Mixture Of Propylene Glycol Research Articles

Analytical Method for Measurement of Tobacco-Specific Nitrosamines in E-Cigarette Liquid and Aerosol

An experimental method was developed and validated for the collection and analysis of tobacco-specific nitrosamines (TSNAs) that are present in electronic cigarette (EC) liquid or are released from aerosol samples using a liquid chromatography-tandem mass spectrometry (LC-MS/MS) system. As part of this study, the relative recovery of four target TSNAs was assessed by spiking standards in a mixture of propylene glycol and vegetable glycerin. Recovery was assessed against two major variables: (1) the chemical media (solution) selected for sample dilution (acetonitrile [ACN] vs. ammonium acetate [AA]) and (2) the type of sampling filter used (Cambridge filter pad [CFP] vs. quartz wool [QW] tube). The average recovery of TSNAs in terms of variable 1 was 134 ± 22.1% for ACN and 92.6 ± 8.27% for AA. The average recovery in terms of variable 2 was 83.4 ± 7.33% for QW and 58.5 ± 12.9% for CFP. Based on these conditions, the detection limits of N′-nitrosonornicotine (NNN), 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), N′-nitrosoanatabine (NAT), and N′-nitrosoanabasine (NAB) were calculated as 4.40, 4.47, 3.71, and 3.28 ng mL−1, respectively. The concentration of TSNAs in liquid and aerosol samples of six commercial EC solutions was measured as below the detection limit.

Thermodynamic solubility modeling, solvent effect and preferential solvation of curcumin in aqueous co-solvent mixtures of ethanol, n-propanol, isopropanol and propylene glycol

The equilibrium solubility of curcumin in solvent mixtures of ethanol (1) + water (2), n-propanol (1) + water (2), isopropanol (1) + water (2) and propylene glycol (PG, 1) + water (2) was determined experimentally by using saturation shake-flask method within the temperature range from (278.15 to 318.15) K under atmospheric pressure (101.1 kPa). At the same temperature and mass fraction of ethanol (n-propanol, isopropanol or PG), the mole fraction solubility of curcumin was greater in (n-propanol + water) than in the other three co-solvent mixtures. The solid phase was tested by X-ray power diffraction, which showed that no polymorphic transformation, solvate formation or crystal transition during entire experiments. Linear solvation energy relationship in terms of the solvent polarity parameters was used to study of the solvent effect on the mole fraction solubility. The preferential solvation parameters were derived from their thermodynamic solution properties by means of the inverse Kirkwood–Buff integrals. The preferential solvation parameters for ethanol, n-propanol, isopropanol or PG were positive in the four co-solvent mixtures in intermediate and co-solvent-rich compositions, which indicated that curcumin was preferentially solvated by co-solvent. It could act mainly as a Lewis acid interacting with proton-acceptor functional groups of the co-solvents. Temperature had a little effect on the preferential solvation magnitudes for the n-propanol and PG mixtures. In addition, the drugs’ solubilities were mathematically represented by using the Jouyban-Acree model obtaining average relative deviations lower than 0.19% for correlative studies.

Abstract 16718: Electronic Cigarette Aerosols Alter Cardiac Expression of Genes Key to Electrical and Structural Remodeling in Mice

Background: Electronic cigarette (e-cig) use has mounted. Some health authorities have even proclaimed e-cigs are profoundly safer than conventional cigarettes. However, e-cigs generate several potentially cardiotoxic constituents by heating their solvent vehicles propylene glycol (PG) and vegetable glycerin (VG) into aerosols to deliver nicotine and flavors. Objectives: To investigate the effects of chronic E-cig exposures, with or without nicotine, on cardiac gene expression compared to mainstream cigarette smoke (MCS). Methods: Healthy C57BL/6J male mice were exposed chronically (12 weeks, 3 hours/day) to e-cig aerosols from an equal-ratio mixture of PG and VG (PG:VG) with nicotine (36 mg/mL) or without nicotine, or to MCS, and compared to filtered air control group (Air). Hearts (n=8/group) were assayed by quantitative PCR for expression of genes associated with electrical and structural remodeling. Results: PG:VG exposure increased gene expression for a gap junction protein (connexin 43, 1.8-fold), voltage-gated potassium and sodium channels (K v 4.3, 2.5-fold; Na v 1.5, 1.6-fold), calcium sequestration protein (sarco/endoplasmic reticulum calcium ATP-ase, 1.4-fold), cytokines (TGFβ1, 1.8-fold; TNF-α, 3.8-fold), and collagen III (3.8-fold) relative to Air (all P < 0.05). Nicotine did not enhance PG:VG’s effects on gene expression relative to PG:VG-alone (all P > 0.05), and cigarette smoke did not significantly affect any of the transcripts assayed (all P > 0.05 vs. Air). Conclusions: E-cigs may induce cardiac electrical and structural remodeling via their primary vehicle ingredients and irrespective of nicotine or flavors. Such effects could precipitate fatal arrhythmia, stroke, and/or heart failure. Electronic nicotine delivery systems may pose cardiac risks distinct from conventional cigarettes.

