Karl-Fischer Titration Research Articles

Room-temperature-storable PCR mixes for SARS-CoV-2 detection

ObjectivesA novel coronavirus (severe acute respiratory syndrome coronavirus 2, SARS-CoV-2) emerged in late 2019, causing an outbreak of pneumonia [coronavirus disease 2019 (COVID-19)] globally. Although the use of ready-made reaction mixes can enable more rapid PCR-based diagnosis of COVID-19, the need to transport and store these mixes at low temperatures presents challenges to already overburdened logistics networks. MethodsHere, we present an optimized freeze-drying procedure that allows SARS-CoV-2 PCR mixes to be transported and stored at ambient temperatures, without loss of activity. Additive-supplemented PCR mixes were freeze-dried. The residual moisture of the freeze-dried PCR mixes was measured by Karl-Fischer titration. ResultsWe found that the freeze-dried PCR mixes with ~1.2% residual moisture are optimal for storage, transport, and reconstitution. The sensitivity, specificity, and repeatability of the freeze-dried reagents were similar to those of freshly prepared, wet reagents. The freeze-dried mixes retained activity at room temperature (18 ~ 25 °C) for 28 days, and for 14 and 10 days when stored at 37 °C and 56 °C, respectively. ConclusionThe uptake of this approach will ease logistical challenges faced by transport networks and make more cold storage space available at diagnosis and hospital laboratories.

Heat flux sensor to create a design space for freeze-drying development

Freeze-drying methodology requires an in-depth understanding and characterization for optimal processing of biopharmaceuticals. Particularly the primary drying phase, the longest and most expensive stage of the process, is of interest for optimization. The currently used process analytical technology (PAT) tools give highly valuable insights but come with limitations. Our study describes, for the first time, the application of a heat flux sensor (HFS) to build a primary drying design space and predict the process evolution. First, the heat transfer coefficient (Kv) generated by HFS and by the most accurate, but time-consuming and invasive, gravimetric method were compared. Second, the applicability to generate a design space was tested and verified. Obtained results revealed a good agreement of the values generated from this new and fast HFS compared to the gravimetric determination. Additionally, residual moisture assessed by Karl-Fischer titration and frequency modulated spectroscopy (FMS) support the quality of the obtained predictions. Thus, the HFS approach can substantially accelerate evaluation, development and transfer of a freeze-drying cycle.

Development of Four Certified Reference Materials for Water Content in Solids

Water content in solid materials is usually measured by loss on drying and Karl Fischer titration (KFT) methods. The validation of KFT methods requires the certified reference materials (CRMs) for the water content in solids, especially those with lower water content. In the present study, two mixtures of sodium tartrate dihydrate and 4-methoxybenzoic acid were prepared using the gravimetric method and then used as candidates of CRMs with water content of 10.0 and 1.0 mg·g−1, respectively. Furthermore, the CRM of lactose monohydrate and that of 4-methoxybenzoic acid were also developed. The stability against the humidity of the raw materials was characterized using water sorption isotherms. The thermal stability of the raw materials was characterized by the thermogravimetric analyzer. These four CRMs for water content were certified using Karl Fischer coulometric and volumetric titration. To make the water content traceable, both KFT methods were calibrated using a home-made water content standard prepared by the gravimetric method. The average value of the two methods was used as the certified value. The certified water contents and their expanded uncertainties (U, k = 2) of four CRMs were (50.7 ± 0.6) mg·g−1, (9.90 ± 0.2) mg·g−1, (0.878 ± 0.044) mg·g−1 and (0.142 ± 0.013) mg·g−1, respectively. This series of CRMs were suitable for the validation of KFT methods for the water contents in solids.

Determination of Water Content in Liquid Insulation of High-Voltage Equipment by Different Methods

Control of the formation and behavior of water in a liquid dielectric during the operation of high-voltage equipment is of paramount importance because water provokes intensive oxidation and aging of the entire oil-solid insulation system. The electrophoretic ability of water has a strong effect on the insulating properties of dielectrics inside a high-voltage apparatus, and, in general, on its uninterrupted long-term operation. Problems associated with the determination of moisture in the complex hydrocarbon matrix of transformer oil by all available methods are considered. It is shown how different states of water in transformer oil of various grades can be determined by varying the temperature in the evaporator of the chromatographic unit. Chromatographic data are compared with data obtained by conventional methods (Karl-Fischer coulometric titration, calcium-hydride method, coulometric sensor based electrolysis).

