Gas Chromatography-flame Ionization Detector Research Articles

Evaluation of blood BTEX levels in fuel stations workers using vortex-assisted dispersive liquid-liquid microextraction based on deep eutectic solvent followed by gas chromatography flame-ionization detector

In this research, an eco-friendly method was established by vortex-assisted dispersive liquid-liquid microextraction based on the deep eutectic solvent (VA–DLLME–DES). The performance of the proposed method was demonstrated by the determination of benzene, toluene, ethylbenzene, and xylene (BTEX) in blood samples of fuel stations workers combined with GC–FID. The selected hydrophilic deep eutectic solvent is consisting of l-menthol and (1S)-(+)-camphor-10-sulfonic acid (CSA) at a 5:1 molar ratio as a green solvent instead of traditional toxic organic solvents. Under the optimal extraction conditions, the introduced method exhibited good linearity with a coefficient of determinations (r 2) higher than 0.9985 and an acceptable linear range of 0.03–80 µg l–1. Accordingly, the limits of detection (S/N = 3) and limits of quantification (S/N = 10) were in the ranges of 0.01–0.04 µg l−1 and 0.03–0.10 µg l−1, respectively. Blood BTEX levels of fuel stations workers were analyzed based on age, duration of working at the station, smokers or nonsmokers, and station type (CNG, gasoline, and dual-purpose). The results showed that there was no significant difference between blood BTEX levels in different age groups, while the concentration of BTEX compounds increases with the increase of working time in the station. Blood BTEX levels were much higher in smokers than in nonsmokers.

First Approach to the Aroma Characterization of Monovarietal Red Wines Produced from Varieties Better Adapted to Abiotic Stresses.

Adaptation strategies in the wine sector consist of the use of cultural techniques to limit damages caused by climate change, using, among other resources, varieties better adapted to the scenarios of abiotic stress exacerbation, namely water and thermal stress, as well as those more tolerant to heatwaves. With the intention to determine the aromatic characterization of ten monovarietal wines produced from cultivars with high productive performance in a global warming scenario ('Petit Verdot', 'Marselan', 'Merlot', 'Touriga Franca', 'Syrah', 'Vinhão', 'Bobal', 'Preto Martinho', 'Trincadeira', and 'Alicante Bouschet'), grown in Esporão vineyard (Alentejo, Portugal) and submitted to deficit irrigation (Ks ± 0.5), their aromatic character has been analyzed. Each grape variety was vinified at a small scale, in duplicate, and the wines were evaluated by a sensory panel, which rated several sensory attributes (visual, olfactory, and gustatory). Sensory analysis revealed a discrete appreciation for the monovarietal wines tasted, showing a differentiation at the olfactory level that was not too marked, although present, between the samples. The free volatile compounds were analysed using gas chromatography-olfactometry (GC-O), identified using a gas chromatography-mass spectrometry (GC-MS) technique and semi-quantified using the gas chromatography-flame ionization detector (GC-FID) technique. Based on the interpolation of the results of the various statistical analyses carried out, 49 probable odor active compounds (pOACs) were identified and based on the odor activity values (OAVs), 24 of them were recognized as odor active compounds (OACs) originated mainly during the fermentation processes. An aromatic characterization of the varieties has been proposed.

Isolation of Alpha-linolenic acid (ALA) from tasar, Antherea mylitta pupal oil and its anticancer activity

Previously, we reported that tasar silkworm pupal oil (TPO) is a rich source of alpha-linolenic acid (ALA) (37%). In this study, we have used three chromatographic techniques, namely preparative HPLC, gas chromatography-mass spectroscopy (GC-MS), and gas chromatography flame ionization detection (GC-FID), to purify, determine, and quantify alpha-linolenic acid (ALA), respectively, from TPO. Additionally, to determine the potential of the purified ALA as an anticancer drug, the sulforhodamine B (SRB) assay was utilised for in vitro investigation. Results revealed that ALA was successfully purified in a fraction of TPO by preparatory HPLC. It was discovered that only ALA was present in the purified fraction of ALA when it underwent GC-MS analysis, further confirming its purity. In addition, the quantification analysis using GC-FID showed that the concentration of ALA was 11760 ppm. Furthermore, anticancer analysis revealed purified ALA significantly inhibited the growth of a colon cancer cell line, (COLO-205) with a GI 50 ≤20. This is the initial investigation into isolating and purifying ALA from Tasar pupal oil.
 Keywords: Alpha-linolenic acid; GC-FID; HPLC; Omega-3Preparative, Tasar pupal oil.

