Rapid detection of volatile organic compounds emitted from plants by multicapillary column-ion mobility spectrometry.

This study presents a novel rapid analytical method for the detection of volatile organic compounds (VOCs) emitted from blueberry leaves using the Tenax adsorbent followed by separation using a multicapillary column (MCC) and Ion Mobility Spectrometry (IMS) detection. The emitted VOCs including caryophyllene, benzene acetonitrile, linalool, ocimene, and methyl salicylate initiated by different stress factors including mechanical damage (punching), herbivore attack (aphids) and methyl jasmonate (MeJA) spraying were detected and quantified. Limits of Detection (LODs) for the VOCs were determined in the range of 8 to 33 ng.

Laser Desorption of Explosives from the Surface of Different Real-World Materials Studied Using CCl-Dopant-Assisted Ion Mobility Spectrometry.

A highly efficient and sensitive ion mobility spectrometry (IMS) system with laser desorption sampling was applied for rapid explosive detection using different surface materials. This portable IMS detector, powered by a battery, offers mobility and is suitable for use in the field or combat zones. The laser desorption (LD) sampling of common explosives (Trinitrotoluene-TNT; Dinitrotoluenes-DNTs; Hexogene-RDX; pentaerythritol tetranitrate-PETN; plastic explosives-Compound 4 (C-4) and Semtex) on a wide range of common surface materials, such as metal, ceramic, plastic, glass, drywall, paper, wood, and textiles, was studied.

Thermal electron attachment to halogenated silanes in the gas phase.

Rationale: Silane derivatives play a crucial role in industrial plasma processes for the fabrication of various electronic devices such as lighting devices, solar cells, and displays. Accurate quantitative data are essential for modeling technological plasmas. This study reports the rate coefficients (k) and activation energies (E) for thermal electron attachment to SiCl, Si (CH)CHF, and SiCl (CH)Si(CH), which are key parameters for understanding the underlying processes in plasmas.

Using dopants in the atmospheric pressure chemical ionization ion source to determine the site of protonation by ion mobility spectrometry.

Rationale: Compounds like caffeine metabolites with more than one proton acceptor site can produce a mixture of isomeric protonated ions (protomers) in electrospray ionization and atmospheric pressure chemical ionization (APCI) ion sources. Discrimination between the protomers is of interest as the charge location influences ion structure and chemical and physical properties.

Methods: Protonation of caffeine in an APCI ion source was studied using ion mobility spectrometry.

Formation of negative ions from cobalt tricarbonyl nitrosyl Co(CO)NO clusters.

Electron attachment and corresponding dissociative electron attachment (DEA) to cobalt tricarbonyl nitrosyl (Co(CO)NO) clusters have been studied by co-expansion with Ar gas into a high vacuum. A monochromatic electron beam was utilized to generate negative ions and the resulting reaction products were identified using mass spectrometry. The ion fragments corresponding to Co(CO)NO monomers closely resemble results from earlier gas phase experiments and studies conducted on Co(CO)NO in He nanodroplets.

Formic Acid as a Dopant for Atmospheric Pressure Chemical Ionization for Negative Polarity of Ion Mobility Spectrometry and Mass Spectrometry.

Formic acid (FA) is introduced as a potent dopant for atmospheric pressure chemical ionization (APCI) for ion mobility spectrometry (IMS) and mass spectrometry (MS). The mechanism of chemical ionization with the FA dopant was studied in the negative polarity using a corona discharge (CD)-IMS-MS technique in air. Standard reactant ions of the negative polarity present in air are O·(CO)·(HO) (m = 0, 1 and n = 1, 2) clusters.

Solid Phase Microextraction-Multicapillary Column-Ion Mobility Spectrometry (SPME-MCC-IMS) for Detection of Methyl Salicylate in Tomato Leaves.

Methyl salicylate (MeSA) is a plant-signaling molecule that plays an essential role in the regulation of plant responses to biotic and abiotic pathogens. In this work, solid phase microextraction (SPME) and a multicapillary column (MCC) are coupled to ion mobility spectrometry (IMS) to detect MeSA in tomato leaves. The SPME-MCC-IMS method provides two-dimensional (2D) separation by both MCC and IMS, based on the retention and drift times.

Negative Atmospheric Pressure Chemical Ionization of Chlorinated Hydrocarbons Studied by Ion Mobility Spectrometry (IMS) and IMS-MS Techniques.