Decomposition of deep eutectic solvents based on choline chloride and phenol in aqueous phase

Deep eutectic solvents (DESs) are compounds formed by donor and acceptor of hydrogen bond in a liquid state at ambient temperature. They are non-volatile, with high thermal stability and readily dissolve many organic and inorganic compounds. DESs based on choline chloride and phenol have recently appeared in analytical practice and have already found wide application in various fields. The numerous articles have been reported efficient liquid-liquid extraction using these DESs as extraction solvents. In this paper the process of liquid-liquid extraction using DESs based on choline chloride and phenol was investigated. It was established that the DES decomposition in aqueous phase takes place due to the dissociation of choline and phenol, which leads to the destruction of the hydrogen bond. In addition, with the addition of an aprotic solvent, tetrahydrofuran, the extraction of organic phase is observed. This phase was mistakenly used as DES, but in our study we showed that this phase consists of tetrahydrofuran, water and phenol, which is not the initial phase of DES. This phenomenon was investigated by gas chromatography with mass spectrometric detection and coulometric Karl-Fischer titration It was confirmed that these DESs cannot be considered as extraction solvents in liquid-liquid extraction from aqueous solutions. The main goal of the present work is to pay attention of researchers to a wrong conception in liquid-liquid extraction using DESs based on choline chloride and phenol to avoid mistakes in the future.

Extraction Performance of a Fluorous Phosphate for Zr(IV) from HNO3 Solution: Comparison with Tri-n-Butyl Phosphate

ABSTRACTWe compare the extraction performance of new extractant, fluorous phosphate tris(4,4,5,5,6,6,7,7,7-nonafluoroheptyl) phosphate (TFP) in the fluorinated diluent perfluorohexane, for Zr(IV) with a conventional organic extractant, tri-n-butyl phosphate (TBP) in n-octane. It is surprising that fluorinating TBP to TFP improved the extraction performance, as normally fluorinating the hydrocarbon substituents on neutral extractants tends to decrease the extraction strength. We examined the origin of the superior extraction performance of TFP by analyzing the equilibrium of the chemical reaction during the extraction. The equilibrium reaction of Zr(IV) with TFP is , whereas that with TBP is . Phosphorus-31 nuclear magnetic resonance and infrared spectroscopy measurements of TFP and TBP showed similar electron densities at the phosphorus atom and vibration modes of the P=O group, implying similar coordination to Zr(IV). In addition, the concentrations of all components (Zr(IV), HNO3, and water) in the fluorous and organic phases after solvent extraction were evaluated by inductively coupled plasma-mass spectrometry, ion chromatography, and Karl-Fischer titration. The concentrations of water and HNO3 molecules in the fluorous phase become low during the Zr(NO3)4(TFP)3 extraction, indicating that water and HNO3 molecules do not preferentially interact with Zr(NO3)4(TFP)3 in contrast to Zr(NO3)4(TBP)2 in n-octane We speculate that the excellent performance originated from the stability of Zr(NO3)4(TFP)3 in the fluorous phase. Hence, TFP is expected to be used as an alternative extractant to TBP.

Electrodeposition of Lithium in LiPF6-Based Electrolyte with Trace-Amount of Water

