Application Of Ion Mobility Spectrometry Research Articles

IDSimF: An Open-Source Framework for the Simulation of Molecular Ion Dynamics in Mass Spectrometry and Ion Mobility Spectrometry.

The development of mass spectrometric and ion mobility devices heavily depends on a comprehensive understanding of the behavior of ions within such systems. Therefore, numerical modeling of ion paths helps to optimize and verify existing devices, and contributes to the development of innovative ion optical systems and multipole geometries. This Article introduces IDSimF (Ion Dynamics Simulation Framework), an open-source simulation tool tailored to the nonrelativistic dynamics of molecular ions in mass and ion mobility spectrometry applications. Addressing limitations in existing software packages, as for example SIMION, OpenFOAM, and COMSOL, IDSimF offers a specialized platform for simulating ion trajectories in electric fields. IDSimF efficiently accounts for space charge effects and considers various ion-neutral collision models while handling chemical kinetics. The framework is highly modular with reduced user input configuration complexity and aims to support simulation efforts in development and optimization of in mass spectrometers.

Ion Moblity Mass Spectrometry in Multi-omics Studies

Mass spectrometry (MS) as an analytical technique enables the identification and quantitative determination of proteins, metabolites, or lipids in a studied sample. However, this method has limitations regarding the number of molecules that can be identified at a given time. To increase the number of identifications, the application of ion mobility spectrometry (IMS) can be employed. This technique allows the separation of ions based on their mobility while traversing the analyser in a gradient of an electromagnetic field and opposing gas pressure. The separation is performed in conjunction with MS analysis, adding another dimension to the analysis, resulting in a significant improvement in the number of identified compounds and a reduction in noise. Alternatively, while maintaining the same number of identifications, analysis can be performed in a shorter time period. It is crucial to pay special attention to the type of IMS analyser used, as its specific implementation dictates further stages of analysis and ion detection capabilities.

Geographical authentication of saffron by chemometrics applied to the ion mobility spectrometry data

There is a lack of a reliable tool for quickly determining the geographical origins of saffron (SFR). Ion mobility spectrometry (IMS) has emerged as a promising method for rapid authentication. In this study, 232 Iranian SFR samples harvested in five distinct areas (Khorasan, Azerbaijan, Golestan, Fars, and Isfahan) were analyzed by IMS coupled with chemometric methods. The principal component analysis (PCA) was applied for analyzing the collected IMS data, utilizing three principle components (PCs) that accounted for 81 % of the explained variance. Moreover, the partial least squares-discriminant analysis (PLS-DA) demonstrated the average sensitivity and specificity rates, of 72.3 % to 92.5 % for the exernal test set and 75.5 % to 94.3 % for training set. The accuracy values were ≥ 85.0 % for the prediction set for all classes of samples. The results of this study revealed a successful application of IMS and chemometric methods for rapid geographical authentication of saffron samples in Iran.

Application of Ion Mobility Spectrometry and the Derived Collision Cross Section in the Analysis of Environmental Organic Micropollutants.

Ion mobility spectrometry (IMS) is a rapid gas-phase separation technique, which can distinguish ions on the basis of their size, shape, and charge. The IMS-derived collision cross section (CCS) can serve as additional identification evidence for the screening of environmental organic micropollutants (OMPs). In this work, we summarize the published experimental CCS values of environmental OMPs, introduce the current CCS prediction tools, summarize the use of IMS and CCS in the analysis of environmental OMPs, and finally discussed the benefits of IMS and CCS in environmental analysis. An up-to-date CCS compendium for environmental contaminants was produced by combining CCS databases and data sets of particular types of environmental OMPs, including pesticides, drugs, mycotoxins, steroids, plastic additives, per- and polyfluoroalkyl substances (PFAS), polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs), as well as their well-known transformation products. A total of 9407 experimental CCS values from 4170 OMPs were retrieved from 23 publications, which contain both drift tube CCS in nitrogen (DTCCSN2) and traveling wave CCS in nitrogen (TWCCSN2). A selection of publicly accessible and in-house CCS prediction tools were also investigated; the chemical space covered by the training set and the quality of CCS measurements seem to be vital factors affecting the CCS prediction accuracy. Then, the applications of IMS and the derived CCS in the screening of various OMPs were summarized, and the benefits of IMS and CCS, including increased peak capacity, the elimination of interfering ions, the separation of isomers, and the reduction of false positives and false negatives, were discussed in detail. With the improvement of the resolving power of IMS and enhancements of experimental CCS databases, the practicability of IMS in the analysis of environmental OMPs will continue to improve.

