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1.
Sci Total Environ ; 927: 172270, 2024 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-38583627

RESUMO

Recent studies show that greenhouse gas (GHG) emissions from urban landscape water are significant and cannot be overlooked, underscoring the need to develop effective strategies for mitigating GHG production from global freshwater systems. Calcium peroxide (CaO2) is commonly used as an eco-friendly reagent for controlling eutrophication in water bodies, but whether CaO2 can reduce GHG emissions remains unclear. This study investigated the effects of CaO2 dosage on the production of methane (CH4) and nitrous oxide (N2O) in urban landscape water under anoxic conditions during summer. The findings reveal that CaO2 addition not only improved the physicochemical and organoleptic properties of simulated urban landscape water but also reduced N2O production by inhibiting the activity of denitrifying bacteria across various dosages. Moreover, CaO2 exhibited selective effects on methanogens. Specifically, the abundance of acetoclastic methanogen Methanosaeta and methylotrophic methanogen Candidatus_Methanofastidiosum increased whereas the abundance of the hydrogenotrophic methanogen Methanoregula decreased at low, medium, and high dosages, leading to higher CH4 production at increased CaO2 dosage. A comprehensive multi-objective evaluation indicated that an optimal dosage of 60 g CaO2/m2 achieved 41.21 % and 84.40 % reductions in CH4 and N2O production, respectively, over a 50-day period compared to the control. This paper not only introduces a novel approach for controlling the production of GHGs, such as CH4 and N2O, from urban landscape water but also suggests a methodology for optimizing CaO2 dosage, providing valuable insights for its practical application.


Assuntos
Metano , Óxido Nitroso , Peróxidos , Qualidade da Água , Metano/análise , Óxido Nitroso/análise , Peróxidos/análise , Poluentes Químicos da Água/análise , Gases de Efeito Estufa/análise
2.
J Forensic Sci ; 69(3): 888-904, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38528830

RESUMO

There are many factors that may affect the longevity of or guide the use of canine training aids. Literature to date has mainly focused on identifying the headspace volatiles associated with training aids or odors and only minimal research exists into how different variables may alter those volatiles. The current study examines several factors affecting canine training aids: humidity, air flow, transportation, and operational deployment, using the triacetone triperoxide polymer odor capture-and-release canine training aid (TATP POCR) as the target. The TATP POCR is an absorption-based canine training aid developed to be used to safely train canines to detect the odor of the explosive TATP in operational settings. Comparisons of the TATP POCR to neat TATP are made throughout the manuscript. First, humidity increased the background components of the POCR matrix, as well as the amount of TATP recovered was above the POCR. Humidity thus affected the amount of TATP detected but did not prevent detection. Second, air flow lessened the lifetime of the TATP POCR. Third, the practice of using primary and secondary containment successfully prevented contamination, cross-contamination, and significant target loss, thereby maintaining kit integrity. Finally, the absorption of background odors from training environments was not observed. TATP headspace concentrations between a Deployed and Control POCR kit were not significantly different at time 0 (i.e., upon opening), which suggests that the operational use does not affect the function of the TATP POCR system. This information provides pivotal evidence for explosives detection canine handlers or trainers who utilize the TATP POCR.


Assuntos
Umidade , Odorantes , Cães , Animais , Compostos Heterocíclicos com 1 Anel , Peróxidos/análise , Movimentos do Ar , Polímeros , Substâncias Explosivas
3.
Environ Sci Pollut Res Int ; 31(8): 11886-11897, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38225488