Lithium metal has been considered as an attractive candidate of the anode material for the next-generation secondary batteries because of its high theoretical capacity and low redox potential. Among a lot of strategies in order to suppress the inhomogeneous or dendritic growth of lithium during deposition have been proposed so far, some reports suggested that the trace-amount of water leads to smooth the morphology of deposited lithium metal. (1, 2) However, the relationship between the morphology of deposited lithium metal and the content of the electrolyte which changes with the time after addition of the water is not clear. In the present study, we investigated the electrodeposition of lithium in LiPF6-based electrolyte with trace-amount of water. Especially, we focused on the change of the morphology and surface state of the deposited lithium metal with the content of the electrolyte. 100 ppm of water was added into 1.0 mol dm–3 LiPF6 in propylene carbonate (PC) in the Ar-filled glove box and temporal change of its water content was checked by Karl-Fischer titration method. The water content was gradually decreased with time due to the reaction of LiPF6 and water. (3) When the electrodeposition of lithium was conducted on the copper electrode in the electrolyte, the morphology of the deposited lithium changed from inhomogeneous to granular and smooth as time passes after addition of water. This result proposed that the decomposed product in the electrolyte was strongly affected to the morphology of the deposit. (4) We also checked the surface state of the deposits by auger electron spectroscopy, X-ray and hard X-ray photoelectron spectroscopy, suggesting that the component of the film greatly influences the morphology of the deposit. Acknowledgement This work was supported by the New Energy and Industrial Technology Development Organization (NEDO) under the “Research and Development Initiative for Scientific Innovation of New Generation Batteries 2 (RISING2)” References J. Qian, W. Xu, P. Bhattacharya, M. Engelhard, W. A. Henderson, Y. Zhang and J.-G. Zhang, Nano Energy, 15, 135 (2015).H. Koshikawa, S. Matsuda, K. Kamiya, Y. Kubo, K. Uosaki, K. Hashimoto and S. Nakanishi, J. Power Sources, 350, 73 (2017).D. Strmcnik, I. E. Castelli, J. G. Connell, D. Haering, M. Zorko, P. Martins, P. P. Lopes, B. Genorio, T. Østergaard, H. A. Gasteiger, F. Maglia, B. K. Antonopoulos, V. R. Stamenkovic, J. Rossmeisl and N. M. Markovic, Nature Catalysis, 1, 255 (2018).K. Kanamura, S. Shiraishi and Z. Takehara, J. Electrochem. Soc., 143, 2187 (1996).

Co-pyrolysis of softwood with waste mussel shells: Liquid analysis

Fast pyrolysis bio-oil (FPBO) from lignocellulosic feedstocks can be limited to applications such as heating due in part to the high oxygen and resulting acid content of the oil which complicates storage, handling, and use in traditional petroleum-based systems. Research has been carried out to enhance the oil quality, both catalytically and non-catalytically. This work focuses on utilizing by-product from the fisheries industry as a co-pyrolysis additive to enhance oil quality. Mussel shells (MS) were co-pyrolyzed with softwood forestry residues in a lab-scale, tube furnace reactor. The pyrolysis temperature (400–525 °C), nitrogen flow rate (50–300 mL/min), wood-to-MS ratio (0–50 wt% MS), and operational mode (in-situ and ex-situ) were varied in a designed experiment. The produced pyrolysis oils were analyzed for water content (Karl-Fischer titration), high heating value (HHV), total acid number (TAN), pH, density, volatility and ash content via thermogravimetric analysis (TGA), and chemical composition via gas chromatography-flame ionization detector (GC-FID) and C/H/N(O) elemental analysis. Co-pyrolysis with MS in-situ decreased the TAN of FPBO from 68 to 48mgNaOH/gOil), while the water content increased from 29 wt% to 39 wt%. However, the HHV of the water free oil increased from 22.4 to 23.6 MJ/kg indicating a reduction in oxygenated compounds, and therefore, an improvement in fuel quality of FPBO.

Fast pyrolysis of acid-washed oil palm empty fruit bunch for bio-oil production in a bubbling fluidized-bed reactor

Oil palm empty fruit bunch (EFB) contains the inorganic materials such as K, Na, Mg, and Ca, which cause some problems during fast pyrolysis reaction. In this paper, we report the effect of pretreatment by acid washing with dilute nitric acid to both remove the inorganic materials and increase the bio-oil production at fast pyrolysis in a bubbling fluidized-bed reactor. By pretreating dilute nitric acid at EFB, the total liquid yield enhancement was from 52.2 wt% to 63.9 wt% and the char yield reduction was from 39.9 wt% to 41.9 wt% compared to original EFB. Using various analytical tools including elemental analysis, thermogravimetric analysis, inductively coupled plasma atomic emission spectroscopy, pH meter, Karl-Fischer titration, gas chromatography, gas chromatography-mass spectrometry, and 13C nuclear magnetic resonance, the properties and components of bio-oil in original EFB and acid-washed EFB samples were investigated. Through analytical tools, the biomass and bio-oil both in original and acid-washed EFB were analyzed to obtain various properties such as compositions, higher heating value, product yield, 13C NMR spectra, and carbon number.