Stimulus effects of propylene glycol and vegetable glycerin in electronic cigarette liquids

BackgroundLittle is known about the behavioral effects of non-nicotine ingredients in electronic cigarette liquids. Propylene glycol (PG) and vegetable glycerin (VG) are the most common humectants used in electronic cigarette liquids. These ingredients may influence stimulus effects (e.g., visibility of exhalant, taste, or smell), which have played a role in the abuse liability of conventional cigarettes. In the current study, the stimulus effects of aerosol from liquids varying only in PG and VG content were assessed. MethodsSixteen electronic cigarette users completed five sessions (one practice and four testing sessions). Following one hour of nicotine deprivation, two sampling puffs from liquid formulations containing 100/0, 75/25, 50/50, 25/75, and 0/100% PG/VG concentrations were administered in random order during five assessments, each separated by 20 min. Measures included self-reported stimulus effects and breakpoint on a multiple-choice procedure with options consisting of sampled puffs or varying amounts of money. ResultsVG content was associated with greater reports of visibility of the exhalant (i.e., “cloud”). Liquids with only PG or VG engendered lower reports of inhalation sensations (e.g., throat hit) and greater reductions of systolic blood pressure compared to mixtures of PG and VG. There was no effect of liquid formulation on the multiple-choice procedure, but puffs were rarely chosen over even the smallest monetary option ($0.05), suggesting minimal reinforcing efficacy. ConclusionsLiquids containing greater concentrations of VG are more capable of producing visible exhalant and mixtures of PG and VG engender greater airway sensory effects than either ingredient alone.

Experimental analysis of heat transfer in spiral coils using nanofluids and coil geometry change in a solar system

Thermal coils have been extensively used as heat exchanger in many industrial and air-conditioning systems. The present study experimentally investigated three different geometries of thermal coils, including cylindrical spiral, conical spiral and conical-cylindrical spiral coils as well as working fluids water and MWCNT, CuO and TiO2 nanoparticles. The effects of coil geometry and working fluid on the coil performance were evaluated. The working fluid in nanoparticles was 70:30 volumetric mixture of water and propylene glycol. Surfactant was used for more dispersion of nanoparticles in solution, and concentration of nanoparticles in all states was stable and equal to 0.1% of volume and that of surfactant was 0.1% of mass. To evaluate the performance of thermal coils, an evacuated heat pipe solar cycle was used, and the effect of thermal coil on the performance of collector was investigated. Validation of the obtained results showed a good match between experimental findings and empirical relations of other researchers. Results showed a better performance for the working fluids with higher thermal conductivity during the day; and use of CuO, TiO2 and MWCNT nanofluids in the base fluid, compared to water, increased the coil heat transfer by 39%, 25% and 53%, respectively. Considering the Nusselt number, conical-cylindrical spiral coil was thermally superior to the other two geometries, and use of conical-cylindrical spiral coil and conical spiral coil enhanced the efficiency of system by 17.1% and 5.7%, respectively in comparison with cylindrical spiral coil.

Gas/Particle Partitioning Constants of Nicotine, Selected Toxicants, and Flavor Chemicals in Solutions of 50/50 Propylene Glycol/Glycerol As Used in Electronic Cigarettes.

