Gas Chromatographic Method Research Articles

OMEGA-UNSATURATED FATTY ACIDS – THEIR PRESENCE IN THENUTRITIONAL REGIME FOR THE PREVENTION OF CERTAIN SOCIALLY SIGNIFICANT DISEASES

The essential fatty acids provide normal biological functions of the human body and are an important part of the dietary intake in the prophylaxis and prevention of various diseases cardiovascular diseases, hypertension, arthritis, asthma, and autoimmune disorders. In this study, we present the results of a survey on the intake of dietary supplements containing omega-unsaturated fatty acids in addition to the diet to prevent some socially significant diseases. As a result of the survey, to satisfy the respondents' desire regarding the quality of the food supplements offered, we have developed a gas chromatographic method. The results of the study highlight the benefits of taking omega-3 unsaturated fatty acid among different age groups for a better quality of life. We also offer a fast and reliable analytical method to verify the quality and safety of the food supplements on the market in Bulgaria.

Insights into the enhanced performance of ignition and self-sustained combustion of n-decane over Co3O4-based catalysts

Aiming to achieve efficient utilization of high-energy–density fuels in the promising portable power systems, self-sustained combustion of n-decane over Co3O4-based catalysts in a narrow quartz reactor was investigated. Chemiluminescence, gas chromatography and various physicochemical characterization methods were used in this study. The evidences suggest that Co3O4-based catalysts can significantly reduce the ignition temperature and broaden the flammability limits of n-decane. The heat release stored in the catalyst bed can help improve the flame stability, delay the flame extinction, and achieve auto-ignition without forced heating. Besides, great promotion of the catalytic performance of Co3O4 spinel is achieved by doping with 6 wt% PdO. PdO/Co3O4 catalysts exhibit higher activity and enhanced ability in effectual resistance toward deactivate than pure Co3O4. Furthermore, the coupling of heterogeneous and homogeneous reactions of n-decane has been analyzed. It can be revealed that both the adsorbed and gaseous OH* radicals play greatly different roles when using different catalysts. These findings promote the use of heavy hydrocarbon fuels for energy supply and contribute to designing efficient Co3O4-based catalysts rationally.

Revealing the adulteration of sesame oil products by portable Raman spectrometer and 1D CNN vector regression: A comparative study with chemometrics and colorimetry

Identification and quantification of sesame oil products are crucial due to the existing problems of adulteration with lower-priced oils and false labeling of sesame proportions. In this study, 1D CNN models were established to achieve discrimination of oil types and multiple quantification of adulteration using portable Raman spectrometer. An improved data augmentation method involving discarding transformations that alter peak positions was proposed, and synchronously injecting noise during geometric transformations. Furthermore, a novel neural network structure was introduced incorporating vector regression to accurately predict each component simultaneously. The proposed method has achieved higher accuracy in detecting multi-component adulteration compared with chemometrics (100 % accuracy in classifying different oils; R2 over 0.99 and RMSE within 2 % in predicting unknown adulterated samples). Finally, commercially available sesame oil products were tested and compared with gas chromatography and colorimetric methods, demonstrating the effectiveness of our proposed model in achieving higher detection accuracy at low-concentration adulteration.

Serum Values of Cholesterol Absorption and Synthesis Biomarkers in Japanese Healthy Subjects: The CACHE Study HEALTHY Analysis.