Structural investigation of hydrous phosphate glasses

Dissolved water has major impact on the physical and chemical properties of phosphate glasses. In the present study we have investigated the structural response to water incorporation for glasses in the system Li2O–MgO–Al2O3–P2O5. Glasses containing 0–8 wt% H2O were synthesised at 500 MPa confining pressure in internally heated gas pressure vessels at 1323 K (LMP, Al-poor glass) and 1423 K (LMAP, Al-enriched glass). Water contents of glasses were determined by pyrolysis and subsequent Karl-Fischer titration (KFT) and/or by infrared spectroscopy. Density varies nonlinearly with water content implying large structural changes when adding up to 2 wt% H2O to the dry glass. Glass Transition temperatures measured by differential thermal analysis (DTA) continuously decrease with water content. The trend can be explained by depolymerisation of the phosphate network. Near-infrared spectroscopy shows that even in Al poor glasses only a minority of dissolved water is present as H2O molecules, but the largest amount is present as OH Groups formed by hydrolysis of P–O–P bonds. The network is stabilised by aluminium which is predominantly six-coordinated in these glasses as shown by 27Al MAS NMR spectroscopy. With increase of Al in the glasses, breaking up of the Phosphate network through hydrolysis is depressed, i.e. much lower OH Contents are formed at same total water content. Network depolymerisation upon addition of H2O is evident also from 31P MAS NMR spectroscopy. While Phosphate tetraheda are crosslinked by two to three bridging oxygen in dry glasses, diphosphate Groups are dominant in glasses containing 8 wt% H2O.

Crystallizing amino acids as bulking agents in freeze-drying

Bulking agents as mannitol (Man) and glycine (Gly) require high bulking agent to stabilizer ratios to ensure their crystallization during the freeze-drying process. The aim of this study was to investigate several amino acids (AA) as potential alternative bulking agents in low AA to sucrose (Suc) ratios. A fast freeze-drying process was performed above the collapse temperature (Tc) of the amorphous phase challenging the crystalline AA scaffold. Lyophilizates and liquid formulations were characterized by differential scanning calorimetry. Karl-Fischer titration and X-ray powder diffraction as well as macroscopic cake appearance and reconstitution times were evaluated. Stability of a monoclonal antibody was investigated by UV–Vis spectroscopy, light obscuration and size exclusion chromatography. Phenylalanine (Phe), leucine (Leu) and isoleucine (Ile) crystallized upon freeze-drying at 5/45 and 10/40 AA/Suc ratios. 2.5/47.5 AA/Suc ratio showed less pronounced crystallization. Crystallization peaks were not suppressed by 2 or 50 mg/mL antibody in Leu and Ile lyophilizates. Reconstitution times could be improved by addition of surfactant. No signs of protein aggregation were detected after freeze-drying. Man and Gly yielded inacceptable cake appearance when dried with the fast freeze-drying cycle in such low bulking agent to Suc ratios. Leu, Ile and Phe can be used as alternate bulking agents at lower bulking agent to Suc ratios compared to Man or Gly. The selected AAs provided promising cake characteristics and good protein process stability.

Improved method for measuring moisture content of mineral-oil-impregnated cellulose pressboard based on dielectric response

