Gas Chromatography Coupled To Mass Spectrometry Research Articles (Page 6)

Background: In recent years, significant resistance of microorganisms to antibiotics has been observed. A biofilm is a structure that significantly aids the survival of the microbial population and also significantly affects its resistance. Methods: Thyme and clove essential oils (EOs) were subjected to chemical analysis using gas chromatography coupled to mass spectrometry (GC-MS) and gas chromatography with a flame ionization detector (GC-FID). Furthermore, the antimicrobial effect of these EOs was tested in both the liquid and vapor phases using the volatilization method. The effect of the EOs on growth parameters was monitored using an RTS-8 bioreactor. However, the effect of the EOs on the biofilm formation of commonly occurring bacteria with pathogenic potential was also monitored, but for less described and yet clinically important strains of Arcobacter spp. Results: In total, 37 and 28 compounds were identified in the thyme and clove EO samples, respectively. The most common were terpenes and also derivatives of phenolic substances. Both EOs exhibited antimicrobial activity in the liquid and/or vapor phase against at least some strains. The determined antimicrobial activity of thyme and clove oil was in the range of 32-1024 µg/mL in the liquid phase and 512-1024 µg/mL in the vapor phase, respectively. The results of the antimicrobial effect are also supported by similar conclusions from monitoring growth curves using the RTS bioreactor. The effect of EOs on biofilm formation differed between strains. Biofilm formation of Pseudomonas aeruginosa was completely suppressed in an environment with a thyme EO concentration of 1024 µg/mL. On the other hand, increased biofilm formation was found, e.g., in an environment of low concentration (1-32 µg/mL). Conclusions: The potential of using natural matrices as antimicrobials or preservatives is evident. The effect of these EOs on biofilm formation, especially Arcobacter strains, is described for the first time.

The development of methods for determining volatile and semi-volatile organic compounds in public spaces has become necessary to identify potential health and environmental risks. This study presents a practical methodology for sampling, extracting, detecting, and identifying these compounds in a vehicular traffic region in Belo Horizonte, Brazil. The methodology uses direct-immersion solidphase microextraction (DI-SPME) and static headspace (SHS) to extract SVOCs/VOCs. Comprehensive time-of-flight gas chromatography mass spectrometry (GC×GC/Q-TOFMS) and gas chromatography coupled to mass spectrometry (GC/MS) were used to detect and identify compounds. The analysed samples, collected with a high-volume sampler (Hi-Vol) with quartz filters and in which particulate matter (PM2.5) was retained, showed the presence of more than 200 compounds, both biogenic (natural origin) and anthropogenic (human origin). Regarding the distribution of chemical classes, aromatic compounds were predominantly found at 29.2%, followed by esters at 20.8%, non-aromatic hydrocarbons at 5.6%, and carboxylic acids at 9.4%. Static headspace gas chromatography (HS-GC) enabled the identification and quantification of 21 volatile compounds, including BETX, dichloromethane, chloroform, and naphthalene, which are currently regulated by the US Environmental Protection Agency (EPA).

Objective: The objective of this study was to identify and quantify the presence of pesticides in green corn grains grown in the northwest region of Paraná, Brazil, and to evaluate their potential toxicological effects on human health, with a focus on food safety. Theoretical Framework: The state of Paraná, although one of the largest grain producers in Brazil, is also one of the states that consumes the most pesticides. The increasing use of pesticides can lead to serious environmental and health risks. Method: The samples were collected and analyzed in triplicate in the northwestern region of the state of Paraná. Identification and quantification were carried out by gas chromatography coupled with mass spectrometry (GC-MS), using a modified QuEChERS extraction method. Results and Discussion: The results revealed the presence of 38 extracted chemical substances, 27 of which were chemical compounds present in corn and 11 were contaminant residues. Of these contaminants, 6 pesticides (Pyriproxyfen, p¬-DCB, Atrazine, Benzyl Benzoate, Pendimethalin and 2,4-D), 2 by-products of agricultural activities and pesticides (Naphthalene and Acenaphthene), 2 persistent organic pollutants (Tetrahydro-2,5-dimethoxyfuran, Bisphenol A) and 1 solvent (Mesitylene) were identified. All residues were quantified below the maximum permitted limit. Research Implications: The implications of this study highlight the relevance of developing analytical methods and strategies that minimize food exposure to chemical contaminants. Originality/Value: The originality of this work lies in the application of the modified QuEChERS method for the analysis of pesticide residues in corn, contributing to the literature with new data on food contamination and its potential impacts on human health.

