Persistent organic pollutants (POPs) are harmful to the environment and human health. A simple method was developed for the determination of 58 POPs, including 16 polycyclic aromatic hydrocarbons ...(PAHs), 18 polychlorinated biphenyls (PCBs), and 24 organochlorine pesticides (OCPs), in atmospheric gaseous and particle-phase samples. Different extraction solvents, solid-phase extraction (SPE) cartridges and elution steps were used and compared to optimize the extraction efficiency. The POPs were isolated from the atmospheric samples by Soxhlet extraction using 1:1 acetone:n-hexane and separated using SPE cartridges. The fractions were collected by two-step elution with10 mL of n-hexane and 10 mL of 1:1 n-hexane:dichloromethane. The method validation showed that PAHs, PCBs and OCPs had good linearity, with the coefficients of determination higher than 0.995, from 2.5 to 800, 2.5 to 800, and 2.5 to 600 ng/mL, respectively. The average recoveries were 67-117%, 67-113%, and 73-114% for the PAHs, PCBs, and OCPs. The limits of detection for PAHs, PCBs, and OCPs were from 0.55 to 3.29, 0.09 to 2.00, and 0.57 to 4.86 pg/m
3
. The limits of quantification (LOQs) for PAHs, PCBs and OCPs were 1.80 to 10.48, 0.29 to 6.37, and 1.82 to 15.48 pg/m
3
. The applicability of the method was confirmed using an urban dust standard reference material. The method was employed for the analysis of atmospheric samples collected weekly for one-half year on the rooftop of a 14 m tall building in the downtown Mianyang, Sichuan, China. The developed method is demonstrated to accurately monitor persistent organic pollutants in the atmosphere.
A low solvent consumption method was developed to determine 27 different classes of pesticides (including organochlorine pesticide, organophosphorus pesticide, pyrethroid pesticide, fungicide, ...herbicide and acaricide) in wine using dispersive liquid–liquid microextraction (DLLME). Extraction parameters including type and volume of extraction solvent, type and volume of disperser solvent, salinity, pH, centrifugation time, vortex extraction time and wine volumes were optimized. A mixture of 60μL chloroform (extraction solvent) and 940μL acetonitrile (disperser solvent) was injected into 5mL wine diluent. After shaking and centrifugation, the sedimented phase was transferred into a 200μL glass insert and determined by gas chromatography–mass spectrometry method (GC–MS). The results demonstrated that the recoveries for all the pesticides spiked at three different levels ranged from 66.7 to 126.1%. The intra-day repeatabilities (RSDs) ranged from 2.0 to 27.2%. The limits of detection ranged from 0.025 to 0.88μg/L, and the limits of quantification ranged from 0.082 to 2.94μg/L. The proposed method is very low cost, rapid and convenient, and could be an effective method for monitoring of multi-pesticide in wine.
•A sensitive DLLME method was developed to determine 27 pesticides in wine.•The method covered different classes of pesticides in one analysis.•The method was low cost, rapid and convenient.
Effect of storage on metabolites of brown rice Wang, Changyuan; Feng, Yuchao; Fu, Tianxin ...
Journal of the science of food and agriculture,
September 2020, 2020-Sep, 2020-09-00, 20200901, Volume:
100, Issue:
12
Journal Article
Peer reviewed
Background
Storage is an essential part of brown rice circulation. During the storage process, the metabolic activity of brown rice is still ongoing, and long‐term storage leads to the deterioration ...of brown rice. Metabolomics analysis was performed using gas chromatography–mass spectrometry to investigate the changes in metabolites of brown rice after storage at 18 °C for 12 months.
Results
In terms of quantity, sugar, fatty acids, and other metabolites in brown rice decreased after storage, and alcohols, aldehydes, phenols, and amines increased. A total of 34 differential metabolites were screened. In terms of contents, carbohydrates, amino acids, and fatty acids of brown rice decreased after storage, while those of sugar alcohol, amines, and aldehydes increased after storage. Cluster analysis of the samples at zero storage time revealed that the metabolites expressed least became highly expressed after storage and those expressed highly became low after storage. Metabolic pathway analysis showed that storage significantly influenced the lipid metabolism in brown rice. Palmitoleic acid, cholesterol, linoleic acid, and lauric acid are four key metabolites in lipid metabolism during storage of brown rice.
Conclusion
Significant changes occurred in quantity and type of brown rice metabolites after storage. Storage has the greatest effect on lipids. Storage caused a ‘reverse change’ in the metabolites content of brown rice. The results obtained may help in understanding the changes in metabolites profile and delaying of the quality deterioration of brown rice during storage.
•Determination, for the first time, of NPS in vitreous humor and pericardial fluid.•Good LOD using 100μL of vitreous humor and 250μL of pericardial fluid and blood.•A simple and sensible methodology ...with a microwave fast derivatization procedure.