RESUMO

The wastewater from organic peroxide production has high chemical oxygen demand (COD) concentration and poor biodegradability, so it is necessary to find a cost-effective treatment method. The iron-carbon microelectrolysis (IC-ME) technology was used to pretreat the organic peroxide production wastewater, and the influence of reaction conditions on the removal effect of pollutants and the degradation mechanism were studied. The effects of initial pH, iron filings, iron-carbon ratio, and reaction time on the wastewater treatment were investigated by single-factor and response surface optimization experiments, and the degradation mechanism was analyzed by three-dimensional fluorescence spectroscopy, UV-Vis, and gas chromatography mass spectrometry (GC-MS). The experimental results showed that the COD removal efficiency was 35.67% and the biodegradability of wastewater was increased from 0.113 to 0.173 under the conditions of initial pH of 3.1, the dosage of iron filings of 30.5 g/L, the ratio of iron-carbon of 1.01, and the reaction time of 122.8 min, and the process of IC-ME for degrading COD of wastewater from the production of organic peroxide was consistent with the secondary reaction. The IC-ME process could decompose macromolecular organic compounds such as tyrosine proteins and aromatic proteins, and improve the biodegradability of wastewater. It provides a theoretical reference for the practical application of IC-ME to treat this type of wastewater.


Assuntos
Águas Residuárias , Poluentes Químicos da Água , Ferro/química , Eliminação de Resíduos Líquidos/métodos , Peróxidos/análise , Carbono/química , Poluentes Químicos da Água/análise , Eletrólise/métodos , Peróxido de Hidrogênio/química , Oxirredução
4.
Molecules ; 28(24)2023 Dec 09.
Artigo em Inglês | MEDLINE | ID: mdl-38138512

RESUMO

This study aimed to assess the efficacy of a bacterioruberin-rich carotenoid extract (HAE) derived from the halophilic archaea Halorubrum ezzemoulense DSM 19316 in protecting crude fish oil against thermal oxidation. The research used fish oil derived from anchovies, which had a peroxide value (PV) of 6.44 ± 0.81 meq O2 kg-1. To assess the impact of HAE on the thermal stability and post-oxidation characteristics of fish oil, several concentrations of HAE were added to the fish oil samples: 0 ppm (no additive) (HAE0), 50 ppm (HAE50), 100 ppm (HAE100), 500 ppm (HAE500), and 1000 ppm (HAE1000). Furthermore, a control group was established with the addition of 100 ppm butylated hydroxytoluene (BHT100) in order to evaluate the effectiveness of HAE with a synthetic antioxidant that is commercially available. Prior to the fast oxidation experiment, thermogravimetric analysis was conducted on samples from all experimental groups. At the conclusion of the examination, it was seen that the HAE500 and HAE1000 groups exhibited a delay in the degradation temperature. The experimental groups underwent oxidation at a temperature of 55.0 ± 0.5 °C for a duration of 96 h. The measurement of PV was conducted every 24 h during this time. PV in all experimental groups exhibited a time-dependent rise (p < 0.05). However, the HAE500 group had the lowest PV measurement at the conclusion of the 96 h period (p < 0.05). Significant disparities were detected in the fatty acid compositions of the experimental groups at the completion of the oxidation experiment. The HAE500 group exhibited the highest levels of EPA, DHA, and ΣPUFA at the end of oxidation, with statistical significance (p < 0.05). Through the examination of volatile component analysis, specifically an oxidation marker, it was shown that the HAE500 group exhibited the lowest level of volatile components (p < 0.05). Consequently, it was concluded that the addition of HAE to fish oil provided superior protection compared to BHT at an equivalent rate. Moreover, the group that used 500 ppm HAE demonstrated the highest level of performance in the investigation.


Assuntos
Carotenoides , Óleos de Peixe , Óleos de Peixe/farmacologia , Oxirredução , Carotenoides/farmacologia , Peróxidos/análise , Estresse Oxidativo
5.
Food Chem ; 425: 136495, 2023 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-37276665

RESUMO

Bee pollen is a byproduct of pollination, which is a necessary process to produce foods. However, bee pollen can induce significant food-borne allergies. We previously identified a bee pollen-derived pan-allergen in the profilin family, Bra c p. Herein, we aimed to reduce Bra c p allergenicity via protein oxidation with hydrogen peroxide and explore the changes induced. Ion-mobility mass spectrometry revealed aggregation of the oxidized product; we also found irreversible sulfonation of the free sulfhydryl group of the Bra c p Cys98 residue to a more stable cysteine derivative. A significant proportion of the α-helices in Bra c p were transformed into ß-sheets after oxidation, masking the antigenic epitopes. An immunoassay demonstrated that the IgE-binding affinity of Bra c p was decreased in vitro after oxidation. To our knowledge, this is the first report describing the application of protein oxidation to reduce the allergenicity of profilin family member in foods.