The moisture content in transformer insulation pressboards is an important index to evaluate the insulation aging in the transformer. The dielectric-response technique based on frequency domain spectroscopy is used to accurately measure the moisture content in transformer insulation pressboard. In this study, according to the distribution of water molecules in oil-impregnated cellulose pressboard and the polarization behaviour of water molecules at different frequencies, a theoretical calculation method for moisture content in a composite model of cellulose pressboard, mineral oil, and moisture based on a typical transformer structure is proposed. To verify the effectiveness of the numerical iterative calculation method further, a typical structure model of a transformer with different proportions was prepared under laboratory conditions of natural moisture absorption and accelerated aging. Three groups of comparison tests were done. In the stage temperature rise test (40–90 °C), the moisture contents are compared and analysed by the method proposed in this research and the IDAX-300 software fitting method. It was found that the fitting of the dielectric loss factor curve is more accurate in the high-temperature and low-frequency region. In a room temperature (25 °C) test, the moisture contents obtained by the method proposed in this study, the IDAX-300 instrument test method, and the traditional Karl–Fischer titration method are compared and analysed. After testing the XY model with different moisture absorptions at 25 °C, it was found that the accuracy of the algorithm is higher. Testing the XY model at different degrees of aging at 25 °C, showed the effect of the aging of the oil-impregnated cellulose pressboard. The selected fitting frequency range should be (10−1–103) Hz, and the accuracy of the numerical iterative calculation method is high.

Mutual Solubilities of Cyclohexane and Water in Aqueous Methyldiethanolamine /Cyclohexane Liquid–Liquid Equilibria

The aim of this work is to study the solubility of cyclohexane in aqueous methyldiethanolamine (MDEA) solutions. Thermostated jacketed double glass equilibrium cells were used to measure the mutual solubility between two liquid phases of aqueous MDEA and cyclohexane at 298–318 K under atmospheric pressure. The cyclohexane solubility in the aqueous liquid samples was analyzed using GC–MS coupled with purge and trap technique, while that of water in the cyclohexane-rich phase was measured via the Karl-Fischer titration method. It was observed that the solubility of cyclohexane in the aqueous phase increases with increasing temperature. Furthermore, an increase in amine composition, increases the solubility of cyclohexane. The mutual water solubility in the cyclohexane-rich phase increases rapidly with increasing temperature while it was rather nonsensitive toward the amine composition. A simple correlation for the salting-in ratio has been used that allows for a direct comparison between the solubilities of...

Impact of fast and conservative freeze-drying on product quality of protein-mannitol-sucrose-glycerol lyophilizates

PurposeMannitol/sucrose formulations are employed to generate lyophilizates for biopharmaceuticals with an elegant cake appearance. The aim of this study was to dry protein/mannitol/sucrose formulations as fast as possible without loss of cake appearance and protein stability. Glycerol was included as potential additional protein stabilizer. Three proteins (lysozyme and two monoclonal antibodies) at low and high concentration were analyzed comparing fast with conservative freeze-drying. MethodsFreeze-drying cycle development was carried out with mannitol/sucrose formulations. A product temperature (Tp) close to the Te of mannitol and clearly above the Tg’ of sucrose was targeted. Protein formulations were exposed to the final fast lyophilisation process and to a conservative freeze-drying cycle. Lyophilizates were characterized by differential scanning calorimetry, Karl-Fischer titration and X-ray diffractometry. Additionally, macroscopic cake appearance and reconstitution times were evaluated. Protein stability was characterized by UV/Vis spectroscopy, light obscuration and size exclusion chromatography. ResultsThe fast freeze-drying cycle resulted in a primary drying time of 7 h (Tp: −10 °C) and a secondary drying time of 2 h in contrast to 47 h (Tp: −39 °C) and 12 h for the conservative cycle. Lyophilizates showed Tg values above 60 °C, a residual moisture level of 1%, reconstitution times of less than 35 s, δ-mannitol and elegant cake appearance. Mannitol/sucrose ratios below 4/1 did not lead to complete mannitol crystallization and were therefore not suitable for the selected process conditions. Characterisation of protein stability rendered low aggregation and particle levels for both, fast and conservative freeze-drying conditions. ConclusionsIt was shown that fast freeze-drying of mannitol/sucrose formulations above Tg’ at a Tp of −10 °C resulted in good protein process stability and appropriate cake characteristics at maximum time reduction.

