Polymeric ionic liquids containing copper(I) and copper(II) ions as gas chromatographic stationary phases for olefin separations.

Copper(I) ions (Cu+) are used in olefin separations due to their olefin complexing ability and low cost, but their instability in the presence of water and gases limits their widespread use. Ionic liquids (ILs) have emerged as stabilizers of Cu+ ions and prevent their degradation, providing high olefin separation efficiency. There is limited understanding into the role that polymeric ionic liquids (PILs), which possess similar structural characteristics to ILs, have on Cu+ ion-olefin interactions. Moreover, copper ions with diverse oxidation states, including Cu+ and Cu2+ ions, have been rarely employed for olefin separations. In this study, gas chromatography (GC) is used to investigate the interaction strength of olefins to stationary phases composed of the 1-hexyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([C6MIM+][NTf2-]) IL and the poly(1-hexyl-3-vinylimidazolium [NTf2-]) (poly([C6VIM+][NTf2-])) PIL containing monovalent and divalent copper salts (i.e., [Cu+][NTf2-] and [Cu2+]2[NTf2-]). The chromatographic retention of alkenes, alkynes, dienes, and aromatic compounds was examined. Incorporation of the [Cu2+]2[NTf2-] salt into a stationary phase comprised of poly(dimethylsiloxane) resulted in strong retention of olefins, while its addition to the [C6MIM+][NTf2-] IL and poly([C6VIM+][NTf2-]) PIL allowed for the interaction strength to be modulated. Olefins exhibited greater affinities toward IL and PIL stationary phases containing the [Cu2+]2[NTf2-] salt compared to those with the [Cu+][NTf2-] salt. Elimination of water from both copper salts was observed to be an important factor in promoting olefin interactions, as evidenced by increased olefin retention upon exposure of the stationary phases to high temperatures. To evaluate the long-term thermal stability of the stationary phase, chromatographic retention of probes was measured on the [Cu2+]2[NTf2-]/[C6MIM+][NTf2-] IL stationary phase after its exposure to helium at a temperature of 110 °C.

A practical and eco-friendly method for the determination of polycyclic aromatic hydrocarbons in açaí-based food products by vacuum-assisted sorbent extraction coupled to gas chromatography-mass spectrometry.

For the first time, a method for the simultaneous analysis of fifteen polycyclic aromatic hydrocarbons (PAHs), including light and heavy PAHs, in açaí-based food products (AFPs) was developed using vacuum-assisted sorbent extraction (VASE) combined with gas chromatography-mass spectrometry (GC-MS). The method requires no organic solvents and is amenable to full automation. To achieve optimal analytical extraction conditions, VASE parameters including stirring rate, extraction time, desorption temperature, desorption time, preheat time, and preheat temperature were optimized using sequential multivariate optimization. The method was validated and yielded limits of quantification below 1 µg kg-1 for all analytes, with recoveries ranging from 65 % to 112 % and good precision (≤11 % relative standard deviation). Additionally, the greenness and practical aspects of the method were investigated using the Green Analytical Procedure Index (GAPI), eco-scale, and the Blue Applicability Grade Index (BAGI), respectively. The VASE-GC-MS approach is suitable for routine analysis and exhibits characteristics of a green analytical method. No PAHs were detected above the limits of detection in thirty samples of AFPs.

Investigating a new approach for magnetic ionic liquids: Dispersive liquid-liquid microextraction coupled to pyrolysis gas-chromatography-mass spectrometry to determine flame retardants in sewage sludge samples.

