Methylsulfate Research Articles

Employment of 1-Methoxy-5-Ethyl Phenazinium Ethyl Sulfate as a Stable Electron Mediator in Flavin Oxidoreductases-Based Sensors.

In this paper, a novel electron mediator, 1-methoxy-5-ethyl phenazinium ethyl sulfate (mPES), was introduced as a versatile mediator for disposable enzyme sensor strips, employing representative flavin oxidoreductases, lactate oxidase (LOx), glucose dehydrogenase (GDH), and fructosyl peptide oxidase (FPOx). A disposable lactate enzyme sensor with oxygen insensitive Aerococcus viridans-derived engineered LOx (AvLOx), with A96L mutant as the enzyme, was constructed. The constructed lactate sensor exhibited a high sensitivity (0.73 ± 0.12 μA/mM) and wide linear range (0–50 mM lactate), showings that mPES functions as an effective mediator for AvLOx. Employing mPES as mediator allowed this amperometric lactate sensor to be operated at a relatively low potential of +0.2 V to 0 V vs. Ag/AgCl, thus avoiding interference from uric acid and acetaminophen. The lactate sensors were adequately stable for at least 48 days of storage at 25 °C. These results indicated that mPES can be replaced with 1-methoxy-5-methyl phenazinium methyl sulfate (mPMS), which we previously reported as the best mediator for AvLOx-based lactate sensors. Furthermore, this study revealed that mPES can be used as an effective electron mediator for the enzyme sensors employing representative flavin oxidoreductases, GDH-based glucose sensors, and FPOx-based hemoglobin A1c (HbA1c) sensors.

Ionic liquid-tolerant cellulase system of Stachybotrys microspora exploited in the in situ saccharification of lignocellulosic biomass

Ionic liquids (ILs) are used as green solvents for pretreatment of lignocellulosic biomass before enzymatic hydrolysis for bioenergy production. The enzymatic saccharification of regenerated biomass must be carried in a two steps process (IL treatment followed by enzymatic one) because the majority of cellulase are inactive in the presence of ILs. In this study, a highly tolerant IL-cellulase system from the halophilic cellulolytic fungus Stachybotrys microspora is developed. The cellulase activity was enhanced to 115.5% and 114.5% in the presence of 5% (v/v) of 1-Ethyl-3-methylimidazolium diethyl phosphate [EMIM][DEP] and 1-Allyl-3-methylimidazolium chloride [AMIM][Cl] and retained 84.4% and 76.7% of activity in presence of 30% (v/v) of each compound, respectively. The cellulase was most sensitive to 1-Ethyl-3-methylimidazolium methyl sulphate [EMIM] [MtSO4] loosing 72% and 25% of initial activity after incubation in 5% and 30% solution of IL, respectively. The effectiveness of ILs for wheat bran pretreatment process shows the sequence: [EMIM][DEP] > [AMIM][Cl] > [EMIM] [MtSO4]. The IL-activated wheat bran slurry was enzymatically hydrolyzed in the best solvent [EMIM][DEP] diluted to 5, 10, 15 and 20% (v/v), the highest yield of reducing sugars, 52.4%, was obtained with the 15% pretreated substrate. Results showed a very high digestibility of the slurry and confirmed a high glucose yield for the pretreatment methodology. Indeed, the in situ saccharification of IL-pretreated wheat bran was significantly improved compared to the untreated (2.6 fold). Thus, a successful system in a one-pot procedure was developed.

Specifics of kaolin dispersion flocculation due to a polyelectrolyte complex formation on particle surface

The paper describes the study of flocculation characteristics of kaolin aqueous dispersion in successive introduction of high molecular weight oppositely charged polymers. It was established that flocculation in successive modes of introduction of cationic polyelectrolyte of poly-trimethyloxyethylmethacryloylammonium methyl sulfate (K) and anionic polyelectrolyte poly-2-acrylamido-2-methyl-1-propane sulfonic acid (A) is accompanied by an increase in sedimentation rate and formation of more dense floccules compared with the use of individual polyelectrolytes. The paper discusses the difference in the mechanisms of flocculation in the presence of oppositely charged polymers, including the possibility of forming a polyelectrolyte complex on the surface of colloidal particles.