Despite worldwide efforts aiming to ban the marketing and subsequent abuse of psychoactive substances such as synthetic cathinones and phenethylamines, there has been an alarming growth of both in recent years. Different compounds similar to those already existing are continuously appearing in the market in order to circumvent the legislation.
An analytical methodology has been validated for qualitative and quantitative determinations of d-cathine (d-norpseudoehedrine), ephedrine, methcathinone, 1-(4-methoxyphenyl)-propan-2-amine (PMA), mephedrone, methedrone, 2,5-dimethoxy-4-methylamphetamine (DOM), 4-bromo-2,5-dimethoxyamphetamine (DOB), 2,5-dimethoxyphenethylamine (2C-H), 4-bromo-2,5-dimethoxyphenethylamine (2C-B), 4-iodo-2,5-dimethoxyphenethylamine (2C-I), 2-2,5-dimethoxy-4-(ethylthio)phenylethanamine (2C-T-2), 2,5-dimethoxy-4-isopropylthiophenethylamine (2C-T-4) and 2-2,5-dimethoxy-4-(propylthio)phenylethanamine (2C-T-7), in low volumes of vitreous humor (100μL), pericardial fluid (250μL) and whole blood (250μL), using deutered amphetamine, ephedrine and mephedrone as internal standards. The validation parameters included selectivity, linearity and limits of detection and quantification, intra- and interday precision and trueness, recovery and stability. The method included mixed-mode solid phase extraction, followed by microwave fast derivatization and analysis by gas chromatography-mass spectrometry operated in selected ion monitoring mode. The procedure was linear between 5 and 600ng/mL, with determination coefficients higher than 0.99 for all analytes. Intra- and interday precision ranged from 0.1 to 13.6%, while accuracy variability was within 80–120% interval from the nominal concentration at all studied levels. The extraction efficiencies ranged from 76.6 to 112.8%. Stability was considered acceptable for all compounds in the studied matrices. The developed assay was applied to authentic samples of the Laboratory of Chemistry and Forensic Toxicology, Centre Branch, of the National Institute of Legal Medicine and Forensic Sciences, Portugal.
A simple and efficient liquid-phase microextraction (LPME) technique was developed using directly suspended organic microdrop coupled with gas chromatography–mass spectrometry (GC–MS), for the ...extraction and the determination of phthalate esters (dimethyl phthalate, diethyl phthalate, diallyl phthalate, di-
n-butyl phthalate (DnBP), benzyl butyl phthalate (BBP), dicyclohexyl phthalate and di-2-ethylhexyl phthalate (DEHP)) in water samples. Microextraction efficiency factors, such as nature and volume of the organic solvent, temperature, salt effect, stirring rate and the extraction time were investigated and optimized. Under the optimized extraction conditions (extraction solvent: 1-dodecanol; extraction temperature: 60
°C; microdrop volume: 7
μL; stirring rate: 750
rpm, without salt addition and extraction time: 25
min), figures of merit of the proposed method were evaluated. The values of the detection limit were in the range of 0.02–0.05
μg
L
−1, while the R.S.D.% value for the analysis of 5.0
μg
L
−1 of the analytes was below 7.7% (
n
=
4). A good linearity (
r
2
≥
0.9940) and a broad linear range (0.05–100
μg
L
−1) were obtained. The method exhibited enrichment factor values ranging from 307 to 412. Finally, the designed method was successfully applied for the preconcentration and determination of the studied phthalate esters in different real water samples and satisfactory results were attained.
In this study, the flavor compounds of Camellia seed oils obtained by four processes were characterized by headspace solid phase microextraction/gas chromatography/mass spectrometry (HS-SPME/GC/MS). ...A variety of about 76 volatile flavor compounds were identified from all the oil samples. Of the four processing processes, the pressing process can retain a lot of volatile components. Among these, compounds nonanal and 2-undecenal were predominantly in the majority of the samples. Meanwhile, other compounds such as octyl ester formic acid, octanal and 2-nonenal (E), 3-acetyldihydro 2(3H)-furanone, (E)-2-decenal, dihydro-5-penty 2(3H)-furanone, nonanoic acid, and dodecane were also among the most consistently found compounds among the oil samples analyzed. The principal component analysis carried out to categorize the data produced seven clusters of the total oil samples based on the number of flavor compounds obtained in each sample. This categorization would lead to understanding the components which highly contributed to the characteristic volatile flavor and build up the flavor profile of Camellia seed oil.
