Volatile organic compounds as fingerprints for identifying marine plastics.

Coal and plastic waste co-pyrolysis by thermal analysis–mass spectrometry

Study of microplastics with semicrystalline and amorphous structure identification by TGA and DSC.

Concerns regarding marine plastic pollution and its affinity for chemical pollutants led us to quantify relationships between different types of mass-produced plastic and organic contaminants in an urban bay. At five locations in San Diego Bay, CA, we measured sorption of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) throughout a 12-month period to the five most common types of mass-produced plastic: polyethylene terephthalate (PET), high-density polyethylene (HDPE), polyvinyl chloride (PVC), low-density polyethylene (LDPE), and polypropylene (PP). During this long-term field experiment, sorption rates and concentrations of PCBs and PAHs varied significantly among plastic types and among locations. Our data suggest that for PAHs and PCBs, PET and PVC reach equilibrium in the marine environment much faster than HDPE, LDPE, and PP. Most importantly, concentrations of PAHs and PCBs sorbed to HDPE, LDPE, and PP were consistently much greater than concentrations sorbed to PET and PVC. These data imply that products made from HDPE, LDPE, and PP pose a greater risk than products made from PET and PVC of concentrating these hazardous chemicals onto fragmented plastic debris ingested by marine animals.

Characteristics and ozone formation potential of volatile organic compounds in emissions from a typical Chinese coking plant

Microplastics are plastic particles less than 5 mm in size but larger than 0.1 µm. Widespread microplastic pollution in aquatic and terrestrial environment is raising serious concern globally due to its detrimental impacts on living beings. This urge for the necessity of a sensitive analytical tool, which can facilitate reliable identification of microplastics. Micro-Raman spectroscopy enables molecular level structural details of samples and thus highly preferable for the identification of microplastics in water. Besides being a non-destructive technique enabling fast analysis, this technique requires minimal/no sample preparation. The present work demonstrates the performance of a custom built Micro-Raman spectrometer for the discrimination of various microplastics in water based samples. Micro- Raman analysis have been found quite successful in the identification of Polystyrene (PS), Polyethylene terephthalate (PET), High Density Poly ethylene (HDPE), Low Density Poly ethylene (LDPE) etc. The Micro-Raman spectral data have been capable enough for the discrimination of high-density polyethylene (HDPE,> 0.940 g/cm3) and low-density polyethylene (LDPE,< 0.930 g/cm3) microplastics, especially due to the variations in the C-H stretching vibrations (2825-2970 cm−1). The ratio of intensities of asymmetric CH2 stretching mode (2879 cm−1) and the symmetric CH2 stretching mode (2847 cm−1) are found to be higher for HDPE with respect to LDPE. Moreover, intensity variations were also observed for the antisymmetric and symmetric C-C stretching bands present at 1059 cm−1 and 1126 cm−1 respectively. The band at 1167 cm−1 arising from CH vibration have also shown an intensity enhancement in HDPE samples.

Release of harmful volatile organic compounds (VOCs) from photo-degraded plastic debris: A neglected source of environmental pollution

In this study, volatile organic compounds (VOCs) were generated by Pseudomonas fluorescens ZX with incubation in nutrient broth (NB), on NA (NB with agar), and on healthy orange fruits, and pure individual components of VOCs were used to manage citrus green mold infected by Penicillium digitatum. At a concentration of 1 × 1010 cfu/mL, the VOCs from antagonist-containing NA plates inhibited P. digitatum conidial germination and mycelial growth by about 60%, while the VOCs from bacterial fluid exhibited approximately 75% inhibitory effect. Biofumigation by VOCs significantly reduced the disease index, with a higher biocontrol efficacy by VOCs from bacterial fluid (about 51%) than from antagonist-containing NA plates (around 40%) or from antagonist-infested fruit (approximately 24%). Exposure to VOCs led to morphological abnormalities of P. digitatum conidia and hyphae. However, VOCs exhibited poor preventative and curative action against P. digitatum. The storage test showed that biofumigation had no negative effects on fruit quality. Antifungal assays suggested that dimethyl disulfide and dimethyl trisulfide exhibited the highest inhibitory effects, which afforded complete inhibition at the lowest concentrations. In addition, organic acids were also promising in controlling green mold, but only at suitable low concentrations to avoid eliciting fruit's physiological diseases.