In-situ cyclic voltammetry of an ionic liquid as a lubricant additive in a steel-ceramic contact

The tribochemical interaction of the ionic liquid triethylmethylammonium methyl sulphate as an additive in poly(ethylene glycol) base fluid with a steel surface sliding against alumina was investigated by in-situ electrochemical methods based on Open Circuit Potential (OCP) measurement and Cyclic Voltammetry (CV). In the current-potential relationships of the lubricant with and without sliding interaction, significant differences were observed. Additionally, contributions of the neat base fluid, selected added contaminants, and atmosphere composition to the entire reactivity were studied. In the presence of the ionic liquid, subtle changes of the current influence friction substantially. Protective atmosphere was shown to sensitize the chemical response to potential excursions, giving evidence of a redox couple possibly existing temporarily on the wear track surface.

Metabolite identification and profile of endosulfan sulfate in three human liver preparations using liquid chromatography-high resolution mass spectrometry

In this study, we performed the metabolism of endosulfan sulfate in human liver preparations (human liver microsomes, S9 fractions and hepatocytes) to identify new metabolites using liquid chromatography-high resolution mass spectrometry (LC-HRMS). Endosulfan sulfate is a major oxidized metabolite of the organochlorine insecticide endosulfan, and it exhibits a similar toxicity to endosulfan. Six metabolites, including 5 novel metabolites of endosulfan sulfate, were identified in the three different human liver reaction mixtures and metabolic pathways of endosulfan sulfate were proposed. The phase I metabolites M1 and M2 were observed in human liver microsomes, S9 fractions and hepatocytes. M1 was suggested to be an endosulfan diol monosulfate and M2 was identified as (1,4,5,6,7,7-hexachloro-3-formylbicyclo[2,2,1]hept-5-en-2-yl)methyl hydrogen sulfate through the interpretation of the HRMS spectrum. The phase II metabolite M3 was produced as an endosulfan sulfate-GSH conjugate in those three liver preparations and transformed to M5 (dipeptide) in S9 fractions and hepatocytes. M3 was the most predominant metabolite identified in the three liver preparations. M4 was only detected in microsomes as an M2-GSH conjugate and was metabolized to M6 (monopeptide) in hepatocytes. These results are different from the metabolic pathway of endosulfan and suggest the possible detoxification metabolic reaction of endosulfan sulfate in living organisms.

Effect of temperature, nature of anion and alkyl chain length on the volumetric and acoustic properties of ionic liquid [C4C1im][MeSO4] with alkyl nitriles

Densities (ρ) and speeds of sound (u) of 1-butyl-3-methylimidazolium methyl sulphate, [C4C1im][MeSO4] with acetonitrile (ACN), propionitrile (PCN) and n-butyronitrile (n-BCN) in the complete composition range at temperatures between 298.15 K and 313.15 K with 5 K intervals and atmospheric pressure is reported. Solute-solvent interactions have been evaluated in the mixtures of [C4C1im][MeSO4] with alkyl nitriles by calculating excess volumes (VE) and excess isentropic compressibilities (κsE). The VE and κsE values as a function of mole fraction are correlated using a Redlich-Kister type expression. The excess functions (VE and κsE) are found to be negative over the complete range of mole fraction for the investigated binary solutions. The studied excess properties are found to increase with the increase in the alkyl chain length of alkyl nitriles. The excess thermodynamic properties of the mixed solvents are discussed in relation to intermolecular interactions and structural effects existing between the component molecules. In addition, the effect of the nature of anion of ionic liquid and temperature on the excess thermodynamic properties has been investigated.

NMR investigations on binding and dynamics of imidazolium-based ionic liquids with HEWL.