Assessment of polycyclic aromatic hydrocarbons (PAHs) in alcoholic beverages consumed in Awka, Southeast Nigeria

ABSTRACT. The aim of this investigation was to assess the presence of 16 PAHs (naphthalene, acenaphthylene, acenaphthene, fluorene, anthracene, phenanthrene fluoranthene, benz[a]anthracene, pyrene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, dibenzo[a,h]anthracene, benzo[ghi]perylene, and indeno[1,2,3-cd]pyrene with symbols Nap, Ace, Ane, Flu, Ant, Phe, Flt, BaA, Pyr, Chr, BbF, BkF, BaP, DahA, BghiP and InP, respectively) in alcoholic beverages consumed in Awka, Southeast Nigeria. The samples used were sourced from international, national, and local-based alcoholic beverages sold in Nigeria, which were analysed for the 16 priority PAHs components using gas chromatography-flame ionization detector (GC-FID) in order to quantify and offer advice to the public on the health implications of consuming these alcoholic beverages. The results show the absence of all the PAHs in all the alcoholic beverages, which could be due to lower temperature and shorter production duration utilized in the production process. This is because during the intense heating of raw materials or additives, PAHs are released. Therefore, the consumption of these alcoholic beverages is safe for consumers and poses no health risk that is detrimental to adults or children. As such, further research into other micropollutants and toxins is advocated to maintain current good manufacturing practices for quality.
 KEY WORDS: Alcoholic beverages, Food analysis, Public health, PAHs, GC-FID, Southeast Nigeria
 
 Bull. Chem. Soc. Ethiop. 2023, 37(4), 805-815. 
 DOI: https://dx.doi.org/10.4314/bcse.v37i4.1 

Association of circulating branched chain fatty acids with insulin sensitivity and beta cell function in the PROMISE cohort.

Branched chain fatty acids (BCFAs) are mainly saturated fatty acids with a methyl branch on the penultimate or antepenultimate carbon atom. While BCFAs are endogenously produced via the catabolism of branched chain amino acids, the primary exogenous source of BCFAs in the human body is via the diet, including dairy products. Recently, BCFAs have been identified as having a potentially protective role in the etiology of cardiometabolic disorders although current literature is limited. We aimed to investigate the longitudinal associations of circulating BCFAs across four serum pools with insulin sensitivity, beta cell function, and glucose concentrations in the PROMISE Cohort. Estimates of insulin sensitivity were assessed using Matsuda's insulin sensitivity index (ISI) and the homeostasis model assessment of insulin sensitivity (HOMA2). Estimates of beta cell function were determined using the insulinogenic index divided by HOMA insulin resistance and the insulin secretion-sensitivity index-2 (ISSI-2). Baseline serum samples were analyzed for BCFAs using gas-chromatography flame ionization detection. Longitudinal associations were determined using generalized estimating equations. In the free fatty acid (FFA) pool, iso15:0 and anteiso15:0 were positively associated with logHOMA2 (iso15:0 logHOMA2-%S: β = 6.86, 95% CI: [1.64, 12.36], p < 0.05, anteiso15:0 logHOMA2-%S: β = 6.36, 95% CI: [0.63, 12.42], p < 0.05) while anteiso14:0 was inversely associated with measures of insulin sensitivity (iso14:0 logHOMA2-%S: β = -2.35, 95% CI: [-4.26, -0.40], p < 0.05, logISI: β = -2.30, 95% CI: [-4.32, -0.23], p < 0.05, anteiso14:0 logHOMA2-%S: β = -4.72, 95% CI: [-7.81, -1.52], p < 0.05, logISI: β = -6.13, 95% CI: [-9.49, -2.66], p < 0.01). Associations in other pools were less consistent. We identified the potential importance of specific BCFAs, specifically iso14:0, anteiso14:0, iso15:0, anteiso15:0, in cardiometabolic phenotypes underlying type 2 diabetes.

