Corona Discharge Ionization Research Articles

Direct detection of glyphosate in drinking water using corona-discharge ion mobility spectrometry: A theoretical and experimental study

Glyphosate is utilized extensively as a herbicide in the world. According to EPA regulation in 2009, it is recommended to monitor of glyphosate in drinking water. In this work the capability of ion mobility spectrometry (IMS) as an analytical technique for determination of glyphosate in drinking water is presented. The measurements were carried out in positive mode of a corona discharge ionization source with NH3 as a dopant. Glyphosate was directly detected in concentration higher than 10 μg/L in drinking water without sample preparation. Also, mechanism of ionization of glyphosate in corona discharge with and without NH3 dopant is discussed, theoretically.

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. The mass spectra of the low basic molecules such as formaldehyde exhibited larger clusters of MnH+(H2O)n, while for compounds with high basicity such as pyridine, only MH+ and MH+M peaks were observed. The results of DFT calculations show that enthalpies of hydrations and cluster formation decrease as basicities of the molecules increases. Using comparison of mass spectra of formic acid, formaldehyde, and ethanol, effect of structure on the cluster formation was also investigated. Formation of symmetric (MH+M) and asymmetric proton-bound dimers (MH+N) was studied by ion mobility and mass spectrometry techniques. Both theoretical and experimental results show that asymmetric dimers are formed more easily between molecules (M and N) with comparable basicity. As the basicity difference between M and N increases, the enthalpy of MH+N formation decreases.

Development and application of SBA‐15 assisted electromembrane extraction followed by corona discharge ion mobility spectrometry for the determination of Thiabendazole in fruit juice samples

A new sample preparation method based on SBA-15 assisted electromembrane extraction coupled with corona discharge ion mobility spectrometer was developed for the determination of Thiabendazole as a model basic pesticide in fruit juice samples. The addition of SBA-15 in the supported liquid membrane in electromembrane extraction system not only can lead to enhancement of the effective surface area, but also introducing the negatively charged silanol groups into supported liquid membrane might improve migration of positively charged analytes toward the supported liquid membrane and finally into the acceptor solution. To investigate the effect of the presence of SBA-15 in the supported liquid membrane on the extraction efficiency, a comparative study was carried out between the conventional electromembrane extraction and SBA-15/electromembrane extraction methods. Under the optimized conditions, SBA-15/electromembrane extraction method showed higher extraction efficiencies in comparison with conventional electromembrane extraction method. SBA-15/electromembrane extraction method exhibited a low limit of detection (0.9ng/mL), high preconcentration factor (167) and high recovery (83%). Finally, the applicability of SBA-15/electromembrane extraction method was studied by the extraction and determination of Thiabendazole as a model basic pesticide in fruit juice samples.

Ultrasound assisted dispersive solid phase extraction of triazole fungicides by using an N-heterocyclic carbene copper complex supported on ionic liquid-modified graphene oxide as a sorbent.

An ultrasound-assisted method is described for dispersive solid phase extraction of trace levels of triazole fungicides. A sorbent was prepared from an N-heterocyclic carbene copper complex that was supported on ionic liquid-modified graphene oxide. The sorbent was characterized by scanning electron microscopy, transmission electron microscopy, Raman and FT-IR spectroscopy, energy-dispersive X-ray spectroscopy and elemental mapping. The capability of sorption and extraction is mainly based on complexation with Cu (I) ions. The variables affecting extraction were optimized. Following desorption with ethanol, the fungicides were quantified by corona discharge ion mobility spectrometry. Under optimized conditions (solution pH value: 7.0; amount of sorbent: 10mg; extraction time: 3min; desorption agent: ethanol), the technique provides good linearity (>0.994), repeatability (RSD < 4.1%), low limits of detection (0.18ng.mL-1), excellent preconcentration factors (468-476) and high recoveries from spiked environmental water samples (92-94%). The sorbent can be reused over five cycles without significant loss of its activity. Graphical abstract Schematic presentation of design and synthesis of the N-heterocyclic carbene copper complex supported on ionic liquid-modified graphene oxide as a sorbent for triazole fungicides and its application in ultrasound-assisted dispersive solid phase extraction with ion mobility spectrometric detection.

