Use Of Ion Mobility Spectrometry Research Articles

Effective Chiral Discrimination of Amino Acids through Oligosaccharide Incorporation by Trapped Ion Mobility Spectrometry.

Chiral analysis is critical to many research fields due to different biological functions of enantiomers in living systems. Although the use of ion mobility spectrometry (IMS) has become an alternative technology in the area of chiral measurements, there is still a lack of a general chiral selector for IMS-based chiral recognition, especially for small chiral molecules. Here, a new method using oligosaccharides as the chiral selector has been developed to discriminate chiral amino acids (AAs) by trapped ion mobility spectrometry-mass spectrometry (TIMS-MS). We analyzed 21 chiral amino acids, including small molecules (e.g., alanine and cysteine). Our data showed that the use of nonreducing tetrasaccharides was effective for the separation of chiral AAs, which differentiated 21 chiral AAs without using metal ions. By further incorporating a copper ion, the separation resolution could be improved to 1.64 on average, which accounts for an additional 52% improvement on top of the already achieved separation in metal-free analysis. These results indicate that the use of tetrasaccharides is an effective strategy for the separation of AA enantiomers by TIMS. The method developed in this study may open up a new strategy for effective IMS-based chiral analysis.

Indoor and outdoor determination of pesticides in air by ion mobility spectrometry

The use of ion mobility spectrometry (IMS) has been evaluated as analytical methodology to detect and evaluate the occupational exposure to pesticides. The developed IMS methodology was used, in positive and negative modes, to determine the presence of pesticides in air and to evaluate possible inhalation exposures of workers and users based on active sampling on Teflon membranes and direct thermal desorption IMS. The negative IMS mode was used to determine bensulfuron, clorpyrifos, diniconazole, diuron, flutolanil and imidacloprid, while the positive mode was employed to evaluate formetanate, metalaxyl, metamitrone, metribuzin, paclobutrazol and pirimicarb. The IMS measurements provided limits of detection from 8pg to 600pg. Indoor air samples, from phytosanitary plants, and outdoor samples, obtained from pesticide treatments in a local farm, were analysed providing pesticide air concentrations in the range of 0.04 to>0.25mgm−3. Occupational exposure of workers and pesticide users were evaluated and compared with values recommended by the authorities, providing useful information to improve the prevention programs in the phytosanitary field.

Consistency of Label Claims of Internet-Purchased Hemp Oil and Cannabis Products as Determined using IMS and LC-MS : A Marketplace Survey

In this paper we describe the use of ion mobility spectrometry (IMS) and liquid chromatography – high resolution mass spectrometry (LC-HRMS) to screen for the presence of cannabinoids and other potential hazards in a set of products with hemp oil and/or cannabinoid label claims purchased via the internet. Preliminary screening was performed using IMS to examine the products for the presence of cannabinoids, illicit drugs or undeclared pharmaceuticals before analysis by LC-HRMS to quantitatively determine the presence of four of the most common naturally occurring cannabinoids while simultaneously qualitatively screening for the presence of nine of the most common cannabinoids. No other illicit drug or undeclared pharmaceutical was detected in any sample from IMS screening. Eighteen of twenty-three samples tested positive for the presence of at least one cannabinoid by LC-HRMS, with three products containing less than 0.01%(w/w) of a cannabinoid. Four products with explicit CBD label claims were found to not contain any CBD, while three products featured levels of cannabinoids below label claim.https://doi.org/10.21423/jrs-v04n03p001 (DOI assigned 5/31/2019)

Passive exposure to nicotine from e-cigarettes

A procedure based on the use of ion mobility spectrometry (IMS), after liquid–liquid microextraction (LLME), has been successfully employed for the determination of passive exposure to nicotine from cigarette and e-cigarette smoking. Nicotine has been determined in exhaled breath and oral fluids of both, active and passive smokers. The aforementioned studies, made in closed environments, evidenced that the exhaled breath after conventional blend cigarette smoke provides nicotine levels of the order of 220ng per puff, in the case of experienced smokers, being exhaled only 32ng in the case of e-cigarettes. On the other hand, the nicotine amount in oral fluids of passive vapers was between 8 and 14µgL−1 lower than the average value of 38±14µgL−1 found for passive smokers of rolling tobacco and clearly lower than the 79±36µgL−1 obtained from passive smokers of classical yellow blend. This study was also placed in the frame of the verification of the e-cigarettes composition.