Comprehensive analysis of alkenones by reversed-phase HPLC-MS with unprecedented selectivity, linearity and sensitivity

Alkenones are among the most widely used paleotemperature biomarkers. Traditionally, alkenones are analyzed using gas chromatography-flame ionization detector (GC-FID), or GC-chemical ionization-mass spectrometry (GC-CI-MS). However, these methods encounter considerable challenges for samples that exhibit matrix interference or low concentrations, with GC-FID requiring tedious sample preparations and GC-CI-MS suffering from nonlinear response and a narrow linear dynamic range. Here we demonstrate that reversed-phase high pressure liquid chromatography-mass spectrometry (HPLC-MS) methods provide excellent resolution, selectivity, linearity and sensitivity for alkenones in complex matrices. We systematically compared the advantages and limitations of three mass detectors (quadrupole, Orbitrap, and quadrupole-time of flight) and two ionization modes (electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI)) for alkenone analyses. We demonstrate that ESI performs better than APCI as response factors of various unsaturated alkenones are similar. Among the three mass analyzers tested, orbitrap MS provided the lowest limit of detection (0.4, 3.8 and 8.6 pg injected masses for Orbitrap, qTOF and single quadrupole MS, respectively) and the widest linear dynamic range (600, 20 and 30 folds for Orbitrap, qTOF and single quadrupole MS, respectively). Single quadrupole MS operated in ESI mode provides accurate quantification of proxy measurements over a wide range of injection masses, and with its modest instrument cost, represents an ideal method for routine applications. Analysis of global core-top sediment samples confirmed the efficacy of HPLC-MS methods for the detection and quantification of paleotemperature proxies based on alkenones and their superiority over GC-based methods. The analytical method demonstrated in this study should also allow highly sensitive analyses of diverse aliphatic ketones in complex matrices.

Method Validation and Residues determination of Mineral oil Arbofine on apple and soil by gas chromatography-flame ionisation detector under temperate conditions of Kashmir, India.

The present innovative study was carried out to ascertain the persistence of a mineral oil (Arbofine) on apple and soil at four locations. Arbofine destroys the vast majority of dormant insects and mites (mite and asphid eggs, scales, and psyllids) on fruit trees (cherry, apple, plum and peach) and thus reduces the number of treatments required in summer. The mineral oil was applying at recommended dose of 2.0% and 0.75% and double the recommended dose of 4.0% and 1.5% in dormant and summer season respectively. The soil samples were taken during the dormant season, whereas both soil and apple samples were taken during the summer season after treatment at 0, 1, 3, and 5 days. The recovery study of all the eleven paraffinic constituents (n-Pentane, n-Hexane, n-Heptane, n-Octane, n-Nonane, n-Decane, n-Undecane, n-Dodecane, n-Tridecane, n-Tetradecane, n-Pentadecane) in soil and apple which constituents 60% of mineral oil in soil and apple was carried out at the fortification level of 1.0μg mL-1 and found between 72.1-99.0 %. No residue of all the eleven paraffinic compounds of arbofine mineral oil detected in soil and apple at 0 day after recommended doses and double the recommended doses in both the seasons at four locations. Therefore mineral oil can be used on apples without any risk.

Determination of phytochemical constituents, antibacterial and antioxidant activities of ethanolic leaf extracts of Pterocarpus erinaceus

Abstract. Okoli EC, Umaru IJ, Olawale O. 2023. Determination of phytochemical constituents, antibacterial and antioxidant activities of ethanolic leaf extracts of Pterocarpus erinaceus. Biodiversitas 24: 2272-2277. Many people in Nigeria and West Africa have long used the leaves, stem bark, and roots of Pterocarpus erinaceus Poir. as a medicine to treat ailments such as malaria, ulcers, coughs, and fevers. The antioxidant, antimalarial, antiulcer, and antibacterial activities of stem bark, leaves, and roots of P. erinaceus have been investigated. The aim of this study was to determine the phytochemical composition, antimicrobial activity, and antioxidant activity of the P. erinaceus leaf. Phytochemical compounds in ethanolic leaf extracts of P. erinaceus were analyzed and quantified by Gas Chromatography/Flame Ionization Detector (GC-FID). The antibacterial test was performed against Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa, and Escherichia coli by agar diffusion. The antioxidant activity was evaluated by DPPH scavenging activity. Phytochemicals content in the extract include flavonoids (44.71%), alkaloids (19.47%), steroids (6.01%), tannins (1.73%), saponins (4.70%), glycosides (7.00%), tannins (2.60%), anti-nutrient (12.77%). Ethanol extracts of P. erinaceus leaves were effective against all selected bacterial strains (E. coli, S. aureus, B. subtilis, and P. aeruginosa). DPPH scavenging activity of the ethanol extract of P.erinaceus at a concentration of 1000 ?g/mL was 49.51% and 27.20% at 40 ?g/mL, categorized as moderate antioxidant activity. This study showed that crude ethanol extracts of P. erinaceus leaf contained pharmacologically active compounds and exhibited significant antibacterial and DPPH free radical scavenging activities in a concentration-dependent manner.