In-line moisture monitoring in fluidized bed granulation using a novel multi-resonance microwave sensor

Microwave resonance technology (MRT) is known as a process analytical technology (PAT) tool for moisture measurements in fluid-bed granulation. It offers a great potential for wet granulation processes even where the suitability of near-infrared (NIR) spectroscopy is limited, e.g. colored granules, large variations in bulk density. However, previous sensor systems operating around a single resonance frequency showed limitations above approx. 7.5% granule moisture. This paper describes the application of a novel sensor working with four resonance frequencies. In-line data of all four resonance frequencies were collected and further processed. Based on calculation of density-independent microwave moisture values multiple linear regression (MLR) models using Karl-Fischer titration (KF) as well as loss on drying (LOD) as reference methods were build. Rapid, reliable in-process moisture control (RMSEP≤0.5%) even at higher moisture contents was achieved.

A simple method for determination of total water in PM1 on quartz fiber filters

A method is proposed for applying the coulometric Karl-Fischer titration in analyzing the water content of submicron ambient particles (PM1) collected on quartz fiber filters of the most commonly used size (Ø47mm). The developed and validated method was applied to determine the water content of 24-h PM1 samples from two urban sites, one located in Warsaw and the other one in Zabrze, Poland.In some circumstances a number of analyses of particulate matter (PM) (e.g. for mass closure) are performed on the same PM sample, and some of them (e.g. those for carbon) imply application of quartz fiber filters. However, the hygroscopicity of quartz fiber filters interferes with determination of water content of PM sampled onto such filters.The water content of clean quartz fiber filters is high compared to water content of PM1 samples and differs from filter to filter significantly. Therefore, in order to determine water content of a PM1 sample on a quartz filter correctly one must know the water content of this particular filter. The proposed method is simple and allows for avoiding the artefacts related to water bound to filters. The estimated error of a single measurement in the proposed method is 4–17%, the detection limit is 27μg.The water content of 24-h samples of PM1 from the two urban sites in Poland was between 0.3 and 68%; in average it was 19% in Warsaw and 20% in Zabrze. Both the ambient concentrations and the difference between seasonal concentrations of PM1 bound water were higher in Zabrze.

Characterization of solar fuels obtained from beech wood solar pyrolysis

Solar pyrolysis of biomass is a smart way to upgrade biomass and, thus, store intermittent solar energy as solar fuels (gas, bio-char and bio-oil). Distribution and energy content of gas, char and oil depend on experimental conditions. In order to determine these characteristics, experiments have been performed at temperatures of 600, 900, 1200 and 2000°C, heating rate of 50°C/s and argon flow rate of 6NL/min. The gas product was analyzed by micro-GC. The char product was characterized by CHNS, whereas the oil product was subjected to CHNS, Karl-Fischer titration and GC–MS analysis. The LHVs (lower heating values) for gas, char and oil were determined from empirical equations. The gas product yield and LHV significantly increase with temperature, which is mainly due to more H2 and CO formation by the enhanced secondary tar reactions. The char and oil characteristics highly depend on the temperature. Their high energy contents show that the obtained char and oil can be utilized as valuable solid and liquid fuels. The biomass energy upgrading due to solar processing is discussed. At optimum temperature 900°C, it ranges from 38% to 53% accounting for the uncertainty of bio-oil water content.

An Ionic Liquid Consisting of Crown Ether – Coordinated Hydronium Cation and Amide Anion