Inflammatory bowel disease (IBD) is a chronic immune-mediated pathology associated with the dysregulation of lipid metabolism. The administration of nervonic acid, a very long-chain fatty acid, has been shown to improve colonic inflammation in a mouse model of colitis. Our study aimed to quantify fecal levels of nervonic acid, as well as the very long-chain fatty acids, lignoceric acid, and pentacosanoic acid, to identify associations with IBD activity. Stool samples were collected from 62 patients with IBD and 17 healthy controls. Nervonic acid, lignoceric acid, and pentacosanoic acid were quantified by gas chromatography coupled with mass spectrometry (GC-MS). Lipid levels, normalized to the dry weight of fecal homogenates, were used for calculations. Patients with IBD exhibited elevated fecal nervonic acid levels compared to healthy controls, with no significant differences observed between ulcerative colitis and Crohn's disease. A fecal nervonic acid concentration of 0.49 µmol/g distinguished IBD patients from controls, achieving a sensitivity of 71% and a specificity of 82%. Fecal nervonic acid levels showed a positive correlation with both C-reactive protein and fecal calprotectin and increased proportionally with rising fecal calprotectin levels. IBD patients treated with corticosteroids or interleukin-12/23 antibodies had higher levels of fecal nervonic acid than those in other therapies, with no difference in serum C-reactive protein and calprotectin levels between these groups. In summary, this analysis indicates that fecal nervonic acid may emerge as a novel specific biomarker for IBD diagnosis and disease monitoring.

Hexachlorobenzene (HCB) is a persistent organic pollutant (POP) commonly detected in milk and dairy products. These compounds pose a serious threat to the health of consumers due to their considerable bioaccumulation potential, high stability, and toxicity. (2) Methods: The study evaluated the potential of Lactiplantibacillus plantarum and Lacticaseibacillus rhamnosus probiotic cultures to reduce HCB residues in fermented goat milk beverages during 21-day refrigerated storage. HCB content was determined by gas chromatography coupled with mass spectrometry (GC/MS). (3) Results: A strong negative correlation was found between HCB concentration in fermented milk and storage time. After 21 days, a 75-78% reduction in HCB content was observed, with L. plantarum showing greater efficiency in reducing hexachlorobenzene levels than L. rhamnosus. (4) Conclusions: The use of probiotic cultures contributed to a significant reduction in the HCB content of fermented goat milk. Our findings support the hypothesis that the lactic acid bacteria Lactiplantibacillus plantarum and Lacticaseibacillus rhamnosus can lower hexachlorobenzene levels in fermented products.

This study aimed to evaluate the chemical composition and the antioxidant and antifungal activities of the essential oil (EO) extracted from the aerial parts (leaves and flowers) of Ageratum conyzoides (Asteraceae). The EO was extracted by the hydrodistillation process (3h), and the compounds were identified by gas chromatography coupled to mass spectrometry (GC-MS). Antioxidant activity was performed by the β-carotene/linoleic acid co-oxidation system and 2,2-diphenyl-1-picryl-hydrazyl (DPPH) free radical scavenging and the iron reduction method (FRAP). The antifungal activity was performed by the broth microdilution (MIC) method using the strains Rhizopus oryzae ATCC 7560; Aspergillus flavus ATCC 1217; Aspergillus ochraceus ATCC 6787 and Penicillium verrucosum ATCC 7680. The results indicated a yield of 0.82 mg/kg. Sesquiterpenes hydrocarbons (33.28%) were the major class, and precocene I (48.19%), precocene II (7.38%) and β-caryophyllene (19.66%) were the major constituents. The co-oxidation system of β-carotene/linoleic acid showed 52.18% inhibition of oxidation in the concentration of 1.0 mg/mL. Of the four fungi evaluated, only Aspergillus ochraceus showed results, with a MIC of 1250 μL/mL, and the importance of finding activity on this fungus lies in the fact that it is a producer of ochratoxin A, infesting mainly green coffee beans. The results found open up new perspectives in valuing a species considered invasive.