Rapid on-site screening of five prohibited ingredients in cosmetics using thermal desorption-corona discharge ionization coupled with ion mobility spectrometry

A rapid on-site analytical method is developed for screening lidocaine and four other types of prohibited ingredients in cosmetics using thermal desorption-corona discharge ionization together with ion mobility spectrometry. Performing no pretreatment, we dropped or sprayed cosmetic samples onto a Nomex sampling swab. The sampler was placed into a compartment for thermal desorption and corona discharge ionization; then, ion mobility spectrometry analysis was performed. The limits of detection (LODs) for the five analytes ranged from 10 to 50 ng. The instrumental analysis time for a single run was less than 20 ms, and the total sample analysis period was within 1 min. The proposed method is simple, fast, and has low cost, and could be used as an analytical tool for rapid on-site screening of prohibited ingredients in cosmetics.

Rapid and high-sensitivity determination of phenylarsine oxide in environmental samples by a new technique: solid-phase microextraction followed by corona discharge ion mobility spectrometry

A new, rapid and sensitive method using solid-phase microextraction coupled with corona discharge ion mobility spectrometry was employed for determining phenylarsine oxide in environmental samples after derivatization with 1,3-propanedithiol.

Size, structure, and conductivity of plant oil-derived carbon nanospheres synthesized by atmospheric ionization CVD

Abstract Particle size of the as-deposited carbon spheres (CSs) from plant-derived oil precursor was modified through the addition of a corona discharge ionizer as an attachment to the conventional atmospheric chemical vapor deposition (CVD) setup. Influences of synthesis parameters such as temperature, solvent-oil concentration, and the presence of ionization on the particle size distribution, graphitization, and conductivity of the CSs were also investigated. The addition of pyridine as a solvent to the Calophyllum inophyllum (CI) oil improved precursor atomization, breaking down the viscous oil into finer vapor intermediates and consequently, the process of decomposition. Measured particle size distribution from scanning electron microscope (SEM) and atomic force microscope (AFM) images show a decrease in mean particle diameter, from >180 nm without ionization to

Study of Atmospheric Pressure Chemical Ionization Mechanism in Corona Discharge Ion Source with and without NH3 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 NH3 dopant, the reactant ion (RI) was H+(H2O) n, n = 3,4, and the MH+(H2O) x clusters were produced as product ions. Modeling of hydration shows that the amount of hydration ( x) depends on basicity of M, temperature and water concentration of drift tube. In the presence of ammonia (NH4+(H2O) n as RI) two kinds of product ions, MH+(H2O) x and MNH4+(H2O) x, were produced, depending on the basicity of M. With NH4+(H2O) n as RI, the product ions of pyridine and DTBP with higher basicity were MH+(H2O) x while cyclopentanone, 2-nonanone, and acetophenone with lower basicity produce MNH4+(H2O) x. To interpret the formation of product ions, the interaction energies of M-H+, H+-NH3, and H+-OH2 in the M-H+-NH3 and M-H+-OH2 and M-H+-M complexes were computed by B3LYP/6-311++G(d,p) method. It was found that for a molecule M with high basicity, the M-H+ interaction is strong leading in weakening of the H+-NH3, and H+-OH2 interactions in the M-H+-NH3 and M-H+-OH2 complexes.

Fabric-phase sorptive extraction coupled with ion mobility spectrometry for on-site rapid detection of PAHs in aquatic environment

The contamination of water is a high risk to human health, so there is an urgent need to rapidly detect water pollution in the field. Ion mobility spectrometry (IMS) is suitable for on-site analysis with the merit of rapid analysis and compact size. In this study, we developed a new method which coupled fabric phase sorptive extraction (FPSE) with IMS for rapid detection of polycyclic aromatic hydrocarbons (PAHs) in water present in the field. Polydimethylsiloxane (PDMS) was coated on the glass fiber cloth through a sol-gel reaction. After extracting the PAHs in water, the fabric coated PDMS could be directly put into the inlet of IMS instrument for thermal desorption. The PAHs were analyzed by the IMS instrument operated in the positive ion mode with a corona discharge (CD) ionization source. The primary parameters affecting extraction efficiency such as extraction time, extraction temperature, and ionic strength were investigated and optimized by using phenanthrene (Phe), benzo[a]anthracene (BaA) and benzo[a]pyrene (BaP) as model compounds. Under the optimal conditions, the FPSE-IMS detection limits were 5 ng ml−1,8 ng ml−1 and 10 ng ml−1 respectively. Satisfactory recoveries were obtained in the range from 80.5% to 100.5% by testing the spiked real water samples and validated by the standard method（HJ487-2009）. Based on the results, the method of FPSE-IMS could be feasibly applied for monitoring the water quality on-site and providing early warning in the field.