Blood cholesterol absorption and synthesis biomarkers predict cardiovascular risk. This study aimed to determine the values of serum non-cholesterol sterol markers [lathosterol (Latho), campesterol (Campe), and sitosterol (Sito)] in healthy individuals and factors affecting these markers. The CACHE Consortium compiled clinical data, including serum Latho (cholesterol synthesis marker), and Campe and Sito (cholesterol absorption markers), by a gas chromatography method in 2944 individuals. Healthy subjects were selected by excluding those with prior cardiovascular disease, diabetes mellitus, hypertension, chronic kidney disease, familial hypercholesterolemia, sitosterolemia, current smokers, those with low ( ＜17 kg/m 2 ) or high (≥ 30 kg/m 2) body mass index (BMI), and those with treatment for dyslipidemia or hyperuricemia. Nonlinear regression stratified by sex was used to examine the associations of cholesterol metabolism markers with age, BMI, and serum lipid levels. Of 479 individuals selected, 59.4% were female; the median age was 48 years in females and 50 years in males. The three markers showed positively skewed distributions, and sex differences were present. Age was associated positively with Latho, inversely with Campe, but not significantly with Sito. BMI was associated positively with Latho, but not significantly with Campe or Sito. High-density lipoprotein cholesterol (HDL-C) was positively associated with Campe and Sito, but not significantly with Latho. Non-HDL-C was positively associated with the three markers. Our study results in the healthy subjects help to interpret the non-cholesterol sterol markers for cardiovascular risk assessment in patients with cardiovascular risk factors.

1,1,6-Trimethyl-1,2-dihydronaphthalene Content of Riesling Wines in Hungary.

1,1,6-Trimethyl-1,2-dihydronaphthalene (TDN) is known to give a petrol note when smelling and tasting wine, which is most pronounced in Riesling varieties. Its increasing concentration has been linked to climate change. In the present work, a gas chromatographic method was used to quantify free TDN in "Italian Riesling", "Rhine Riesling", and "Kéknyelű" wines from Hungary. From the vintages 2010 to 2020, 39 bottles of wine from different wine regions were evaluated by instrumental analysis and sensory evaluation. Our aim is to determine the extent to which the Riesling wines in Hungary show a petrol character. The other objective was a comparison of sorts to see if there is a difference in TDN production potential between Italian Riesling and Rhine Riesling. We also aimed to clarify the question whether the Hungarian variety Kéknyelű is also capable of developing a petrol character. The wines we tested were corked and screw-locked. This allowed us to compare the difference in TDN concentration variation over time between the two closure methods.

Enhancing Chromatographic Analysis: A Novel Cryo-Enrichment Module for GC Analysis of Terpenes in Cannabis sativa.

This study presents the development and validation of a gas chromatography (GC) method using cryo-enrichment for the analysis of α-pinene and β-caryophyllene in Cannabis sativa plant. Cryo-enrichment is a method that involves cooling part of the GC column to improve some aspect of chromatographic analysis. The aim of this study was to improve upon previous GC cryo-enrichment prototype and to create and validate a method for the analysis of these terpene compounds, which have received increasing attention for their medicinal properties. The improved cryo-enrichment device used in this study was built in-house and used a custom-built aluminum GC column holder cooled by a two-stage cryo-cooler. The validated method was found to be precise, accurate and sensitive, with good repeatability.

Chiral isotopic fractionation in lemon essential oil: A tool for authenticity assessment?

The present research aimed to retrieve key information about the genuineness of Sicilian lemon essential oils by evaluating simultaneously the chiral and isotopic data of target terpene components. With respect to previous literature references, where chiral recognition and isotope discrimination were performed by distinct gas chromatographic methods, this study aimed to develop a single analytical approach. To overcome limitations associated to monodimensional gas chromatographic approaches, an enantio‑selective multidimensional gas chromatographic approach coupled to isotopic ratio mass spectrometry and to parallel single quadrupole detection (Es-MDGC-C-IRMS/qMS) was developed. Thanks to the features of this system, enantiomeric excesses and target δ13C of the chiral and achiral components were evaluated in a single gas chromatographic run, allowing to reduce total time analysis, as well the consumption of electricity, solvents and samples. Moreover, due to the capability to baseline separate the enantiomeric couples, further considerations were done about the specific δ13C value of the target separated enantiomers. Dealing with the genuine lemon oils analysed, a different δ13C value was found between the enantiomers of the same chiral component, namely (-) and (+) of α and β-pinene, suggesting a different isotopic fractionation related to a specific biosynthetic pathway. This research aimed to evaluate the reasons behind this behaviour, paving the way to newer considerations in the field of authenticity assessment.

A state-of-the-science review of analytical methods for urinary dialkylphosphate metabolites in the assessment of exposure to organophosphate pesticides: From 2000 to 2022.