Assuntos
Alérgenos , Profilinas , Abelhas , Animais , Profilinas/análise , Pólen/química , Peróxido de Hidrogênio/análise , Peróxidos/análise , Proteínas de Plantas/análise , Reações Cruzadas
6.
J Forensic Sci ; 68(3): 898-907, 2023 May.
Artigo em Inglês | MEDLINE | ID: mdl-36991527

RESUMO

Contamination of canine training aids is a pervasive issue that may lead to incorrect canine discrimination of target odors. It is therefore important to properly store training materials to maintain their integrity and efficiency. First, this study demonstrated the potential for contamination using GloGerm™ as a proxy for odor/particulate transfer. Then, eight types of containers were evaluated to determine (1) the ability to prevent odor permeation and (2) the likelihood of maintaining the ab/adsorbed odor. Lastly, a longitudinal study evaluated how the permeation of the target odor changed over time. Analysis occurred using a direct analysis in real-time mass spectrometer (DART-MS) to detect triacetone triperoxide (TATP) from the non-hazardous canine training aid known as the polymer odor capture-and-release (POCR) system. Results showed that Mylar and Opsak bags were most effective for short-term storage, maintaining low levels of ab/adsorption. Over time, the amount of TATP permeating through the primary containers and collecting in a secondary container (i.e., outer packaging) increased at 1 week and decreased thereafter (up to 4 months). The amount of TATP collecting in the primary containers, however, increased up to 1 month and decreased thereafter.


Assuntos
Compostos Heterocíclicos com 1 Anel , Peróxidos , Animais , Cães , Estudos Longitudinais , Espectrometria de Massas , Compostos Heterocíclicos com 1 Anel/análise , Peróxidos/análise
7.
Braz J Biol ; 82: e268209, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36651445

RESUMO

The objective of seed extracts from Anisophyllea boehmii and Aframomum sanguineum were to evaluate their ability to stabilize against oxidation of oils exposed to sunlight on one hand and subjected to high temperatures on the other hand. Determination of the peroxide value (PV) showed that the extracts had reduced the oxidation of sunflower oils. After 8 weeks of sunlight exposure, the concentration of 265.45 mg/l of A. boehmii extract showed a PV of 30.78 meq O2/kg, 67.4 mg/l extract of A. sanguineum had a PV of 42.75 meq O2/kg while the oils without extracts had a very high PV (125.06 meq O2/kg). Heating of the oils to 180°C for 8 hours was found, with A. boehmii extract (265.45 mg/l), to have a PV of 29.66 meq O2/kg, with that of A. sanguineum, while the PV of the oils without extract reached 50.66 meq O2/kg. In the light of these results, the seeds of A. boehmii and A. sanguineum contain antioxydant compounds, which, once extracted, can be used for many purposes in the food processing, pharmaceutical and cosmetic industries.


Assuntos
Óleos de Plantas , Sementes , Óleos de Plantas/farmacologia , Burundi , Oxirredução , Peróxidos/análise , Extratos Vegetais/farmacologia
8.
Food Chem ; 403: 134345, 2023 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-36174343

RESUMO

Peroxide value (PV) is one of the most typically used quality parameters to monitor lipid oxidation. Here, a simple paper-based analytical device (PAD) has been developed to determine PV in vegetable oils. The analysis is based on setting up the iodometric titration, where hydroperoxides in the oil are reacted with excess iodide ions to generate iodine molecules, on the paper substrate. The device is composed of two paper layers acting as reaction and detection zones, aligned in a metallic mold. A well-defined inverse logarithmic calibration curve was established between the measured PV by the official iodometric method (ISO;3960, 2017) and the color intensity of PAD. It offered a working range of 0.01-30.0 meq/Kg. The limit of detection of 0.015 meq/Kg demonstrated enough sensitivity of the method to estimate peroxide value in edible oils. On-site and visual detection, low cost, simplicity, and less solvent consumption are advantages of the proposed device.