Molecular level insights on protein-ionic liquid (P-IL) interactions are beneficial for assessing protein stability, binding and dynamics. In the present work, interactions of ILs, namely, 1-butyl 3-methylimidazolium methyl sulfate (IL1), 1-butyl 3-methylimidazolium octyl sulfate (IL2) and 1-butyl 3-methylimidazolium chloride (IL3) with hen egg white lysozyme (HEWL) protein were investigated using solution-state nuclear magnetic resonance (NMR) spectroscopy. To ascertain the binding and dynamics from the perspective of both protein and IL, various ligand based NMR approaches such as selective and non-selective nuclear spin-relaxation (R1SEL and R1NS), saturation transfer difference (STD), difference of inversion recovery rate with and without target irradiation (DIRECTION), 35Cl line-shape and spin-relaxation, and protein back bone amide chemical shift perturbations (CSPs) from 1H-15N HSQC were utilized. Among the ILs investigated, IL2 experiences significant interaction relative to those of IL1 and IL3, as revealed by the combined R1SEL and R1NS analysis, which is further supported by STD NMR. CSP analyses of 1H-15N HSQC spectra of aqueous P-IL mixtures enabled to identify the potential binding sites of ILs with HEWL. Whereas, 15N longitudinal (R1) and transverse (R2) spin-relaxation rates and 15N{1H} heteronuclear nuclear Overhauser effect (hetNOE) data subjected to the model free analysis for IL2 yielded the rotational correlation times and order parameters of various residues of HEWL. Furthermore, the results could discern the nature of interactions between studied ILs and HEWL in terms of specific and non-specific interactions.

Rational design, supramolecular synthesis and solid state characterization of two bicomponent solid forms of mebendazole

MBZ methyl sulfate and perchlorate were designed based on the statistical probability of the formation of an R22(8) supramolecular heterosynthon.

Mathematical modeling of CO2 absorption with ionic liquids in a membrane contactor, study of absorption kinetics and influence of temperature

AbstractBACKGROUNDThis work presents a comprehensive study of carbon dioxide (CO2) capture from CO2/N2 mixtures in a hollow fiber membrane contactor (HFMC). The absorbents considered were three different ionic liquids (ILs): 1‐ethyl‐3‐methylimidazolium acetate ([emim][OAc]), 1‐ethyl‐3‐methylimidazolium ethylsulfate ([emim][EtSO4]) and 1‐ethyl‐3‐methylimidazolium methyl sulfate ([emim][MeSO4]). A comprehensive two‐dimensional (2D) mathematical model for the transport of CO2 was developed and solved for steady‐state and pseudo steady‐state modes. For pseudo steady‐state mode, the 2D model was linked with a dynamic model applied on a tank from which the IL was recirculated into the shell side of the HFMC.RESULTSThe model showed excellent agreement between the simulations and experimental data within the range of 2 to 5% standard deviation. Initially, overall mass transfer coefficients of 7.6 × 10−6 (m s−1), 1.6 × 10−6 (m s−1) and 3.7 × 10−6 (m s−1) were obtained for [emim][OAc], [emim][EtSO4] and [emim][MeSO4], respectively. Solubility, diffusivity and absorption efficiency of CO2 in ILs showed strong dependence on the temperature. Furthermore, concentration drop in the wetted portion of the membrane, effect of porosity, tortuosity, gas and absorbent flow rates were systematically studied.CONCLUSIONFindings of both experimental and modeling work suggests that in spite of the difference of extraction efficiency, these ILs are potential absorbents for CO2 in membrane contactors. Moreover, the modeling approach was found very effective to predict the absorption behavior of CO2 in ILs and to study the wetting phenomena and parametric effects. © 2019 Society of Chemical Industry

An environmentally benign, green, and efficient ionic liquid catalyzed synthesis of Quinoline derivatives via Knoevenagel condensation

AbstractThe present investigation is in the interest of one‐pot, environmentally friendly and efficient protocol for the synthesis of quinoline derivatives from 2‐aminoarylketones and active methylene compounds in the presence of L‐proline and ionic liquid 1,3‐dimethylimidazolium methyl sulfate [MMIm][MSO4]. The Ionic liquid which is used as a catalyst can be reused several times. The results obtained by using [MMIm][MSO4] were also compared with those described in the literature. The advantages of the method are shorter reaction time, milder conditions, easy workup and better yields. The catalyst [MMIm][MSO4] can be recovered for the subsequent reactions and reused without any appreciable loss of efficiency. This method of synthesis widens the applicability of Ionic liquids in heterocyclic compounds.