Studies on black cumin genotypes of Turkiye: Agronomy, seed and thymoquinone yields

Black cumin, Nigella sativa L. belonging to Ranunculaceae family, is a valuable medicinal plant due to the taste and curative effects of seed and oil. Although there are studies on the agronomical and chemical characterization of black cumin, there is not any study on the thymoquinone yield, and the thymoquinone content in the cold pressed seed oil. The study investigated thymoquinone content in cold-pressed seed oil and the thymoquinone yield per hectare of Turkish black cumin genotypes from two cultivated Nigella species, N. sativa and N. damascena, along with their agronomic properties, seed yield, and fatty acid composition. Field studies were carried out in the same climatic and soil conditions in a randomized block design for two years. The fatty acid composition of the seed oils was analyzed by gas chromatography flame ionization detector (GC-FID), and the amount of thymoquinone in the cold-pressed seed oil was analyzed by the Waters Acquity UPC2 system. As a result of the field and analytic studies, significant differences were observed in other agronomic characteristics, except for the number of branches. In the studies, the highest seed yield was obtained in the Genotype 3 with 2.690 kg/ha, Genotype 17 with 2.227 kg/ha and Genotype 16 with 2.003 kg/ha. However, the variations were observed in the yields under the changing climatic conditions of the years. In the study, the seed oil ratios of the genotypes varied between 33.8% and 38.4% in the first year, and between 28.8% and 38.7% in the second year, but the difference between the genotypes in the second year was statistically significant (p < 0.05). While thymoquinone was not found in the damascena seed oil samples, it was found between 0.45% and 4.57% in the cold-pressed seed oil of the sativa genotypes. Thymoquinone yields per hectare were between 1.24 and 18.41 kg/ha. Linoleic, oleic, and palmitic acids are the major fatty acids, and their values were found close to each other in the all genotypes. As a result of the study, the genotypes with high thymoquinone content were classified as medicine and folk medicine, and the genotypes with low thymoquinone content were classified as spice and food. It was also concluded that the sectoral classification, called "bitter black cumin" or “sweet black cumin”, is related to the thymoquinone contents in the cold-pressed seed oil.

Chemometrics-assisted-liquid phase microextraction based on deep eutectic solvents followed by gas chromatography for determination of polycyclic aromatic hydrocarbons in aqueous and juice samples

In the present study, an optimized liquid-phase microextraction technique based on the deep eutectic solvent (LPME-DES) followed by gas chromatography-flame ionization detector (GC-FID) is developed to determine 13 carcinogenic polycyclic aromatic hydrocarbons (PAHs) in water and juice samples. In this regard, central composite design (CCD) was used to design, multiple linear regression (MLR) to model, and Nelder-Mead simplex optimization to optimize the effective LPME-DES factors. The optimum values for DES volume, temperature, extraction time, and salt amount were 112 µL, 72 °C, 9.14 min, and 2.5% (w/v), respectively. Afterward, multivariate calibration based on partial least squares regression (PLSR) was developed in the concentration range of (0.2–70 ng mL−1) and its performance in terms of sensitivity (SEN), analytical sensitivity (γ), limit of detection (LOD), limit of quantitation (LOQ), and root mean square error of prediction (RMSEP) was compared with classical univariate calibration. Finally, to test the applicability of the proposed method in real samples, sea/well waters and orange/apple juices were analyzed at 10 and 30 ng mL−1 concentration levels. The relative recoveries were obtained in the range of 66.5%–130.4% for 10 ng mL−1 and 65.4%–124.5% for 30 ng mL−1. In conclusion, the developed method based on LPME-DES combined with GC-FID and chemometric techniques can be used as an efficient method for determining PAHs in real matrices.