Cyanide determination in postmortem blood samples using Headspace-Ion Mobility Spectrometry (HS-IMS)

Interest in facile and sensitive methods for cyanide detection is related to the extreme cyanide toxicity and its importance in forensic toxicology. In this research a novel application of Ion Mobility Spectrometry (IMS) was demonstrated for rapid determination of cyanide poisoning in postmortem toxicology. In addition, a simple method for the sample preparation was applied based on the analyte (cyanide anion) transfer as HCN to the headspace and direct injection to IMS. The method showed a linear dynamic range of 50–2000 µg/L with R2 > 0.99, a high sensitivity (LOD of 20.4 µg/L and LOQ of 68.1 µg/L). Good repeatability (intra- and inter-assays, CV < 15 %) and excellent extraction recovery (82 -94 %) were obtained. After validation, the method was applied in the analysis of postmortem human blood samples in forensic cases. In all samples, the cyanide was promptly quantified.

Pyoverdine Analysis - From High-resolution MS/MS Fragmentation to Ion Mobility Measurements.

Microorganisms produce iron chelators called siderophores that are a rich source for drug discovery or plant protective agents. Pyoverdines are a class of siderophores from fluorescent Pseudomonas members and consist of different peptide chains specific to each bacterial species. The structural elucidation and characterization of pyoverdines require comprehensive analytical methods as bacterial extracts are complex mixtures. Here, we present a high-throughput UHPLC-MS/MS pipeline and the application of ion mobility spectrometry to facilitate research in the field of medicine and agriculture.

Rapid screening of 14 antibacterial drugs in anti-acne cosmetics using ion mobility spectrometry coupled with solid-phase extraction

The main methods currently used to detect illegally added chemicals in cosmetics include thin-layer chromatography, high performance liquid chromatography (HPLC), gas chromatography (GC), and liquid chromatography-mass spectrometry (LC-MS). Compared with other analytical techniques, these methods have the advantages of high sensitivity, specificity, and accuracy, all of which are required in practical detection work. However, they also present a number of limitations, such as long analysis times and requirements for skilled operators and strictly controlled laboratory environments. Supervision, a growing trend in market surveillance, requires rapid and effective methods to screen illegally added chemicals. The suspected samples are sealed for some time and then sent to the laboratory for further testing. Ion mobility spectrometry (IMS) is a new type of trace gas separation technology that was developed in recent years. The principle behind IMS is the separation and characterization of chemical species based on differences in the migration speed of their gas-phase ions under an electric field. As this technology has the advantages of miniaturization, easy operation, and quick responses, it is widely used in food and drug quality testing, as well as other related fields. However, it is rarely used in cosmetic detection, likely because the cosmetics matrix is highly complex, which can interfere with ion determination. Thus, optimizing the pretreatment process of cosmetics for IMS is important. In this work, solid-phase extraction (SPE) is combined with IMS to establish a method for the rapid screening of 14 antibacterial drugs in anti-acne cosmetics. The IMS detection parameters, sample extraction conditions, and SPE clean-up conditions (SPE column, type of leachate, type and volume of eluent) were studied and optimized in detail. The sample was extracted with 80%(v/v) acetonitrile aqueous solution (containing 0.2% (mass fraction) trichloroacetic acid), loaded onto an activated Oasis® MCX SPE column, leached with 3.0 mL of methanol, and eluted with 1.0 mL of 2% ammonia methanol solution. The eluate was then directly injected into the IMS instrument. The IMS parameters were as follows: positive ion source voltage=2200 V, transfer tube voltage=8000 V, inlet temperature=180 ℃, transfer tube temperature=180 ℃, ion gate voltage=50 V, gate voltage pulse width=85 μs, and migration gas flow rate=1.2 L/min. The migration times for the 14 antibacterial drugs ranged from 11 to 17 ms, and the detection limits for the target compounds ranged from 0.2 to 1.2 μg/g. Owing to the narrow linear range of IMS, a quantitative method employing HPLC was also established to optimize the SPE pretreatment step and verify the positive samples. Chromatographic separation was conducted on a Phenomenex Luna C18 column (250 mm×4.6 mm, 5 μm), with a column flow rate of 1.0 mL/min and gradient elution with mobile phases A (0.01 mol/L potassium dihydrogen phosphate adjusted to pH 4.0 with phosphoric acid) and B (acetonitrile). The column temperature was set to 35 ℃, and the injection volume was fixed at 5 μL. A total of 25 cosmetics samples were screened, and one positive sample was found to be consistent with the results of HPLC. The proposed method is fast, simple, and efficient, and it can be used for the rapid screening of the 14 antibacterial drugs in anti-acne cosmetics. Pretreatment can significantly reduce the influence of the cosmetic matrices on the determination results, improve instrument sensitivity, and effectively decrease the occurrence rate of false positives and negatives. The technique developed in this work can improve the efficiency of screening for illegally added chemicals and expand the applications of IMS for detecting various chemicals in complex matrices, such as cosmetics.