Assuntos
Peróxidos , Óleos de Plantas , Peróxidos/análise , Óleos de Plantas/química , Colorimetria/métodos , Solventes , Calibragem
9.
J Food Sci ; 87(10): 4504-4521, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-36124403

RESUMO

The potential uses of Ligustrum robustum (Rxob.) Blume extract as a natural antioxidant to protect the quality of different oils during storage and frying process were studied. The results showed that L. robustum extract has been shown to retard the decline in the quality of both oils based on the tests of acid value, peroxide value, p-anisidine value, color, volatile flavor, and fatty acid compositions, and the protective effect of L. robustum extract on the quality of peanut oil was better than that of palm oil. By the component analysis, L. robustum extract was found to have a total phenols content of 140.75 ± 1.52 mg/g, and ligurobustoside C was identified as the main phenolic compound. The thermogravimetric and differential scanning calorimetry results showed that L. robustum extract enhanced the oxidative stability of peanut and palm oils. In addition, Fourier transform infrared results indicated that L. robustum extract had protective effects on the C=C bond and ester bond of oil molecule. Moreover, by using electron spin resonance technique, L. robustum extract showed the ability to inhibit and scavenge alkyl-free radicals in both oils. The present results suggested that L. robustum extract may protect the quality of oils during the storage and frying process by inhibiting the oxidation of unsaturated fatty acids and might be a potential natural antioxidant in the food industry. PRACTICAL APPLICATIONS: The excellent antioxidant ability of Ligustrum robustum (Rxob.) Blume extract on the oxidation of different oils and its low price indicated that it could be used as a new low-cost natural antioxidant in oil processing.


Assuntos
Ligustrum , Ligustrum/química , Óleo de Palmeira , Antioxidantes/química , Arachis , Óleo de Amendoim , Fenóis/química , Extratos Vegetais/química , Ácidos Graxos/análise , Peróxidos/análise , Ácidos Graxos Insaturados , Ésteres
10.
Molecules ; 27(18)2022 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-36144797

RESUMO

The food quality of edible oils is dependent on basic chemical and structural changes that can occur by oxidation during preparation and storage. A rapid and efficient analytical method of the different steps of oil oxidation is described using a time-domain nuclear magnetic resonance (TD-NMR) sensor for measuring signals related to the chemical and physical properties of the oil. The degree of thermal oxidation of edible oils at 80 °C was measured by the conventional methodologies of peroxide and aldehyde analysis. Intact non-modified samples of the same oils were more rapidly analyzed for oxidation using a TD-NMR sensor for 2D T1-T2 and self-diffusion (D) measurements. A good linear correlation between the D values and the conventional chemical analysis was achieved, with the highest correlation of R2 = 0.8536 for the D vs. the aldehyde concentrations during the thermal oxidation of poly-unsaturated linseed oils, the oil most susceptible to oxidation. A good correlation between the D and aldehyde levels was also achieved for all the other oils. The possibility to simplify and minimize the time of oxidative analysis using the TD NMR sensors D values is discussed as an indicator of the oil's oxidation quality, as a rapid and accurate methodology for the oil industry.


Assuntos
Qualidade dos Alimentos , Óleos de Plantas , Aldeídos/análise , Espectroscopia de Ressonância Magnética/métodos , Peróxidos/análise , Óleos de Plantas/química
11.
Molecules ; 27(12)2022 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-35745025