Use of Ion Mobility Spectrometry-Mass Spectrometry to Elucidate Architectural Dispersity within Star Polymers.

The power of ion mobility spectrometry-mass spectrometry (IMS-MS) as an analytical technology for differentiating macromolecular architecture is demonstrated. The presence of architectural dispersity within a sample is probed by sequentially measuring both the drift time and the mass-to-charge ratio for every component within a polymer sample. The utility of this technology is demonstrated by investigating three poly(ethylene glycol) (PEG) architectures with closely related average molecular weights of about 9000 Da: a linear PEG, an unevenly branched miktoarm star PEG, and evenly branched homoarm star PEGs. The three architectures were readily distinguished when analyzed separately as "pure" architectures or when analyzed as mixtures. IMS-MS results are contrasted with matrix-assisted laser desorption/ionization-MS and viscometry measurements.

Mass and Charge Distribution Analysis in Negative Electrosprays of Large Polyethylene Glycol Chains by Ion Mobility Mass Spectrometry

The mass spectrometric (MS) complexity associated with the quasi-continuous distribution of mass and charge (m, z) of electrosprayed industrial polymers may be moderated by use of ion mobility spectrometry (IMS) and MS in series. However, when the high charge levels typical of polar polymers stretch the gas phase ions into linear configurations, the mobility Z tends to be closely correlated with m/z, and IMS-MS does not yield spectra more readily interpretable than pure MS spectra. Here we note that the usual high charge states observed in the ESI of polyethylene glycol (PEG) arise because the stretched gas phase chain is able to strongly bind solution cations. We weaken this binding and therefore moderate the charge level by electrospraying in negative mode (NESI). This produces exclusively globular gas phase ions. IMS-MS then readily separates into distinct bands the different z-states, enabling an unambiguous assignment of all ions and simplifying the determination of mass distributions fz(m) for each charge state. The measured probability pz(m) that a polymer ion of given mass m will carry z charges spans a surprisingly narrow z range, each mass being present at most in two charge states. PEG ions of a given charge state z become unstable at a critical mass, below which they shed just one elementary charge, evidently by ion evaporation. We argue that NESI-IMS-MS offers significant analytical advantages over alternative methods previously demonstrated, particularly at increasing masses, when individual ion peaks can no longer be discerned.

Real-time monitoring of breath ammonia during haemodialysis: use of ion mobility spectrometry (IMS) and cavity ring-down spectroscopy (CRDS) techniques

The diffusion of high-performance analytical technology has opened prospects for breath diagnosis as a non-invasive diagnostic tool. In this study, ion mobility spectrometry (IMS) and cavity ring-down spectroscopy (CRDS) techniques were used to analyse ammonia gas (NH3) in real-time in breath from patients undergoing haemodialysis (HD) treatment and any correlation with blood urea nitrogen (BUN) levels and Kt/V were investigated. We studied 20 patients on intermittent HD treatment. The first breath samples were taken before the start of dialysis and further breath samples were taken every hour during the treatment and after the end of the session. An evaluation was also made of 20 healthy volunteers, acting as controls [healthy subjects (HS)]. Breath ammonia concentrations were higher in CRDS-HD (914.5±301.4 versus 280±120 parts per billion (p.p.b.), P<0.0001) and IMS-HD patients (964.4±402.4 versus 280±120 p.p.b., P<0.0001) than in HS. We assessed real-time variations in the levels of NH(3) and showed a continuous decrease in the levels of NH3. Expired NH3 correlated directly with BUN levels, both in the IMS-HD (P=0.002; r=0.84; P=0.009; r=0.76) and in the CRDS-HD group (P=0.005; r=0.80; P=0.008; r=0.77), respectively, both before and at the end of dialysis. A direct correlation with Kt/V was found in both groups studied (IMS-HD: P=0.003; r=0.82; CRDS-HD: P=0.006; r=0.79). Breath monitoring of NH3 with IMS and CRDS techniques could be useful to assess the real-time clinical status of patients during HD. By using pre-dialysis ammonia values, an approximate calculation of the Kt/Vurea ratio can be established.