Surface resistivity, surface wettability and thermal stability of the 1-ethyl-2,3-dimethylimidazolium ethyl sulfate and methyl-tri-n-butylammonium methyl sulfate modified polyethylene

ABSTRACTIn this paper, experiments have been performed to further the development of conductivity of the polyethylene. This study mainly investigated the surface resistivity and surface wettability of the polyethylene (PE) after ionic liquid modifications. In order to activate the surface, PE was pre-treated with chromic acid and then modified with 1-ethyl-2,3-dimethylimidazolium ethyl sulfate (IL1) and methyl-tri-n-butylammonium methyl sulfate (IL2) ionic liquids. The effect of the type and concentration of the ionic liquid IL1 and IL2 concentrations is examined by Fourier Transform Infrared (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), surface resistivity and surface wettability. Results showed that thermal stability of the PE deteriorated after ionic liquid modifications. Both untreated and modified fabrics exhibited resembling crystallinity parameters. Nearly 57% enhancement in surface wettability of the PE was achieved. The pre-treatment process decreased the surface resistivity and increased surface wettability of the PE. The main success in this research is that IL1 and IL2 modifications reduced the resistivity data from 1011 ohm/sq to 107 ohm/sq and 108 ohm/sq, respectively.

Identification of Monomethyl Sulfate and Sulfate Impurities in Zidebactam Using LC–MS and Application of Mixed-Mode Liquid Chromatography with Charged Aerosol Detection and Ion Chromatography for Quantification

Zidebactam (ZID), a novel β-lactam enhancer drug being developed to treat infections caused by Gram-negative bacteria, currently is in phase III clinical development. Two ionic impurities observed in liquid chromatography with charged aerosol detector (CAD) analysis were identified through liquid-chromatography mass spectrometry (LC–MS) as sulfate (SO4−2) and monomethyl sulfate (CH3OSO3−1, MMS). There genesis was attributed to the use of pyridine sulfur trioxide as a reagent in ZID synthesis. A new chromatographic method using mixed-mode stationary phase and CAD was developed and validated. The separation of ionic impurities was achieved on Obelisc-N column using buffer gradient. The new method was found to be simple, specific, sensitive, precise, accurate and robust for controlling these impurities in new drug substance. Accuracy of the method was verified by comparing the results with that of ion chromatography (IC) with conductivity detector. The IC method was employed to monitor the impurities in ZID drug substance used for clinical trials and stability analysis.

Three wood isotopic reference materials for δ2H and δ13C measurements of plant methoxy groups

Methoxy groups (OCH3) of plants show specific stable carbon and hydrogen isotope patterns that are used for applications in biogeochemical, atmospheric, paleoclimatic and food research. The method of choice for determining stable hydrogen and carbon isotope values of methoxy groups (δ2HOCH3 and δ13COCH3 values) is the conversion to gaseous iodomethane (CH3I) and subsequent measurement by stable isotope ratio mass spectrometry. However, comparative measurements particularly for stable hydrogen isotopes of plant methoxy groups are limited due to the lack of suitable reference materials. We have prepared three batches of powdered wood samples (birch HUBG3, beech HUBG4, and tineo HUBG5) collected from different geographical locations to serve as long-term reference materials for normalization of δ2HOCH3 but also δ13COCH3 values. Methoxy contents of the three wood samples range between 4.7 and 5.4%. Methoxy groups from subsamples of the three homogenized wood samples were quantitatively converted to CH3I and δ2HOCH3 and δ13COCH3 values of this CH3I were calibrated against international reference substances by high-temperature conversion- and elemental analyzer isotope ratio mass spectrometry. The δ2HOCH and δ13COCH3 values of HUBG3 and HUBG4 at 1σ uncertainty calibrated to the VSMOW and VPDB isotopic δ-scale, respectively are −272.9 ± 1.5 mUr and −29.40 ± 0.13 mUr; and −239.1 ± 1.4 mUr and −30.17 ± 0.13 mUr, respectively. In addition, the calibrated δ2HOCH value of HUBG5 is −191.7 ± 0.8 mUr. Whilst the δ2HOCH3 values of the three wood samples span a relatively wide range (~−280 to −190 mUr) suitable for normalization of δ2HOCH3 values of most plant samples that have been reported so far, δ13COCH3 values are restricted to a composition (~−30 mUr) typical of wood methoxy groups. We suggest that the three investigated wood materials HUBG3–5 are ideally suited for long-term usage, inter-laboratory comparison, and together with the two recently reported methyl sulfate salts (HUBG1 and HUBG2) complete a new set of solid methoxy reference materials that cover almost the full range of plant methoxy groups reported so far. Therefore, we recommend replacing liquid CH3I and instead use the solid reference materials set HUBG1–5 for normalizing δ2HOCH3 and δ13COCH3 values to the respective δ-scales.