HKUST-1 metal-organic framework for dispersive solid phase extraction of 2-methyl-4-chlorophenoxyacetic acid (MCPA) prior to its determination by ion mobility spectrometry.

The authors describe a method for the extraction of the herbicide 2-methyl-4-chlorophenoxyacetic acid (MCPA) from agricultural products. The metal organic framework (MOF) HKUST-1 (acopper(II) benzene-1,3,5-tricarboxylate) was used as a sorbent for efficient clean-up and preconcentration of MCPA. The effects of pH value, stirring time, amount of sorbent on extraction were optimized by central composite design. Ultrasonic waves were used for desorption procedure and its advantage was demonstrated for an increase in extraction recovery. Corona discharge ion mobility spectrometry (IMS) was then applied for fast and sensitive determination of MCPA. The method was validated in terms of sensitivity, recovery and reproducibility. Under the optimum conditions the calibration plot is linear between 0.035-0.200μg. L-1. The detection limit is 10ngL-1, with relative standard deviations of <5%. Real samples (water, soil and agricultural product) were spiked and then analyzed by this method, and the results revealed efficient solid phase extraction and recovery. Graphical abstract Schematic presentation of a procedure for extraction of an organochlorine pesticide (2-methyl-4-chlorophenoxyacetic acid) from agriculture products using theHKUST-1 metal-organic framework prior to determination by ion mobility spectrometry based on its ionization in drift cell.

Optimization of N-acetylcysteine Determination by Ion Mobility Spectrometry using Central Composite Design

In this study, a simple and rapid method for N-acetylcysteine (NAC) determination was proposed using positive corona discharge ion mobility spectrometry. To optimize cell and injection temperature, central composite design was used. Other parameters such as corona and drift voltage, carrier and drift gas flow rate, and pulse width were adjusted. The calibration curve was linear under optimum conditions in the range of 3–100 ng with a correlation coefficient (R2) of 0.99. The relative standard deviations were 8.1 and 6.1%, for 20 and 50 ng of analyte (n = 9), respectively. Limits of detection and quantification were 1 and 3 ng, respectively. The developed method was successfully applied for the determination of NAC in pharmaceutical and human plasma samples.

Design of an ultrasonic piezoelectric injection port for analysis of thermally unstable compounds using corona discharge ion mobility spectrometry

This paper reports on a novel ultrasonic injection port designed and constructed to analyze thermally unstable chemical compounds using corona discharge ion mobility spectrometry (CD-IMS). In order to achieve the highest possible efficiency with the device, some parameters such as the solvent type, carrier gas flow rate and sample volume were exhaustively investigated. Through a comparative study conducted, it was revealed that unlike the thermal desorption system, the proposed ultrasonic injection port could easily be used for the analysis of some thermally unstable compounds such as carbaryl, propoxur and vitamin B1, by means of CD-IMS. To evaluate the potential of the device, carbaryl, extracted from different samples by dispersive liquid-liquid microextraction technique, was quantitatively analyzed. The CD-IMS-based results brought forth the detection limit of 0.03 mg L−1, and dynamic range of 0.1–10.0 mg L−1 with the determination coefficient of 0.9981. The relative standard deviations for one day and three consecutive days were 4 and 6%, respectively. Further, the spiked samples of agricultural wastewater, underground water, and tomato analyzed culminated in the recovery values of 83%, 98% and 82%, respectively. The satisfactory results proved an acceptable capability of the sample introduction system, to be conveniently used for routine analysis of thermally unstable compound, without any tedious derivatization.

Particle precipitation by bipolar corona discharge ion winds

The paper reports the development of a particle precipitation based aerosol sampler using bipolar corona discharge ion winds with collected particles of minimized net charge. For the new approach, neutralized particles move towards a sampler under the effect of electric field and dual ion winds. Since there is no electrode or sampling chip installed inside the air-flow channel, impediments to airborne particle flow or ion winds are removed along the flow direction. In addition, the isolation of ion winds, which generate circuit, allows using various materials for the sampling chip including non-conductors and also protecting collected particles from any discharge ignition on the chip. The device mechanism is numerically simulated in OpenFOAM to study the electrofluidodynamic interaction of charged particles and bipolar ion winds. The efficiency of the new approach has been investigated by experiment with a maximum efficiency of 94%. The effects of flow rate, discharge voltage and electrode distances on the method are also evaluated.