For an electronic cigarette (e-cigarette) aerosol with known total particulate matter concentration (TPM, μg/m3), predictions of the fractions of some compound i in the gas and particle phases ( fg, i and fp, i) at equilibrium can be made based on Kp, i (m3/μg), the compound-dependent gas/particle partitioning equilibrium constant. fg, i and fp, i affect the modes and locations of deposition in the respiratory tract. Kp, i depends inversely on (1) the pure compound liquid vapor pressure ( pL, io), (2) mole fraction activity coefficient (ζ i) in the absorbing liquid, and (3) mean molecular weight of the absorbing liquid (MW). Kp, i values were measured at 20 °C for 32 compounds as spiked into simulated e-cigarette liquids prepared as 50/50 mixtures (by weight) of propylene glycol (PG) and glycerol (GL). Kp, i values at 37 °C were estimated. The 32 compounds were nicotine (in free-base form), seven toxicants (propanal, acetone, hydroxyacetone, benzene, toluene, p-xylene, and ethylbenzene), and 24 flavor chemicals (2,3-pentanedione ("acetyl propionyl"), isobutyl acetate, ethyl butyrate, butyl butyrate, isoamyl acetate, 2,3-dimethylpyrazine, 3-methyl-1-butanol, limonene, 2,3,5-trimethylpyrazine, p-cymene, benzaldehyde, ( Z)-3-hexen-1-ol, menthol, 2-acetylpyrrole, benzyl alcohol, methyl salicylate, cinnamaldehyde, methyl anthranilate, (+)-aromadendrene, cinnamyl alcohol, methyl cinnamate, maltol, ethyl maltol, and coumarin). The measured log Kp, i values were found to be generally correlated with literature values of log pL, io; the scatter is caused by variation in ζ i between ∼1 and ∼1000. Kp measurements were attempted, but values were not reported for acetaldehyde, 2,3-butanedione (diacetyl), vanillin, and ethyl vanillin. Acetaldehyde was found to form significant amounts of its cyclic trimer and cyclic tetramer; for diacetyl, the evidence suggested significant amounts of reaction products, possibly hemiketals and ketals with PG/GL, and for vanillin and ethyl vanillin, the Kp values are large and accordingly more difficult to measure. fg values are calculated using a range of Kp and TPM values.

PERLINDUNGAN KONSUMEN TERHADAP PEREDARAN, PENGGUNAAN, DAN PENGGUNAAN E-LIQUID DI DALAM ROKOK ELEKTRIK

Smoking is one activity that is still done by individuals in all ages, from teenegers to adulthood. Many ways that can be done in the effort to stop smoking, such as commited, seplacing cigarettes by consuming candy, divert cigarettes with activity, but now smokers try to quit smoking by using electric cigarettes. Which electric cigarette is one alternative that can be done as a substitute for conventional cigarettes. Electric cigarette is a set of tools that function to convert the chemicals intp steam form, and electric cigarette consists of three(3) parts, Battery(the part contains the battery), atomizer(the part that will heat and vaporize the nicotine solution), and catridge( the part contains a nicotine solution). Electric cigarette doesn’t contain tobacco but using a liquid compound which concists of a mixture of water, nicotine, propylene glycol and flavors. According Badan Pengawasan Obat dan Makanan(BPOM) electric cigarette containing liquid nicotine, propylene glycol, diethyl glycol, and glycerin. If all of the materials is heated it wil produce nitrosamine compounds. And that compounds can cause cancer.Therefoe consumer protection must be strcly enforced.

Boiling points of the propylene glycol + glycerol system at 1 atmosphere pressure: 188.6–292 °C without and with added water or nicotine

In electronic cigarettes (“electronic nicotine delivery systems”, ENDS), mixtures of propylene glycol (PG) and/or glycerol (GL; aka “vegetable glycerin”, VG) with nicotine are vaporized to create a nicotine-containing aerosol. For a given composition, the temperature required to boil the liquid at 1 atmosphere must be at least somewhat greater than the boiling point (BP). The use of ENDS is increasing rapidly worldwide, yet the BP characteristics of the PG + GL system have been characterized as the mixtures; here we re-do this, but significantly, also study the effects of added water and nicotine. BP values at 1 atmosphere pressure were measured over the full binary composition range. Fits based on the Gibbs–Konovalov theorem provide BP as a function of composition (by mole-percent, by weight-percent, and by volume-percent). BPs of PG + GL mixtures were then tested in the presence of additives such as water (2.5 and 5 mol% added) and nicotine (3 mol%). Water was found to decrease the BP of PG + GL mixtures significantly at all compositions tested, and nicotine was found to decrease the BP of PG + GL mixtures containing ∼75 GL: 25 PG (by moles) or more. The effect of added water (5, 10, and 15 mol% added) on electronic cigarette degradation production (some aldehydes and formaldehyde hemiacetals) was examined and found to have no significant impact on solvent (PG or GL) degradation for the particular device used.