It evaluated the chemical profile, antioxidant and anti-inflammatory activity, in an unprecedented way, of silver nanoparticles (AgNPs) synthesized from the essential oil nanoemulsion (NEO) of Piper nigrum. For essential oil extraction (EO), the hydrodistillation technique was used, and the chemical constituents were identified by Gas Chromatography Coupled to Mass Spectrometry (GC-MS). The nanoemulsions were prepared using the phase inversion method, and the synthesis of the AgNPs were performed by the AgNO3 reduction method using NEO. The AgNPs was characterized in terms of chemical profile by UV-Vis Spectrophotometry and particle size by Dynamic Mirroring of Light. Antioxidant activity was evaluated using the ABTS radical discoloration method and anti-inflammatory activity by protein denaturation. The majority constituent of the EO was limonene (42.41%). The maximum SPR band was centered at 420 nm, indicating the characteristic peak of the AgNPs. The lowest IC50 16.26 mg/L for antioxidant activity was obtained for AgNP pH 11. The IC50 that demonstrated the best result for anti-inflammatory activity was pH 11 was 0.217 mg/mL. This study brought in unprecedented results for AgNPs of P. nigrum, demonstrating to be efficient in improving the activities tested in this study and also demonstrating the effect of pH in these formulations.

This study examines a boreal peatland (the Sagnes peatland, Fanay, Limousin, France) with a depth of 1 m. This peatland is currently in the late stages of organic deposition, as evidenced by the growth of Carex species, along with Sphagnum mosses, in the uppermost level. To gain molecular insights, we conducted an analysis of the lignin and polyphenolic counterparts using HMDS (hexamethyldisilazane) thermochemolysis, enabling the identification of lignin degradation proxies. The goal was to develop characteristic indicators for the state of lignin degradation based on the relative distribution of lignin phenols, measured by gas chromatography coupled with mass spectrometry (GC-MS) after the HMDS thermochemolysis. For that purpose, the singular contribution of the 11 aromatic moieties yielded, along with SGC (sum of lignin moieties) and the most lignin degradation proxies, were applied. It has been shown that HMDS thermochemolysis exhibited the capacity to reveal oxidized and degraded lignin fractions, following the increasing trend yielded for most moieties and SGC proxy, in the mesotelm and catotelm layers. In addition, the C/G (Cinnamyl/Guaiacyl) and S/G (Syringyl/Guaiacyl) ratios showed their highest input in the upper half of the core. This bias in the aforementioned ratios could indicate that HMDS thermochemolysis is to be applied for geological samples, where low G-compounds exist. For the sake of validating HMDS thermochemolysis' application, Principal Component Analysis (PCA) was then applied to the molecular fingerprint. For ratios and proxies of aromatic moieties of HMDS thermochemolysis, the PCA approach exhibited a higher contribution (79%). This indicates the efficiency of these ratios in describing the molecular fingerprint of peat depth records. In addition, a higher separation between the contributions of the investigated variables (molecular proxies) along the first two PCs was noticed. In other words, the variables that showed a high contribution towards PC1 exhibited a low contribution towards PC2, and vice versa. These findings indicate the high reliance of applying the ratios and proxies of HMDS thermochemolysis.

Beeswax is one of the most important products for the well-being of bee colonies. The wax glands of young worker bees produce beeswax, which serves as a building material for honeycomb construction. Beekeepers using hives with mobile frames mainly utilize local beeswax to make foundations. Any paraffin addition represents adulteration, resulting in a high degree of contamination. During the preparation of re-used beeswax, losses during the process may instigate producers to add cheaper, wax-like substances like paraffin and tallow. This article presents a systematic investigation of the quality of beeswax foundation from six major producers in Vojvodina, Serbia, by applying the classic analytical procedure for the determination of selected physicochemical parameters and instrumental gas chromatography coupled with mass spectrometry (GC-MS) and Fourier transform infrared attenuated total reflection (FTIR-ATR) spectroscopy techniques. FTIR-ATR detected possible paraffin and beef tallow in 72 foundation sheet samples. This technique was complemented with GC-MS. This analysis revealed that paraffin content ranged between 19.75 and 85.68%, while no tallow was detected over the two-year period. Two sheets from each manufacturer were placed into wired Langstroth-Ruth frames and placed in beehives. The construction, based on built cells, was monitored every 24 h. Evaluating newly inserted sheets proved that without quality nectar, there is no intensive building, regardless of adulteration.