Negative polarity atmospheric pressure chemical ionization of selected chlorinated hydrocarbons (tetrachloromethane CCl and hexachloroethane CCl, dichloromethane CHCl, trichloromethane CHCl, 1,1,1,2-tetrachloroethane 1,1,1,2-CHCl, 1,1,2,2-tetrachloroethane 1,1,2,2,-CHCl 1,1,2-trichloroethane 1,1,2-CHCl, and 1,1,2-trichloroethane 1,1,2-CHCl) was studied using ion mobility spectrometry (IMS) and IMS combined with time-of-flight mass spectrometer (IMS-TOF MS) techniques, in the dry air and at two different drift gas temperatures (323 and 373 K). The ionization was performed using the OCO(HO) reactant ions (RIs), and the dominant ionization reaction was the dissociative electron transfer. The ionization resulted in the appearance of Cl ions for all substances and [OH.

Effect of ion source polarity and dopants on the detection of auxin plant hormones by ion mobility-mass spectrometry.

Ion mobility spectrometry (IMS) equipped with a corona discharge (CD) ion source was used for measurement of three auxin plant hormones including indole-3-acetic acid (IAA), indole-3-propionic acid (IPA), and indole-3-butyric acid (IBA). The measurements were performed in both positive and negative polarities of the CD ion source. Dopant gases NH, CCl, and CHBr were used to modify the ionization mechanism.

An atmospheric pressure field effect ionisation source for ion mobility spectrometry.

An atmospheric Pressure Field Effect (APFE) ionisation source for drift tube ion mobility spectrometry has been developed for operation in positive and negative polarities. The formation of negative and positive ions in synthetic air was studied and compared with the Atmospheric Pressure Corona Discharge (APCD) ionisation source. The APFE ionisation source is of point-to-plane geometry with a 10 μm Pt point electrode, a stainless steel plate electrode and ultra-high resistance (20 GΩ) current limiters.

Dissociative Excitation of Nitromethane Induced by Electron Impact in the Ultraviolet - Visible Spectrum.

The excitation of nitromethane (CH NO ), which is an important propellant and prototypic molecule for large class of explosives, has been investigated by electron impact and subsequent emission of photons in the UV-VIS spectral region between 300 nm and 670 nm. Emission spectrum of nitromethane was recorded at an electron energy of 50 eV. New dissociative excitation channels were observed through the appearance of different CH, CN, NH, OH and NO bands, and the Balmer series of atomic hydrogen.

Development of Microchip Isotachophoresis Coupled with Ion Mobility Spectrometry and Evaluation of Its Potential for the Analysis of Food, Biological and Pharmaceutical Samples.

An online coupling of microchip isotachophoresis (µITP) with ion mobility spectrometry (IMS) using thermal evaporation interface is reported for the first time. This combination integrates preconcentration power of the µITP followed by unambiguous identification of trace compounds in complex samples by IMS. Short-chain carboxylic acids, chosen as model analytes, were first separated by the µITP in a discontinuous electrolyte system at pH 5-6, and subsequently evaporated at 130 °C during their transfer to the IMS analyzer.

Analysis of positional isomers of 2-3-4-alkoxyphenylcarbamic acid derivatives by a combination of TLC and IMS.

In this study, we have demonstrated a separation of positional isomers of some derivatives of alkoxyphenylcarbamic acid. These compounds belong to drugs with local anesthetics activity. The low volatility compounds were analysed by a Thin Layer Chromatography (TLC) and Ion Mobility Spectrometry (IMS) using diode laser desorption for sample introduction to IMS.

Low Energy Electron Attachment by Some Chlorosilanes.

In this paper, the rate coefficients () and activation energies () for SiCl, SiHCl, and Si(CH)(CHCl)Cl molecules in the gas phase were measured using the pulsed Townsend technique. The experiment was performed in the temperature range of 298-378 K, and carbon dioxide was used as a buffer gas. The obtained depended on temperature in accordance with the Arrhenius equation.

Online detection and measurement of elemental mercury vapor by ion mobility spectrometry with chloroform dopant.

A rapid and simple method is proposed for detection of elemental mercury (Hg) vapor by ion mobility spectrometry (IMS). Negative corona discharge (CD) as the ionization source and chloroform as the dopant gas were used to produce Cl reactant ion. A mass spectrum of the product ions confirmed that the mechanism of ionization is based on Cl anion attachment to Hg and formation of HgCl ion.

Ion chemistry of phthalates in selected ion flow tube mass spectrometry: isomeric effects and secondary reactions with water vapour.

