Potential Of Ion Mobility Spectrometry Research Articles

Ion mobility-mass spectrometry to extend analytical performance in the determination of ergot alkaloids in cereal samples

This work evaluates the potential of ion mobility spectrometry (IMS) to improve the analytical performance of current liquid chromatography-mass spectrometry (LC-MS) workflows applied to the determination of ergot alkaloids (EAs) in cereal samples. Collision cross section (CCS) values for EA epimers are reported for the first time to contribute to their unambiguous identification. Additionally, CCS values have been inter-laboratory cross-validated and compared with CCS values predicted by machine-learning models. Slight differences were observed in terms of CCS values for ergotamine, ergosine and ergocristine and their corresponding epimers (from 3.3 to 4%), being sufficient to achieve a satisfactory peak-to-peak resolution for their unequivocal identification. A LC-travelling wave ion mobility (TWIM)-MS method has been developed for the analysis of EAs in barley and wheat samples. Signal-to-noise ratio (S/N) was improved between 2.5 and 4-fold compared to the analog LC-TOF-MS method. The quality of the extracted ion chromatograms was also improved by using IMS.

Discriminative potential of ion mobility spectrometry for the detection of fentanyl and fentanyl analogues relative to confounding environmental interferents.

The opioid crisis and emergence of fentanyl, fentanyl analogues, and other synthetic opioids has highlighted the need for sensitive and robust detection for interdiction at screening points, notably vehicles at border crossings and packages at postal facilities. This work investigates the discriminative potential, sensitivity and specificity, of ion mobility spectrometry (IMS) for the detection of fentanyl and fifteen (15) fentanyl-related compounds (analogues, other opioids, and metabolites) relative to confounding environmental interferents. The environmental background interferent levels, frequency and intensity, were derived from over 10 000 screening samples collected from delivery vehicles entering a federal site. A receiver operating characteristic (ROC) curve methodology was employed to quantify the relationship between sensitivity and specificity for these target compounds on two instruments/configurations. These instrument configurations differed in desorption and drift tube temperatures, reactant ion dopant chemistry, and analysis time. This work identified reduced mobility areas of high interference that resulted in increased false positive rates (FPR), effectively reducing sensitivity (true positive rate: TPR) in those regions. Except for a few target compounds on either of the instruments that exhibited elevated FPRs, detection of fentanyl and fentanyl-related species was achieved at single to tens of nanograms with ≥90% TPR and ≤2% FPR. This work established the importance of systematic environmental background characterization at each specific screening setting in evaluating a platform's true performance.

Smell the change: On the potential of gas-chromatographic ion mobility spectrometry in ecosystem monitoring.

Plant volatile organic compounds (pVOCs) are being recognized as an important factor in plant–environment interactions. Both the type and amount of the emissions appear to be heavily affected by climate change. A range of studies therefore has been directed toward understanding pVOC emissions, mostly under laboratory conditions (branch/leaf enclosure). However, there is a lack of rapid, sensitive, and selective analytical methods, and therefore, only little is known about VOC emissions under natural, outdoor conditions. An increased sensitivity and the identification of taxon‐specific patterns could turn VOC analysis into a powerful tool for the monitoring of atmospheric chemistry, ecosystems, and biodiversity, with far‐reaching relevance to the impact of climate change on pVOCs and vice versa. This study for the first time investigates the potential of ion mobility spectrometry coupled to gas‐chromatographic preseparation (GC‐IMS) to dramatically increase sensitivity and selectivity for continuous monitoring of pVOCs and to discriminate contributing plant taxa and their phenology. Leaf volatiles were analyzed for nine different common herbaceous plants from Germany. Each plant turned out to have a characteristic metabolite pattern. pVOC patterns in the field would thus reflect the composition of the vegetation, but also phenology (with herbaceous and deciduous plants contributing according to season). The technique investigated here simultaneously enables the identification and quantification of substances characteristic for environmental pollution such as industrial and traffic emissions or pesticides. GC‐IMS thus has an enormous potential to provide a broad range of data on ecosystem function. This approach with near‐continues measurements in the real plant communities could provide crucial insights on pVOC‐level emissions and their relation to climate and phenology and thus provide a sound basis for modeling climate change scenarios including pVOC emissions.