RESUMO

Jojoba oil (JO) extracted from seeds has outstanding properties, including anti-inflammatory, antioxidant, and antibacterial activities, and can be stored forlong periodsof time. The unique properties of jojoba oil depend on its chemical composition; therefore, the effect of the jojoba genotype on the chemical properties and active components of the seed oil was evaluated in this study. Oil samples were collected from 15 elite Egyptian jojoba lines. The chemical composition, such as moisture, crude fiber, crude oil, ash, and crude protein of elite lines' seeds was determined to investigate the variation among them based on the jojoba genotype. In addition, the iodine value was obtained to measure the degree of jojoba oil unsaturation, whereas the peroxide number was determined as an indicator of the damage level in jojoba oil. Fatty acid composition was studied to compare elite jojoba lines. Fatty acid profiles varied significantly depending on the jojoba genotype. Gadoleic acid exhibited the highest percentage value (67.85-75.50%) in the extracted jojoba oil, followed by erucic acid (12.60-14.81%) and oleic acid (7.86-10.99%). The iodine value, peroxide number, and fatty acid composition of the tested elite jojoba lines were compared withthose reported by the International Jojoba Export Council (IJEC). The results showed that the chemical properties of jojoba oils varied significantly, depending on the jojoba genotype.


Assuntos
Caryophyllales , Iodo , Ácidos Graxos/química , Iodo/análise , Peróxidos/análise , Óleos de Plantas/química , Sementes/química
12.
Environ Res ; 212(Pt B): 113329, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-35472460

RESUMO

Microplastic (MP) surfaces are common sites for microbial colonization and promote biofilm formation in aquatic environments, resulting in changes to the surface properties of MPs and their interaction with pollutants. Although the diversity of microbial communities adhering to MPs has been well documented in aquatic environments, surface changes in MPs due to microbial colonization are still poorly understood. In this study, we aimed to evaluate the variations in the chemical structure and components of biofilms on the surface of polystyrene microplastics (PS-MPs) collected from the shore of the Tuul River in Mongolia, using micro-Fourier transform infrared (micro-FTIR) spectroscopy. We applied a spectral subtraction approach, and the differences in spectra between peroxide-treated and untreated PS-MP particles enabled us to obtain the structural features of biofilms that developed on the plastic surface. In addition, the surface photooxidation status of the sampled PS-MPs was calculated from the subtracted spectra of peroxide-treated and pristine PS-MPs. Various functional groups of N-containing organic substances from bacterial and fungal communities were detected in the obtained biofilm spectra. Based on the spectral characteristics, biofilm spectra were classified into four groups by applying principal component analysis (PCA). A wide range of carbonyl indices (CIs: 0.00-1.40) was found in the subtracted spectra between peroxide-treated and pristine PS-MPs, revealing that different levels of surface oxidation progressed by physical influences such as solar radiation and freeze-thaw cycles. Furthermore, lignocellulose and silicate were found on the PS-MP surface as allochthonous attachments. Considering the variation in residence time of PS-MPs, they attract plant residues and mineral particles through the development of biofilms and travel together in the river environment. Given that the dynamic behavior of MPs can be greatly affected by changes in their surfaces, further studies are needed to emphasize their link to organic matter dynamics.


Assuntos
Microplásticos , Poluentes Químicos da Água , Biofilmes , Mongólia , Peróxidos/análise , Plásticos/análise , Poliestirenos , Rios , Poluentes Químicos da Água/análise
13.
J Oleo Sci ; 71(1): 57-66, 2022 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-34880148

RESUMO

Storage is an important step after peanut harvest and drying. Many factors could affect the peanut quality during storage. The quality change differences of peanut after being dried by solar radiation and at 35°C, 40°C, 45°C, 50°C during later storage were investigated, including moisture content (MC) and germination percentage (GP) of peanut kernels, acid value (AV), peroxide value (PV), iodine value (IV), vitamin E (VE) content and fatty acid composition (FAC) of extracted peanut oil. And the impact of four storage conditions, air-room temperature (A-RT), air-low temperature (A-LT), vacuum-room temperature (V-RT) and nitrogen-room temperature (N-RT) on peanut quality after 10 months' storage were also studied in this paper. The results revealed that drying conditions had only a little influence on peanut quality during later storage. Peanut dried by solar radiation was more easily oxidized than that dried under other drying conditions. The effects of storage time were much greater. The GP, AV, PV, VE content and FAC, showed significantly changes along with storage. GP and VE content decreased, AV and PV increased, and some linoleic acid was oxidized to oleic acid after 10 months' storage. In addition, A-LT exhibited best performance in keeping peanut quality than A-RT, V-RT and N-RT, which demonstrated that low temperature was more advantageous for peanut storage than controlled atmosphere. These results above would provide useful information and reference for the peanut storage to apply in food industry.