This study addresses the analysis of emerging contaminants, often using chromatographic techniques coupled to mass spectrometry. However, sample preparation is often required prior to instrumental analysis, and dispersive liquid-liquid microextraction (DLLME) is a viable strategy in this context. DLLME stands out for its ability to reduce sample and solvent volumes. Notably, dispersive liquid-liquid microextraction using magnetic ionic liquids (MILs) has gained relevance due to the incorporation of paramagnetic components in the chemical structure, thereby eliminating the centrifugation step. A pyrolizer was selected in this work to introduce sample onto the GC column, since the MIL is extremely viscous and incompatible with direct introduction through an autosampler. This study is the first to report the use of a DLLME/MIL technique for sample introduction through a pyrolizer in gas chromatography coupled to mass spectrometry (GC-MS). This approach enables the MIL to be compatible with gas chromatography systems, resulting in optimized analytical and instrument performance. The analysis of polybrominated diphenyl ether flame retardants (PBDEs) was focused on the PBDE congeners 28, 47, 99, 100, and 153 in sewage sludge samples. The [P6,6,6,14+]2[MnCl42-] MIL was thoroughly characterized using UV-Vis, Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy, as well as thermal analysis. In the chromatographic method, a pyrolyzer was used in the sample introduction step (Py-GC-MS), and critical injection settings were optimized using multivariate approaches. Optimized conditions were achieved with a temperature of 220 °C, a pyrolysis time of 0.60 min, and an injection volume of 9.00 µL. DLLME optimization was performed through central compound planning (CCD), and optimized training conditions were achieved with 10.0 mg of MIL, 3.00 µL of acetonitrile (ACN) as dispersive solvent, extraction time of 60 s, and volume of a sample of 8.50 mL. Precision was observed to range from 0.11 % to 12.5 %, with limits of detection (LOD) of 44.4 µg L-1 for PBDE 28, 16.9 µg L-1 for PBDE 47 and PBDE 99, 33.0 µg L-1 for PBDE 100 and 375 µg L-1 for PBDE 153. PBDE 28 was identified and analyzed in the sludge sample at a concentration of 800 µg L-1. The use of MIL in dispersive liquid-liquid microextraction combined with pyrolysis gas chromatography-mass spectrometry enables identification and quantification of PBDEs in sewage sludge samples at concentrations down to the µg L-1 level.

Deep eutectic solvents as green and sustainable diluents in headspace gas chromatography for the determination of trace level genotoxic impurities in pharmaceuticals.

Genotoxic impurities (GTIs) are potential carcinogens that need to be controlled down to ppm or lower concentration levels in pharmaceuticals under strict regulations. The static headspace gas chromatography (HS-GC) coupled with electron capture detection (ECD) is an effective approach to monitor halogenated and nitroaromatic genotoxins. Deep eutectic solvents (DESs) possess tunable physico-chemical properties and low vapor pressure for HS-GC methods. In this study, zwitterionic and non-ionic DESs have been used for the first time to develop and validate a sensitive analytical method for the analysis of 24 genotoxins at sub-ppm concentrations. Compared to non-ionic diluents, zwitterionic DESs produced exceptional analytical performance and the betaine : 7 (1,4- butane diol) DES outperformed the betaine : 5 (1,4-butane diol) DES. Limits of detection (LOD) down to the 5-ppb concentration level were achieved in DESs. Wide linear ranges spanning over 5 orders of magnitude (0.005-100 µg g-1) were obtained for most analytes with exceptional sensitivities and high precision. The method accuracy and precision were validated using 3 commercially available drug substances and excellent recoveries were obtained. This study broadens the applicability of HS-GC in the determination of less volatile GTIs by establishing DESs as viable diluent substitutes for organic solvents in routine pharmaceutical analysis.

Exploring a new generation of bimetallic magnetic ionic liquids with ultra-low viscosity in microextraction that enable direct coupling with high-performance liquid-chromatography.

BACKGROUND: The incorporation of bimetallic magnetic ionic liquids (MILs) in microextraction methods is an emerging trend due to the improved magnetic susceptibility offered by these solvents, which relies on the presence of metallic components in both the cation and the anion. This feature favors easy magnetic separation of these solvents in analytical sample preparation strategies. However, reported liquid-phase microextraction methods based on bimetallic MILs still present an important drawback in that the MILs are highly viscous, making a dispersive solvent during the microextraction procedure necessary, while also requiring a tedious back-extraction step prior to the chromatographic analysis. RESULTS: We propose for the first time a new generation of ultra-low viscosity bimetallic MILs composed of two paramagnetic Mn(II) complexes characterized by their easy usage in dispersive liquid-liquid microextraction (DLLME). The approach does not require dispersive solvent and the MIL-DLLME setup was directly combined with high-performance liquid chromatography (HPLC) and fluorescence detection (FD), without any back-extraction step. The approach was evaluated for the determination of five monohydroxylated polycyclic aromatic hydrocarbons, as carcinogenic biomarkers, in human urine. Optimum conditions of the MIL-DLLME method included the use of a low MIL volume (75 µL), a short extraction time (5 min), and no need of any dispersive solvent neither NaCl. The method presented limits of detection down to 7.50 ng L-1, enrichment factors higher than 17, and provided inter-day relative standard deviation lower than 11%. Analysis of urine samples was successfully performed, with biomarker content found at levels between 0.24 and 7.8 ng mL-1. SIGNIFICANCE: This study represents the first liquid-phase microextraction method using the new generation of low-viscous bimetallic MILs. The proposed MIL-DLLME approach represents 2 important advances with respect to previous methods employing bimetallic MILs: 1) no dispersive solvent is required, and 2) direct injection of the MIL in the HPLC is possible after minor dilution (no back extraction steps are required). Therefore, the microextraction strategy is simple, rapid, and consumes very small amounts of energy.

