstrate an approach combining ion mobility mass spectrometry (IM-MS), ultrahigh-resolution mass spectrometry, and theoretical collisional cross-section (CCS) calculations to determine the molecular structures of aromatic compounds found in crude oils. The approach is composed of three steps. First, chemical structures are suggested based on the elemental formulas determined from ultrahigh-resolution mass spectra. Second, theoretical CCS values are calculated based on these proposed structures. Third, the calculated CCS values of the proposed structures are compared with experimentally determined CCS values from IM-MS data to provide proposed structures. For proof of concept, 31 nonalkylated and short-chain alkyl (n < 5, (CH2)n) aromatic compounds commonly observed in crude oils were analyzed. Theoretical and experimental CCS values matched within a 5% RMS error. This approach was then used to propose structures of compounds in selected m/z regions of crude oil samples. Overall, the combination of ion mobility mass spectrometry, ultrahigh-resolution mass spectrometry, and theoretical calculations was shown to be a useful tool for elucidating chemical structures of compounds in complex mixtures.

Evaluation of the psychometric properties of the Reproductive Autonomy Scale for use in the UK.

BACKGROUND: Reproductive autonomy-control over outcomes including contraceptive use and childbearing-is a human right and vital to women's empowerment. Those whose reproductive autonomy is threatened by the structures and relationships in their lives are at risk of coercion and unplanned pregnancy and could benefit from additional services. The Reproductive Autonomy Scale (RAS) was developed in the USA to assess women's reproductive autonomy; this study evaluates the RAS for use in the UK. METHODS: After testing, the RAS was incorporated into an online survey of women of reproductive age. Those who were sexually active were asked to complete the RAS, which was evaluated according to classical test theory. Reliability was assessed via internal consistency and a 3-month test-retest. Construct validity was assessed using hypothesis testing and confirmatory factor analysis. RESULTS: For 826 women the RAS was highly acceptable, with a response rate of >97.7%. Almost the whole range of reproductive autonomy scores were captured. Internal consistency was good, with a Cronbach's α of 0.75. Test-retest reliability was fair-good with an intraclass correlation coefficient of 0.67. Construct validity analysis found the scale to be valid based on our hypothesis that among women who want to avoid pregnancy, those with higher reproductive autonomy will be more likely to use contraception. The three-factor structure of the scale was confirmed on confirmatory factor analysis. CONCLUSION: The RAS is valid and reliable for use in the UK. This tool holds potential utility across research, clinical practice, health interventions and policy development.

Cyclic Ion Mobility Spectrometry Coupled to High-Resolution Time-of-Flight Mass Spectrometry Equipped with Atmospheric Solid Analysis Probe for the Molecular Characterization of Combustion Particulate Matter.

Anthropogenic air pollution has a severe impact on climate and human health. The immense molecular complexity and diversity of particulate matter (PM) is a result of primary organic aerosol (POA) as well as secondary organic aerosols (SOAs). In this study, a direct inlet probe (DIP), i.e., atmospheric solids analysis probe (ASAP), with ion mobility high-resolution mass spectrometric detection is applied. Primary particulate matter emissions from three sources were investigated. Furthermore, photochemically aged emissions were analyzed. DIP introduction allowed for a direct analysis with almost no sample preparation and resulted in a complex molecular pattern. This pattern shifted through oxidation processes toward heavier species. For diesel emissions, the fuel's chemical characteristic is partially transferred to the particulate matter by incomplete combustion and characteristic alkylated series were found. Polycyclic aromatic hydrocarbons (PAHs) were identified as major contributors. Ion mobility analysis results in drift time profiles used for structural analysis. The apex position was used to prove structural changes, whereas the full-width-at-half-maximum was used to address the isomeric diversity. With this concept, the dominance of one or a few isomers for certain PAHs could be shown. In contrast, a broad isomeric diversity was found for oxygenated species. For the in-depth specification of fresh and aged spruce emissions, the ion mobility resolving power was almost doubled by allowing for three passes in the circular traveling wave design. The results prove that ASAP coupled with ion mobility spectrometry-mass spectrometry (IMS-MS) serves as a promising analytical approach for tackling the vast molecular complexity of PM.

Conferences in the time of COVID: notes on organizing and delivering the first Brain Conference.

To further fulfil their missions of promoting teaching, education and research in neurology and related clinical-academic disciplines, the Guarantors of Brain and the Brain journal family invited delegates to the first Brain Conference in Spring of this year. This event aimed to deliver excellent teaching and scientific presentations across a broad spectrum of neuroscience fields, with the key aim of making the content as accessible as possible. We hoped to capitalize on the benefits of an online format, whilst trying to capture a little of the joy of the in-person meeting. This article reports on the approach and practical choices made to achieve these goals, and we hope this will provide some guidance and advice to others organizing their own online conference.

Effective Ion Mobility Peak Width as a New Isomeric Descriptor for the Untargeted Analysis of Complex Mixtures Using Ion Mobility-Mass Spectrometry.

Ion mobility coupled with mass spectrometry was proven to be an efficient way to characterize complex mixtures such as petroleum samples. However, the identification of isomeric species is difficult owing to the molecular complexity of petroleum and no availability of standard molecules. This paper proposes a new simple indicator to estimate the isomeric content of highly complex mixtures. This indicator is based on the full width at half maximum (FWHM) of the extracted ion mobility peak measured in millisecond or square angstrom that is corrected for instrumental factors such as ion diffusion. This value can be easily obtained without precisely identifying the number of isomeric species under the ion mobility peaks. Considering the Boduszynski model, the ion mobility profile for a particular elemental composition is expected to be a continuum of various isomeric species. The drift time-dependent fragmentation profile was studied and confirmed this hypothesis, a continuous evolution of the fragmentation profile showing that the larger alkyl chain species were detected at higher drift time values. This new indicator was proven to be a fast and efficient method to compare vacuum gas oils for which no difference was found using other analytical techniques. Graphical Abstract ᅟ.

Progress in mass spectrometry for the analysis of set-off phenomena in plastic food packaging materials.

In most cases, food packaging materials contain inks whose components can migrate to food by diffusion through the material as well as by set-off phenomena. In this work, different mass spectrometry approaches had been used in order to identify and confirm the presence of ink components in ethanol (95%) and Tenax(®) as food simulants. Three different sets of materials, manufactured with different printing technologies and with different structures, were analyzed. Sample analysis by ultra performance liquid chromatography mass spectrometry (UPLC-MS), using a quadrupole-time of flight (Q-TOF) as a mass analyser proved to be an excellent tool for identification purposes while ion mobility mass spectrometry (IM-MS) shown to be very useful for the confirmation of the candidates proposed. The results showed the presence of different non-volatile ink components in migration such as colorants (Solvent Red 49), plasticizers (dimethyl sebacate, tributyl o-acetyl citrate) or surfactants (SchercodineM, triethylene glycol caprilate). An oxidation product of an ink additive (triphenyl phosphine oxide) was also detected. In addition, a surface analysis technique, desorption electrospray mass spectrometry (DESI-MS), was used for analyzing the distribution of some ink components (tributyl o-acetyl citrate Schercodine L, phthalates) in the material. The detection of some of these compounds in the back-printed side confirmed the transference of this compound from the non-food to the food contact side. The results also showed that concentration of ink migrants decreased when an aluminum or polypropylene layer covered the ink. When aluminum was used, concentration of most of ink migrants decreased, and for 5 out of the 9 even disappeared.