Assuntos
Arachis/química , Dessecação/métodos , Manipulação de Alimentos/métodos , Qualidade dos Alimentos , Armazenamento de Alimentos/métodos , Óleo de Amendoim/química , Luz Solar , Temperatura , Ácidos/análise , Arachis/anatomia & histologia , Arachis/fisiologia , Ácidos Graxos/análise , Indústria Alimentícia , Germinação , Iodo/análise , Óleo de Amendoim/análise , Peróxidos/análise , Vitamina E/análise , Água/análise
14.
Acta Chim Slov ; 68(3): 728-735, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34897537

RESUMO

Hydroperoxides are of great importance in the fields of atmospheric and biological chemistry. However, there are several analytical challenges in their analysis: unknown and usually low UV absorption coefficients, high reactivity, thermal instability, and a lack of available reference standards. To overcome these limitations, we propose a GC-FID approach involving pre-column silylation and quantification via the effective carbon number approach. Four hydroperoxides of α-pinene were synthesized in the liquid phase with singlet oxygen and identified using literature data on isomer yield distribution, MS spectra, estimated boiling temperatures of each isomer (retention time), their thermal stability and derivatisation rate. The developed procedure was used for the determination of hydroperoxides in bottled and autooxidised turpentine. We anticipate that this method could also be applied in atmospheric chemistry, where the reactivity of singlet oxygen could help explain the high formation rates of secondary organic aerosols.


Assuntos
Monoterpenos Bicíclicos/análise , Peróxidos/análise , Cromatografia Gasosa , Ionização de Chama , Espectrometria de Massas , Terebintina/análise
15.
J Oleo Sci ; 70(11): 1585-1606, 2021 Nov 03.
Artigo em Inglês | MEDLINE | ID: mdl-34645744

RESUMO

Olive growing in Palestine plays an important role at social and economic levels. Nevertheless, the quality of olive oil produced in the country has not been fully addressed. This study examined oil content, peroxide values, acid values, fatty acid profile, and total phenolic content for old olive trees located in different climatic regions in Palestine during the years 2008-2010. Oil content was determined using both Soxhlet and Abencor systems. Acid and peroxide values were determined using standard methods. Total phenolic content was determined using the Folin-spectrophotometric method. Gas chromatography was used to analyze the main fatty acids found in olive oil e.g., palmitic, palmitoleic, stearic, oleic, linoleic. Different ratios indicating olive oil quality were also determined e.g., sum ratio of unsaturated fatty acids to the sum of saturated fatty acids; ratio between the sum of monounsaturated fatty acids to the sum of polyunsaturated fatty acids, and the ratio between the oleic to linoleic fatty acids. Significant differences were found between geographic regions for the overall studied oil parameters. Wide variation ranges were obtained for fatty acids in the different West Bank locations in the three years. The major fatty acids in the olive oil samples were found to be oleic, palmitic, stearic, linoleic, and palmitoleic acids. The oil samples were found to contain more oleic acid and less linoleic and linolenic acids that is, more monounsaturated than polyunsaturated fatty acids. Total phenolic content was found to range from 125.0-978.0, 207.4-763.8, and 103.0-747.6 mg/kg in 2008, 2009, and 2010, respectively. The acidity percentage was in the range of 0.10%-1.05%, 0.11%-1.29%, and 0.10%-1.91% in 2008, 2009, and 2010, respectively. Peroxide values ranged from 2.26-13.1, 2.94-14.95, and 2.49-17.21 in 2008, 2009, and 2010, respectively.