Matrix Polymerization of Trimethylmetacryloyloxyethylethylammonium Methyl Sulfate in Sodium Dodecyl Sulfate Micellar Solutions

Matrix Polymerization of Trimethylmetacryloyloxyethylethylammonium Methyl Sulfate in Sodium Dodecyl Sulfate Micellar Solutions

Electron transfer mediators for PQQ dependent soluble glucose dehydrogenase catalyzed lactose oxidation reaction

The aim of this work was to investigate the application of artificial electron transfer mediators for the pyrroloquinoline quinone-dependent soluble glucose dehydrogenase (PQQ-sGDH) catalyzed lactose oxidation reaction. 1-(N,N-dimethylamine)4-(4-morpholine)benzene (AMB) and N,N’-dimethyl-4,4’-azopyridinium methyl sulfate (MAZP) were used as mediators. The mediators showed a high reactivity with a reduced form of PQQ-sGDH and were used to determine the PQQ-sGDH catalyzed lactose oxidation parameters at pH 7.0 and pH 8.0. The use of MAZP and AMB for the regeneration of the oxidized form of PQQsGDH was investigated by applying the electrochemical oxidation of the mediator. The maximum electroenzymatic lactose bioconversion yield and the biggest average PQQ-sGDH turnover number were reached when the buffer solution pH was 8.0 and AMB was used as an electron acceptor, which was oxidized on a carbon fiber electrode of a large surface area.

Deep eutectic solvents (DES) based on sulfur as alternative lubricants for silicon surfaces

Deep eutectic mixtures composed of hydrogen-bond donors (HBDs) and hydrogen-bond acceptors (HBAs), the so-called DESs, have recently being proposed as possible “green” alternatives to mineral oils and ionic liquids (ILs) in the lubrication of steel surfaces. DESs have similar physical properties to ILs but have the advantage of being cheaper and easier to prepare. In this work, new DESs containing sulfur units in their composition were prepared and tested in the lubrication of silicon surfaces which are relevant for nano/microelectromechanical systems (NEMS/MEMS). The following new DESs were prepared: ethyldibutyl sulfonium ethylsulfate: polyethylene glycol ([S4,4,2][EtSO4]:PEG), 1-ethyl-tetrahydrothiophenium ethylsulfate: polyethylene glycol ([C2-THT][EtSO4]:PEG), 1-ethyl-3-methylimidazolium (S)-camphorsulfonate: polyethylene glycol ([C2MIM][(S)CSA]:PEG), and 1-methyl-3-picolinium methyl sulfate: polyethylene glycol ([C1-3-pic][MeSO4]:PEG). Other DES, already reported, were tested for comparison purposes: tetrabutylammonium bromide: sulfolane ([N4,4,4,4][Br]:Sulf), choline chloride: polyethylene glycol (ChCl:PEG), and tetrabutylammonium bromide: polyethylene glycol ([N4,4,4,4][Br]:PEG). All DESs were characterized in terms of their water content, viscosity, wettability, and tribological properties. The friction coefficients were measured in a nanotribometer using steel spheres against Si surfaces. The new DES prepared from salts based on the sulfur-containing anions showed good tribological performance, but the best results were obtained with [C2MIM][(S)-CSA]:PEG and [C1-3-pic][MeSO4]:PEG which reduced the friction coefficients to values <0.1, typical of excellent lubrication conditions.

Phenomenological Changes in Lignin Following Polymerization and Its Effects on Flocculating Clay Particles.

Cationic kraft lignin (CKL) macromolecules were produced via polymerizing kraft lignin (KL) with [2-(acryloyloxy)ethyl]trimethylammonium chloride (ATAC) or [2-(methacryloyloxy)ethyl]trimethylammonium methyl sulfate (METAM). Despite slightly different charge densities (2.3-2.5 mmol/g) of CKL, lignin-METAM (KL-METAM) had a significantly larger molecular weight and radius of gyration. A correlation was observed between the structure of CKLs and their impacts on the surface hydrophilicity of kaolin particles. In interacting with kaolin particles, KL-METAM generated larger and stronger flocs with looser structures than did KL-ATAC. Compared to ATAC, METAM had one additional methyl substituent on its structure, which provided fundamental evidence on how a small group (i.e., a methyl group) on the structure of a cationic monomer can have a substantial influence on its polymerization with lignin and subsequently on the efficiency of the induced macromolecule as a flocculant in a kaolin suspension system.