Extraction of volatile organic compounds liberated upon filament extrusion by 3D pen and its comparison with a desktop 3D printer using solid-phase microextraction fiber and Arrow.

Desktop 3D printers that operate by the fused deposition modeling (FDM) mechanism are known to release numerous hazardous volatile organic compounds (VOCs) during printing, including some with potential carcinogenic effects. Operating in a similar manner to FDM 3D printers, 3D pens have gained popularity recently from their ability to allow users to effortlessly draw in the air or create various 3D printed shapes while handling the device like a pen. In contrast to numerous modern 3D printers, 3D pens lack their own ventilation systems and are often used in settings with minimum airflow. Their operation makes users more vulnerable to VOC emissions, as the released VOCs are likely to be in the breathing zone. Consequently, monitoring VOCs released during the use of 3D pens is crucial. In this study, VOCs liberated while extruding acrylonitrile butadiene styrene (ABS) filaments from a 3D pen were measured by solid-phase microextraction (SPME) combined with gas chromatography/mass spectrometry (GC/MS). SPME was investigated using the traditional fiber and Arrow geometries with the DVB/Carbon WR/PDMS sorbent while four different brands of ABS filaments-Amazon Basics, Gizmodork, Mynt 3D, and Novamaker-were used with the 3D pen. Heatmap analysis showed differentiation among these brands based on the liberated VOCs. The nozzle temperature and printing speed were found to affect the number and amount of released VOCs. This study goes a step further and presents for the first time a comparison between 3D pen and a desktop 3D printer based on liberated VOCs. Interestingly, the findings reveal that the 3D pen releases a greater number and amount of VOCs compared to the printer. The amounts of liberated VOCs, as indicated by the corresponding chromatographic peak areas, were found to be 1.4 to 62.6 times higher for the 3D pen compared to the 3D printer when using SPME Arrow.

Multivariate optimization for extraction of 2-methylimidazole and 4-methylimidazole from açaí-based food products using polymeric ionic liquid-based sorbent coatings in solid-phase microextraction coupled to gas chromatography-mass spectrometry.

In this study, polymeric ionic liquids featuring different functional moieties were applied as sorbent coatings in direct-immersion solid-phase microextraction (DI-SPME) for the extraction of 2-methylimidazole (2-MI) and 4-methylimidazole (4-MI) from açaí-based food products followed by gas chromatography-mass spectrometry (GC-MS) analysis. The analytical method was optimized using a sequential experimental design. Variables used in GC-MS such as desorption time, as well as for SPME-DI, including extraction time, extraction temperature, incubation time of extraction, amount of NaCl in the extract, and stirring rate, were optimized. The fitness-for-purpose of the method was verified by the linearity of matrix-matched calibration curves (R2 ≥ 0.9921), adequate recoveries (81.7-89.7 %), and precision (relative standard deviations ≤11.2 %). The method was applied to twenty-five samples of açaí-based food products. 4-MI was found in four samples whereas 2-MI was not detected above the limit of detection. The method was found to be suitable for quality control analysis.

Elucidating the role of temperature and water on the π-complexation strength of copper(I) ion-containing ionic liquids using inverse gas chromatography.