Development of electrospun nanofibers based on Poly (vinyl alcohol) for thin film solid-phase microextraction of antidepressant drugs in biological samples

Today, antidepressants are widely used and it is important to determine their trace amounts due to harmful consequences. Here, a new nano sorbent was reported for the simultaneous extraction and determination of three types of antidepressant drugs (Clomipramine (CLO), Clozapine (CLZ), and Trimipramine (TRP) by the thin-film solid-phase micro-extraction (TFME-μSPE) method followed by the Gas Chromatography-flame ionization detector (GC-FID) analysis. So, the compound poly (vinyl alcohol) (PVA)/citric acid(CA)/β-cyclodextrin/Bi2S3@g-C3N4 nano sorbent was constructed by electrospinning technique. Then, nano sorbent was studied to optimize the many parameters impacting the extraction performance. Electrospun nanofiber has a large surface area, high porosity, and homogeneous morphology with a uniform bead-free structure. In optimal conditions, the limits of detection and quantification were calculated to be 0.15–0.03 ng mL−1 and 0.5–0.1 ng mL−1, respectively. The dynamic linear range (DLR) was in the range of 0.1 to 1000 ng mL−1 for CLO and CLZ, and 0.5 to 1000 ng mL−1 for TRP with correlation coefficients (R2) of 0.999. The relative standard deviations (RSDs) were achieved in the range of 4.9–6.8% (intra-day, n = 4) and 5.4–7.9% (inter-day, n = 3) in the period of 3 days. Finally, the capability of the method was evaluated to simultaneously measure trace amounts of antidepressants aqueous sample with desirable extraction efficiency (78 to 95%).

Ecological pollution and health risk monitoring assessment of polycyclic aromatic hydrocarbons and heavy metals in surface water, southeastern Nigeria.

Polycyclic aromatic hydrocarbons (PAHs) and heavy metals (HMs) are predominant pollutants linked with anthropogenic activities across a host of environmental mediums. The level of pollution, ecological and health risk were assessed in surface water from Ekulu in Enugu metropolis, Nigeria for 17 PAHs and selected HMs (As, Cd, Cr, Cu, Pb, Ni, Zn) components. PAHs and HMs were determined using a gas chromatography-flame ionization detector (GC-FID) and atomic adsorption spectrophotometer (AAS). The total PAHs in station A (3.17mg/l), B (1.51mg/l), and C (1.83mg/l) were due to high molecular weight (HMW) PAHs than low molecular weight (HMW) PAHs. HMs contents were within USEPA and WHO minimum contamination levels (MCL) except Cr and Pb. The molecular diagnostics of PAHs showed that incomplete combustion of carbonaceous compounds was dominant, while petrogenic was insignificant across all samples. The ecological indices of PAHs and HMs varied from medium to high pollution due to anthropogenic activities that pose a threat to the ecosystem. The non-carcinogenic models showed that hazard index (HI) ranged from PAHs (0.027 - 0.083) and HMs (0.0067 - 0.087) which is less than unity implying no adverse health issues. The lifetime cancer risk (LCR) for PAHs (4.21×10-4 - 9.61×10-4) and HMs (1.72×10-5 - 3.98×10-5) suggested significant cancer risk is possible over some time for a population of 1 in 10,000 and 100,000 for both PAHs and HMs exposure for 70 years. Therefore, there is an urgent need for proper pollution control and mitigation plan to preserve both age groups from being continuously exposed to anthropogenic activities in the Ekulu River and further study should be carried out to monitor the available toxicants.

Impacts of Nutrients on Alkene Biodegradation Rates and Microbial Community Composition in Enriched Consortia from Natural Inocula.