Assuntos
Ácidos Graxos/análise , Análise de Alimentos , Qualidade dos Alimentos , Olea/química , Azeite de Oliva/química , Israel , Peróxidos/análise , Fenóis/análise , Fatores de Tempo
16.
Anal Methods ; 13(43): 5173-5178, 2021 11 11.
Artigo em Inglês | MEDLINE | ID: mdl-34668496

RESUMO

Triacetone triperoxide (TATP) and its byproduct diacetone diperoxide (DADP) are commonly used home-made high explosives in bombing cases and terrorist attacks. However, these two peroxide explosives are unstable and prone to thermal decomposition, leading to challenges in sample collection and preparation in bombing cases. Therefore, there is an urgent need to develop an in situ identification method for TATP and DADP. Compared to the solvent-based swabbing methods commonly used for trace explosive collection, the tape lifting method can collect explosive particles and other potential evidence without damaging fingerprints or DNA. This study aims to develop a tape lifting method to collect trace explosive particles in bombing cases and an in situ method to identify TATP and DADP particles on the sticky side of transparent tape directly using laser confocal Raman spectroscopy. One type of fingerprint tape and two types of office tape were used to collect peroxide explosive particles followed by particle fixation on glass slides. Laser confocal Raman spectroscopy was applied to directly identify target particles, without peeling the attached tape off the glass slide. A solid-state laser emitting at 473 nm was suitable for Raman and imaging analysis of TATP and DADP. To mimic the real situation, the synthetic TATP and DADP were passed through a 100-mesh sieve, respectively. Fifty µg of each explosive powder was weighed, mixed and spread on a wooden table with dust in an area of 10 × 10 cm2. Subsequently, the samples were collected with the fingerprint tape. A targeted area of the tape with suspicious particles was imaged for analysis. Based on the difference between the characteristic Raman bands of TATP and DADP, the band ranges of 530-550 cm-1 and 750-770 cm-1 were selected, respectively, for obtaining the distribution information. The combination of Raman technology and the tape lifting method shows great potential for in situ identification of forensic samples by providing chemical and spatial information.


Assuntos
Substâncias Explosivas , Análise Espectral Raman , Substâncias Explosivas/análise , Substâncias Explosivas/química , Compostos Heterocíclicos com 1 Anel/análise , Compostos Heterocíclicos com 1 Anel/química , Peróxidos/análise , Peróxidos/química
17.
Food Chem ; 358: 129834, 2021 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-33933972

RESUMO

Edible oils are prone to oxidation during processing and storage that may negatively affect the oil quality and human health. Determining the peroxide value (PV) of edible oils is essential because PV is one of the most typically used quality parameters to monitor lipid oxidation and control oil quality. Many approaches have been developed to determine the PV of oils. Among them, iodometric titration is the commonly used method for PV determination. Considering the limitations related to titrimetric methods, such as time and environmental concerns, several instrumental techniques have been considered as reliable alternatives. The advantages and limitations of classical titration and instrumental methods are summarized in this review. The prospects and reformative aspects for the future applications of these approaches in PV determination are also discussed.


Assuntos
Análise de Alimentos , Peróxidos/análise , Óleos de Plantas/análise , Óleos/análise
18.
J Oleo Sci ; 70(5): 615-632, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33952787

RESUMO

The skin of the walnut kernels can get dark during the pre- and post-harvest stages of the production. Dark kernels are less palatable for most consumers but are still edible and maybe preferable, especially in the ground form, for industrial use. In this study, we investigated the differences between oil oxidation indexes, fatty acid and tocopherol compositions of the oils, total polyphenol contents and antioxidant capacities of the extracts of light and dark walnuts. In addition, we evaluated the effects of packaging under nitrogen and vacuum-packaging techniques and storage temperature on these characteristics of both light and dark walnuts during storage for 6 months. Peroxide values and free fatty acid contents of all samples were higher at the end of storage compared to initial values, being more noticeable at 20°C than at 4°C. Increases in the free fatty acid contents were quite higher in dark walnuts than the light ones (6.1 and 3.1 fold, respectively) and the highest values of conjugated diene and peroxide were determined in the samples packaged under air and stored at 20℃. Dark walnuts had lower total phenolic, α- and γ-tocopherol contents and antioxidant activities compared to the light ones. Total phenolic and tocopherol contents decreased over time. We conclude that due to the antioxidant compounds in the fruit, oxidation parameters of dark walnuts are still acceptable at the end of 6-month storage even in the packages with air and at non-refrigerated conditions.