Synthetic musks have been reported in wastewaters at concentrations as high as tens of micrograms per litre. The two most significant polycyclic musk fragrance compounds are ...1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta(g)-2-benzopyran (HHCB, trade name galaxolide®) and 7-acetyl-1,1,3,4,4,6-hexamethyltetrahydronaphthalene (AHTN, trade name tonalide®). We report the result of several irradiation and advanced oxidation processes carried out on samples of the effluent of a wastewater treatment plant located in Alcalá de Henares, Madrid. Wastewater samples were pre-ozonated and spiked with 500 ng/L of tonalide or galaxolide in order to obtain final concentrations in the same order as the raw effluent. The treatments assayed were ozonation with and without the addition of hydrogen peroxide (O3, O3/H2O2), ultraviolet (254 nm low pressure mercury lamp) and xenon-arc visible light irradiation alone and in combination with ozone (UV, O3/UV, Xe, O3/Xe) and visible light photocatalytic oxidation using a Ce-doped titanium dioxide photocatalyst performed under continuous oxygen or ozone gas bubbling (O2/Xe/Ce–TiO2, O3/Xe/Ce–TiO2). In all cases, samples taken at different contact times up to 15 min were analyzed. An analytical method based on stir bar sorptive extraction (SBSE), followed by comprehensive two-dimensional gas chromatography (SBSE-GC × GC–TOF-MS), was used for the automatic searching and evaluation of the synthetic musks and other nonpolar or semipolar contaminants in the wastewater samples. In all cases tonalide was more easily removed than galaxolide. The best results for the latter (more than 75% removal after 5 min on stream) were obtained from ozonation (O3) and visible light photocatalytic ozonation (O3/Xe/Ce–TiO2). A significant removal of both pollutants (∼60% after 15 min) was also obtained during visible light photocatalysis (O2/Xe/Ce–TiO2). UV radiation was able to deplete tonalide (+90%) after 15 min but only reduced the concentration of galaxolide to about half of its initial concentration. The toxicity of treated samples decreased for O3/UV and O3/Ce–TiO2, but increased during irradiation processes UV, Xe and Xe/Ce–TiO2. Ozone treatments tend to decrease toxicity up to a certain dosage, from which point the presence of toxic transformation products has adverse effects on aquatic microorganisms.
Display omitted
► Depletion of galaxolide and tonalide by ozone and irradiation treatments. ► Real wastewater spiked with environmentally relevant concentrations. ► Comprehensive two-dimensional gas chromatography (GC × GC) for analyses. ► Galaxolide-lactone obtained as transformation product in oxidative runs. ► Toxicity to aquatic microorganisms may increase for prolonged treatments.
We report the first common methodology for the simultaneous determination of methylmercury (MeHg), ethylmercury (EtHg), and inorganic mercury (Hg(II)) in human blood hair and urine. With the ...exception of the initial sample mass (0.15 g for blood, 0.5 g for urine, and 0.1 g for hair), the same sample preparation and gas chromatography-inductively coupled plasma mass spectrometry (GC-ICPMS) measurement conditions are employed for the three matrixes providing experimental values in agreement with the certified values in the analysis of NIST SRM 955c (Caprine Blood) Level 3 and the certified human hairs IAEA 085 and IAEA 086. Also, the method provides quantitative recoveries for the three Hg species in the analysis of fortified human urine samples at 1, 2, and 5 ng Hg g
. Mercury species concentrations for levels 2 and 4 of SRM 955c are reported here for the first time. A systematic interconversion of EtHg into Hg(II) was obtained for all matrixes reaching values up to 95% in blood, 29% in hair, and 11% in urine. MeHg dealkylation was also observed in a lesser extent in blood and hair analyses, but it was not observed when analyzing urine samples. Hg methylation was not observed in any matrix. The amount of NaBPr
added for derivatization has been found to be the main factor responsible for Hg species interconversion. This work demonstrates for the first time that experimental conditions optimized for SRM 955c (caprine blood) are not valid for human blood samples as the optimum initial sample amount for a real sample is more than 3 times lower than that for SRM 955c.
Conventional diagnostic methods for lung cancer are unsuitable for widespread screening because they are expensive and occasionally miss tumours. Gas chromatography/mass spectrometry studies have ...shown that several volatile organic compounds, which normally appear at levels of 1-20 ppb in healthy human breath, are elevated to levels between 10 and 100 ppb in lung cancer patients. Here we show that an array of sensors based on gold nanoparticles can rapidly distinguish the breath of lung cancer patients from the breath of healthy individuals in an atmosphere of high humidity. In combination with solid-phase microextraction, gas chromatography/mass spectrometry was used to identify 42 volatile organic compounds that represent lung cancer biomarkers. Four of these were used to train and optimize the sensors, demonstrating good agreement between patient and simulated breath samples. Our results show that sensors based on gold nanoparticles could form the basis of an inexpensive and non-invasive diagnostic tool for lung cancer.
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