Aims: This study was designed to set macro/micro morphological standards, phytochemical and physicochemical parameters for the identification of E. nutans, a traditional remedy for the management of many disesases. Study Design: To establish pharmacognostic standards for proper identification of E. nutans and also study its phytochemicals using Gas Chromatography coupled to Mass Spectrometry (GC-MS). Place and Duration: This work was undertaken at the Department of Pharmacognosy and Natural Medicine, Faculty of Pharmacy, University of Uyo, Uyo, Nigeria for three month spanning from April through June, 2022. Methodology: Examination of microscopic characters, venation, chemomicroscopy, micromeritic properties, fluorescence analysis and phytochemical profiling using Gas Chromatography-Mass Spectrometry (GC-MS) were carried out. Results: Epidermal cell shapes were irregular with undulate-sinuous anticlinal walls. Stomatal distribution was amphistomatic with anisocytic and anomocytic stomata on both surfaces. Areolation was quadrangular, linear and biforked vein termination. The fluorescence characteristics showed the presence of different colours supporting the presence of various phytoconstituents for both leaf and stem. The flow properties for both leaf and stem were poor while GC-MS analysis of the dichloromethane extracts revealed lupeol (64.05%), 2-methylhexacosane (9.37%), stigmasterol (4.16%) and campesterol (1.29%) as major components in the leaf while campesterol (0.67%), stigmasterol (2.15 %), beta.-sitosterol (6.22%), lupeol (9.85%) and vitamin E (1.05%) for the stem extract. Conclusion: The results of the study could be useful for correct identification, standardization and preparation of monograph.

In recent years, the use of electronic cigarettes (e-cigs) has increased. However, their long-term effects on oral health and saliva remain poorly understood. Therefore, this study aimed to evaluate the saliva of e-cig users and investigate possible biomarkers. Participants were divided into two groups: the Electronic Cigarette Group (EG)-25 regular and exclusive e-cig users-and Control Group (CG)-25 non-smokers and non-e-cig users, matched in sex and age to the EG. The clinical analysis included the following parameters: age, sex, heart rate, oximetry, capillary blood glucose, carbon monoxide (CO) concentration in exhaled air, and alcohol use disorder identification test (AUDIT). Qualitative and quantitative analyses of saliva included sialometry, viscosity, pH, and cotinine concentrations. Furthermore, the EG and CG salivary metabolomes were compared using gas chromatography coupled with mass spectrometry (GC-MS). Data were analyzed using the Mann-Whitney test. The MetaboAnalyst 6.0 software was used for statistical analysis and biomarker evaluation. The EG showed high means for exhaled CO concentration and AUDIT but lower means for oximetry and salivary viscosity. Furthermore, 10 metabolites (isoleucine, 2-hydroxyglutaric acid, 3-phenyl-lactic acid, linoleic acid, 3-hydroxybutyric acid, 1,6-anhydroglucose, glucuronic acid, valine, stearic acid, and elaidic acid) were abundant in EG but absent in CG. It was concluded that e-cig users had high rates of alcohol consumption and experienced significant impacts on their general health, including increased cotinine and CO concentration in exhaled air, decreased oximetry, and low salivary viscosity. Furthermore, they showed a notable increase in salivary metabolites, especially those related to inflammation, xenobiotic metabolism, and biomass-burning pathways.

White dammar is an oleo-gum resin obtained from Vateria indica L. (Dipterocarpaceae) and is known to possess diverse biological activities. This study examines the chemical composition, antimicrobial, and antioxidant activities of essential oil extracted from white dammar. The chemical constituents of essential oil were identified by gas chromatography coupled with mass spectrometry (GC-MS) and flame ionization detection (FID). A total of 18 compounds constituting 97.15% of the oil were identified, which consist of β-caryophyllene (36.32%), α-humulene (14.31%), β-humulene (9.73%), caryophyllene oxide (8.28%), allo-aromadendrene (5.63%) and junenol (5.1%). The antimicrobial activity of the essential oil obtained was measured by means of disc diffusion assay, minimum inhibitory concentration (MIC), and minimum bactericidal/fungal concentrations (MBC/MFC). The highest antimicrobial activity was shown against Bacillus cereus (MIC/MBC = 31.2/62.5 μg/mL) and also Staphylococcus aureus (MIC/MBC = 62.5/125 μg/mL), whereas only a moderate level of activity was recorded against Salmonella typhi (MIC/MBC = 125/250 μg/mL), Vibrio cholerae, MRSA (MIC/MBC = 250/500 μg/mL) and Candida albicans (MIC/MFC = 125/250 μg/mL). Antioxidant activity was evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric-reducing antioxidant power (FRAP) assays; IC50 value, of 29.42 μg/mL and FRAP value, of 166.5 ± 2.2 μmol Fe2+/g indicated that the essential oil exhibited adequate antioxidant activity. These results substantiate the possible medicinal application of white dammar as an antimicrobial and antioxidant agent.