BACKGROUND: The π-complexation capability of copper(I) ion has been exploited in olefin/paraffin separations, but its propensity of undergoing disproportionation to copper(II) ion and copper metal has limited its use. Imidazolium-based ionic liquids (ILs) can serve as solvents for copper(I) ions as they facilitate copper(I) ion-olefin complexation and can enhance its stability. To precisely monitor how copper(I) ions complex with olefins in ILs and evaluate the effects of environmental factors, it is necessary to construct an experimental platform capable of quantitatively measuring their molecular-level interactions. RESULTS: This study employs an innovative inverse chromatography platform to measure changes in molecular-level interactions between copper(I) ions and olefins when the temperature and water content in the system are carefully controlled. Gas chromatographic stationary phases comprised of the 1-decyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([C10MIM+][NTf2-]) IL containing 0.5 M [Cu+][NTf2-] were pre-heated to 140 °C maximizing copper(I) ion's π-complexation capability. The chromatographic retention of alkenes, dienes, and alkynes on the copper(I) ion/IL stationary phase was observed to be predominantly influenced by their partitioning between the carrier gas and copper(I) ion as well as between the IL and copper(I) ion. Upon introducing water to the system, the Gibbs free energy of solvation for olefins showed less favorable solvation into the stationary phase. In contrast, their solvation was significantly enhanced when the [Cu+][NTf2-]/[C10MIM+][NTf2-] stationary phase was heated to an elevated temperature, indicating that the π-complexation capability of copper(I) ion can be regenerated as needed. SIGNIFICANCE: This study demonstrates that the stability of copper(I) ions can be improved by dissolving them into appropriate IL solvents. Moreover, the olefin separation performance of the copper(I) ion/IL stationary phase was found to be adjustable by the application of different column treatment conditions (i.e., heating and water introduction), opening the possibility of devising more stable, reliable, and efficient olefin separation systems based on copper(I) ion and IL solvents.

Polymeric ionic liquid sorbent coatings in thin film microextraction: Insight into sorbent selectivity for pesticides and cannabinoids.

Polymeric ionic liquid (PIL) sorbent coatings consisting of polymerizable cations and anions were employed as sorbent coatings in thin film microextraction (TFME) for the extraction of pesticides and cannabinoids. The blades consisted of a thin film of PIL sorbents chemically bonded to vinyltrimethoxysilane-functionalized nitinol sheets. The imidazolium- or ammonium-based PIL sorbents contained aromatic benzyl moieties as well as polar hydroxyl groups or aliphatic functional groups within the chemical structure of the IL monomer. The chemical structure of the IL crosslinkers of the PILs were kept constant across each sorbent, except for the anion, which consisted of either bis[(trifluoromethyl)sulfonyl]imide ([NTf2-]), p-styrenesulfonate ([SS-]), or 3-sulfopropyl acrylate ([SPA-]). Temperature, salt content, and methanol content were optimized as extraction conditions to maximize pesticide-cannabinoid selectivity using Doehlert design of experiments (DOE). Effects of these three factors on selectivity and extraction efficiency are discussed. The optimal extraction conditions consisting of sample temperature (31°C), sodium chloride (30% w/v), and methanol content (0.25% v/v) are compared to initial sorbent screening conditions at a sample temperature of 40°C, 15% (w/v) sodium chloride, and 2.5% (v/v) methanol content. PIL sorbent swelling behavior at different salt and methanol content conditions and its effect on extraction efficiency are hypothesized. Selectivity factors for the sorbents indicated that aromatic moieties within the IL monomer may enhance pesticide-cannabinoid selectivity under optimized conditions, but the extraction efficiency of pesticides that are known to coelute with cannabinoids in the chromatographic separation may be enhanced by employing sorbent coatings with [SPA-] anions.

Ultrasound-assisted dispersive solid-liquid microextraction with eutectic solvents for the determination of cannabinoids in different hemp products.

The wide range of applications of hemp products, together with the environmental benefits that come from hemp cultivation are driving up the market demand for Cannabis sativa L. plant. One of the main restrictions for hemp cultivation and marketing concerns the content of delta-9-tetrahydrocannabidiol (Δ9-THC), which is known to have psychotomimetic effect. If the recent growing of hemp market is beneficial by an economic and environmental point of view, it is necessary to develop reliable analytical methods for the chemical characterization of hemp products, to guarantee the safety of use for the customers. This study aimed to develop a simple ultrasound-assisted dispersive solid-liquid microextraction (UA-DSLME) method for the extraction of cannabinoids in hemp products, using eutectic solvents (ESs) as extraction material. Two types of ESs were compared: one prepared with a [Ch+][Br-]-modified salts as hydrogen bond acceptor and one based on natural terpenoids. The ultrasound-assisted dispersive solid-liquid microextraction method was optimized to be applied for the analysis of aerial parts of hemp collected before flowering, hemp inflorescences and a commercial sample called CBD oil, and proved to be robust and versatile. Under optimal conditions, only 100 µL of ES and 2 mL of water as co-solvent were used in the US-assisted extraction, before the analysis in the UHPLC-PDA system. The developed approach allowed to obtain the same chemical profile of conventional methods, while improving the greenness of the method and the enrichment of the marker analytes. To overcome the strong matrix effect for cannabinoids, a matrix-matched calibration was used. Blank matrices of the samples under study were easily obtained by performing an exhaustive extraction of the marker analytes in the hemp samples. These matrices were successfully used for validation, achieving accuracy values between 82% and 118%.