There is a growing need for biological and chemical methods for upcycling plastic waste streams. Pyrolysis processes can accelerate plastic depolymerization by breaking polyethylene into smaller alkene components which may be more biodegradable than the initial polymer. While the biodegradation of alkanes has been extensively studied, the role microorganisms play in alkene breakdown is not well understood. Alkene biodegradation holds the potential to contribute to the coupling of chemical and biological processing of polyethylene plastics. In addition, nutrient levels are known to impact rates of hydrocarbon degradation. Model alkenes were used (C6, C10, C16, and C20) to follow the breakdown capability of microbial communities from three environmental inocula in three nutrient levels over the course of 5 days. Higher-nutrient cultures were anticipated to exhibit enhanced biodegradation capabilities. Alkene mineralization was assessed by measuring CO2 production in the culture headspace using GC-FID (gas chromatography-flame ionization detection), and alkene breakdown was directly quantified by measuring extracted residual hydrocarbons using gas chromatography-mass spectrometry (GC/MS). Here, the efficacy of enriched consortia derived from the microbial communities of three inoculum sources (farm compost, Caspian Sea sediment, and an iron-rich sediment) at alkene breakdown was investigated over the course of 5 days across three nutrient treatments. No significant differences in CO2 production across nutrient levels or inoculum types were found. A high extent of biodegradation was observed in all sample types, with most samples achieving 60% to 95% biodegradation of all quantified compounds. Here, our findings indicate that alkene biodegradation is a common metabolic process in diverse environments and that nutrient levels common to culture media can support the growth of alkene-biodegrading consortia, primarily from the families Xanthamonadaceae, Nocardiaceae, and Beijerinkiaceae. IMPORTANCE Excess plastic waste poses a major environmental problem. Microorganisms can metabolize many of the breakdown products (alkenes) of plastics. While microbial degradation of plastics is typically slow, coupling chemical and biological processing of plastics has the potential to lead to novel methods for the upcycling of plastic wastes. Here, we explored how microbial consortia derived from diverse environments metabolize alkenes, which are produced by the pyrolysis of polyolefin plastics such as HDPE, and PP. We found that microbial consortia from diverse environments can rapidly metabolize alkenes of different chain lengths. We also explored how nutrients affect the rates of alkene breakdown and the microbial diversity of the consortia. Here, the findings indicate that alkene biodegradation is a common metabolism in diverse environments (farm compost, Caspian sediment, and iron-rich sediment) and that nutrient levels common to culture medium can support growth of alkene-biodegrading consortia, primarily from families Xanthamonadaceae, Nocardiaceae, and Beijerinkiaceae.

Sampling of Gas-Phase Intermediate Pyrolytic Species at Various Temperatures and Residence Times during Pyrolysis of Methane, Ethane, and Butane in a High-Temperature Flow Reactor

Air pollution in many major cities is endangering public health and is causing deterioration of the environment. Particulate emissions (PM) contribute to air pollution as they carry toxic polyaromatic hydrocarbons (PAHs) on their surface. Abatement of PM requires continuous strict emission regulation and, in parallel, the development of fuels with reduced formation of PM. Key processes in the formation of PM are the decomposition of hydrocarbon fuels and the synthesis of potential precursors that lead to the formation of benzene rings and thereafter growth to PAHs and eventually PM. Methane, ethane and butane are important components of natural gas and liquefied petroleum gas, and are also widely used in transportation, industrial processes and power generation. This paper reports on a quantitative investigation of the intermediate gaseous species present during pyrolysis of methane, ethane and butane in a laminar flow reactor. The investigation aimed to further the understanding of the decomposition process of these fuels and the subsequent formation of aromatic rings. The pyrolysis of methane, ethane and butane were carried out in a tube reactor under laminar flow conditions and within a temperature range of 869–1213 °C. The fuels were premixed in nitrogen carrier gas at a fixed carbon atom concentration of 10,000 ppm, and were pyrolysed under oxygen-free conditions. Intermediate gaseous species were collected from within the tube reactor at different residence times using a specially designed high-temperature ceramic sampling probe with arrangements to quench and freeze the reactions at entry to the probe. Identification and quantification of intermediate species were carried out using a gas chromatography-flame ionization detector (GC-FID). During methane pyrolysis, it was observed that as the concentration of acetylene increased, the concentration of benzene also increased, suggesting that the benzene ring is formed via the cyclo trimerisation of acetylene. With all three fuels, all intermediate species disappeared at higher temperatures and residence times, suggesting that those species converted into species higher than benzene, for example naphthalene. It was observed that increasing carbon chain length lowered the temperature at which fuel breakdown occurred and also affected the relative abundance of intermediate species.

Separation and quantification of diazinon in water samples using liquid-phase microextraction-based effervescent tablet-assisted switchable solvent method coupled to gas chromatography-flame ionization detection.

