Static Headspace Gas Chromatography Research Articles

Temporal, Developmental, and Comparative Characterization of the Floral Volatile Emissions of the Famously Scented Violet Species, Viola odorata

Violets (Viola) are potential candidates for aroma-focused breeding research. Though most Viola species and modern hybrids lack fragrance, the genus contains a famously scented species, Viola odorata L. This species and its cultivars are genetic resources of aroma traits that could be used to investigate the selection for and transmission of fragrance during the breeding process. Despite its famous scent, however, the floral volatile emissions of V. odorata have not been characterized using modern headspace techniques. Using static and dynamic headspace volatile collection methods and gas chromatography–mass spectrometry, the floral volatile emissions of V. odorata were temporally and developmentally characterized. Floral volatiles were also sampled from 10 V. odorata cultivars, three Parma violet cultivars, five violet species, and one hybrid, and variation in scent among these violets was investigated. Total volatile emissions in V. odorata were highest from 0600 HR to 1900 HR, suggesting a diurnal pattern of emission. Volatile emissions also varied over the developmental lifespan of the flower, with the highest emission of individual and total volatiles occurring, in general, from stages 0 or +1 to stages +3 or +4. Floral scent qualitatively and quantitatively differed among assorted violets. The floral volatile emissions of V. odorata exhibit temporal and developmental variation. Compared with the other violet species in this study, sweet violets are intensely fragrant. The quantity and quality of floral scent differs among V. odorata cultivars, providing genetic variation from which selections could be made in a fragrance-focused breeding program.

Effects of temperature and pressure on volatile compounds of black cumin seeds (Nigella sativa L.) oil extracted by supercritical carbon dioxide

AbstractThis study investigated the effects of temperature and pressure on the yield and volatile compound contents of black cumin seed oil (BCO) extracted from black cumin seeds using supercritical carbon dioxide (SCCO2). The solubility of BCO in SCCO2 increased 2.5‐fold as the pressure increased by 10 MPa. Major volatile compounds in BCO were identified using a static headspace gas chromatography–mass spectrometry (SH–GC–MS). Evidence indicated the main volatile components in SCCO2‐extracted BCO to be hexanal, p‐cymene, and thymoquinone. BCO extracted from China‐cultivated black cumin seed contained similar amounts of p‐cymene and thymoquinone. This black cumin seed is classified as the cymene/thymoquinone chemotype and is also found in Indian, Iranian, and Algerian black cumin seeds. Thymoquinone contents in BCO were more sensitive to the extraction temperature than hexanal and p‐cymene contents. The maximum oil yield of 36.28 ± 1.38 wt%, with approximately 2.0 mg of thymoquinone per milliliter of oil, was obtained at extraction temperatures of 50°C and pressures of 30 MPa. A SH–GC–MS could detect small molecules in black cumin seed oil such as hexanal. The results of this work reveal that temperature has more impact on the selectivity of volatile compounds than pressure in supercritical carbon dioxide extraction.

Analysis of volatile compounds in roasted Liberica Coffee in the Philippines by gas chromatography mass spectrometry

The study is aimed at evaluating volatile compounds of Liberica coffee (Coffea liberica) collected from Lipa Batangas. Sample analysis was performed using Static Headspace Gas Chromatography. The roasting process also generated furans, pyridines, aldehydes ,and pyrazines potent volatile compounds in Liberica beans including unique volatile compounds including Terpinene 4-acetate (0.65%) and trans-β-Ocimene (0.47%). Furthermore, the presence of the abovementioned compounds revealed the essential marker as Liberica coffee beans. This finding may help to add more information with regards to the volatile compounds of Liberica Coffee.

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.

A Static Headspace Gas Chromatography Method for Quantitation of Residual Solvents in Nanoformulations.