Assuntos
Cor , Embalagem de Alimentos/métodos , Qualidade dos Alimentos , Armazenamento de Alimentos/métodos , Juglans/química , Óleos de Plantas/isolamento & purificação , Antioxidantes/análise , Ácidos Graxos/análise , Peroxidação de Lipídeos , Nitrogênio , Peróxidos/análise , Óleos de Plantas/análise , Polifenóis/análise , Temperatura , Fatores de Tempo , Tocoferóis/análise , Vácuo
19.
J Phys Chem A ; 125(21): 4513-4523, 2021 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-33904735

RESUMO

The fates of organic hydroperoxides (ROOHs) in atmospheric condensed phases are key to understanding the oxidative and toxicological potentials of particulate matter. Recently, mass spectrometric detection of ROOHs as chloride anion adducts has revealed that liquid-phase α-hydroxyalkyl hydroperoxides, derived from hydration of carbonyl oxides (Criegee intermediates), decompose to geminal diols and H2O2 over a time frame that is sensitively dependent on the water content, pH, and temperature of the reaction solution. Based on these findings, it has been proposed that H+-catalyzed conversion of ROOHs to ROHs + H2O2 is a key process for the decomposition of ROOHs that bypasses radical formation. In this perspective, we discuss our current understanding of the aqueous-phase decomposition of atmospherically relevant ROOHs, including ROOHs derived from reaction between Criegee intermediates and alcohols or carboxylic acids, and of highly oxygenated molecules (HOMs). Implications and future challenges are also discussed.


Assuntos
Atmosfera/química , Peróxidos/química , Concentração de Íons de Hidrogênio , Espectrometria de Massas , Peróxidos/análise , Termodinâmica , Água/química
20.
Acta Sci Pol Technol Aliment ; 20(2): 127-133, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33884851

RESUMO

BACKGROUND: Cold-pressed berry seed oils are used for consumption and other applications including skin and hair care. They are natural products which gain the attention of customers. In this study, strawberry, raspberry and blackberry seed oils used for cosmetic purposes, purchased from three different European producers, were analyzed. The aim of the study was to assess the quality and oxidative stability of the berry fruit oils, thus they were analyzed after purchase and after 4 and 8 weeks of storage at room temperature. METHODS: Acid and peroxide values were determined in the tested oils, as was oxidative stability, which was measured using pressure differential scanning calorimetry (PDSC). Additionally, fatty acid profiles and thei. RESULTS: nd. Cold-pressed berry seed oils are used for consumption and other applications including skin and hair care. They are natural products which gain the attention of customers. In this study, strawberry, raspberry and blackberry seed oils used for cosmetic purposes, purchased from three different European producers, were analyzed. The aim of the study was to assess the quality and oxidative stability of the berry fruit oils, thus they were analyzed after purchase and after 4 and 8 weeks of storage at room temperature. Materials and methods. Acid and peroxide values were determined in the tested oils, as was oxidative stability, which was measured using pressure differential scanning calorimetry (PDSC). Additionally, fatty acid profiles and their distribution at sn-1,3 and sn-2 positions of triacylglycerols were characterized. Results, principal. Most of the fatty acids of the tested berry seed oils are polyunsaturated fatty acids (67.04-74.95%). The results show the low quality of the tested oils in terms of oxidative stability (high peroxide values: 21.9-249.6 mEq O2/kg oil). CONCLUSIONS: Based on this study, it is necessary to evaluate the effects of these products on the body. Moreover, standards clarifying the oxidation of cosmetic oils should be set internationally.


Assuntos
Cosméticos/química , Ácidos Graxos Insaturados/análise , Fragaria/química , Óleos de Plantas/química , Rubus/química , Sementes/química , Ácidos/análise , Temperatura Baixa , Europa (Continente) , Peroxidação de Lipídeos , Oxirredução , Peróxidos/análise , Óleos de Plantas/normas , Triglicerídeos/química
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