Rapid metabolites fingerprinting by ion mobility spectrometry: A novel evaluation method for bio-adulteration of saffron (Crocus sativus L.)

This research presents an application of ion mobility spectrometry (IMS) for investigating adulteration of saffron (SA) with five specific bio-adulterants of plant source i.e., safflower (SAF), calendula (CAL), curcumin (CUR), sumac (SUM), and SA-stamens (SST). For this purpose, 10 SA spices were adulterated with different proportions (ranging from 0% to 50%) of these bio-adulterants. Each sample type had unique metabolites, and the fingerprints of SA metabolites significantly changed with increasing the bio-adulteration ratio, particularly at drift zones ranging from 6.51 to 14.34 ms. Principal component analysis and hieratical clustering provided excellent grouping patterns for discriminating pure SA and its bio-adulterants. In addition, promising results were obtained for predicting the adulteration ratio of SAF, CAL, CUR, SUM, and SST by partial least square regression (PLSR). The values of root-mean-square error (RMSE) and correlation of multiple determination (R 2 ) were in the ranges of 4.82–10.23%, and 0.644–0.920 for the test set samples, respectively. • A good and rapid IMS-CDI + method introduced for detecting fraud in saffron. • The developed PCA/HCA models are able to detect some bio-adulterants in saffron. • The VIP-PLSR analysis can predict content of different bio-adulterants in saffron. • The selected multivariate analysis revealed acceptable performance in LVs ≤ 13.

Isoflurane as an Accurate Negative Mode Calibrant for Ion Mobility Spectrometry.

The search for suitable ion mobility spectrometry (IMS) calibrant compounds is ongoing and necessitates the use of highly accurate reduced ion mobility (K0) values across a range of instrumental conditions. Such values will be used in calibrating devices to shift the ion mobility scales and alarm windows for chemicals of interest to their proper locations based on the instrumental conditions present during calibration and sampling. Many positive ion mode calibrants have been investigated, whereas investigations for a negative ion detection mode calibrant have been more limited. Isoflurane (IsoF) is a strong candidate as a negative ion mode calibrant. This report documents the accurately measured K0 values for IsoF product ions as a function of multiple instrumental parameters. K0 values were measured in two instrumentation modes as a function of drift gas temperature, water concentration, and dopant concentration. This report culminates with our evaluation of the suitability of IsoF as a negative ion mode calibrant for IMS applications.

Pharmaceutical and Bio-analytical Applications of Ion Mobility Spectrometry for Determination of Clopidogrel (Plavix)

Clopidogrel with trade name plavix, is used effectively to reduce the incidence of ischaemic strokes, heart attacks and claudication. In this study, an ion mobility spectrometry (IMS) method was proposed for the clopidogrel determination in analytical and bio-analytical fields. Under experimental conditions, the analytical validation parameters of the proposed method were calculated and reported. The calibration graph was linear in range 30.0–2000.0 µg mL-1 for clopidogrel with two orders of magnitude and a goodness of fit, R > 0.99. The coefficient of variation (precision, n=10) was found to be within 7.5–8.6%, and also the concentration levels of 3.0 and 10.0 µg mL-1 from analyte were obtained for the limits of detection and quantification, respectively. The developed IMS method was successfully applied to determine clopidogrel with accurate recovery range (90.0–103.7%) in different matrices. The validation studies showed that the applied IMS was a simple, rapid, sensitive and reliable method for the clopidogrel analysis in the pharmaceutical and biological samples.