Various organic solvents are widely used in the manufacturing, processing, and purification of drug substances, drug products, formulations, excipients, etc. These solvents must be removed to the lowest amount permitted, as they do not possess any therapeutic advantages and may cause undesirable toxicities. Therefore, a rapid and sensitive analytical method for the quantitation of residual solvents is needed. The following chapter presents a static headspace gas chromatographic (HSGC) method for determining the concentration of common residual solvents in various nanoformulations. An efficient and sensitive HSGC method has been developed using PerkinElmer's headspace autosampler/gas chromatographic system with a flame ionization detector (FID) and validated according to the International Conference for Harmonization (ICH) guideline Q3C. The method validation indicates that the method is specific, linear, accurate, precise, and sensitive for the analyzed solvents. The method is suitable for the analysis of 13 residual solvents (methanol, ethanol, acetone, diethyl ether, 2-propanol, acetonitrile, 1-propanol, ethyl acetate, tetrahydrofuran, dichloromethane, chloroform, 1-butanol, and pyridine) and utilizes an Elite 624 Crossbond 6% cyanopropylphenyl, 94% dimethylpolysiloxanes column with helium as a carrier gas.

Degradation Mechanism Study for Secondary Degradants in Rosuvastatin Calcium and Determination of Degradant Acetaldehyde Using Static Headspace Gas Chromatography Coupled with Matrix Precipitation

During the development of headspace gas chromatography (HSGC) method for assessing residual solvents in rosuvastatin calcium (RSV) drug substance, acetaldehyde (AA) was detected in obtained chromatograms, with a calculated concentration of up to 226 ppm. After a series of experiments, it was established that acetaldehyde originates from matrix interference due to direct degradation of Imp-C, which is accompanied by the formation of impurity at relative retention time (RRT) 2.18, without the involvement of impurity at RRT 2.31. The thermal instability of Imp-C also results in the formation of impurity at RRT 2.31 through dehydration and decarboxylation. In addition, cyclization reaction of degradant at RRT 2.18 further resulted in the generation of impurity at RRT 2.22. The structure of these three degradants, were confirmed by liquid chromatography-mass spectrometry (LC-MS), 1D and 2D nuclear magnetic resonance (NMR) measurement. In order to minimize the said matrix interference, a simple precipitation procedure was proposed as a pretreatment to mitigate the impact of Imp-C. Subsequently, an HSGC method was developed for the simultaneous determination of the degradant AA and the other five residual solvents used in RSV synthetic process. The final method was validated concerning precision, limit of detection (LOD) and limit of quantitation (LOQ), linearity, and accuracy.

Low melting mixtures: Neoteric green solvents for flavor formulation

Flavors are considered among the most valuable ingredients in any formula. However, aromatic substances are volatile and can be lost during processing and storage. Thus, it is beneficial to develop strategies for their retention in formulations. The aim of the present study was to evaluate the ability of two low melting mixtures (LMMs) based on food additives, β-cyclodextrin (β-CD) or maltodextrin (MD) and L-lactic acid, and their aqueous solutions, to retain and produce sustained release of flavors. Firstly, β-CD:L-lactic acid and MD:L-lactic acid systems were successfully prepared and characterized. Karl Fischer titration, water activity measurements and 13C NMR showed that these solvents are shelf-stable during long-term storage at room temperature (>5 months). Rheology measurements showed that they were Newtonian fluids. Thermogravimetry (TG) and differential scanning calorimetry (DSC) indicated that they were stable up to 100 °C and that no alteration in their physical properties occurred during several heating/cooling cycles. Their ability to retain and delay the release of two flavors, (-)-limonene and (-)-terpinen-4-ol, was evaluated using static headspace-gas chromatography (SH-GC). The effect of water dilution on their performance was also assessed. The results demonstrated greater efficiency of the supramolecular LMM, β-CD/L-lactic acid, mainly upon rigorous dilution. This was attributed to the ability of β-CD to maintain its encapsulation capacity as confirmed by 2D-DOSY. Additionally, FTIR experiments proved that only physical adsorption takes place. The findings suggest that β-CD:L-lactic acid and MD:L-lactic acid LMMs can be considered for developing easy-to-handle flavor solutions.