The general population and workers are exposed to organophosphate insecticides, one of the leading chemical classes of pesticides used in rural and urban areas. This paper aims to conduct an integrative review of the most used analytical methods for identifying and quantifying dialkylphosphate-which are metabolites of organophosphate insecticides-in the urine of exposed workers, discussing their advantages, limitations and applicability. Searches utilized the PubMed, the Scientific Electronic Library Online and the Brazilian Digital Library of Theses and Dissertations databases between 2000 and 2021. Twenty-five studies were selected. The extraction methods most used were liquid-liquid extraction (LLE) (36%) and solid-phase extraction (SPE) (36%), with the SPE being more economical in terms of time and amount of solvents needed, and presenting the best percentage of recovery of analytes, when compared with LLE. Nineteen studies (76%) used the gas chromatography method of separation, and among these, 12 records (63%) indicated mass spectrometry used as a detection technology (analyzer). Studies demonstrate that dialkylphosphates are sensitive and representative exposure biomarkers for environmental and occupational organophosphate exposure.

Validation of Amphetamine and Methamphetamine Measurement Method by Gas Chromatography-Mass Spectrometry

Drug abuse is still very common in Indonesia, including in West Sumatra, which will result in psychological changes in users. A reliable method is needed to be able to detect the presence of narcotics and their metabolites in human specimens. The purpose of the study was to validate the mass spectrophotometric gas chromatography method for the measurement of amphetamine and metamphetamine. The benefits of research to ensure that the analytical method is accurate, specific, reproducible and resistant to the range of analytes to be analysed. The research method is by measuring the sample with GCMS (gas chromatography mass spectrometry) and then conducting a linearity test, detection limit test, accuracy test and precision test. The matrix used is urine specimen, spike is done with amphetamine and methamphetamine standards. From the results of the validation of amphetamine and methamphetamine measurement methods obtained MDL (method detection limit) 3.10 µg/L, LoD (limit of detection) 2.962 µg/L and LoQ (limit of detection) 2.962 µg/L. of Quantification) 9.873 µg/L. In the measurement of methamphetamine MDL 7.072 µg/L, LoD 6.757 µg/L and LoQ 22.253 µg/L. Accuracy of amphetamine and methamphetamine measurement methods 101.9% and 95.2% and reproducibility of amphetamine and methamphetamine measurements 3.83% and 6.743%. Measuring range and linearity of measurement of amphetamine and methamphetamine 25.0 µg/L - 200 µg/L with r = 0.9972 and 0.9992. Based on these data, the amphetamine and methamphetamine measurement method with gas chromatography-mass spectrometry is sensitive to measure amphetamine and methamphetamine in urine and fulfils the required criteria.

БАКТЕРИИ-НЕФТЕДЕСТРУКТОРЫ С УСТОЙЧИВОСТЬЮ К ПРИСУТСТВИЮ ДОПОЛНИТЕЛЬНЫХ ПОЛЛЮТАНТОВ

Throughout the world, significant areas of agricultural land are polluted with hydrocarbons. Their microbiological purification is hampered by the presence of residual amounts of pesticides (herbicides, in particular), which inhibit the vital activity of oil-destructing bacteria. In addition, along with crude oil, heavy metals and salts (mainly chlorides) can enter arable soils, which, in turn, have a negative effect on microorganisms. Therefore, for the bioremediation of such territories, hydrocarbon-oxidizing bacteria resistant to the presence of additional pollutants should be used. In the present work, three isolates were identified that are capable of active growth in a liquid medium with oil. Using time-of-flight matrix-activated laser desorption-ionization (MALDI-TOF) mass spectrometry of the cellular protein fraction, sequencing of the nucleotide sequence of the 16S rRNA gene and phylogenetic analysis, the species of microorganisms belonging to the genus Acinetobacter was determined. The bacteria had a significant ability to biodegrade oil (71.8-74.1%), which was estimated from the degree of destruction of the aliphatic oil fraction by the gas chromatographic method after preliminary extraction with hexane. The resistance of microorganisms to the presence of herbicides, heavy metals, and sodium chloride was determined by their growth on meat-peptone agar with different concentrations of preparations, salts of these metals, or NaCl. The strains showed resistance to the presence in the medium of herbicides based on 2,4-D and imazethapyr at a concentration of 10.0 ml/l, sodium chloride in an amount of 5.0-6.0%, and lead ions (1.00-1.25 g/l). In addition, they produced lipase and were capable of fixing atmospheric nitrogen and dissolving inorganic phosphate. The last two properties are important for stimulating the growth and development of remedial plants. The obtained results indicate that all three strains have certain prospects of application for cleaning oil-contaminated agricultural soils and require further study of their biotechnological potential.