Solute-solvent and solvent-solvent interactions and preferential solvation of hesperidin in aqueous cosolvent mixtures of ethanol, isopropanol, propylene glycol and n-propanol

Solute-solvent and solvent-solvent interactions were investigated from the available solubility data by using the linear solvation energy relationships concept. The variation of hesperidin solubility depended upon hydrogen bond basicity for ethanol (1) + water (2), hydrogen bond basicity and dipolarity/polarizability for isopropanol (1) + water (2), hydrogen bond basicity, dipolarity/polarizability and cavity term for n-propanol (1) + water (2), and dipolarity/polarizability and cavity term of PG (1) + water (2). Furthermore, the preferential solvation parameter (δx1,3) of hesperidin in four cosolvent mixtures of ethanol (1) + water (2), isopropanol (1) + water (2), propylene glycol (PG) (1) + water (2) and n-propanol (1) + water (2) was deduced from the solubility data with the inverse Kirkwood–Buff integrals method. In water-rich compositions for the four aqueous cosolvent mixtures, the value of δx1,3 was negative at temperatures ranging from 293.15 K to 313.15 K, which indicated that the hesperidin was preferentially solvated by water. In intermediate composition and cosolvent-rich composition, hesperidin was preferentially solvated by the cosolvent (ethanol, isopropanol or n-propanol).

Solubility of bosentan in {propylene glycol + water} mixtures at various temperatures: experimental data and mathematical modelling

ABSTRACTSolubility measurements were performed for bosentan (BST) in binary mixtures of propylene glycol (PG) and water at atmospheric pressure within the temperature range, T = 293.2 – 313.2 K by employing a shake-flask method. Generated solubility data were correlated with Jouyban-Acree-van’t Hoff model and the accuracies of the predicted solubilities and model performance were illustrated by mean relative deviations (MRD). Furthermore, the apparent thermodynamic properties of BST dissolving in all the mixed solvents were calculated, and the obtained results show that the dissolution process is endothermic. By using the inverse Kirkwood–Buff integrals, it was observed that BST is preferentially solvated by water in water-rich solvent mixtures and preferentially solvated by PG (as a cosolvent) in the composition range of 0.20 < x1 < 1.00 at 298.2 K.

Cyclic Acetalization of Furfural on Porous Aluminosilicate Acid Catalysts

Porous aluminosilicate materials included microporous and mesoporous ZSM-5, hierarchical aluminosilicates, and mesoporous aluminosilicate were tested for acetalization of furfural (furan-2-carbaldehyde) with propylene glycol. The existing synthesis methods for aluminosilicate and ZSM-5 were modified to produce aluminosilicate material with hierarchical porous structure. Catalytic activity in acetalization of furfural by propylene glycol were conducted by refluxed of the mixture of furfural, propylene glycol and catalyst, using toluene as solvent and nitrobenzene as internal standard, at 106 °C for 4 h. The result showed that a combination of two structure directing agents, tetrapropylammonium hydroxide (TPAOH) and cetyltrimethylammonium bromide (CTAB) and modification of catalytic crystallization produced an active aluminosilicate framework that provides a wide access for a bulky reactants and strong acid sites to catalyze the reaction. The pore structure and the strength of the Brønsted acid sites were crucial for the high conversion of furfural to produce a cyclic acetal.

Experimental Investigation of the Thermophysical Properties of TiO2/Propylene Glycol–Water Nanofluids for Heat-Transfer Applications

Nanofluids have been prepared by dispersing TiO2 nanoparticles in 70:30% (by weight) water–propylene glycol mixture. The thermal conductivity and viscosity were found experimentally at various temperatures with the volume concentrations 0.1–0.8%. The results indicate that the thermal conductivity of the nanofluids increases with the volume concentration and temperature. Similarly, the viscosity of the nanofluids increases with the volume concentration but decreases with increase in the temperature. Correlations have been proposed for estimating the thermal conductivity and viscosity of the nanofluids. The potential heat transfer benefits of their use in laminar and turbulent flow conditions has been explained.

Potentiation of Sodium Metabisulfite Toxicity by Propylene Glycol in Both in Vitro and in Vivo Systems.