Analytical method development, validation, and out-of-specification investigations for polyethylene glycol

This work was motivated by the United States Pharmacopeia monograph modernization initiative and European directorate for the quality of medicines and healthcare. An out-of-specification (OOS) occurrence prompted OOS investigations for the cGMP (cGMP refers to the Current Good Manufacturing Practice regulations enforced by the FDA) release testing of residual ethylene oxide in polyethylene glycol (PEG) according to the standards detailed within the United States Pharmacopeia/National Formulary (USP-NF) for polyethylene glycol, and the European Pharmacopoeia (Ph. Eur.) for macrogols. During the OOS root cause investigations, we observed a PEG degradant and identified it as methyl formate, which co-elutes with ethylene oxide using the GC (gas chromatography) methods published in current USP-NF and Ph. Eur. for PEGs. To address this, a novel method utilizing static headspace gas chromatography with flame ionization detection (HS-GC-FID) was developed to test various grades of PEGs for the presence of residual ethylene oxide, along with other process related impurities and degradation products. With this new method, ethylene oxide, a known genotoxic impurity and IARC (International Agency for Research on Cancer) Class 1 human carcinogen, can be well resolved from methyl formate, a newly identified and comparatively innocuous degradant derived from PEG. The currently available official compendial methods are unable to separate the specific impurities in PEGs. However, the new GC method presented in this paper has been shown to have a high and unique selectivity, allowing for baseline separations (chromatographic resolutions greater than 1.5) of all related impurities in PEGs, which is a challenging task. Additionally, this method has been found to be stability-indicating based on a forced degradation study. During stress stability study of PEGs involving acid, alkali, heat, light, and oxidation, some other PEG degradants, including formaldehyde, were identified. It is possible that formaldehyde undergoes a disproportionation reaction known as the Cannizzaro reaction, leading to the formation of formic acid and methanol. The formic acid then undergoes an esterification reaction with methanol to produce methyl formate. To the best of our knowledge, this is the first stability-indicating HS-GC-FID method that accomplishes this separation in a single run, and it was successfully validated as per ICH (the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use) guidelines. Therefore, this method is suitable for the conduct of cGMP batch release and stability testing of PEGs in regulated quality control (QC) laboratories.

Insights on cyclodextrin inclusion complexes in deep eutectic solvents:Water mixtures

The use of cyclodextrins (CDs) in combination with deep eutectic solvents (DESs) is nowadays an emerging and promising strategy for the solvation of hydrophobic compounds, such as aromas. This approach combines the solvation efficiency of the solvent bulk and the complexation ability of CDs. However, literature lacks information about the complexation mechanism in CDs in these non-conventional solvents. Hence, this study aims to elucidate such mechanism by investigating the complexation behavior and the binding ability of β-CD and α-CD towards verbenone and camphor, respectively, in choline chloride:urea DES:water (70:30 wt%) mixture. First, the formation constants (Kf) of the chosen model inclusion complexes were determined by static headspace-gas chromatography (SH-GC). Then, the formation of inclusion complexes was demonstrated by 1H 2D DOSY and 2D ROESY NMR studies. Finally, isothermal titration calorimetry (ITC) experiments were carried out, for the first time in a DES:water mixture, in order to evaluate the thermodynamic parameters of the inclusion phenomenon. Altogether, results proved the formation of stable inclusion complexes in the new non-conventional medium constituted of choline chloride:urea DES:water (70:30 wt%). Interestingly, the thermodynamic signatures and the stoichiometries of interactions were similar between water and choline chloride:urea DES:water (70:30 wt%). In particular, the present study of the α-CD/camphor system constitutes the first report of a 2:1 complex in a DES:water mixture.

Development of an analytical method to determine methyl alcohol and isopropyl alcohol in food using static headspace gas chromatography.