The performance of saliva test strips for determining ethanol levels, as compared to gas chromatography and breathalyser methods

We set out to determine the performance of the Testi Technologies enzymatic assay saliva ethanol test strips of three different detection levels: 0 g/L, 0.2 g/L and 0.5 g/L, using as the reference method a gas chromatography analyser (GC). Alcohol levels were measured in 104 volunteers at up to three points in time, using up to three test strips per measurement, while gathering blood samples and breathalyser readings in parallel. The plasma alcohol concentrations (PAC) were determined from the plasma samples using GC. The qualitative results of the test strips were compared to the quantitative results from the reference method, as well as the breathalyser readings, and the amount of true and false positive and true and false negative results were classified using predetermined cut-off levels. The best performing test strips were the 0 g/L and the 0.2 g/L strips. The 0 g/L strips had a sensitivity and specificity of 1.00, as false negatives and false positives were not detected. The 0.2 g/L strips had a sensitivity and specificity [95% confidence interval (CI)] of 0.98 (0.96 − 1.00) and 0.83 (0.62 − 1.00) respectively, an accuracy of 0.97 (0.95 − 0.99), and a diagnostic odds ratio of 205.00 (35.33 − 1189.66). The test strips perform their intended purpose of screening for alcohol consumption well, with their great sensitivity as a defining property compared to other testing methods. For them to be able to be implemented in a clinical setting however, further refinement of the tests’ characteristics would be required.

Quality control and evaluation of Xiaozhong Zhitong tincture by multi-wavelength fingerprint combined with electrochemical fingerprint

Xiaozhong Zhitong tincture (XZZTT), a prominent Traditional Chinese Medicine (TCM) formulation comprising 21 intricate herbal components, poses a challenge in terms of quality control due to its complex composition and the interplay of diverse chemical constituents. To address this issue, a comprehensive assessment strategy was devised by integrating chromatographic and electrochemical techniques to construct a multidimensional fingerprint for XZZTT samples. This study encompassed the evaluation of 42 XZZTT samples through a systematic quantitative fingerprinting method (SQFM), while also quantifying the concentrations of four specific compounds—Geniposide, Palmatine hydrochloride, Paeonol, and Chlorogenic acid. The experimental approach encompassed the establishment of fingerprints using High-Performance Liquid Chromatography (HPLC), Gas Chromatography (GC), and GC-HPLC tandem fingerprints methods. Furthermore, electrochemical fingerprints (ECFP) were established using the B-Z oscillation system, and eight characteristic parameters in the oscillation system were recorded and compared among samples. Hierarchical Clustering Analysis (HCA) was subsequently employed to classify the distinct fingerprints and compare outcomes from one-dimensional spectroscopy, GC-HPLC tandem chromatography, and the fusion fingerprints. Finally, Grey Relation Analysis (GRA) was harnessed to unravel the relationship between ECFP outcomes and peak areas in fusion fingerprints, facilitating predictions regarding the substances' reducing potency. In conclusion, the rational combination of multidimensional fingerprinting and multidimensional analysis provides a reliable and comprehensive method for the evaluation of XZZTT and its related products.