There are reports on ionic liquids (ILs) with strongly Lewis-acidic metal cations such as Li+ and K+ coordinated by ether-ligands to decrease charge density [1-2]. Crown ether 18-crown-6 (18C6) has a suitable cavity for encapsulation of K+ and hydronium ion (H3O+) [3-4]. Various compounds with H3O+ encapsulated by 18C6 ligand ([H3O+·18C6] cation) have been reported, the counteranions of which are such as hexafluorophosphate (PF6 –), tetrafluoroborate (BF4 –) and trifluoromethanesulfonate (TfO–; Tf = CF3SO2) ions [3-4]. However, their melting point are higher than 100 °C. Furthermore, as far as we know, nothing has been reported on [H3O+·18C6] complexes using bis(trifluoromethylsulfonyl)amide (Tf2N–) anion. Here, we report ILs that consist of [H3O+·18C6] cation or [H3O+· dicyclohexyl-18C6 (Dh18C6)] cation and an amide anion. The IL comprised of [H3O+·18C6] cation or [H3O+·Dh18C6] cation and Tf2N– anion was synthesized by adding equimolar amount of 18C6 or Dh18C6 and HTf2N in water, followed by vacuum-drying. In the obtained samples, a characteristic infrared band appeared at 2200 cm–1 that was not observed in pure 18C6, was attributable to the first harmonic of symmetric bending mode (Figure 1) [5]. The H2O content of the 18C6 complex and the Dh18C6 complex was estimated to be 3.29 wt% and 2.61 wt% from Karl-Fischer titration, in good agreement with the ideal value (3.20 wt% and 2.68 wt%). From elemental analysis, infrared spectra and Karl-Fischer titration, the composition of the obtained complexes were concluded as [H3O+·18C6][Tf2N–] and [H3O+·Dh18C6][Tf2N–] (Figure 2). 1H NMR spectrum of [H3O+·18C6][Tf2N–] contained a sharp singlet near 11 ppm, characteristic of H3O+ encapsulated by 18C6. The melting point of [H3O+·18C6][Tf2N–] was 66–68 °C and [H3O+·Dh18C6][Tf2N–] was a yellowish transparent liquid at room temperature (RT) (Figure 3). At 70 °C, the viscosity and conductivity of [H3O+·18C6][Tf2N–] were 39.5 mPa s and 1.9 mS cm–1, while those of [H3O+·Dh18C6][Tf2N–] were 33.8 mPa s and 1.4 mS cm–1. In linear sweep voltammetry, potential for hydrogen production by [H3O+·18C6][Tf2N–] was similar to those of general protic liquids. The crown ether-coordinated hydronium amide IL may have potential application as electrolyte materials toward a new class of fuel cells. [1] T. Tamura et al., Chem. Lett., 39, 753 (2010). [2] Y. Song, H. Jing, B. Li, and D. Bai, Chem. Eur. J., 17, 8731 (2011). [3] R. Chénevert et al., Can. J. Chem., 60, 853 (1982). [4] G. S. Heo and R. A. Bartsch, J. Org. Chem., 47, 3557 (1982). [5] R. Chénevert et al., Can. J. Chem., 62, 2293 (1984). Figure 1

Determination of Trace Water Content in Petroleum and Petroleum Products

Measurement of water in petroleum and petroleum-based products is of industrial and economic importance; however, the varied and complex matrixes make the analyses difficult. These samples tend to have low amounts of water and contain many compounds which react with iodine, causing Karl Fischer titration (KFT) to give inaccurate, typically higher, results. A simple, rapid, automated headspace gas chromatography (HSGC) method which requires modified instrumentation and ionic liquid stationary phases was developed. Measurement of water in 12 petroleum products along with 3 National Institute of Standards and Technology reference materials was performed with the developed method. The range of water found in these samples was ∼12-3300 ppm. This approach appeared to be unaffected by complicated matrixes. The solvent-free nature of the HSGC method also negates the solubility limitations which are common with KFT.

Probing the Distribution of Water in a Multi-Component System by Solid-State NMR Spectroscopy.

To characterize the distribution of water among various components in a powder blend using solid-state NMR spectroscopy. Water sorption behavior of theophylline anhydrate and excipients was determined by dynamic vapor sorption (DVS) and Karl Fischer Titration (KFT) after storing them in humidity chambers for 1week at room temperature (RT) and calibration curves were generated for water content vs. (1)H T 1 relaxation times. Powder blends (either with microcrystalline cellulose or lactose as diluent) were stored at different relative humidity (RH) conditions and analyzed periodically using solid-state NMR, powder X-ray diffraction, and KFT. Anhydrous theophylline converted to the hydrate at ≥ 84% RH. Based on the calibration curves of water content vs. relaxation times, the distribution of water in the powder blends was estimated. The total water content calculated using ssNMR was in good agreement with values measured using KFT. In blends stored at 90% RH, theophylline anhydrate-to-hydrate conversion did not occur in 1week. The distribution of water in multi-component powder blends was successfully determined using correlation between (1)H T 1 relaxation times and total water content. Excipient water sorption inhibited hydrate formation in theophylline at 90% RH. Water distribution was affected by excipient type. The extent of water sorbed by excipients in blends was found to be different than their standalone equilibrium water content.