A method to determine methanol (MeOH) and isopropyl alcohol (IPA) was developed using static headspace sampling (HSS) with gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS). The optimized HSS-GC and HSS-GC/MS methods were validated according to the parameters. The limit of quantification (LOQ) values for MeOH analyzed by HSS-GC/MS and HSS-GC were 0.50-0.56 and 1.97mg/L, and the corresponding values for IPA were 0.14-0.21 and 1.51mg/L, respectively. Recoveries were determined by spiking sample matrices, such as vinegar and tea. MeOH and IPA showed excellent recoveries of 93.80-107.60% and 93.92-104.32% with corresponding precisions of 0.51-7.38% and 0.90-7.70%, respectively. Compared to solid-phase microextraction-GC/MS and HSS-GC, the HSS-GC/MS method showed outstanding values for limit of detection and LOQ with improved precision and accuracy. This HSS-GC/MS method was successfully used to monitor residual solvents in 100 food and functional food products.

Static headspace gas chromatography–mass spectrometry for volatile organic compounds in bovine milk samples

AbstractVolatile organic compounds (VOCs) provide insight into the taste and aroma of milk. VOCs in milk are typically analyzed using headspace gas chromatography–mass spectrometry (GC‐MS). While static headspace GC‐MS is a simple and widely applicable analytical technique for the analysis of VOCs in various samples, it has not been frequently applied to milk samples. In this study, static headspace GC‐MS was used to compare the VOCs of three different brands of commercial milk. Three components were identified in the samples, that is, acetone, toluene, and 2‐heptanone, where the concentration ranges of acetone, toluene, and 2‐heptanone in the milk samples were 2.284–3.256, 0.028–0.178, and 0.014–0.020 μg/mL, respectively. A literature review found that all three components were previously reported in milk, while toluene and 2‐heptanone were newly identified using headspace GC‐MS in this study.

144 Development of a New Hs-Gc-Ms Method for Concurrent Analysis of Acetone, Methylethylketone, Methylisobutylketone and Cyclohexanone in Urine

Abstract Mixed exposure to chemical products is a topical issue for occupational health. Because very few methods are available for evaluating these mixed exposures, the aim of this work was to develop a simple biomonitoring method for assessing simultaneous occupational exposures to four ketones: acetone, methylethylketone (MEK), methylisobutylketone (MIBK) and cyclohexanone in urine. These ketones were selected for their industrial use and their adverse effects on the workers’ health. Some sectors of activity, like the plastic industry for instance, may even expose workers simultaneously to several of these ketones. Volatile organic compounds were analyzed using static headspace gas chromatography coupled to mass spectrometry (sHS-GC-MS), and the four unmetabolized ketones were measured in the headspace phase, after an in-vial pentafluorobenzylhydroxylamine (PFBHA) derivatization step. The calibration was performed using synthetic urines spiked with known amounts of the four ketones. A satisfactory level of sensitivity, whose limits of quantification (LOQ) were between 5 and 20 µg/L was achieved. Calibration curves were linear in the 5-2000 µg/L range, with R2 correlation coefficients from 0.9967 to 0.9990. At 20 µg/L, within-day precision varied from 1.7 to 5.6 % and between-day precision ranged from 4.5 to 9.5 %. Tests on real urinary samples obtained from unexposed persons showed concentrations coherent with those of the general population for acetone and MEK. In conclusion, a fast, sensitive, specific and easy-to-use method was developed for extracting and quantifying simultaneously four ketones from urinary samples using sHS-GC-MS. This method will be a valuable tool for the monitoring of occupational exposures.

Thermodynamic characterization of interactions between environmental contaminants and room temperature ionic liquids using static headspace gas chromatography with vacuum ultraviolet detection