Many consumer products used in our daily lives result in inhalation exposure to a variety of chemicals, although the toxicities of the active ingredients are not well known; furthermore, simultaneous exposure to chemical mixtures occurs. Sodium metabisulfite (SM) and propylene glycol (PG) are used in a variety of products. Both the cytotoxicity and the sub-acute inhalation toxicity of each chemical and their mixtures were evaluated. Assays for cell viability, membrane damage, and lysosome damage demonstrated that SM over 100 μg/ml induced significant cytotoxicity; moreover, when PG, which was not cytotoxic, was mixed with SM, the cytotoxicity of the mixture was enhanced. Solutions of 1, 5, and 20% SM, each with 1% PG solution, were prepared, and the whole body of rats was exposed to aerosols of the mixture for 6 h/day, 5 days/week for 2 weeks. The rats were sacrificed 1 (exposure group) or 7 days (recovery group) after termination of the exposure. The actual concentration of SM in the low-, medium-, and high-exposure groups was 3.91 ± 1.26, 35.73 ± 6.01, and 80.98 ± 5.47 mg/m3, respectively, and the actual concentration of PG in each group was 6.47 ± 1.25, 8.68 ± 0.6, and 8.84 ± 1.77 mg/m3. The repeated exposure to SM and PG caused specific clinical signs including nasal sound, sneeze, and eye irritation which were not found in SM single exposure. In addition, the body weight of treatment group rats decreased compared to that of the control group rats in a time-dependent manner. The total protein concentration and lactate dehydrogenase activity in the bronchoalveolar lavage fluid (BALF) increased. Histopathological analysis of the lungs, liver, and nasal cavity was performed. Adverse effects were observed in the nasal cavity, with squamous cell metaplasia identified in the front of the nasal cavity in all high-exposure groups, which completely recovered 7 days after exposure was terminated. Whereas inhalation of SM for 2 weeks only reduced body weight in the high-dose group, inhalation of SM and PG mixtures for 2 weeks significantly decreased body weight and induced metaplasia of the respiratory epithelium into squamous cells in the medium- and high-dose groups. In conclusion, PG potentiated the toxicity of SM in human lung epithelial cells and the inhalation toxicity in rats.

Flow behaviour of suspensions of functionalized graphene nanoplatelets in propylene glycol–water mixtures

The low thermal conductivity of the fluids usually used in heat exchange processes (water, oils, glycols…) has proved to be one of the limiting factors in improving their heat transfer performance. These traditional fluids enhance their thermal capabilities by dispersing nano-sized particles with high thermal conductivity, as many researches have revealed in the last decades. Although the thermal conductivity of nanofluids has centred the interest of the heat transfer community, the rheological behaviour of the resulting dispersions is very influential in the heat transfer process, pressure drops and pumping powers. In this work, different samples of functionalized graphene nanoplatelets dispersed into two different binary mixtures of propylene glycol and water at 10:90wt% and 30:70wt% have been analysed by using a DHR-2 rotational rheometer equipped with concentric cylinder geometry. Firstly, the flow curves for Krytox GPL102 oil, pure propylene glycol, and the two binary mixtures of propylene glycol and water used as base fluids were experimentally obtained. These values were used to check our experimental procedure finding a good agreement between them and those reported and well known in the literature, with an absolute average deviation of 2.0%. Then, the viscosity-shear rate curves in the temperature range from 278.15 to 323.15K were obtained for the different graphene nanofluid sets. Furthermore, a new equation was proposed in this work to describe the viscosity dependence on both the temperature and the nanoparticles volume concentration of graphene nanoplatelet nanofluids with an absolute average deviation with respect to our experimental data lower than 2%. Additionally, oscillatory tests of the samples were performed observing pseudoplastic behaviour for the nanofluids at lower angular frequencies.

Dietary supplementation with glucogenic precusors and fatty acids improves performance and health of periparturient dairy cows