Ion Mobility–Mass Spectrometry for Bioanalysis

This paper aims to cover the main strategies based on ion mobility spectrometry (IMS) for the analysis of biological samples. The determination of endogenous and exogenous compounds in such samples is important for the understanding of the health status of individuals. For this reason, the development of new approaches that can be complementary to the ones already established (mainly based on liquid chromatography coupled to mass spectrometry) is welcomed. In this regard, ion mobility spectrometry has appeared in the analytical scenario as a powerful technique for the separation and characterization of compounds based on their mobility. IMS has been used in several areas taking advantage of its orthogonality with other analytical separation techniques, such as liquid chromatography, gas chromatography, capillary electrophoresis, or supercritical fluid chromatography. Bioanalysis is not one of the areas where IMS has been more extensively applied. However, over the last years, the interest in using this approach for the analysis of biological samples has clearly increased. This paper introduces the reader to the principles controlling the separation in IMS and reviews recent applications using this technique in the field of bioanalysis.

Application of Ion Mobility Spectrometry for Permeability Studies of Organic Substances through Polymeric Materials.

Drift tube ion mobility spectrometers (DT IMS) allow the concentration of different organic compounds to be measured. This gives the opportunity to use these detectors in measuring the penetration of various substances through polymer membranes. Permeation measurements of two substances (2-heptanone and dimethyl methylphosphonate (DMMP)) through a cylindrical silicone rubber membrane were carried out. The membrane separated the aqueous solution from the air. The analyte was introduced into water, and then its concentration in air on the opposite side of the membrane was recorded. Based on the dynamics of detector signal changes, the diffusion coefficients for both tested substances were determined. Determination of permeability coefficients was based on precise quantitative measurements, which took into account the non-linearity of the detector characteristics and the effect of water on detection sensitivity. The analysis of measurement results was based on a mathematical description of diffusion process.

Ion mobility spectrometry - Mass spectrometry coupling for synthetic polymers.

This review covers applications of ion mobility spectrometry (IMS) hyphenated to mass spectrometry (MS) in the field of synthetic polymers. MS has become an essential technique in polymer science, but increasingly complex samples produced to provide desirable macroscopic properties of high-performance materials often require separation of species prior to their mass analysis. Similar to liquid chromatography, the IMS dimension introduces shape selectivity but enables separation at a much faster rate (milliseconds vs minutes). As a post-ionization technique, IMS can be hyphenated to MS to perform a double separation dimension of gas-phase ions, first as a function on their mobility (determined by their charge state and collision cross section, CCS), then as a function of their m/z ratio. Implemented with a variety of ionization techniques, such coupling permits the spectral complexity to be reduced, to enhance the dynamic range of detection, or to achieve separation of isobaric ions prior to their activation in MS/MS experiments. Coupling IMS to MS also provides valuable information regarding the 3D structure of polymer ions in the gas phase and regarding how to address the question of how charges are distributed within the structure. Moreover, the ability of IMS to separate multiply charged species generated by electrospray ionization yields typical IMS-MS 2D maps that permit the conformational dynamics of synthetic polymer chains to be described as a function of their length.

Ion Mobility Spectrometry as a Potential Tool for Flavor Control in Chocolate Manufacture.

Chocolate has a complex flavor profile composed of more than 600 volatile compounds that mainly arise from the thermo-mechanical treatment during roasting and conching. The aim of this study was to evaluate the applicability of ion mobility spectrometry (IMS), as a real-time method for process monitoring in chocolate manufacture. It is evident from the ion mobility (IM) fingerprint spectra that individual processing steps affect the signal intensities at particular drift time regions. The analysis of individual IM spectra by principal component analysis (PCA) revealed that it is possible to distinguish with respect to conching temperature and time. PCA also allowed identifying those parts of the IM spectra that were predominantly affected by the respective treatment. It was, on the basis of the IM flavor fingerprints and subsequent PCA, possible to distinguish between the different states of processing of bulk cocoa. The results of the study imply that, using appropriate post-data treatment, IMS could be used for process control in cocoa processing.