Understanding the thermodynamic interactions between an analyte and the sample phase is of paramount importance when choosing a co-solvent in headspace analysis. A sample phase – gas phase equilibrium partition coefficient (Kp) is used fundamentally to describe the distribution of the analyte between the two phases. Kp determinations by headspace gas chromatography (HS-GC) were acquired by two methods: vapor phase calibration (VPC) and phase ratio variation (PRV). Here, we demonstrated a pressurized – loop headspace system in conjunction with gas chromatography vacuum ultraviolet detection (HS-GC-VUV) to directly calculate the concentration of analytes in the gas phase from room temperature ionic liquids (RTILs) sample phases, using pseudo-absolute quantification (PAQ). PAQ, an attribute of VUV detection, allowed for quick determination of Kp and other thermodynamic properties, such as enthalpy (ΔH) and entropy (ΔS) of the system through the use of van't Hoff plots in the temperature range of 70–110 °C. The Kp determinations by PAQ were comparable to those obtained using the VPC method with percent difference ranging from ≤ 1–33%. Kp determinations were made for analytes (cyclohexane, benzene, octane, toluene, chlorobenzene, ethylbenzene, m-,p-, and o-xylene) at the varying temperatures (70–110 °C) using different RTILs (1-ethyl-3-methylimidazolium ethylsulfate ([EMIM][ESO4]), 1-ethyl-3-methylimidazolium diethylphosphate ([EMIM][DEP]), and tris(2-hydroxyethyl)methylammonium methylsulfate ([MTEOA][MeOSO3])) and (1-ethyl-3-methylimidazolium bis(trisfluoromethanesulfonyl)imide ([EMIM] [NTF2])). The results from the van't Hoff analysis revealed that [EMIM] cation-based RTILs exhibit strong solute-solvent interactions with analytes that have π- electrons.

Metabolomics approach to identify key volatile aromas in Thai colored rice cultivars.

In addition to white jasmine rice, Thailand has many native-colored rice varieties with numerous health benefits and the potential to become a global economic crop. However, the chemical characteristics of aromatic substances in native-colored rice are still mostly unknown. This study aimed to identify the key volatile aroma compounds and the biosynthetic pathways possibly involved in their formation in Thai native-colored rice varieties, and thus leading to the search for potential genetic markers for breeding colored rice with better aromatic properties. Twenty-three rice varieties in four categories: aromatic white, aromatic black, non-aromatic black, and non-aromatic red, were investigated (n=10 per variety). Seed husks were removed before the analysis of rice volatile aromas by static headspace gas chromatography-mass spectrometry. Untargeted metabolomics approach was used to discover the key volatile compounds in colored rice. Forty-eight compounds were detected. Thirty-eight of the 48 compounds significantly differed among groups at p<0.05, 28 of which at p<0.0001, with the non-aromatic black and red rice containing much lower content of most volatile constituents than the aromatic black and white rice. Focusing on the aromatic black rice, the samples appeared to contain high level of both compound groups of aldehydes (3-methylbutanal, 2-methylbutanal, 2-methylpropanal, pentanal, hexanal) and alcohols (butane-2,3-diol, pentan-1-ol, hexan-1-ol). Biosynthetically, these distinctive black-rice volatile compounds were proposed to be formed from the metabolic degradation of branched-chain amino acids (L-leucine, L-isoleucine and L-valine) and polyunsaturated fatty acids (linoleic acid and α-linolenic acid), involving the branched-chain aminotransferases and keto-acid decarboxylases and the 9-lipoxygonases and 13-lipoxygeases, respectively. The proposed degradative pathways of amino acids and fatty acids were well agreed with the profiles key volatile compounds detected in the Thai native-colored rice varieties.

Optimizing the Distillation of Greek Oregano-Do Process Parameters Affect Bioactive Aroma Constituents and In Vitro Antioxidant Activity?

The aim of the present work was to optimize the conditions of the distillation process at a pilot scale to maximize the yield of specific bioactive compounds of the essential oil of oregano cultivated in Greece, and subsequently to study the in vitro antioxidant activity of these oils. Steam distillation was conducted at an industrial distillery and a Face-Centered Composite (FCC) experimental design was applied by utilizing three distillation factors: time, steam pressure and temperature. Essential oil composition was determined by static headspace gas chromatography-mass spectrometry (HS-GC/MS). To obtain a comprehensive profile of the essential oils, instrumental parameters were optimized, including sample preparation, incubation conditions, sampling process, injection parameters, column thermal gradient and MS conditions. With the applied GC-MS method, more than 20 volatile compounds were identified in the headspace of the oregano essential oils and their relative percentages were recorded. Carvacrol was the most prominent constituent under all distillation conditions applied. Data processing revealed time as the main factor which most affected the yield. The Desired Space (DSc) was determined by conducting a three-dimensional response surface analysis of the independent and dependent variables, choosing yields of thymol and carvacrol as optimization criteria. The in vitro antioxidant activity of the essential oils of all samples was measured in terms of the interaction with the stable free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) after 20 and 60 min. The most prominent essential oils at different distillation conditions were also tested as inhibitors of lipid peroxidation. Higher % values of carvacrol and thymol were correlated to higher antioxidant activity. Evaluating the impact of the distillation conditions on the in vitro results, it seems that lower pressure, less time and higher temperature are crucial for enhanced antioxidant activities.