Potential of ion mobility spectrometry versus FT-MIR and GC-MS to study the evolution of a heat transfer fluid after its heating process in a thermosolar plant

Heat transfer fluid (HTF) is commonly used in heat transfer industrial processes such as those performed in thermosolar plants. Although HTF is thermally stable, the high temperatures used in such plants (around 400°C) and overheating in continuous cycles can alter its composition. The potential changes in its initial composition (biphenyl and diphenyl ether), and the likely production of new compounds, such as benzene and phenol, require using fast-response portable instruments for on-site quality control at thermosolar plants. In this work, the degradation profile of HTF heated for a variable time was for the first time characterized by using two different ion mobility spectrometry (IMS) instruments. The simple one used a UV lamp as ionization source (UV-IMS), whereas the other included a chromatographic column coupled to a tritium source (GC-3H-IMS). Other analytical techniques such as Fourier transform-mid infrared spectroscopy (FT-MIR) and gas chromatography–mass spectrometry (GC-MS) were also used for the same purpose. Based on the results, both IMS instruments can be useful for online quality control of HTF in a thermosolar plant. Thus, the UV-IMS instrument can be used for screening purposes and the GC-3H-IMS instrument for selective detection of benzene and phenol as degradation products.

The potential of ion mobility spectrometry (IMS) for detection of 2,4,6-trichloroanisole (2,4,6-TCA) in wine

The off-flavor of “tainted wine” is attributed mainly to the presence of 2,4,6-trichloroanisole (2,4,6-TCA) in the wine. In the present study the atmospheric pressure gas-phase ion chemistry, pertaining to ion mobility spectrometry, of 2,4,6-trichloroanisole was investigated. In positive ion mode the dominant species is a monomer ion with a lower intensity dimer species with reduced mobility values (K0) of 1.58 and 1.20cm2V−1s−1, respectively. In negative mode the ion with K0=1.64cm2V−1s−1 is ascribed to a trichlorophenoxide species while the ions with K0=1.48 and 1.13cm2V−1s−1 are attributed to chloride attachment adducts of a TCA monomer and dimer, respectively. The limit of detection of the system for 2,4,6-TCA dissolved in dichloromethane deposited on a filter paper was 2.1μg and 1.7ppm in the gas phase. In ethanol and in wine the limit of detection is higher implying that pre-concentration and pre-separation are required before IMS can be used to monitor the level of TCA in wine.

Determination of trace impurities in cosmetic intermediates by ion mobility spectrometry

The cosmetic and pharmaceutical industries are continuously demanding fast, efficient, cost-effective analytical methods to monitor production processes and assure end-product quality. The presence of residual reagents or impurities formed during a synthetic process can have an adverse impact on product quality, assurance of which requires using increasingly sensitive analytical methods to facilitate the detection and/or determination of toxic compounds with potentially hazardous effects on consumer's health. In this work, we assessed the potential of ion mobility spectrometry (IMS) for the detection and quantitation of dimethylaminopropylamine (DMAPA) residues in stearamidopropyldimethylamine (SAPDA) production samples. The influence of instrumental variables including solvent, solution drying time, injected volume and volatilization temperature was examined. The ensuing analytical method takes less than 1 min per analysis and uses only a few microlitres of sample. The calibration curve was linear over the DMAPA concentration range 0.030–0.500 μg mL −1. The proposed method was validated for use in control processes. The complex plasmagram for amidoamines allows the origin of cosmetic oils to be easily, expeditiously identified. Based on the results, IMS holds great promise for the qualitative and quantitative determination of the studied amide and various others in cosmetic products.

Ion mobility spectrometry as a high-throughput technique for in vitro transdermal Franz diffusion cell experiments of ibuprofen

Rapid, low-cost and sensitive analytical methods are needed to analyse the large number of samples that are generated when investigating the absorption profile of drugs through the skin using Franz diffusion cell experiments (FDC). The goal of this study was to evaluate the potential of ion mobility spectrometry (IMS) for the quantitative analysis of active pharmaceutical ingredients (API) in transdermal research. Ibuprofen was used as a model drug and the optimal IMS parameters were determined using a Doehlert experimental design. To assess the usefulness of the IMS method, FDC experiments using human skin were conducted, covering a concentration range of 0.32–69.57 μg/ml. The resulting analytical samples were analysed using IMS and subsequently compared to HPLC as a reference method. No significant differences were found between the results obtained using both analytical methods, with a mean skin permeability coefficient ( K p) value of 0.013 cm/h. The combination of fast detection times, sensitivity, low costs and easy maintenance of IMS instruments makes this technique an attractive alternative for HPLC in this type of experiments.