Cancer is a prominent cause of death globally, with breast cancer and prostate cancer being among the most devastating types. Therefore, the available anticancer treatments have some drawbacks, like higher toxicity and limited bioavailability. Thus, this study aimed to investigate for the first time the anticancer activity of Algerian Origanum majorana L.’s essential oil (OMEO). This research assessed the chemical profile of Algerian OMEO by gas chromatography coupled with mass spectrometry (GC-MS). The analysis revealed 29 compounds, which represent 98.08% of total volatile oil. The major compounds identified in OMEO were terpinen-4-ol (21.37%), γ-terpinene (15.78%), α-terpinene (10.43%), and trans-sabinene hydrate (9.27%). Additionally, MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) was also used to test the cytotoxicity on prostate cancer (PC-3), breast cancer (SKBR3), and normal retinal pigment epithelium (ARPE-19) cell lines. The results showed a selective cytotoxicity effect by decreasing cell viability of PC-3 cancer cells with half inhibitory concentration (IC50) of 608.57 μg/mL and 672.5 μg/mL after 48h and 72h, respectively. Regarding SKBR3 cancer cells, the IC50 was 991.5 μg/mL. OMEO exhibited no significant cytotoxicity against normal (ARPE-19) cells. Furthermore, we conducted a cell apoptosis assay using Hochest 33342 dye to explore the potential mechanism pathway of OMEO. The findings verified that OMEO could trigger apoptosis in PC-3 and SBKR3 cancer cells. The ability of OMEO to inhibit cell migration assessed via wound healing assay revealed a significant decrease in cell migration. Our results imply that OMEO decreases cell viability by inducing cell apoptosis. Moreover, the oil suppresses cell migration in prostate cancer and breast cancer cells.

The goal of this research work was to investigate the improvement of bio-oil issued from beechwood biomass through catalytic de-oxygenation. Pyrolysis was conducted in an auger reactor and the catalytic treatment was performed in a fluidized catalytic bed reactor. Lab-synthesized Fe-HZSM-5 catalysts with different iron concentrations were tested. BET specific surface area, BJH pore size distribution, and FT-IR technologies were used to characterize the catalysts. Thermogravimetric analysis was used to measure the amount of coke deposited on the catalysts after use. Gas chromatography coupled to mass spectrometry (GC-MS), flame ionization detection (GC-FID), and thermal conductivity detection (GC-TCD) were used to identify and quantify the liquid and gaseous products. The pyrolysis temperature proved to be the most influential factor on the final products. It was observed that a pyrolysis temperature of 500 °C, vapor residence time of 18 s, and solid residence time of 2 min resulted in a maximum bio-oil yield of 53 wt.%. A high percentage of oxygenated compounds, such as phenolic compounds, guaiacols, and the carboxylic acid group, was present in this bio-oil. Catalytic treatment with the Fe-HZSM-5 catalysts promoted gas production at the expense of the bio-oil yield, however, the composition of the bio-oil was strongly modified. These properties of the treated bio-oil changed as a function of the Fe loading on the catalyst, with 5%Fe-HZSM-5 giving the best performance. A higher iron loading of 5%Fe-HZSM-5 could have a negative impact on the catalyst performance due to increased coke formation.

Acute oral toxicity and genotoxicity assessment of the essential oil from Croton pulegiodorus Baill (Euphorbiaceae) leaves in mice

With the growing demand in the cosmetic industry for plant-based ingredients, this article presents a novel approach to developing a lip balm from butter extracted from bacuri seeds (Platonia insignis Mart.). The physical-chemical characterization of the bacuri seed butter was conducted, including determining the melting point and fatty acid (AG) content by gas chromatography coupled with mass spectrometry (GC-MS). The lip balm formulation, obtained using the phase inversion method, was evaluated for its applicability through a rheological study. The melting point values found were 35 and 79 ºC for the formulation, aligning with values described in the literature. The AG composition of the butter sample revealed significant levels of palmitic acid (42,2%), oleic (28,8%), and palmitoleic (10,8%). In the rheological study, the lip balm exhibited the physical characteristics of a non-Newtonian fluid of the pseudoplastic thixotropic type, an ideal behavior for topical formulations. These results underscore the potential of the butter extracted from bacuri seeds as a promising alternative input for a unique and innovative lip balm product, instilling a sense of optimism in the reader.