This study used a liquid-phase microextraction-based effervescent tablet-assisted switchable solvent method coupled to gas chromatography-flame ionization detection as an eco-efficient, convenient-to-use, cost-effective, sensitive, rapid, and efficient method for extracting, preconcentrating, and quantifying trace amounts of diazinon in river water samples. As a switchable solvent, triethylamine (TEA) was used. In situ generation of CO2 using effervescent tablet containing Na2 CO3 and citric acid changed the hydrophobic TEA to the hydrophilic protonated triethylamine carbonate (P-TEA-C). CO2 removal from the specimen solution using NaOH caused P-TEA-C to be converted into TEA and led to phase separation, during which diazinon was extracted into the TEA phase. The salting-out process was helpful in enhancing extraction efficiency. In addition, a number of significant parameters that affect extraction recovery were examined. Under optimum conditions, the limit of detection and limit of quantitation were 0.06 and 0.2ng/ml, respectively. The extraction recovery percentage and pre-concentration factor were obtained at 95 and 190%, respectively, and the precision (inter- and intra-day, relative standard deviation %, n= 5) was <5%.

Online detection of alkanes by a biological-phase microextraction and biosensing (BPME-BS) device

Oil spill incidents occur frequently and threaten ecosystems and human health. Solid-phase microextraction allows direct alkane extraction from environmental matrices to improve the limit of detection but is unable to measure alkanes on site. A biological-phase microextraction and biosensing (BPME-BS) device was developed by immobilising an alkane chemotactic Acinetobacter bioreporter ADPWH_alk in agarose gel to achieve online alkane quantification with the aid of a photomultiplier. The BPME-BS device had a high enrichment factor (average 7.07) and a satisfactory limit of detection (0.075 mg/L) for alkanes. The quantification range was 0.1–100 mg/L, comparable to a gas chromatography flame ionisation detector and better than a bioreporter without immobilisation. ADPWH_alk cells in the BPME-BS device maintained good sensitivity under a wide range of environmental conditions, including pH (4.0–9.0), temperature (20–40 °C), and salinity (0.0–3.0%), and its response remained stable within 30 days at 4 °C. In a 7-day continual measurement, the BPME-BS device successfully visualised the dynamic concentration of alkanes, and a 7-day field test successfully captured an oil spill event, helping in source apportionment and on-scene law enforcement. Our work proved that the BPME-BS device is a powerful tool for online alkane measurement, showing substantial potential for fast detection and rapid response to oil spills on site and in situ.

Influence of Tobacco Variety and Curing on Free Radical Production in Cigarette Smoke.

Cigarette smoke contains highly reactive free radicals thought to play an important role in tobacco smoke-induced harm. Previously, large variations in free radical and toxicant output have been observed in commercial cigarettes. These variations are likely because of cigarette design features (paper, filter, and additives), tobacco variety (burley, bright, oriental, etc.), and tobacco curing methods (air, sun, flue, and fire). Previous reports show that tobacco varieties and curing methods influence the production of tobacco smoke constituents like the tobacco-specific carcinogen nicotine-derived nitrosamine ketone (NNK). We evaluated free radical, nicotine, and NNK production in cigarette smoke from cigarettes produced with 15 different types of tobacco. Gas-phase free radicals were captured by spin trapping with N-tert-butyl-α-phenylnitrone and particulate-phase radicals were captured on a Cambridge Filter pad (CFP). Both types of radicals were analyzed using electron paramagnetic resonance spectroscopy. Nicotine and NNK were extracted from the CFP and analyzed by gas chromatography flame ionization detection and liquid chromatography-mass spectrometry, respectively. Gas-phase radicals varied nearly 8-fold among tobacco types with Saint James Perique tobacco producing the highest levels (42 ± 7 nmol/g) and Canadian Virginia tobacco-producing the lowest levels (5 ± 2 nmol/g). Nicotine and NNK levels in smoke varied 14-fold and 192-fold, respectively, by type. Gas-phase free radicals were highly correlated with NNK levels (r = 0.92, p < .0001) and appeared to be most impacted by tobacco curing method. Altogether, these data suggest that tobacco types used in cigarette production may serve as a target for regulation to reduce harm from cigarette smoking. Variations in cigarette free radical and NNK levels vary based on the tobacco variety and curing method. Reducing the ratio of high-producing free radical and NNK tobacco types offer a potential tool for regulators and producers looking to reduce toxicant output from cigarettes.