Analyses of mouse breath with ion mobility spectrometry: a feasibility study

Exhaled breath can provide comprehensive information about the metabolic state of the subject. Breath analysis carried out during animal experiments promises to increase the information obtained from a particular experiment significantly. This feasibility study should demonstrate the potential of ion mobility spectrometry for animal breath analysis, even for mice. In the framework of the feasibility study, an ion mobility spectrometer coupled with a multicapillary column for rapid preseparation was used to analyze the breath of orotracheally intubated spontaneously breathing mice during anesthesia for the very first time. The sampling procedure was validated successfully. Furthermore, the breath of four mice (2 healthy control mice, 2 with allergic airway inflammation) was analyzed. Twelve peaks were identified directly by comparison with a database. Additional mass spectrometric analyses were carried out for validation and for identification of unknown signals. Significantly different patterns of metabolites were detected in healthy mice compared with asthmatic mice, thus demonstrating the feasibility of analyzing mouse breath with ion mobility spectrometry. However, further investigations including a higher animal number for validation and identification of unknown signals are needed. Nevertheless, the results of the study demonstrate that the method is capable of rapid analyses of the breath of mice, thus significantly increasing the information obtained from each particular animal experiment.

Breath analysis—performance and potential of ion mobility spectrometry

Ion mobility spectrometry is a fast and sensitive analytical method for the detection of gas phase analytes in the ppbv–pptv range under ambient conditions (pressure and temperature). Ion mobility spectrometers coupled with rapid pre-separation like multi-capillary columns (MCC/IMS) are suitable for the selective characterization of complex and humid mixtures. Recently, MCC/IMS have been applied to analyses of human breath for early diagnosis as well as medication and therapy control. The complete procedure of breath analyses including evaluation and interpretation of the data obtained is demonstrated for the first time on exhaled breath after the consumption of a particular candy as an example. An MCC/IMS equipped with a β-radiation source (63Ni) requires 5 to 10 min for a complete analysis of exhaled breath. Retention time and reduced ion mobility of the detected signals are compared to an analyte database for the identification of the related analytes. These findings were successfully validated by gas-chromatographic mass spectroscopy of the headspace of the candy via solid-phase micro-extraction and of breath samples on Tenax adsorption tubes. Furthermore, signal height of particular analyte signals as a measure for their concentration was used to monitor the concentration development with time. This exemplary investigation demonstrates that MCC/IMS is a powerful and rapid non-invasive tool for human breath analyses. The method can be used for medical applications (diagnosis, therapy control, metabolic profiling) as well as for a general determination of the metabolic state of a subject (medication, nutrition, fasting). The demonstrated procedure is independent of whether the analytes detected in breath are caused by nutrition or medication or whether they are metabolite characteristics for a particular disease. Therefore, it can directly be transferred to any relevant peak pattern.

Exemplar application of multi-capillary column ion mobility spectrometry for biological and medical purpose

In recent years, ion mobility spectrometry is increasingly in demand for new applications especially on biological samples (cells, bacteria, fungi), in medicine (diagnosis, therapy and medication control e.g. from breath analyses), for food quality control, safety monitoring and characterisation or process control in chemical and pharmaceutical industry. For this purpose instruments based on gas phase separation of ions in weak electric fields were developed at ISAS–Institute for Analytical Sciences, focussing on the particular challenges such as humid and rather complex samples, specific sampling procedures adapted to the application, fast pre-separation techniques like multi-capillary columns and suitable data processing including data bases for relevant analytes and automatic characterisation of IMS-chromatograms. Feasibility studies were carried out successfully for biological and medical purpose at ISAS, including the detection of bacteria, fungi and metabolites of cells and in human breath. For all those samples characteristic pattern of analytes were found and could be used for the identification of cell lines, fungi and bacteria as well as of numerous diseases. Furthermore, the quantification of those analytes could be used to obtain information about the state of the process or person (e.g. growth of cultures, development of diseases, level of medication, grade of cancer). Those examples shall demonstrate the potential of ion mobility spectrometry for the selected applications. However, a general and reliable data bases of reference analytes is required in the near future to enable an exploitation of the metabolic pathways and to confirm the relevance of the detected signals for the investigated topic.