Mass spectrometry and ion mobility spectrometry of G-quadruplexes. A study of solvent effects on dimer formation and structural transitions in the telomeric DNA sequence d(TAGGGTTAGGGT)

We survey here state of the art mass spectrometry methodologies for investigating G-quadruplexes, and will illustrate them with a new study on a simple model system: the dimeric G-quadruplex of the 12-mer telomeric DNA sequence d(TAGGGTTAGGGT), which can adopt either a parallel or an antiparallel structure. We will discuss the solution conditions compatible with electrospray ionisation, the quantification of complexes using ESI-MS, the interpretation of ammonium ion preservation in the complexes in the gas phase, and the use of ion mobility spectrometry to resolve ambiguities regarding the strand stoichiometry, or separate and characterise different structural isomers. We also describe that adding electrospray-compatible organic co-solvents (methanol, ethanol, isopropanol or acetonitrile) to aqueous ammonium acetate increases the stability and rate of formation of dimeric G-quadruplexes, and causes structural transitions to parallel structures. Structural changes were probed by circular dichroism and ion mobility spectrometry, and the excellent correlation between the two techniques validates the use of ion mobility to investigate G-quadruplex folding. We also demonstrate that parallel G-quadruplex structures are easier to preserve in the gas phase than antiparallel structures.

Clearance of biogenic amines from saliva following the consumption of tuna in water and in oil

Biogenic amines, such as cadaverine, putrescine, spermine and spermidine (together with their metabolic derivatives) play an important role in human pathology and physiology [17]. In addition, there is increasing evidence that many of these molecules may also serve as biochemical diagnostic markers for cancer [14], diabetes [9] and bacterial infection [10, 21]. Accordingly, different analytical methods have been developed for the analysis of biogenic amines in biological fluids including ELISA [8], high performance liquid chromatography (HPLC) [2], HPLC linked to mass spectrometry (HPLC-MS) [6], the use of enzymatic sensors [15], capillary electrophoresis [22] and genetic methods employing the polymerase chain reaction (PCR) [4]. In particular, Karpas and co-workers reported the use of Ion Mobility Spectrometry (IMS) for the measurement of various biogenic amines in the development of a diagnostic test for Bacterial Vaginitis (BV) [3, 12] and food freshness [13]. Based on this pioneering work, an instrument (VG-test) has been designed for the diagnosis of BV using samples of vaginal fluid collected by swab. It is now established that the presence of high levels of biogenic amines can also be indicative of bacterial degradation in foodstuffs [7, 16]. On the other hand, fish products such as canned tuna naturally contain relatively high levels of biogenic amines [18]. Consequently, dietary intake of tuna will affect both exogenous and potentially endogenous levels of biogenic amines in biological fluids, particularly in saliva. To assess the diagnostic utility of the VG-test as a convenient tool to determine levels of salivary biogenic amines, swab samples saturated in saliva were collected from a number of volunteers before and after the consumption of 20 g of canned tuna which had been carefully drained of its oil or water.

Multi-capillary column-ion mobility spectrometry: a potential screening system to differentiate virgin olive oils

The potential of a headspace device coupled to multi-capillary column-ion mobility spectrometry has been studied as a screening system to differentiate virgin olive oils ("lampante," "virgin," and "extra virgin" olive oil). The last two types are virgin olive oil samples of very similar characteristics, which were very difficult to distinguish with the existing analytical method. The procedure involves the direct introduction of the virgin olive oil sample into a vial, headspace generation, and automatic injection of the volatiles into a gas chromatograph-ion mobility spectrometer. The data obtained after the analysis by duplicate of 98 samples of three different categories of virgin olive oils, were preprocessed and submitted to a detailed chemometric treatment to classify the virgin olive oil samples according to their sensory quality. The same virgin olive oil samples were also analyzed by an expert's panel to establish their category and use these data as reference values to check the potential of this new screening system. This comparison confirms the potential of the results presented here. The model was able to classify 97% of virgin olive oil samples in their corresponding group. Finally, the chemometric method was validated obtaining a percentage of prediction of 87%. These results provide promising perspectives for the use of ion mobility spectrometry to differentiate virgin olive oil samples according to their quality instead of using the classical analytical procedure.