Application of Nanocube-Functionalized Nitrogen-Doped Melamine Sponge for Dispersive Micro-Solid Phase Extraction (SPE) of Phenolic Compounds From Aquatic Media

A procedure is reported for the efficient extraction and determination of phenolics from aqueous media. The approach is based on the dispersive micro-solid phase extraction using synthesized Co3O4 nanocube-functionalized nitrogen-doped melamine foam. The adsorption and desorption conditions were optimized by response surface methodology and one-variable-at-a-time approaches. The proposed method was fully validated. Under the optimized conditions, the limits of detection were lower than 0.5 ng mL−1. Calibration curves were linear in the range from 1.0 to 250.0 ng mL−1, 0.7 to 200.0 ng mL−1, 0.2 to 250.0 ng mL−1, and 1.0 to 250.0 ng mL−1 for phenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol, and pentachlorophenol, respectively. Enrichment factors and absolute recoveries from 17.5 to 20.7 and 70% to 83% were achieved. The method was successfully applied for trace monitoring of the analytes in environmental and industrial water samples with gas chromatography—flame ionization detection analysis. Satisfactory relative recoveries between 89.0% and 105.8% were obtained along with acceptable precision below 8.1%. This method is a simple, rapid, sensitive, and reliable protocol for efficient screening of the phenolics.

Enhanced Bioactivity of Rosemary, Sage, Lavender, and Chamomile Essential Oils by Fractionation, Combination, and Emulsification.

This study aimed to increase the bioactivity of essential oils by fractionation, combination, and emulsification. In this regard, pharmaceutical quality Rosmarinus officinalis L. (rosemary), Salvia sclarea L. (clary sage), Lavandula latifolia Medik. (spike lavender), and Matricaria chamomilla L. (chamomile) essential oils were fractionated by vacuum-column chromatography. The main components of the essential oils were verified, and their fractions were characterized by thin layer chromatography, gas chromatography-flame ionization detector, and gas chromatography/mass spectrometry. Besides, oil-in-water (O/W) emulsions of essential oils and diethyl ether fractions were obtained by the self-emulsification method, followed by droplet size, polydispersity index, and zeta potential value measurements. The in vitro antibacterial effects of the emulsions and binary combinations (10:90, 20:80, 30:70, 40:60, 50:50, 60:40, 70:30, 80:20, 90:10, v:v) against Staphylococcus aureus were determined by microdilution. In addition, the in vitro anti-biofilm, antioxidant, and anti-inflammatory effects of emulsion formulations were evaluated. According to the experimental results, fractionation and emulsification enhanced essential oil in vitro antibacterial, anti-inflammatory, and antioxidant effects due to increased solubility and nano-sized droplets. Among 22 different emulsion combinations, 1584 test concentrations resulted in 21 cases of synergistic effects. The mechanism of the increase in biological activities was hypothesized to be higher solubility and stability of the essential oil fractions. Food and pharmaceutical industries may benefit from the procedure proposed in this study.

Monoterpene Composition of Phloem of Eastern Larch (Larix laricina (Du Roi) K. Koch) in the Great Lakes Region: With What Must the Eastern Larch Beetle (Dendroctonus simplex LeConte) Contend?

The eastern larch beetle (Dendroctonus simplex LeConte) is the only tree-killing bark beetle that colonizes tamarack, or eastern larch, (Larix laricina (Du Roi) K. Koch) in the Great Lakes region. Historically, outbreaks have been intermittent and of short duration, frequently following predisposing factors such as drought or defoliation. However, over the past two decades, this insect has been in a perpetual state of outbreak in parts of the U.S. Great Lakes region, a deviation from historic norms. From 2001–2021, the insect impacted 300,000 ha, or 60% of the tamarack forests in Minnesota. This activity has prompted renewed interest in the beetle’s chemical ecology, including aspects of host semiochemistry. While foliar chemistry has been well documented in L. laricina, characterization of the monoterpene composition of the phloem has been lacking. We collected phloem samples from 56 tamarack trees across 14 locations in Wisconsin and Minnesota and assessed the relative abundances of the major monoterpenes present using gas chromatography-flame ionization detector (GC-FID). Individual terpenoid components identified included α-pinene (39.4%) and ∆-3-carene (30.0%) followed by several other components in small (&lt;8%) amounts. This knowledge provides a basis for future testing of monoterpene synergists or antagonists in pheromone lures targeting eastern larch beetle and/or its natural enemies.