Phthalates are widely industrially used and their toxicity is of serious environmental and public health concern. Chemical ionization (CI) analytical techniques offer the potential to detect and monitor traces of phthalate vapours in air or sample headspace in real time. Promising techniques include selected ion flow tube mass spectrometry (SIFT-MS), proton transfer reaction mass spectrometry (PTR-MS) and ion mobility spectrometry (IMS).

Step-scan Michelson Fourier-transform spectrometer for optical emission spectroscopy in UV-VIS spectral range.

We present the design, construction, and first spectra of a step-scan Michelson Fourier-transform spectrometer for optical emission spectroscopy in the UV-VIS spectral range. The mirror motion mechanism is based on a long-travel piezo-based linear translation stage with built-in position feedback. The step-scan arrangement allows for signal integration, making the instrument suitable for measurements of less intensive radiation sources and for the photon-counting technique.

Isomer and conformer selective atmospheric pressure chemical ionisation of dimethyl phthalate.

In this work we have studied the ionisation mechanism of Atmospheric Pressure Chemical Ionisation (ACPI) for three isomers of dimethyl phthalate (dimethyl phthalate - DMP (ortho- isomer), dimethyl isophthalate - DMIP (meta) and dimethyl terephthalate - DMTP (para)) using Ion Mobility Spectrometry (IMS) and IMS combined with an orthogonal acceleration Time of Flight Mass Spectrometer (oa-TOF MS). The molecules were chemically ionised using reactant ions H·(HO) (n = 3 and 4). The positive IMS and IMS-oaTOF mass spectra of the isomers showed significant differences in the ion mobilities and in the ion composition.

Effect of Basicity and Structure on the Hydration of Protonated Molecules, Proton-Bound Dimer and Cluster Formation: An Ion Mobility-Time of Flight Mass Spectrometry and Theoretical Study.

Protonation, hydration, and cluster formation of ammonia, formaldehyde, formic acid, acetone, butanone, 2-ocatanone, 2-nonanone, acetophenone, ethanol, pyridine, and its derivatives were studied by IMS-TOFMS technique equipped with a corona discharge ion source. It was found that tendency of the protonated molecules, MH, to participate in hydration or cluster formation depends on the basicity of M. The molecules with higher basicity were hydrated less than those with lower basicity.

Study of Atmospheric Pressure Chemical Ionization Mechanism in Corona Discharge Ion Source with and without NH Dopant by Ion Mobility Spectrometry combined with Mass Spectrometry: A Theoretical and Experimental Study.

Ionization of 2-nonanone, cyclopentanone, acetophenone, pyridine, and di- tert-butylpyridine (DTBP) in a corona discharge (CD) atmospheric pressure chemical ionization (APCI) ion source was studied using ion mobility (IMS) and time-of-flight mass spectrometry (TOF-MS). The IMS and MS spectra were recorded in the absence and presence of ammonia dopant. Without NH dopant, the reactant ion (RI) was H(HO) , n = 3,4, and the MH(HO) clusters were produced as product ions.

Dissociation of dicyclohexyl phthalate molecule induced by low-energy electron impact.

Experimental investigation of electron ionization (EI) of and electron attachment (EA) onto dicyclohexyl phthalate (DCHP) was carried out using a crossed electron and molecular beam technique. Formation of positive and negative ions by EI and EA with the corresponding dissociation processes was studied and discussed. Due to a low ion yield of the parent positive ion, we were not able to estimate the ionization energy of DCHP.

Dissociative electron attachment and electronic excitation in Fe(CO).

In a combined experimental and theoretical study we characterize dissociative electron attachment (DEA) to, and electronically excited states of, Fe(CO). Both are relevant for electron-induced degradation of Fe(CO). The strongest DEA channel is cleavage of one metal-ligand bond that leads to production of Fe(CO).

Electron interaction with copper(II) carboxylate compounds.

In the present study we have performed electron collision experiments with copper carboxylate complexes: [Cu(-BuNH)(µ-OCCF)], [Cu(-BuNH)(µ-OCCF)], [Cu(EtNH)(µ-OCCF)], and [Cu(µ-OCCF)]. Mass spectrometry was used to identify the fragmentation pattern of the coordination compounds produced in crossed electron - molecular beam experiments and to measure the dependence of ion yields of positive and negative ions on the electron energy. The dissociation pattern of positive ions contains a sequential loss of both the carboxylate ligands and/or the amine ligands from the complexes.