Quantification of capture efficiency, purity, and single-cell isolation in the recovery of circulating melanoma cells from peripheral blood by dielectrophoresis.

This paper describes a dielectrophoretic method for selection of circulating melanoma cells (CMCs), which lack reliable identifying surface antigens and are extremely rare in blood. This platform captures CMCs individually by dielectrophoresis (DEP) at an array of wireless bipolar electrodes (BPEs) aligned to overlying nanoliter-scale chambers, which isolate each cell for subsequent on-chip single-cell analysis. To determine the best conditions to employ for CMC isolation in this DEP-BPE platform, the static and dynamic dielectrophoretic response of established melanoma cell lines, melanoma cells from patient-derived xenografts (PDX) and peripheral blood mononuclear cells (PBMCs) were evaluated as a function of frequency using two established DEP platforms. Further, PBMCs derived from patients with advanced melanoma were compared with those from healthy controls. The results of this evaluation reveal that each DEP method requires a distinct frequency to achieve capture of melanoma cells and that the distribution of dielectric properties of PBMCs is more broadly varied in and among patients versus healthy controls. Based on this evaluation, we conclude that 50 kHz provides the highest capture efficiency on our DEP-BPE platform while maintaining a low rate of capture of unwanted PBMCs. We further quantified the efficiency of single-cell capture on the DEP-BPE platform and found that the efficiency diminished beyond around 25% chamber occupancy, thereby informing the minimum array size that is required. Importantly, the capture efficiency of the DEP-BPE platform for melanoma cells when using optimized conditions matched the performance predicted by our analysis. Finally, isolation of melanoma cells from contrived (spike-in) and clinical samples on our platform using optimized conditions was demonstrated. The capture and individual isolation of CMCs, confirmed by post-capture labeling, from patient-derived samples suggests the potential of this platform for clinical application.

Multi-residue method to determine selected personal care products from five classes in fish based on miniaturized matrix solid-phase dispersion and solid-phase microextraction coupled to gas chromatography-mass spectrometry.

A method featuring matrix solid-phase dispersion combined with solid-phase microextraction coupled to gas chromatography-mass spectrometry was developed to determine parabens, musks, antimicrobials, UV filters, and an insect repellent in fish. Optimization and validation of the method was carried out on tilapia and salmon samples. Acceptable linearity (R2 > 0.97), precision (relative standard deviations < 13 %) and accuracy (recovery > 80 %) at two concentration levels for all analytes were obtained using both matrices. The limits of detection ranged from 0.01 to 1.01 µg g-1 (wet weight) for all analytes except for methyl paraben. The SPME Arrow format was applied to increase the sensitivity of the method, and yielded detection limits more than ten times lower than those achieved with traditional SPME. The miniaturized method can be applied to various fish species, regardless of their lipid content, and represents a useful tool for quality control and food safety purposes.

Comparison of olefin/paraffin separation by ionic liquid and polymeric ionic liquid stationary phases containing silver(I) ion using one-dimensional and multidimensional gas chromatography.

Silver(I) ions have been used in various studies as components within polymer membranes or ionic liquids (ILs) to enable separation of olefins from paraffins. Polymeric ionic liquids (PILs) are a class of polymers synthesized from IL monomers and typically possess higher thermal and chemical stability than the ILs from which they are formed. Until now, very little is known about the difference in strength of silver(I) ion-olefin interactions when they take place in an IL compared to a PIL. In this work, the chromatographic separation of olefins by stationary phases composed of silver(I) bis[(trifluoromethyl)sulfonyl]imide ([Ag+][NTf2-]) incorporated into the 1-hexyl-3-methylimidazolium NTf2 ([HMIM+][NTf2-]) IL and poly(1-hexyl-3-vinylimidazolium NTf2) (poly([HVIM+][NTf2-])) PIL at varying concentrations was investigated. Olefins were more highly retained by silver(I) ions in PILs than in ILs as the silver(I) salt concentration in the stationary was increased. The potential separation power of silver(I)-containing IL and PIL stationary phases in comprehensive two-dimensional gas chromatography (GC×GC) was compared to the conventional one-dimensional system. The separation selectivity of alkenes and alkynes from paraffins was significantly increased, while dienes and aromatic compounds showed insignificant changes in retention. The chemical structural features of IL and PIL that enhance silver(I) ion stability and olefin separation were investigated by using silver(I) trifluoromethanesulfonate ([Ag+][OTf-]), 1-decyl-3-methylimidazolium NTf2 ([DMIM+][NTf2-]) IL, poly(1-decyl-3-vinylimidazolium NTf2 (poly([DVIM+][NTf2-])) PIL, [HMIM+][OTf-] IL and poly([HVIM+][OTf-]) PIL. Longer alkyl substituents appended to the IL (and PIL) cation increased the strength of silver(I) olefin interaction, and [OTf-] anions in the IL (and PIL) tended to preserve silver(I) ion from thermal reduction, while also retaining olefins less than the [NTf2-]-containing columns. In general, silver(I) ions in PILs possessing analogous chemical structures to ILs exhibited higher silver(I) ion-olefin interaction strength but were less thermally stable.