A poly(4-nitroaniline)/poly(vinyl alcohol) electrospun nanofiber as an efficient nanosorbent for solid phase microextraction of diazinon and chlorpyrifos from water and juice samples.

4-Nitroaniline was electropolymerized in a weakly alkaline medium, and the resulting poly(4-nitroaniline) (P4-NA)) was used to fabricate - by electrospinning - a nanofiber consisting of P4-NA and poly(vinyl alcohol) (PVA). ThePVA fractionwas then dissolved in hot water and this causes the porosity of electrospun nanofiber to be largely enhanced. The resulting nanofiber was utilized as a sorbent for solid phase microextraction of the model organophosphorus pesticides diazinon and chloropyrifos from aqueous media. The extracted analytes were then analyzed by corona discharge ion mobility spectrometry (CD-IMS). Under the optimized conditions, the limits of detection (at S/N = 3; for n = 10) are 0.4 and 0.6ngmL-1 for diazinon and chloropyrifos, respectively. The relative standard deviations at the levels of 25, 50 and 100ngmL-1 (for n = 3) ranged from 4.0-12.3% (both intra-day and inter-day). Eventually, the method was used to analyze different water samples, including spiked drinking water, sea water, lagoon water, and groundwater sample in the proximity of rice fields, and in two juice samples. Recoveries ranged between 82 and 102%. Graphical abstract An electrospun nanofiber consisting of highly porous poly(4-nitroaniline) was synthesized and used as a sorbent for solid phase microextraction of diazinon and chlorpyrifos from water and juice samples prior to quantitation bycorona discharge ion mobility spectrometry.

A study of angular rate sensing by corona discharge ion wind

We report an application of ion wind in angular rate sensing. A new design of a jet flow gyroscope using ion wind corona discharge is developed by conducting a numerical simulation and then an experimental analysis with regard to the advantages of a corona-discharge-based jet flow. Ion wind is generated by applying a high–voltage between a pin, as the discharge electrode, and a ring, as the reference electrode. The current–voltage characteristics of the discharge process by experimental works is set up as the boundary condition to describe the ion wind flow in the numerical simulation. A jet flow of ion wind is observed through an experiment and a simulation. When the gyroscope is subjected to an angular rate, the induced Coriolis force deflects the ion wind. This deflection is detected using four hotwires installed downstream of the working chamber behind the reference electrode. The experimental result show that the angular rate can be detected with a sensitivity of 4.7 μV/o/s. Because ion wind can be generated with minimum power and does not require any vibrating components, the device is robust, consumes low power, and is cost-effective.

A Simple Analytical Model for Predicting the Detectable Ion Current in Ion Mobility Spectrometry Using Corona Discharge Ionization Sources.

Corona discharge ionization sources are often used in ion mobility spectrometers (IMS) when a non-radioactive ion source with high ion currents is required. Typically, the corona discharge is followed by a reaction region where analyte ions are formed from the reactant ions. In this work, we present a simple yet sufficiently accurate model for predicting the ion current available at the end of this reaction region when operating at reduced pressure as in High Kinetic Energy Ion Mobility Spectrometers (HiKE-IMS) or most IMS-MS instruments. It yields excellent qualitative agreement with measurement results and is even able to calculate the ion current within an error of 15%. Additional interesting findings of this model are the ion current at the end of the reaction region being independent from the ion current generated by the corona discharge and the ion current in High Kinetic Energy Ion Mobility Spectrometers (HiKE-IMS) growing quadratically when scaling down the length of the reaction region. Graphical Abstract ᅟ.

Investigation of protonation and decomposition of tyrosine by ion mobility spectrometry and DFT calculations

The present study was designed to investigate the ionization and decomposition of tyrosine amino acid via an ion mobility spectrometer equipped with a corona discharge ionization source in the positive ion mode. Several peaks were observed in the ion mobility spectra of tyrosine with adjusting injection port and cell temperature at 250 and 200 °C, respectively. The experimental results were confirmed with density functional theory calculations. The topical proton affinities of the six lowest energy conformers of tyrosine were calculated for the protonation of several sites in each conformer. One of the peaks was assigned to the protonated tyrosine and other peaks were attributed to the fragment ions. The ion mobility spectra of eventual fragments as well as the mass-to-mobility correlation equation were utilized in order to identify of product fragments. The topical proton affinity and bond dissociation energies were calculated as additional hints to the identification of possible fragments. It was revealed that the combination of the theoretical and experimental tools results in a reliable identification of product ions in a corona discharge ionization source.