Gas chromatography for β-caryophyllene determination in St. John’s wort infused oil

Hypericum Perforatum L., commonly known as St. John’s wort, is one of the best-known medicinal herbs. St. John’s wort infused oils are mostly used externally, but can be taken orally for stomach ulcers, are used as a food supplement. Therefore, it is important to develop methods that allow a rapid and reliable determination of β-caryophyllene, which is one of the main active components of St. John’s wort. In this work, two gas chromatographic techniques, static headspace gas chromatography (SHS-GC) and solid phase microextraction, combined with gas chromatography-mass spectrometry (SPME-GC-MS), were examined for the determination of β-caryophyllene in St. John’s wort infused oils. A comparison of these two techniques revealed that SPME-GC-MS can be successfully applied for the analysis. The other method, SHS-GC, is simple and fast, but because of its high detection limit, it can only be applied to oil samples with β-caryophyllene concentration higher than 0.1 mg/g.

Cyclodextrin-based Schiff base pro-fragrances: Synthesis and release studies.

A simple method for the preparation of β-cyclodextrin derivatives containing covalently bonded aldehydes via an imine bond was developed and used to prepare a series of derivatives from 6I-amino-6I-deoxy-β-cyclodextrin and the following volatile aldehydes – cinnamaldehyde, cyclamen aldehyde, lilial, benzaldehyde, anisaldehyde, vanillin, hexanal, heptanal, citral, and 5-methylfurfural. Subsequently, the rate of release of the volatile compound from selected pro-fragrances, as a function of the environment (solvent, pH), was studied by 1H NMR spectroscopy (for benzaldehyde) and static headspace-gas chromatography (for benzaldehyde, heptanal, and 5-methylfurfural). The aldehyde release rate from the imine was shown to depend substantially on the pH from the solution and the air humidity from the solid state.

Ethyl acetate from nail polish remover inhalation in a case of fatal voluntary intoxication