Liquid-liquid equilibrium measurements and interaction exploration for separation of isobutyl alcohol + isobutyl acetate by imidazolium-based ionic liquids with different anions

For separation of the azeotropic mixture isobutyl alcohol and isobutyl acetate, liquid-liquid extraction was adopted in this work and three imidazolium-based ionic liquids with different anions 1-butyl-3-methylimidazolium dihydrogen phosphate ([Bmim][H2PO4]), 1-butyl-3-methylimidazolium hydrogen sulfate ([Bmim][HSO4]) and 1-butyl-3-methylimidazolium methyl sulfate ([Bmim][MeSO4]) were chosen as extractants. The liquid – liquid equilibrium data (LLE) for isobutyl alcohol + isobutyl acetate + ([Bmim][H2PO4]/[Bmim][HSO4]/[Bmim][MeSO4]) were determined at 298.15 K and 101.3 kPa. The distribution coefficient and selectivity were calculated to evaluate extraction capability of the selected extractants. Furthermore, the σ-profiles and interaction energies based on conductor-like screening segment activity coefficient model (COSMO-SAC) were calculated to provide theoretical insight to interactions among the components. Also, the measured LLE data was correlated by the NRTL model and binary interaction parameters were regressed which is helpful for the separation process design and optimization.

Impact of Counter Ions of Cationic Monomers on the Production and Characteristics of Chitosan-Based Hydrogel.

Chitosan-based hydrogel has received considerable interests because of its appealing properties and applications in many areas. The primary objective of this work was to produce novel cationic chitosan-based hydrogels via polymerizing chitosan with two cationic monomers of the same structure but with different counter ions [2-(methacryloyloxy)ethyl]trimethylammonium methyl sulfate (METMS) and [2-(methacryloyloxy)ethyl]trimethylammonium chloride (METAC). Polymerization of chitosan with the cationic monomers performed under the conditions of 50 °C, 5 h, 7 pH, and 2/1 mol/mol monomer/chitosan led to chitosan–METMS and −METAC with the cationic charge densities of 3.22 and 2.88 mequiv/g, respectively. Elemental analysis, gel permeation chromatography, Fourier transform infrared, X-ray diffraction, and differential scanning calorimetry analyses were used to confirm the impact of counter ions of cationic monomers (i.e., polarizability of monomers) on their polymerization performance and the characteristics of induced chitosan-based hydrogels. Also, the results of this work postulated that the counter ions associated with the monomers could dramatically impact the water uptake and swelling properties of the generated chitosan-based hydrogels as well as their performance in adsorbing an anionic dye from a simulated solution.

Structure Determination of Large Isomeric Oligosaccharides of Natural Origin through Multipass and Multistage Cyclic Traveling-Wave Ion Mobility Mass Spectrometry.

Carbohydrate isomers with identical atomic composition cannot be distinguished by mass spectrometry. By separating the ions according to their conformation in the gas phase, ion mobility (IM) coupled to mass spectrometry is an attractive approach to overcome this issue and extend the limits of mass spectrometry in structural glycosciences. Recent technological developments have significantly increased the resolving power of ion mobility separators. One such instrument features a cyclic traveling-wave IM separator integrated in a quadrupole/time-of-flight mass spectrometer. This system allows for multipass ion separations and for pre-, intra-, and post-IM fragmentation. In the present study, we utilize this system to explore a complex mixture of oligoporphyrans derived from the enzymatic digestion of the cell wall of the red alga P. umbilicalis. We are able to deduce their complete structure using IM arrival times and the m/z of specific fragments. This approach was successfully applied for sequencing of oligoporphyrans of up to 1500 Da and included the positioning of the methyl ether and sulfate groups. The structures defined in this study by IM-MS/MS agree with those found in the past but use much more time-consuming analytical approaches. This study also revealed some so far undescribed structures, present at very low abundance. In addition, the results made it possible to compare the abundance of the different isomers released by the enzyme and to draw further conclusions on the specificity of β-porphyranase and more particularly on its accommodation tolerance of anhydro-bridges in subsites. Finally, a separation of two isomers with very similar mobility was obtained after 58 passes around the cIM, with an estimated resolving power of 920 for these triply charged species, confirming the structures attributed to these two isomers.