Background: Croton grewioides Baill., a species native to the Caatinga, popularly known as canela de cunhã, is used in traditional medicine to treat gastrointestinal diseases such as diarrhea, gastritis and stomach ulcers. The combination of essential oils with antibiotics reveals several beneficial effects associated with the increased efficacy of these drugs against pathogenic agents. Through this perspective, this study aimed to identify the chemical composition of the essential oil of C. grewioides (OECG) and evaluate its antibacterial and antibiotic-modifying activities against standard and multiresistant bacteria. Methods: To analyze the compounds present in the oil, the techniques of gas chromatography coupled with mass spectrometry (GC/MS) and gas chromatography with a flame ionization detector (GC/FID) were used. In the bacteriological tests, the Minimum Inhibitory Concentration (MIC) was obtained by the broth microdilution technique. The modulating effect of the essential oil was determined by calculating the subinhibitory concentration, followed by a serial microdilution of the antibiotics. The MIC reduction factor (CRF) was calculated, and its data were expressed as a percentage. Results: The analysis of the chemical composition identified the presence of the major compound estragole with a relative abundance of 50.34%. The MIC values obtained demonstrated efficacy in K. pneumoniae isolated from urine with MIC values of 512 µg/mL. OECG potentiated the effects of all antibiotics tested on the strains S. aureus ATCC 29213, K. pneumoniae Carbapnemase, E. coli ATCC 25922 and S. aureus ATCC 29213 with their CRF of 97.65%, 99.80%, 99.85% and 99.88%, respectively. Conclusions: Thus, the essential oil of C. grewioides presents synergistic effects when combined with the antibiotics tested, in addition to acting in the fight against bacterial resistance to antibiotics.

Sixty-four phenols grouped as nitrated, bromo, amino, methyl, chloro-phenols, and cresols, and thirty-eight organic acids grouped as mono-carboxylic and dicarboxylic are analyzed in forty-two fog samples collected in the Alsace region between 2015 and 2021 to check their atmospheric behavior. Fogwater samples are collected using the Caltech Active Strand Cloudwater Collector (CASCC2), extracted using liquid–liquid extraction (LLE) on a solid cartridge (XTR Chromabond), and then analyzed using gas chromatography coupled with mass spectrometry (GC-MS). The results show the high capability of phenols and acids to be scavenged by fogwater due to their high solubility. Nitro-phenols and mono-carboxylic acids have the highest contributions to the total phenolic and acidic concentrations, respectively. 2,5-dinitrophenol, 3-methyl-4-nitrophenol, 4-nitrophenol, and 3,4-dinitrophenol have the highest concentration, originating mainly from vehicular emissions and some photochemical reactions. The top three mono-carboxylic acids are hexadecenoic acid (C16), eicosanoic acid (C18), and dodecanoic acid (C12), whereas succinic acid, suberic acid, sebacic acid, and oxalic acid are the most concentrated dicarboxylic acids, originated either from atmospheric oxidation (mainly secondary organic aerosols (SOAs)) or vehicular transport. Pearson’s correlations show positive correlations between organic acids and previously analyzed metals (p < 0.05), between mono- and dicarboxylic acids (p < 0.001), and between the analyzed acidic compounds (p < 0.001), whereas no correlations are observed with previously analyzed inorganic ions. Total phenolic and acidic fractions are found to be much higher than those observed for pesticides, polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs) measured at the same region due to their higher scavenging by fogwater.

The use of post-consumer recycled (PCR) plastic materials in sensitive packaging applications, such as for cosmetic products and detergents, requires a clear understanding of the identities and quantities of chemical substances, which they may release into packed products. With many potential sources of and thus different types of potentially releasable substances, a reliable non-targeted screening method is required to assess these materials. Such a method should be readily applicable in industrial practice and provide a realistic estimation of substance release. This investigation focused on the use of gas chromatography/coupled mass spectrometry (GC/MS) to analyze substances, which recycled HDPE (rHDPE) plastic pellets release into 95% ethanol under accelerated testing conditions. The results of the repeated testing of reference samples clearly demonstrated the good reproducibility of the described methodology, with standard deviations of repeated determinations of the total released substance amounts of 6.8–8.1%. The application to several production batches of three commercial rHDPE grades additionally demonstrated that the batch-to-batch variation of substances which rHDPE materials release can be confined to less than 10% of variation of the total detectable substance amount. The described methodology is therefore seen as a pragmatic, repeatable assessment of recycled HDPE plastic batches with a view to substance release.

Exploring the antimicrobial efficacy of tea tree essential oil and chitosan against oral pathogens to overcome antimicrobial resistance