To describe a case of fatal voluntary intoxication involving ethyl acetate (EA) inhalation. A 57-year-old woman was found dead on her bed with a plastic bag over her head filled with cotton balls soaked with nail polish remover. Several empty nail polish remover bottles corresponding to a total volume of approximatly one liter of EA, were found near the body. Among her medical history, gastric banding, an orphan disease that required numerous orthopedic surgeries, depression and suicide attempts were notified. Medications were found at home such as venlafaxine, lorazepam, acetaminophen and zopiclone. At the autopsy, no traumatic injuries were observed. A non-specific asphyxia syndrome with organ congestion was notified with macroscopic lesions in favor of an acute or subacute pathological condition with obstruction of the upper airways by gastric contents up to the main bronchi resulting in pulmonary edema. Anoxia was confirmed by the findings of the microscopic examination. The following samples were available for toxicological analysis: peripheral and cardiac blood, urine, stomach content and bile. A comprehensive forensic toxicological expertise was carried out including investigation of illegal drugs, prescribed drugs, alcohol, volatile substances and other poisons like carbon monoxide with several screenings (immunoassay, gas chromatography-mass spectrometry and liquid chromatography-mass tandem) of various postmortem samples. Each substance detected was quantified by a validated method. Lorazepam, zopiclone and venlafaxine and metabolite were quantified by high-performance liquid chromatography with photodiode-array detection. EA, ethanol and methanol were quantified by gas chromatography and static headspace gas chromatography with flame ionization detector. Peripheral blood concentrations of lorazepam, zopiclone and venlafaxine and O-desmethyl-Venlafaxine were respectively at 55, 49, 414 and < 20 μg/L. EA and ethanol concentrations were at 0.033 and 2.58 g/L in peripheral blood, at 0.034 and 2.76 g/L in cardiac blood, at 0.069 and 2.33 g/L in urine, at 0.155 and 2.27 g/L in stomach content and at 0.014 and 2.87 g/L in bile. EA is commonly used as component in nail polish remover. After exposure to EA vapor, absorption is mainly respiratory and percutaneous. Distribution involves all organs but predominates in fatty tissues. EA is rapidly metabolized by plasma esterases resulting in ethanol and acetic acid synthesis. EA may cause drowsiness, sleepiness, unconsciousness, narcosis, stupor and central nervous system depression. These symptoms are potentiated with ethanol. In this case, the low ratio of EA to ethanol concentrations in all postmortem samples confirmed this rapid biotransformation. This was already mentioned in a case of accidental workplace exposure (Coopman. Forensic Sci Int 2005;154:92–95). Blood concentrations of prescribed drugs were here within the therapeutic range. An EA blood concentration of 0.033 g/L can therefore be considered lethal associated with an ethanol concentration around 2.6 g/L. To our knowledge, this is the first fatal case of voluntary intoxication with EA inhalation. The measured concentrations in all usual autopsy samples can be added to toxicological databases.

Solubilization of Eucalyptus citriodora essential oil and citronellal in deep eutectic solvents:water:cyclodextrins mixtures

• DES:water:CD mixtures efficiently solubilized Eucalyptus citriodora and citronellal. • Water %, DES type and composition, CD type and concentration affected the potency. • Water was essential and ChCl:U (1:2) DES:water 70:30 wt%:CD was the best mixture. • The complexation ability of CD was maintained in DES:water 70:30 wt% • Formation constants were lower in the non conventional medium compared to water. Essential oils (EOs) offer interesting biological properties that can be altered by their high volatility and low solubility. This study examined, for the first time, the effect of the combination of different choline chloride (ChCl) based-deep eutectic solvents (DESs), water and cyclodextrins (CDs) on the retention and solubilization of Eucalyptus citriodora EO and its major component, citronellal. The density, viscosity and polarity of the newly prepared DES:water:CD mixtures were measured. The influence of water content, DES type and composition as well as CD type and concentration on the retention capacity were investigated using static headspace-gas chromatography. Results showed that the mixture composed of choline chloride:urea (ChCl:U) (1:2 molar ratio) DES:water (70:30 wt%) in the presence of CD presented the highest retention capacity. Finally, the formation constant (K f ) values of CD/citronellal inclusion complexes and the vapor-liquid partition coefficients of citronellal were determined in ChCl:U DES:water 70:30 wt%.

Calculation and application of partition coefficients of light hydrocarbons in oil-based mud system

To find out the relationship between the oil-based mud, the formation fluid and the extracted gas, we use a thermodynamic approach based on static headspace gas chromatography technique to calculate the partition coefficients of 47 kinds of light hydrocarbons compounds between nC5 and nC8 in two kinds of oil-based mud-air systems, and reconstruct the original formation fluid composition under thermodynamic equilibrium. The oil-based drilling mud has little effect on the formation fluid compositions in the range of nC5–nC8 (less than 1% for low-toxicity oil-based mud and less than 10% for oil-based mud). For most light hydrocarbon compositions, the partition coefficients obtained by vapor phase calibration and the direct quantitative methods have errors of less than 10%, and the partition coefficients obtained by direct quantitative method are more accurate. The reconstructed compositions of the two kinds of crude oil have match degrees of 91% and 89% with their real compositions, proving the feasibility and accuracy of reconstructing the composition of original formation fluid by using partition coefficients of light hydrocarbon compositions between nC5 and nC8.