Endoscopic surveillance for Barrett’s esophagus (BE) is invasive but remains the standard modality for early diagnosis of esophageal adenocarcinoma (EAC) and intervention. Human breath contains an array of volatile organic compounds (VOC) that change in disease conditions. VOC detection provides a potential source of biomarkers for non-invasive, real-time identification of EAC. This study aimed to characterize a VOC-profile applicable to the detection of EAC and to provide pilot data to design a future validation trial. Methods Breath samples were collected in our endoscopy unit from BE, EAC, and control patients. Samples were collected in FlexFoil bags (SKC ltd) using previously standardized methods. Hydrogen, methane and other VOCs were quantified by QuinTron BreathTracker® and selected-ion flow tube mass spectrometry (SIFT-MS, Syft®) respectively. 250 reported cancer-related VOCs were selected for analysis. Non-parametric tests were used to identify candidate VOCs, and logistic regression analysis was then applied to determine the best predictors for EAC. Receiver Operating Characteristic (ROC) Curves were developed to determine the sensitivity and specificity of the model. Results 68 individuals were enrolled in the study (Controls, n = 37; BE, n = 21; EAC, n = 10). 8 VOCs were identified with significant concentration differences between the three groups: Trimethylbenzene (3 iso-forms), Dimethyl Sulfide, 4-isopropyl toluene, 1-butanol, trichloroethylene, hydrogen sulfide, methyl mercaptan, p-isopropenyl toluene. Logistic regression analysis of these 10 compounds demonstrated predictive probability of EAC from other groups with ROC curves calculating an area under the curve of 0.85. Conclusion Previous studies have supported the utility of VOCs in exhaled breath as non-invasive real-time tests for the identification of some other cancer types. This pilot study has identified potential VOCs which might identify individuals with EAC. A larger study will be needed to validate and confirm these findings.

Oil yield optimization from co-pyrolysis of low-density polyethylene (LDPE), polystyrene (PS) and polyethylene terephthalate (PET) using simplex lattice mixture design

High pressure capillary rheometry of polymeric fluids

Low density polyethylene (LDPE) and high density polyethylene (HDPE) are the principal plastics present in solid plastic waste and are found out as the main components of microplastics in marine and terrestrial environments. Currently, efforts have been made to develop new and effective methods to ensure the identification and separation of plastics in waste, ensuring the necessary purity to obtain quality and economically competitive recycled products. In this contribution, we investigated the usage of Fourier-Transform Infrared Spectroscopy in Attenuated Total Reflection mode (ATR-FTIR) combined with Principal Component Analysis (PCA), Linear Partial Least Squares Regression by Intervals (iPLS-R) and Competitive Adaptive Weighted Sampling (CARS/PLS-R) as chemometric methods to classify and determine the compositional fraction of the pristine and recycled mixtures of HDPE and LDPE from plastic waste in São Paulo, Brazil. Here, the 3D PCA plots were not effective in classifying the different polyethylenes and their polymer blends using the three main Principal Components (PC), but 2D PCA diagrams using PC1 and PC3 presented promising performance for this purpose. The iPLS-R presents the best predictive ability than CARS/PLS-R to determine the LDPE content in HDPE/LDPE recycled blends. However, the presence of different contaminants (in 5 wt%), such as silicon dioxide (SiO2), calcium carbonate (CaCO3), recycled polypropylene (PP), and recycled poly(ethylene terephthalate) (PET), reduces the potential usage of the iPLS-R models as identification tools for LDPE and HDPE sorting in industrial recycling processes.

AimsApproximately 25%–30% of the global population is affected by non-alcoholic fatty liver disease (NAFLD). This study aimed to explore whether NAFLD could be effectively detected using 341 volatile organic compounds (VOCs) via 10 machine learning (Mach-L) algorithms in a cohort of 1,501 individuals.MethodsParticipants were selected from the Taiwan MJ cohort, which includes comprehensive demographic, biochemical, lifestyle, and VOCs data. NAFLD was diagnosed by experienced gastroenterologists. Exhaled breath samples were collected using a 1.0-L aluminum bag (late expiratory fraction) and analyzed with selected-ion flow-tube mass spectrometry. Ten Mach-L techniques were employed to evaluate two predictive models: Model 1 (demographic, lifestyle, and biochemical data), and Model 2 (Model 1 + VOCs), assessed using area under the receiver operating characteristic curve (AUC).ResultsSubjects with NAFLD had significantly higher values for age, BMI, blood pressure, and other biomedical markers, except for eGFR and HDL-C. Key predictors of NAFLD included BMI, triglycerides (TG), uric acid (UA), fasting plasma glucose (FPG), γ-GT, gender, LDL-C, and sleep duration. The addition of VOCs to Model 1 improved the AUC from 0.722 ± 0.149 to 0.770 ± 0.264 (p < 0.001). Ten VOCs were identified as the most influential, in order of importance: 2-propanol, acetone, butyl 2-methylbutanoate, diethylethanolamine, urethane, β-caryophyllene, furfural, tridecane, 4-methyloctanoic acid, and (S)-2-methyl-1-butanol.ConclusionIncorporating VOCs into traditional demographic, biochemical, and lifestyle data significantly enhanced the model’s predictive performance. This suggests that VOCs may be associated with the underlying pathophysiology of NAFLD.