Ion mobility spectrum for Gerdien tubes by integral equation method

Ion mobility is an important parameter used in many ion-related research areas, such as atmospheric electricity, ion flow field around high voltage direct current (HVDC) transmission lines and so on. The spectrum of ion mobility is an elaborate tool that can be utilized to study the impacts of ambient conditions, such as temperature and humidity, on the atmospheric ion chemistry and motion of ions and hence help understand the underlying physics. This paper proposes an integral equation method for the recovery of ion mobility spectrum for Gerdien tubes widely used in ion mobility measurements. In view of the experimental observation of the multiplicity of ion species in the gas ionization products, it is believed that the multiplicity is associated with the difference between the ideal and real current-voltage (I-U) characteristics of the tubes and a qualitative explanation of this association is given. With the introduction of ion mobility spectrum density function, the qualitative explanation is formulated as an integral description which renders us to obtain the ion mobility spectrum by solving a Fredholm integral equation of the first kind. Tikhonov regularization method is utilized to solve this integral equation. To demonstrate the effectiveness of the integral equation method, numerical simulations and practical case studies are conducted. By simulations, it is found that the ion mobility spectrum recovered by the integral equation method is powerful enough for our practical use. Further, the integral equation method is applied to several sets of I-U characteristic data of air corona discharge ions and SF6 ions due to natural radiation recorded by Gerdien tubes. The calculated mean ion mobilities and total ion densities are in consistency with that by the commonly-used graphical method. The peaks in the recovered ion mobility spectrum show that there are several dominant species of ions in the ionization products. This helps us in understanding phenomena that are not comprehensible before. This integral equation method maybe very promising in the measurements of mobility spectrum of the ions under conductors with DC corona discharges.

Magnetic Dual-template Molecularly Imprinted Polymer Nanoparticles for the Simultaneous Determination of Acetaminophen and Codeine in Urine Samples by Ion Mobility Spectrometry.

Dual-template magnetic molecularly imprinted polymer nanoparticles were synthesized and used for the solid-phase extraction of acetaminophen and codeine before simultaneous determination by corona discharge ion mobility spectrometry. The magnetic molecularly imprinted polymer nanoparticles were prepared using silica-coated magnetic nanoparticles as supporters, acetaminophen and codeine as template molecules, 3-aminopropyltriethoxysilane and phenyltriethoxysilane as functional monomers, and tetraethoxysilane as a cross-linker. The obtained molecularly imprinted polymer was characterized by transmission electron microscopy, x-ray diffraction and Fourier-transform infrared spectroscopy. The adsorption performance of the imprinted polymers was studied by a series of experiments, indicating a satisfactory recognition ability of products for acetaminophen and codeine. The detection limits of 0.05 and 0.12 μg mL-1, and the dynamic range of 0.20 - 2.0 and 0.40 - 3.0 μg mL-1 were achieved for acetaminophen and codeine, respectively. The proposed method was used for simultaneous determinations of acetaminophen and codeine in urine samples, and the corresponding recoveries were calculated in the range of 87 - 94%. These satisfactory results revealed the ability of the method for a routine analysis of acetaminophen and codeine, simultaneously.

Zirconium dioxide-reduced graphene oxide nanocomposite-coated stir-bar sorptive extraction coupled with ion mobility spectrometry for determining ethion

In this study, we developed zirconium dioxide-reduced graphene oxide nanocomposite (ZrO2-rGO), as a novel coating for stir bar sorptive extraction (SBSE), prior to analysis by negative corona discharge ion mobility spectrometry (NCD-IMS). Ethion was selected as a test compound to evaluate the method. A stir bar was coated with the ZrO2-rGO nanocomposite using the sol-gel technique. ZrO2 has a high tendency towards the phosphonate group, hence its ability in absorbing ethion with high efficiency. On the other hand, graphene is a good sorbent for polar and semi-polar chemical compounds. Parameters affecting SBSE including extraction temperature, salt effect, stirring rate, desorption temperature, and extraction time were evaluated. The detection limit of this method for ethion was calculated to be 1.5 μg L−1, and the good linear range of 5.0–200 μg L−1 was obtained. The inter-day and intra-day relative standard deviations were 9% and 6%, respectively. This method was used to determine ethion in spiked river water and agricultural wastewater samples, and the obtained spiking recoveries were in the range of 93–97%.