This experiment aimed to make a comparison between the effect of a mix of two energy preparations (a glucogenic preparation (G) and a free fatty acid preparation (F)), administered in the diet during the transition period over different periods of time (5 or 8 weeks), on the animal condition, feed intake, yield and composition of milk, and blood and urine parameters. The experimental additive was a mixture (1:1) of two energy preparations, namely, a loose mixture of propylene glycol and sodium propionate and a free fatty acid preparation in the form of rumen-undegradable pellets. The study included 50 Polish Black-and-White Holstein–Friesian dairy cows, allocated into five treatment groups, including one control (C) and four experimental ones (G1F1, G2F2, G2F1 and G1F2). The preparations were mixed at a 1:1 weight ratio (500 g per head, comprising 250G and 250F) and they were administered to all experimental groups of cows daily as a component of the experimental concentrate for 5 weeks (from the 2nd week before the expected calving and until the 3rd week of lactation). From the 4th until the 6th week of lactation, the supplementation in the experimental groups changed and animals received either no additive (G1F1), or were continuously supplemented with the G–F mix (G2F2), or received only G (G2F1) or only F (G1F2). The preparations used in the study had a long-term influence on the increase in the milk yield of cows, on the improvement of their health condition, and on the reduction of weight loss. The study results confirmed that prolongation of the supplementation until the 6th week of lactation may cause favourable changes in animal performance and milk quality. Due to different modes of action, the simultaneous supplementation of G and F reduced the negative energy balance in the cow and improved milk production and composition. The best results were obtained after administration of the mixture (1:1) of the G and F at the dose of 500 g/cow.day over the 8-week periparturient period.

EXPERIMENTAL INVESTIGATION OF THE CONVECTIVE HEAT TRANSFER IN A SPIRALLY COILED CORRUGATED TUBE WITH RADIANT HEATING

The Archimedean spiral coil made of a transversely corrugated tube was exposed to radiant heating in order to represent a heat absorber of the parabolic dish solar concentrator. The main advantage of the considered innovative design solution is a coupling effect of the two passive methods for heat transfer enhancement - coiling of the flow channel and changes in surface roughness. The curvature ratio of the spiral coil varies from 0.029 to 0.234, while water and a mixture of propylene glycol and water are used as heat transfer fluids. The unique focus of this study is on specific boundary conditions since the heat flux upon the tube external surfaces varies not only in the circumferential direction, but in the axial direction as well. Instrumentation of the laboratory model of the heat absorber mounted in the radiation field includes measurement of inlet fluid flow rate, pressure drop, inlet and outlet fluid temperature and 35 type K thermocouples welded to the coil surface. A thermal analysis of the experimentally obtained data implies taking into consideration the externally applied radiation field, convective and radiative heat losses, conduction through the tube wall and convection to the internal fluid. The experimental results have shown significant enhancement of the heat transfer rate compared to spirally coiled smooth tubes, up to 240% in the turbulent flow regime.

Solubility and Preferential Solvation of Piroxicam in Neat Solvents and Binary Systems

AbstractThe solubilization and solvatochromic behavior of piroxicam (PRX) were analyzed using UV-vis spectroscopy in neat (protic and aprotic) and binary solvent mixtures. The effects of solvent dipolarity/polarizability and solvent–solute hydrogen bonding interactions on the absorption maxima were evaluated by means of the linear solvation energy relationship concept of Kamlet and Taft. This analysis indicated that both interactions play an important role in the position of the absorption maxima in neat solvents. While, the PRX solubility depends on the solute–solvent specific interactions, polarizability and the cohesive forces of the solvent, manifested mainly by means of the Hildebrand’s solubility parameter. Preferential solvation (PS) was studied in 10 binary mixtures. A non-ideal behavior of the wavenumber curve as the function of analytical mole fraction of co-solvent was detected. Index of preferential solvation, as well as the influence of solvent parameters were calculated. The process of dissolution was analyzed in aqueous binary mixtures of ethanol, ethylene glycol and propylene glycol. They were not spontaneous in all proportions, but when water concentration decreases in the mixtures, the process becomes more spontaneous.

Solubility of sildenafil citrate in propylene glycol + water mixtures at various temperatures

ABSTRACTThe solubility of sildenafil citrate (SC) in aqueous mixtures of propylene glycol (PG) was investigated. This study was carried out at different mass fractions of PG ranging from 0.1 to 0.9 at T = 293.2–313.2 K. The solubility of SC in the mixed solutions increased with increasing temperature and PG mass fraction.The solubility values were correlated by two co-solvency models (Jouyban–Acree model and van’t Hoff–Jouyban–Acree model). The mean relative deviations (MRD) were 5.7% and 5.5%, respectively. Density of the SC-saturated solutions over the entire solvent composition and temperature range was also measured and the results correlated with the Jouyban–Acree model. Furthermore, the apparent thermodynamic properties, dissolution enthalpy, dissolution entropy and Gibbs free energy change of dissolution process of SC in all the mixed solvents were calculated according to van’t Hoff and Gibbs equations. Dissolution of SC in these mixed solvents is an endothermic process.