Monitoring the liberation of volatile organic compounds during fused deposition modeling three dimensional printing using solid-phase microextraction coupled to gas chromatography/mass spectrometry.

Three-dimensional (3D) printers have gained tremendous popularity and are being widely used in offices, laboratories, and private homes. Fused deposition modeling (FDM) is among the most commonly used mechanisms by desktop 3D printers in indoor settings and relies on the extrusion and deposition of heated thermoplastic filaments, resulting in the liberation of volatile organic compounds (VOCs). With the growing use of 3D printers, concerns regarding human health have risen as the exposure to VOCs may cause adverse health effects. Therefore, it is important to monitor VOC liberation during printing and to correlate it to filament composition. In this study, VOCs liberated with a desktop printer were measured by solid-phase microextraction (SPME) combined with gas chromatography/mass spectrometry (GC/MS). SPME fibers featuring sorbent coatings of varied polarity were chosen for the extraction of VOCs liberated from acrylonitrile butadiene styrene (ABS), tough polylactic acid, and copolyester+ (CPE+) filaments. It was found that for all three filaments tested, longer print times resulted in a greater number of extracted VOCs. The ABS filament liberated the most VOCs while the CPE+ filaments liberated the fewest VOCs. Through the use of hierarchical cluster analysis and principal component analysis, filaments as well as fibers could be differentiated based on the liberated VOCs. This study demonstrates that SPME is a promising tool to sample and extract VOCs liberated during 3D printing under non-equilibrium conditions and can be used to aid in tentative identification of the VOCs when coupled to gas chromatography-mass spectrometry.

Deconvoluting the Combined Effects of Gas Composition and Temperature on Olefin Selectivity for Separations Using Silver(I) Ions in Ionic Liquids.

Silver(I) ions have the propensity of undergoing reduction to form metallic silver within olefin/paraffin separation systems when they are subjected to hydrogen at elevated temperatures. Ionic liquids (ILs) are versatile solvents known for their low vapor pressure, high thermal stability, and structural tunability and have been shown to minimize hydrogen-induced reduction of silver(I) ions when employed as solvents. In the development of robust separation platforms that employ silver(I) ions, it is essential to deploy reliable approaches capable of measuring and assessing the factors that lower the overall separation performance. In this study, silver(I) ions dissolved in an imidazolium-based IL are subjected to mixed gas streams composed of hydrogen, nitrogen, and methane under varying temperatures. Using inverse gas chromatography, a total of 44 columns with stationary phases containing four different concentrations of silver(I) bis[(trifluoromethyl)sulfonyl]imide ([Ag+][NTf2 -]) dissolved in the 1-decyl-3-methylimidazolium ([C10MIM+]) [NTf2 -] IL were used to measure partition coefficients of olefins and paraffins, as well as aromatics, esters, and ketones. Upon exposing the stationary phases to mixed gases at elevated temperatures, olefin partitioning between the silver(I) ion pseudophase and the two other phases (i.e., carrier gas and IL stationary phase) was observed to decrease over time, while partitioning between the IL stationary phase and carrier gas remained unchanged. It was found that exposure gases composed of 5.0 to 85.0 mol % hydrogen and temperatures ranging from 95 to 130 °C resulted in a remarkable acceleration of silver(I) ion reduction and an approximate 36.4-61.3% decrease in olefin partitioning between the silver(I) ion pseudophase and both the carrier gas and IL stationary phase after 60 h. While binary mixtures of hydrogen and nitrogen resulted in a continuous decrease in silver(I) ion-olefin complexation capability, a ternary gas mixture produced varied silver(I) ion reduction kinetics.