Analysis of carbohydrates and glycoconjugates by matrix‐assisted laser desorption/ionization mass spectrometry: An update for 2007–2008

This review is the fifth update of the original review, published in 1999, on the application of MALDI mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2008. The first section of the review covers fundamental studies, fragmentation of carbohydrate ions, use of derivatives and new software developments for analysis of carbohydrate spectra. Among newer areas of method development are glycan arrays, MALDI imaging and the use of ion mobility spectrometry. The second section of the review discusses applications of MALDI MS to the analysis of different types of carbohydrate. Specific compound classes that are covered include carbohydrate polymers from plants, N- and O-linked glycans from glycoproteins, biopharmaceuticals, glycated proteins, glycolipids, glycosides and various other natural products. There is a short section on the use of MALDI mass spectrometry for the study of enzymes involved in glycan processing and a section on the use of MALDI MS to monitor products of the chemical synthesis of carbohydrates with emphasis on carbohydrate-protein complexes and glycodendrimers. Corresponding analyses by electrospray ionization now appear to outnumber those performed by MALDI and the amount of literature makes a comprehensive review on this technique impractical. However, most of the work relating to sample preparation and glycan synthesis is equally relevant to electrospray and, consequently, those proposing analyses by electrospray should also find material in this review of interest.

Application of ion mobility spectrometry in analytical support of drug substance development

An investigation into the use of ion mobility spectrometry (IMS) for analytical support of drug substance development is reported. A group of thirty compounds including drug substances, starting materials and intermediates were analyzed by IMS, with 87% of the compounds affording a usable signal. The technique was further evaluated for single component quantification and multiple component quantification. A sub-ppm detection limit and a linearity range of 10 to 20 fold were obtained for most compounds tested, with the consecutive injection precision at less than 10% (RSD). Significant matrix effects on instrument response were observed when real reaction mixtures were analyzed. A spike/limit-testing method with a pre-established standard was developed for quick end of reaction monitoring. General advantages and limitations of the use of the IMS technique for drug substance development support are discussed, and some applications in areas such as starting material identification, high throughput screening and end of reaction monitoring are recommended.

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.

Use of ion mobility spectrometry to determine low levels of impurities in gases.

The use of ion mobility spectrometry (IMS) for the determination of trace moisture and oxygen in bulk nitrogen has been explored. IMS utilizes atmospheric pressure ionization to ionize trace impurities in the sample gas. Mobility differences between trace impurity ions are exploited to separate these ions. Our results indicate that an IMS can indeed be used to detect < 1 ppb O2 and H2O in bulk nitrogen. Due to the nature of the interaction between trace moisture and oxygen, a multivariate calibration has to be used to obtain quantitative results, even at levels below 2 ppb.

Ion mobility spectrometry for on-site sensing of SF/sub 6/ decomposition

Although gas-insulated system (GIS) and substations belong to the most reliable components of electric power networks, failures still occur in their long-term operation. In order to estimate the probability of malfunctions in advance, a system for monitoring the quality of the insulating gas SF/sub 6/ was established, which is based on the use of ion mobility spectrometry (IMS). In a set of experiments, partial discharge (PD) was generated inside a test GIS. The SF/sub 6/ was periodically analyzed using IMS. The results of this analysis is presented and the influence of impurities remaining inside the compartment is discussed. The analysis of gas contained in a circuit breaker in a hydroelectric power plant before and after operation is described as well as the structure of a system for automatic on-site sensing of SF/sub 6/ decomposition.

A rapid method for the enumeration of coliforms in processed foods by ion mobility spectrometry

The number of coliforms in processed food was enumerated rapidly by the use of ion mobility spectrometry. This method measured the time to observe o-nitrophenol liberated from the substrate o-nitrophenylgalactoside and was inversely proportional to the logarithm of the initial coliform count. The presence or absence of coliforms was determined within 12 h. This assay was unsuitable for non-processed foods due to the presence of an endogenous β-galactosidase enzyme.