Enhancing the sensitivity of ion mobility spectrometry using the ion enrichment effect of non-uniform electrostatic field

The diversified applications of ion mobility spectrometry (IMS) frequently pose challenges to the sensitivity of IMS measurements. In this work, the ion density evolution profiles of a continuous flow of ions travelling in non-uniform electrostatic fields were studied. Based on that, an ion enrichment method was proposed for enhancing the sensitivity of IMS. It employed a gradually weakening electrostatic field in the ionization region of IMS and achieved ion density enhancement for the ion flow migrating from the ion source to the ion shutter. Using that method, the ion density of the ion flow produced by the ion source was increased by 180% when approaching the ion shutter. With the increased ion density, the limit of detection (LOD) for DMMP dimer peak was lowered from 425 to 200 pptv. Meanwhile, there was a slight reduction in the resolving power, which was tentatively assigned to the enhanced coulomb repulsion along with the increased ion density. The resolving power of the IMS with a drift length of 60 mm was still maintained around 80 at 100 degrees Celsius. The ion enrichment method needs no radial-confining radio frequency voltage. Also, it does not affect the response speed of IMS.

Calibration of complex mixtures in one sweep

The calibration of extremely complex humid gas-phase mixtures – often required in ion mobility spectrometry applications – is challenging, even when high-performance calibration gas generators such as HovaCAL® are applied. Here, we describe an approach to develop and apply mixtures of VOCs in one channel of such a calibration gas generator for a complex calibration in one sweep. As an example, a mixture of so-called “Signs of Life” – compounds available in the exhaled breath and/or in the sweat of everybody was used. The procedure of developing the appropriate mixture and the results of a successful calibration of a GC-ion mobility spectrometer are presented.

Evaluation and validation of an ion mobility quadrupole time-of-flight mass spectrometry pesticide screening approach.

An ion mobility quadrupole time-of-flight mass spectrometry-based pesticide suspect screening methodology was developed and validated covering 20 plant-derived food matrices deriving from six commodity groups of different complexity according to the actual European Commission document SANTE/11813/2017 applying a QuEChERS sample preparation protocol. The method combines ultra-performance liquid chromatography, traveling wave ion mobility, and quadrupole time-of-flight mass spectrometry. Besides the determination of the physicochemical property collision cross-section and the establishment of a corresponding scientific suspect screening database comprising 280 pesticides for several pesticides, different protomers, sodium adducts, as well as dimers were identified in ion mobility spectrometry traces. Additionally, collision cross-section values were included in the validation requirements regarding chromatography and mass spectrometry for the detection of pesticides. A collision cross-section value window was analyzed within a tolerable error of ±2%. For this cross-matrix validation, screening detection limits were determined at concentration levels of 0.100mg/kg (84% of the original pesticide scope), 0.010mg/kg (56%), and 0.001mg/kg (21%). By application of ion mobility spectrometry, the compound identification was improved due to independence of commodity of concern and concentration levels of analyte molecules, as false assignments are reduced by application of a collision cross-section range.

Using ion mobility spectrometry for screening the autoxidation of peanuts

Autoxidation is a critical process in many fat containing foods that leads to reduced palatability because of the formation of off-flavour compounds. The aim of the study was to evaluate the applicability of ion mobility spectrometry (IMS) for detecting volatile off-flavour indicators from roasted peanuts which were subjected to storage at elevated temperature. IMS measurements were carried out using a sample inlet system that allowed to keep the reactant ion peak constant. It is evident from the ion mobility spectra that the level of autoxidation significantly affects the signal intensities in particular drift time regions. Supported by the IMS measurement of pure hexanal, and by qualitative analysis for volatile aldehydes and organic acids, the IMS peaks at relative drift times of approx. 1.7 have a large potential for being used as rancidity indicators.

Gas phase ion chemistry: what do we know about reactions and ion formation?