Effect of silver(I) ion reduction on the selectivity of olefins, paraffins, and aromatic compounds by gas chromatographic stationary phases consisting of silver(I) salts in ionic liquids.

The olefin/paraffin selectivity offered by ionic liquid (IL) stationary phases can be enhanced through the addition of silver(I) ion, which is well-known to undergo selective complexation with unsaturated compounds. However, such stationary phases often suffer from the loss of chromatographic selectivity as silver(I) ion can be reduced to elemental silver. To maintain the separation performance of silver(I) ion/IL stationary phases, an understanding of factors and conditions that promote the reduction of silver(I) ion is needed. In this study, capillary gas chromatography columns featuring a stationary phase consisting of the 1-decyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([C10MIM+][NTf2-]) IL impregnated with [Ag+][NTf2-] were examined to investigate the effects of temperature, hydrogen content in exposure gas stream, and time of heating/exposure events on olefin selectivity. Retention factors of representative analytes, such as C6 olefins and paraffins as well as aromatic compounds, were measured after subjecting the columns to the aforementioned conditions, followed by an evaluation of selectivity factors over time. Selectivity factors of olefins and aromatic compounds were observed to decrease significantly when the stationary phases were heated to temperatures higher than 110°C as well as being subjected to mixed gas streams containing greater than 50 mol% of hydrogen. As constant column heating temperatures were applied under exposure gas mixtures containing hydrogen and nitrogen, a gradual decrease in analyte selectivity factors was observed under prolonged periods of time. However, application of a ternary gas mixture comprised of 25/50/25 mol% hydrogen/nitrogen/methane resulted in an increase in the 3-hexyne/cis-2-hexene selectivity when measured at 120°C for 60 h, due to a smaller decrease in the retention factor of 3-hexyne compared to cis-2-hexene.

Selective isolation of pesticides and cannabinoids using polymeric ionic liquid-based sorbent coatings in solid-phase microextraction coupled to high-performance liquid chromatography.

The high abundance of cannabinoids within cannabis samples presents an issue for pesticide testing as cannabinoids are often co-extracted with pesticides using various sample preparation techniques. Cannabinoids may also chromatographically co-elute with moderate polarity pesticides and inhibit the ionization of pesticides when using mass spectrometry. To circumvent these issues, we have developed a new approach to isolate commonly regulated pesticides and cannabinoids from aqueous samples using tunable, crosslinked imidazolium polymeric ionic liquid (PIL)-based sorbent coatings for direct immersion solid-phase microextraction (DI-SPME). The selectivity of four PIL sorbent coatings towards 20 pesticides and six cannabinoids, including cannabidiol and Δ9-THC, was investigated and compared against a commercial PDMS/DVB fiber. Extraction and desorption conditions, including salt content, extraction temperature, pH, extraction time, desorption solvent, and desorption time, were optimized using high-performance liquid chromatography (HPLC) with ultraviolet (UV) detection. Under optimized conditions, the PIL fiber consisting of 1-vinylbenzyl-3-octylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([VBIMC8+][NTf2-]) and 1,12-di(3-vinylbenzylimidazolium)dodecane dibis[(trifluoromethyl)sulfonyl]imide ([(VBIM)2C122+]2[NTf2-]) sorbent coating provided the best selectivity towards pesticides compared to other PILs and the PDMS/DVB fibers and was able to reach limits of detection (LODs) as low as 1 µg/L. When compared to a previously reported PIL-based SPME HPLC-UV method for pesticide analysis, the amount of cannabinoids extracted from the sample was decreased 9-fold while a 4-fold enhancement in the extraction of pesticides was achieved. Additionally, the PIL-based SPME method was applied to samples containing environmentally-relevant concentrations of pesticides and cannabinoids to assess its feasibility for Cannabis quality control testing. Relative recoveries between 95% and 141% were obtained using the PIL sorbent coating while recoveries ranging from 50% to 114% were obtained using the PDMS/DVB fiber.

Evaluating commercial thermoplastic materials in fused deposition modeling 3D printing for their compatibility with DNA storage and analysis by quantitative polymerase chain reaction.