Multivariate optimization of a gas chromatographic method for the determination of organic impurities in ethanol

Medicinal ethanol obtained from alcoholic fermentation drags traces of organic impurities that have adverse effects in human health. For this reason, it is a priority to carry out a thorough examination of its composition before the final consumption. The identification of these compounds was performed by a gas chromatographic technique which was focused in the reduction of the applied temperatures, and in the minimization of gas consumption, by means of an experimental optimization of the parameters. The effect of six chromatographic parameters was studied over three desired responses. The four factors that did not influence the responses were the injector temperature, the FID temperature, sample injection volume and the hydrogen flow rate. As a consequence, the latter variables were set in their most conservative intervals considering the long life of the spare parts of the gas chromatograph.On the other hand, the starting run temperature and the linear velocity of the carrier gas were optimized to the final values of 49.16 °C and 35.00 cm/s, respectively, achieving a reduction of the run time from 34.96 to 21.38 min, without loss in the resolution between the first two peaks from 1.190 to 1.131. Moreover, the width of the last analyte peak significantly decreased from 0.310 to 0.212 min, and the signal/noise ratio was enhanced, hence improving the quantification of the analytes.

Variation of carbon source and sink along the environmental gradient from lakeside to highlands in Yuanchi swamp wetlands, Changbai Mountains, China.

Lacustrine wetlands have long-term carbon storage capacity and contribute significantly to regional carbon cycle, but it is unclear how its carbon sinks respond to climate change. We measured soil heterotrophic respiration carbon emissions (CO2 and CH4), vegetation carbon sequestration, and related environmental factors (temperature, water level, etc.) of five kinds of natural swamps (Phragmites marsh-L, Carex schmidtii marsh-C, Rhododendron capitatum swamp-D, Betula fruticose swamp-H, Larix olgensis swamp-LT)by using static chamber gas chromatography and relative growth equation methods, along the water environmental gradients from lakeside to highlands in Yuanchi of Changbai Mountains. We quantified the carbon source/sink function (CSS) and global warming potential (GWP) of various swamp types by estimating ecosystem net carbon balance, and revealed the variation patterns and formation mechanisms of CSS and GWP along the environmental gradients, aiming to explore the response of carbon source/sink of lakeside wetland in high altitude area to climate change. The results showed that marshes (L and C) were weak sources (-1.018 and -0.090 t C·hm-1·a-1) at the lower habitats of the water environment gradient, shrub swamps (D and H) were strong or weak sinks (1.956 and 0.239 t C·hm-1·a-1) at the middle habitats, forest swamp (LT) was strong source (-3.214 t C·hm-1·a-1) at the upper habitat. The spatial changes were promoted by water level and suppressed by soil temperature. For GWP, strong thermal radiation for marshes (from 44.682 to 59.282 t CO2·hm-1·a-1), cold radiation for shrub swamps (from -0.920 to -7.008 t CO2·hm-1·a-1), and weak thermal radiation for forest swamp (11.668 t CO2·hm-1·a-1), and their GWP was only promoted by soil temperature. Under current climate change background, marshes and forest swamp at both ends of the water environment gradient from lakeside to highlands played a positive feedback effect due to the increases of CH4 or CO2 emissions, while the middle shrub swamp still maintained a negative feedback effect in Yuanchi located the high-altitude area of the temperate Changbai Mountains.

Genetic analysis of the content of palmytic acid glycerides in the carriers of maize mutation shrunken-1

Aim. The influence of corn shrunken-1 (sh1) mutation on the content of palmitate in corn oil establishing and genetic analysis of this trait. Methods. The effects of the sh1 mutation on the content of palmitate were determined by comparing the inbreds – carriers of this mutation with inbreds of the common type, as well as in the top-crosses of common type inbreds with the mutant inbreds. The genetic components of the variance in terms of the content of palmitate were analyzed in the diallel crosses of mutant inbreds according to the second Griffing method. The determination of oil fatty acid composition was carried out by the Peisker gas chromatographic method. Results. It has been established that the corn inbreds – carriers of sh1 mutation exceed the common type inbreds by an average of 29.2 % in terms of palmitate content. The level of the trait in the inbreds based on the sh1 mutation was notable as having the quantitative variability and varied within 12.2-15.6 %. The content of palmitate in the carriers of sh1 mutation was inherited as incomplete dominance with a predominant contribution of additive effects to the variance. A higher level of the trait was controlled by recessive alleles of polygenes. Conclusions. The obtained results suggests the possibility of spatial linkage of the sh1 mutant gene with palmitate-coding locus, the effect of which is modified by the polygenic complex. It has been confirmed, that the carriers of sh1 mutation expands the genetic diversity of corn in terms of palmitate content.