Pilot Experiment: The Effect of Added Flavorants on the Taste and Pleasantness of Mixtures of Glycerol and Propylene Glycol.

The US Food and Drug Administration banned most "sweet" flavorants for use in cigarettes due to the concern that sweet flavors appeal to young, beginning smokers. However, many of the same flavors, including fruity and confection-associated aromas (e.g. vanilla) are still used in e-cigarettes. Sweet flavors may have a number of effects, including enhancement of the taste of other ingredients. The current work focused on the impact of model flavorants on the taste of a mixture of propylene glycol and vegetable glycerine, solvents used in most e-cigarettes and related products. A device delivered mixtures of propylene glycol and vegetable glycerine into the mouth in parallel with puffs of clean air (control) or odorized air. Aromas included two "fruity" esters ("pineapple" and "banana"), two confection-associated aromas ("vanilla" and "caramel/malty"), menthol (not a "sweet" aroma, but commonly used in e-cigarettes), and a "burnt" aroma not expected enhance flavor. Twenty young adults, aged 18-25, rated the sweetness, bitterness, and pleasantness of all stimuli (within-subjects design). Both fruity aromas significantly enhanced sweetness, both confection-associated aromas significantly enhanced pleasantness, and the caramel/malty aroma significantly reduced bitterness. Menthol and the "burnt" aroma had no measurable effects on the taste of solvent mixtures. Some flavorants modulated the taste of solvents commonly used in e-cigarettes in ways consistent with an enhanced sensory profile. If similar effects occur in actual products, improved flavor profiles could facilitate continued use, particularly in non-smokers experimenting with e-cigarettes and related products.

1,2-Dimethoxyethane Determination in working air with gas chromatography-mass spectrometer

Under normal conditions, 1,2-dimethoxyethane (DME) is a colorless and transparent liquid with a faint odor of ether, very soluble in water, charac-terized by a high vapor pressure. It belongs to the group of alkyl ethers solvents, derivatives of eth-ylene glycol. 1,2-Dimethoxyethane is used as an ex-cipient in preparing and processing industrial chemicals, in the production of fluoric polymers and as a solvent and cleaning agent in the microe-lectronics and printing industries. In the literature there are no data on the acute and chronic toxicity of 1,2-dimethoxyethane. However, long-term epidemiological studies on compounds of similar chemical structure suggest that human exposure to ethylene glycol alkyl ethers can ad-versely affect fertility and fetal development, and hematological parameters. The aim of this study was to develop and validate a sensitive method for determining concentrations of 1,2-dimethoxyethane in workplace air in the range from 1/20 to 2 MAC values, in accordance with the requirements of Standard No. PN-EN 482+A1: 2016-1. The study was performed using a gas chromato-graph (GC). A 7890B Agilent Technologies gas chromatograph with a 5977A mass spectrometry detector (MSD), HP PONA (50 m; 0,2 mm; 0,5 μm) capillary analytical column, auto sampler and Mass Hunter software was used for chromato-graphic separations. The method is based on the adsorption of 1,2-di-methoxyethane on charcoal, desorption with di-chloromethane and GC/MSD analysis of the re-sulting solution. Extraction efficiency of 1,2-di-methoxyethane from charcoal was 96.4%. Samples of 1,2-dimethoxyethane can be stored in refrigera-tor for up to 28 days. The use of a HP-PONA capil-lary column enabled selective determination of 1,2-dimethoxyethane in a mixture of dichloromethane, toluene, carbon disulfide, ethylene and propylene glycol and other compounds. The method is linear (r = 0.9999) within the inves-tigated working range from 5 to 200 μg/ml, which is equivalent to air concentrations from 0.5 to 20 mg/m3 for a 10-L air sample. The limit of quan-tification (LOQ) is 1,306 μg/ml. The analytical method described in this paper ena-bles selective determination of 1,2-dimethoxye-thane in workplace atmosphere in presence of other compounds at concentrations from 0.5 to 20 mg/m3 (1/20 ÷ 2 MAC value). The method is precise, accurate and it meets the criteria for proce-dures for measuring chemical agents listed in Standard No. PN-EN 482+A1: 2016-1. The method can be used for assessing occupational exposure to 1,2-dimethoxyethane and associated risk to work-ers’ health. The developed method of determining 1,2-di-methoxyethane has been recorded as an analytical procedure (see Appendix).