The aim of this study was to characterize the municipal solid waste (MSW) in Nablus city in Palestine, while focusing on the plastic waste fraction. The plastic fraction—an environmentally problematic waste stream—was further characterized into the different polymer types and formats with the aim of suggesting feasible recovery and recycling solutions. Locally generated studies lack data about the recyclable fractions in the MSW and a thorough characterization of the plastic waste stream, although there is global action to minimize and optimally treat this waste fraction. The composition analysis was conducted by collecting 60 samples from five districts with different characteristics (e.g., income, density, level of education, building formats). The fraction of bio- and organic waste is significant in the collected MSW in Nablus, representing about 68% of the total MSW. The recyclables (paper and cardboard, glass, metals and plastics) amount to 27.4% of the generated MSW in the city. The plastic fraction (10.1%) is mainly composed of low-density polyethylene (LDPE) films (39.8%), polyethylene terephthalate (PET) bottles (21.9%), high-density polyethylene (HDPE) rigids (19.0%), and polypropylene (PP) rigids (11.5%), all of which are technologically recyclable. The polymer types and container formats indicated that the collected plastics originate mostly from packaging. The outcomes of this research indicate the need to implement a separate collection system for the organic waste fraction, which could be used to produce compost for the agricultural activities in the region. By having such a system, the dry recyclables (including plastics) can be easily recovered with less degree of contamination for recycling, helping the local recyclers to access cleaner materials. Furthermore, the state of Palestine lacks strict regulations for the end-of-life treatment of the different waste fractions; therefore, having clear guidelines and incentive systems will result in the minimization of the generated waste as well as better achievement of recovery and recycling targets. In addition, expertise, funding, public awareness, facilities, equipment and other provisions are currently lacking or inappropriate. In future, these factors must be addressed to enhance sustainable solid waste management.

Secondary electrospray ionization (SESI) is currently only semi-quantitative. In the Zspray™ arrangement of SESI-MS, the transfer of ions from near atmospheric pressure to a triple quadrupole is achieved by guiding electric fields that partially desolvate both reagent and analyte ions which must be understood. Also, to make SESI-MS more quantitative, the mechanisms and the kinetics of the reaction processes, especially ligand switching reactions of hydrated hydronium reagent ions, H3 O+ (H2 O)n , with volatile organic compound (VOC) molecules, need to be understood. A modified Zspray™ ESI ion source operating at sub-atmospheric pressure with analyte sample gas introduced via an inlet coaxial with the spray was used. Variation of the ion-guiding electric fields was used to reveal the degree of desolvation of both reagent and analyte ions. The instrument sensitivity was determined for several classes of VOCs by introducing bag samples of suitably varying concentrations as quantified on-line using selected ion flow tube MS. Electric field desolvation resulted in largely protonated VOCs, MH+ , and their monohydrates, MH+ H2 O, and for some VOCs proton-bound dimer ions, MH+ M, were formed. There was a highly linear response of the ion signal to the measured VOC sample concentration, which provided the instrument sensitivities, S, for 25 VOCs. The startling results show very wide variations in S from near 0 to 1 for hydrocarbons, and up to 100, on a relative scale, for polar compounds such as monoketones and unsaturated aldehydes. The complex ion chemistry occurring in the SESI ion source, largely involving gas-phase ligand switching, results in widely variable sensitivities for different classes of VOCs. The sensitivity is observed to depend on the dipole moment and proton affinity of the analyte VOC molecule, M, and to decrease with the observed fraction of MH+ H2 O, but other yet unrecognized factors must play a significant role.

Microplastics in freshwater lakes: A case study from Southern India