Nucleic acids are ubiquitous in biological samples and can be sensitively detected using nucleic acid amplification assays. To achieve highly accurate and reliable results, nucleic acid isolation and purification is often required and can limit the accessibility of these assays. Encapsulation of these workflows onto a single device may be achieved through fabrication methodologies featuring commercial three-dimensional (3D) printers. This study aims to characterize fused deposition modeling (FDM) filaments based on their compatibility with nucleic acid storage using quantitative polymerase chain reaction (qPCR). To study the adsorption of nucleic acids, storage vessels were fabricated using six common thermoplastics including: polylactic acid (PLA), nylon, acrylonitrile butadiene styrene (ABS), co-polyester (CPE), polycarbonate (PC), and polypropylene (PP). DNA adsorption of a short 98 base pair and a longer 830 base pair fragment to the walls of the vessel was shown to vary significantly among the polymer materials as well as the color varieties of the same polymer. PLA storage vessels were found to adsorb the least amount of the 98 base pair DNA after 12 hours of storage in 2.5 M NaCl TE buffer whereas the ABS and PC vessels adsorbed up to 97.2 ± 0.2% and 97.5 ± 0.2%. DNA adsorption could be reduced by decreasing the layer height of the 3D printed object, thereby increasing the functionality of the ABS storage vessel. Nylon was found to desorb qPCR inhibiting components into the stored solution which led to erroneous DNA quantification data from qPCR analysis.

Electropolymerization of Pyrrole-Based Ionic Liquids on Selected Wireless Bipolar Electrodes.

This paper describes an electropolymerization-based on-chip valving system, accomplished by electrosynthesis of conductive polymeric ionic liquid (CPIL) films at selected points within an array of bipolar electrodes (BPEs), in which each of these wireless electrodes spans an IL-aqueous phase boundary. The low viscosity and high hydrophobicity of the CPIL precursor allow it to be patterned by established microfluidic methods. This advancement has the potential to impact microscale analysis because it allows on-demand creation of solid CPIL microstructures at locations specified by microfluidics, phase boundaries, and electrode potentials. To achieve this outcome, an imidazolium-based IL was functionalized with a pyrrole moiety, and the viscosity was tuned by choosing the appropriate counterion to form a CPIL with the desired viscosity, hydrophobicity, and oxidation potential. This monomer species was then introduced into a microfluidic device, which was prefilled with an aqueous buffer solution. The device comprised many parallel microchannels lined with nanoliter-scale chambers. BPEs interconnected the channels such that the BPE tips were each aligned to a chamber opening. The electrodes contacting the outermost channels were connected directly to a power supply and functioned as driving electrodes. The CPIL displaced the buffer in the channels and established a phase boundary at the opening of each chamber, thereby digitizing the aqueous phase. Finally, an alternating square waveform (under mode 1) was applied for 5 min to yield immobilized polymer films at a location defined by the BPE poles. In total, three modes were developed and three corresponding polymer film patterns were formed. Under mode 2, a DC power supply was used to achieve a dissymmetrical polymer film pattern, and, under mode 3, a regional polymer film pattern was formed under an AC potential with a DC offset. Our preliminary results demonstrate that the generated polymer films are immobile and sufficiently thick to seal the chambers at room temperature over the duration of our observation window (50 min), and this seal is maintained even at elevated temperatures that induce partial evaporation of the chamber contents. A key point is that this method is compatible with a preceding step─dielectrophoretic capture of single melanoma cells within the nanoliter-scale chambers.

Simple and efficient isolation of plant genomic DNA using magnetic ionic liquids.

BACKGROUND: Plant DNA isolation and purification is a time-consuming and laborious process relative to epithelial and viral DNA sample preparation due to the cell wall. The lysis of plant cells to free intracellular DNA normally requires high temperatures, chemical surfactants, and mechanical separation of plant tissue prior to a DNA purification step. Traditional DNA purification methods also do not aid themselves towards fieldwork due to the numerous chemical and bulky equipment requirements. RESULTS: In this study, intact plant tissue was coated by hydrophobic magnetic ionic liquids (MILs) and ionic liquids (ILs) and allowed to incubate under static conditions or dispersed in a suspension buffer to facilitate cell disruption and DNA extraction. The DNA-enriched MIL or IL was successfully integrated into the qPCR buffer without inhibiting the reaction. The two aforementioned advantages of ILs and MILs allow plant DNA sample preparation to occur in one minute or less without the aid of elevated temperatures or chemical surfactants that typically inhibit enzymatic amplification methods. MIL or IL-coated plant tissue could be successfully integrated into a qPCR assay without the need for custom enzymes or manual DNA isolation/purification steps that are required for conventional methods. CONCLUSIONS: The limited amount of equipment, chemicals, and time required to disrupt plant cells while simultaneously extracting DNA using MILs makes the described procedure ideal for fieldwork and lab work in low resource environments.