Analysis of Bio‐Processes using Ion Mobility Spectrometry

AbstractBio‐processes are ruled by the metabolism of the involved microorganisms. During the process, the metabolism of these microorganisms changes their environment and as a consequence, the metabolites produced by the microorganisms will change too. Therefore, those metabolites can be used to characterize such processes. Many of the metabolites are volatile or semi‐volatile organic compounds which can be identified and quantified with high temporal resolution and sufficient sensitivity using ion mobility spectrometry. The potential of this method, especially when multi‐capillary‐columns are used for rapid pre‐separation, is illustrated on several representative and successful examples such as beer fermentation control, wine characterization, identification of fungi and bacteria as well as quantification of their metabolites as a measure for the growth of the culture. Those examples, representing recent work of the ion mobility spectrometry group at ISAS – Institute for Analytical Sciences in Dortmund, Germany, illustrate the potential of ion mobility spectrometry for bio‐process control, on one hand, and the existing challenges, on the other.

Analysis of pharmaceutical formulations using atmospheric pressure ion mobility spectrometry combined with liquid chromatography and nano-electrospray ionisation

The hyphenation of liquid chromatography with atmospheric pressure ion mobility spectrometry is reported using a custom-made dynamic nano-electrospray ionisation (nano-ESI) interface. The analysis of pharmaceutical actives is described, including beta blocker (timolol), antidepressant (paroxetine), analgesic (paracetamol) and opiate (codeine) preparations. On-line ultraviolet diode array (UV) spectroscopic detection was used prior to sample ionisation, to evaluate chromatographic and nano-ESI interface performance. Active drug responses were characterised by chromatographic retention time and electrophoretic ion mobility drift time, and selected ion mobility responses were used to evaluate method performance. Limits of detection for active drugs were in the low-nmol to pmol range. Quantitative responses were investigated using a series of standard solutions of caffeine, showing good linearity (R(2) = 0.9982, n = 6) and reproducibility (RSD = 2.3 %, n = 6). The analysis of an over the counter pharmaceutical formulation demonstrates the potential of ion mobility spectrometry combined with liquid chromatography and nano-electrospray ionisation for the rapid determination of active drugs, as a result of the electrophoretic separation and selectivity afforded by IMS.

A small subsurface ion mobility spectrometer sensor for detecting environmental soil-gas contaminants

A small subsurface ion mobility spectrometer (SS-IMS) was constructed and tested with several environmental contaminants to determine its potential for monitoring gaseous volatile organic compounds in the vadose zone. Trichloroethylene (TCE) and tetrachloroethylene (PCE) were detected and separated in IMS for the first time. Detection limits as low as 1 part per billion volume-to-volume (ppb(v)) were observed. Reduced mobility (K(0)) values were reported for 11 environmental contaminants. These data demonstrated the potential of ion mobility spectrometry as a viable technology for detecting and separating environmental soil-gas contaminants in the field, which may lead to a practical and simple approach for long-term monitoring of contaminated soils.

Demonstrated Potential of Ion Mobility Spectrometry for Detection of Adulterated Perfumes and Plant Speciation

This initial study evaluates the use of ion mobility spectrometry (IMS) as a rapid test procedure for potential detection of adulterated perfumes and speciation of plant life. Sample types measured consist of five genuine perfumes, two species of sagebrush, and four species of flowers. Each sample type is treated as a separate classification problem. It is shown that discrimination using principal component analysis with K-nearest neighbors can distinguish one class from another. Discriminatory models generated using principal component regressions are not as effective. Results from this examination are encouraging and represent an initial phase demonstrating that perfumes and plants possess characteristic chemical signatures that can be used for reliable identification.

Studies on gas-phase positive ion-molecule reactions initiated by proton transfer to alcohols: the reactions of 2-methyl-2-propanol ( t-butyl alcohol) with H 3O + in a Fourier transform mass spectrometer (FTMS)

An understanding of the chemistry of the ion-molecule reactions occurring in an ion mobility system is a prerequisite to fully exploiting the potential of Ion Mobility Spectrometry for the detection and monitoring of pollutants. Whilst it is commonly thought that clustering around a proton is the dominant process occurring in the positive ion mode, previous studies have shown that much more complex processes can and do occur. The present paper is the first of a series reporting fundamental investigations of the ion-molecule reactions that can be initiated by proton transfer at low pressure in a Fourier transform mass spectrometer. Preliminary studies have shown that carbonium ion formation could be the dominant process. It was therefore decided that, as a first step, the reactions of t-butyl alcohol (2-methyl-2-propanol) would be studied as the carbonium ion would, if formed, not undergo any rearrangement being already in its most stable and energetically well-characterised structure.