It is certainly the case that numerous sensor techniques operate based onmeasuring principles which are far less complex than those associated with ion mobility spectrometry (IMS). However, the additional complexity of IMS provides a higher level of quantitative and qualitative information. The ion mobility measurements provide characteristic spectra for investigated samples and do not merely provide a sum signal. The results are available within seconds and contain a high level of information density with excellent detection limits for numerous chemical substances. The formation of ions from neutral sample molecules is the first and possibly the most significant event during ion mobility measurements. The ionization of a sample occurs in air or nitrogen at ambient pressure. This atmospheric pressure chemical ionization (APCI) provides both the sensitivity and selectivity achieved by IMS. The most common APCI source used in IMS analyzers today is a radioactive ionization source, typically 100 or 370 MBq of Nickel (Ni) or Tritium (H). Unfortunately, these ion sources with radioactive isotopes require special use permits and licensing procedures. Moreover, the freedom to transport such analyzers is limited by certain legal constraints and semi-annual leak tests represent an additional cost and burden of ownership. For these reasons, nonradioactive ion sources have been explored and developed as alternatives to traditional radioactive sources. These developments led to the discovery of a variety of ion sources which can be used for gas sensing with IMS. More than 10 different ionization principles are described in recent review articles and monographs for the measurement of gaseous compounds [H. Borsdorf, T. Mayer, M. Zarejousheghani, G.A. Eiceman, Appl. Spectrosc. Rev. 46 (2011) 472–521; G.A. Eiceman, Z. Karpas, H.H. Hill, Ion Mobility Spectrometry, Third Edition, Taylor & Francis Group, 2013]. Each of these ion sources provides different ionization pathways and ionization reactions. Additionally, the gas phase reactions during and after ionization are considerably affected by experimental parameters (e.g., humidity, temperature, pressure). In particular, differences in temperature and humidity can result in the formation of different reactant ions and product ions. Furthermore, the sample matrix and accompanying substances can affect the gas phase reactions in IMS. All of these parameters not only influence the nature of ions formed during gas phase ion chemistry, but also affect their relative abundance depending on the experimental conditions and sample matrix. As can be seen, gas phase ion chemistry is quite complex and the prediction of possible reaction pathways requires the consideration of numerous parameters. As we move away from radioactive ionization sources and develop new ionization techniques, the study of the ionization chemistry is critical both in maintaining the ability to detect analytes in existing IMS applications as well as the development of methods to detect emerging threats. While IMS was solely used as a gas-phase analyzer in preceding decades, further developments, especially in electrospray ionization and its derivatives, now permit it to be routinely used for the analysis of liquid samples. These ion sources use high electric fields on a solution as a means to ionize polar non-volatile substances using different mechanisms than those in APCI techniques. However, ion chemistry does not stop in front of the shutter grid. Reactions can also occur as ions travel through the * Helko Borsdorf helko.borsdorf@ufz.de

Rapid and Accurate Detection of Urinary Pathogens by Mobile IMS-Based Electronic Nose: A Proof-of-Principle Study

Urinary tract infection (UTI) is a common disease with significant morbidity and economic burden, accounting for a significant part of the workload in clinical microbiology laboratories. Current clinical chemisty point-of-care diagnostics rely on imperfect dipstick analysis which only provides indirect and insensitive evidence of urinary bacterial pathogens. An electronic nose (eNose) is a handheld device mimicking mammalian olfaction that potentially offers affordable and rapid analysis of samples without preparation at athmospheric pressure. In this study we demonstrate the applicability of ion mobility spectrometry (IMS) –based eNose to discriminate the most common UTI pathogens from gaseous headspace of culture plates rapidly and without sample preparation. We gathered a total of 101 culture samples containing four most common UTI bacteries: E. coli, S. saprophyticus, E. faecalis, Klebsiella spp and sterile culture plates. The samples were analyzed using ChemPro 100i device, consisting of IMS cell and six semiconductor sensors. Data analysis was conducted by linear discriminant analysis (LDA) and logistic regression (LR). The results were validated by leave-one-out and 5-fold cross validation analysis. In discrimination of sterile and bacterial samples sensitivity of 95% and specificity of 97% were achieved. The bacterial species were identified with sensitivity of 95% and specificity of 96% using eNose as compared to urine bacterial cultures. In conclusion: These findings strongly demonstrate the ability of our eNose to discriminate bacterial cultures and provides a proof of principle to use this method in urinanalysis of UTI.