The Possibility of Using 1301 and 2402 Mixtures of Halons for Fire Extinguishing Purposes

Halons are usually used for fire extinguishing where other types of extinguishing agents cannot be used. Their use does not require disconnection of electrical networks, does not lead to any damage, and after airing the premises, these substances do not leave any residues. Halons are used as flame retardants in concentrations (from 2 to 12% vol.). In the case of their use, a decrease in the oxygen content in the air of the flame center’s due to dilution is not significant, and extinguishing occurs as a result of the slowing down and interruption of chain chemical reactions in the flame. Combustion inhibitors play the role of a "negative catalyst", the mechanism of their action consists in high reactivity to interact with radicals with the formation of inert compounds, thereby interrupting the chain reaction of combustion and slowing down its development. The concentrations of bromotrifluoromethane (halon 1301) and 1,2-dibromotetrafluoroethane (halon 2402) in the mixtures were determined by the gas chromatographic method, and experimental researches for determining the minimum fire-extinguishing concentration established that the halons 1301 and 2402 mixtures show high efficiency in extinguishing flames. Established, that the mixture of halons 1301 and 2402 with the concentration of the latter in the range of 60÷65% exhibits the best minimum fire-extinguishing concentration. At these values, the minimum fire-extinguishing concentration did not exceed 2.0% vol. It was determined that when reducing the concentration of oxygen in the air by halon 1301 from 20.5 to 19% of volume, the concentration of halon 2402 for extinguishing n-heptane decreases by 2.5 times. Inhibition of the n-heptane flame combustion process by such mixtures of halons is associated with the decomposition of halons under the influence of temperature with the absorption of heat and releasing of combustion inhibitors, a change in the direction of decomposition towards the formation of non-combustible gases and the cessation of oxygen access. This indicates possibility of using available gas extinguishing substances - halons - for fire extinguishing.

Determination of methionine and selenomethionine in food matrices by gas chromatography mass spectrometry after aqueous derivatization with triethyloxonium salts

A novel analytical method for the simultaneous gas chromatography–mass spectrometry (GC–MS) determination of methionine and selenomethionine in food samples is described. Samples were digested with methanesulfonic acid in a closed vessel without the need for reflux. A single step derivatization using triethyloxonium tetrafluoroborate was optimized for the conversion of the analytes into their ethyl derivatives, followed by their extraction with hexane and GC–MS analysis.. This derivatization approach was simpler and/or safer with respect to current methods based on alkyl chloroformate or silylating reagents and it yielded very clean chromatography. A design of experiment approach, based on an open source chemometric software, was used to optimize the experimental conditions. When analysis of a 1 mL volume of aqueous standard was performed, detection limits of 1 ng/g methionine and 10 ng/g for selenomethionine were obtained.The method was validated by analysis of a selenized yeast Certified Reference Material NRC SELM-1.

A comparative evaluation of nutritional composition and antioxidant properties of six Malaysian edible seaweeds

Agriculture in the 21st century faces challenges in adopting efficient and sustainable production methods to feed the growing population. In this context, seaweed offers greater advantages over terrestrial plants. This study investigated the nutritional composition and antioxidant properties of six edible seaweeds found in Malaysia. The seaweeds studied were brown (Padina australis, Sargassum binderi, Sargassum polycystum), green (Caulerpa racemosa, Caulerpa sertularioides), and red (Garcilaria changgi) seaweeds. The moisture, ash, protein, fat, and total dietary fibre contents of the seaweeds were analysed according to the Association of Official Analytical Chemists methods. Total available carbohydrate content was assessed using the Clegg-anthrone method. Mineral, amino acid, and fatty acid contents were determined through atomic absorption spectroscopy, high-performance liquid chromatography, and gas chromatography methods, respectively. Results revealed that the seaweeds were all high in total dietary fibre (53.96–76.97 g/100 g dried weight, dw) and ash (4.46–18.53 g/100 g dw) whereas their fat (0.05–4.62 g/100 g dw) content was generally low. The brown seaweeds were good sources of calcium. Red seaweed G. changii had the highest content of essential amino acids whereas brown seaweed S. binderi had the highest polyunsaturated fatty acid and lowest saturated fatty acid contents. Fucoxanthin could only be detected in brown seaweeds. Methanolic extracts of seaweeds showed good antioxidant activities measured using 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity (DPPH-RSA), ferric reducing antioxidant power (FRAP), and trolox equivalent antioxidant activity (TEAC) assays. Overall, this study contributed knowledge on underexploited Malaysian seaweeds and proposed them as an alternative source of nutrients for humans to meet food security challenges.

Rapid determination of levels of the main constituents in e-liquids by near infrared spectroscopy

Use of e-cigarettes is increasing, alongside an expanding variety of devices and e-liquids. To match this growth and in line with the expanding legal and regulatory requirements applicable to manufacturers of e-cigarettes (e.g. disclosure of list of ingredients and quantities thereof in a product), rapid methods for determining levels of the main e-liquid constituents—namely, propylene glycol (PG), vegetable glycerol (VG), water and nicotine—are needed. We have assessed the ability of near infrared (NIR) spectroscopy, coupled with partial least squares (PLS) regression, to predict the levels of these constituents in e-liquid formulations. Using NIR spectral data from a large set of reference e-liquids incorporating working concentration ranges, flavourings, and other ingredients, linear calibration models were established for PG, VG, water and nicotine (predicted vs theoretical values, all R2 > 0.995). The performance of these models was then evaluated on commercial e-liquids using NIR and compared to results obtained by gas chromatography (GC). A strong correlation was observed between NIR-predicted values and measured values for PG, VG and nicotine (all R2 > 0.955). There was less consistency between predicted and GC measured values for water due to the relatively high limit of quantification (LOQ) of the GC method (2.6% w/w) versus the e-liquid content (0–18% w/w). The LOQ of the NIR method for water was 0.6% w/w, suggesting that NIR may be a more accurate method than GC to predict water concentration in e-liquids, especially at low levels (< 2.6% w/w). Collectively, although limitations of the technique have been identified, specifically for e-liquids containing compounds that might interfere with the set calibrations, our findings suggest that NIR combined with PLS regression is a suitable tool for rapid, simultaneous and high-throughput measurement of PG, VG, water and nicotine levels in most commercial e-liquids.

Controlled Release of Hydrogen-Carrying Perfluorocarbons for Ischemia Myocardium-Targeting 19 F MRI-Guided Reperfusion Injury Therapy.

Hydrogen gas is recently proven to have anti-oxidative and anti-inflammation effects on ischemia-reperfusion injury. However, the efficacy of hydrogen therapy is limited by the efficiency of hydrogen storage, targeted delivery, and controlled release. In this study, H2 -PFOB nanoemulsions (NEs) is developed with high hydrogen loading capacity for targeted ischemic myocardium precision therapy. The hydrogen-carrying capacity of H2 -PFOB NEs is determined by gas chromatography and microelectrode methods. Positive uptake of H2 -PFOB NEs in ischemia-reperfusion myocardium and the influence of hydrogen on 19 F-MR signal are quantitatively visualized using a 9.4T MR imaging system. The biological therapeutic effects of H2 -PFOB NEs are examined on a myocardial ischemia-reperfusion injury mouse model. The results illustrated that the developed H2 -PFOB NEs can efficaciously achieve specific infiltration into ischemic myocardium and exhibit excellent antioxidant and anti-inflammatory properties on myocardial ischemia-reperfusion injury, which can be dynamically visualized by 19 F-MR imaging system.Moreover, hydrogen burst release induced by low-intensity focused ultrasound (LIFU) irradiation further promotes the therapeutic effect of H2 -PFOB NEs with a favorable biosafety profile. In this study, the potential therapeutic effects of H2 -PFOB NEs is fully unfolded, which may hold great potential for future hydrogen-based precision therapeutic applications tailored to ischemia-reperfusion injury.