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Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) is an extraction and clean-up technique originally developed for recovering pesticide residues from fruits and vegetables. Since its introduction, and until December 2013, about 700 papers have been published using the QuEChERS technique, according to a literature overview carried out using SciFinder, Elsevier SciVerse, and Google search engines. Most of these papers were dedicated to pesticide multiresidue analysis in food matrices, and this topic has been thoroughly reviewed over recent years. The QuEChERS approach is now rapidly developing beyond its original field of application to analytes other than pesticides, and matrices other than food, such as biological fluids and non-edible plants, including Chinese medicinal plants. Recently, the QuEChERS concept has spread to environmental applications by analyzing not only pesticides but also other compounds of environmental concern in soil, sediments, and water. To the best of our knowledge, QuEChERS environmental applications have not been reviewed so far; therefore, in this contribution, after a general discussion on the evolution and changes of the original QuEChERS method, a critical survey of the literature regarding environmental applications of conventional and modified QuEChERS methodology is provided. The overall recoveries obtained with QuEChERS and other extraction approaches (e.g., accelerated solvent extraction, ultrasonic solvent extraction, liquid/solid extraction, and soxhlet extraction) were compared, providing evidence for QuEChERS higher recoveries for various classes of compounds, such as biopesticides, chloroalkanes, phenols, and perfluoroalkyl substances. The role of physicochemical properties of soil (i.e., clay and organic carbon content, as well as cation exchange capacity) and target analytes (i.e., log K, water solubility, and vapor pressure) were also evaluated in order to interpret recovery and matrix effect data. [ABSTRACT FROM AUTHOR]

Soluble organic matter had been separated from several palygorskite and bentonite samples in the Jiangsu-Anhui border area (across Jiangsu Province and Anhui Province) and Linze County in Gansu Province of China and was analyzed with the techniques and methods of organic geochemistry. The composition and distribution of hydrocarbons were analyzed by gas chromatography (GC). Organic stable carbon isotopic ratios (δC) in typical samples were determined. The abundance of soluble organic matter in all clay samples analyzed was low. In Jiangsu-Anhui samples, the preservation states of organic matter are different; hydrocarbons in organic matter have some features of aquatic plankton but are short of the input of terrigenous higher plants; organic δC in a palygorskite of Yongxiaoshan in Xuyi County, Jiangsu Province, is −6.72‰. These features may be typical of a sedimentary environment of closed or semi-closed and relatively isolated different waters near coast or seashore. On the contrary, in samples from Gansu, the preservation states of organic matter are good; the GC graphs of hydrocarbons show that the precursors of the organic matter are from a mixed source of aquatic organisms and land-sourced higher plants; organic δC of a palygorskite from Yangtai of Gansu is −15.62‰. It indicated that the sedimentary environment may be an inland salty lake. Preliminary results suggest that palygorskite minerals in the Jiangsu-Anhui area may be evolved from rapidly accumulated fine material or volcanic ash, but clays in Gansu Province may be transformed from terrigenous inorganic clastic components carried to the lake through river and then deposited. The generation process of the samples studied in the paper seems to be related to salty water. [ABSTRACT FROM AUTHOR]

Occurrence and fate of eight kinds of selected endocrine-disrupting compounds (EDCs) in three sewage treatment plants (STPs) of Beijing, China was investigated. These EDCs, composed of 4-octylphenol (4-OP), 4-n-nonylphenol (4-n-NP), bisphenol A (BPA), estrone (E1), 17 α-estradiol (17 α-E2), 17 β-estradiol (E2), estriol (E3) and 17 α-ethinylestradiol (EE2), in every step of STPs, were simultaneously analysed by gas chromatography/mass spectrometry after derivatisation. All the EDCs were detected in the influents of three STPs, and BPA was the most abundant compound. The concentrations of EDCs ranged from 36.6 ng/l of 17 α-E2 (STP C) to 1342.3 ng/l of BPA (STP B) in the influent sewages and from below limits of detection of E2 and E3 (STP C) to 142.5 ng/l of E1 (STP B) in the effluent sewages. The STPs could not remove alkylphenols effectively from the aqueous phase with less than 40% reduction. BPA decreased over 90%, and steroid estrogens achieved considerable reductions from 64.8% of E2 to 94.9% of E3. Generally, biological treatment was more effective in removing alkylphenols, BPA and natural estrogens from the aqueous phase than primary treatment. However, the synthetic estrogen, EE2, was mostly removed by the primary treatment with about 63.5% reduction. It is the first time that the concentration of 17 α-E2 in the sewage of China was reported in this paper. The compound might have a bearing with the waste effluents of dairy farms around urban area of Beijing. [ABSTRACT FROM AUTHOR]

Levels of polycyclic aromatic hydrocarbons (PAHs) were measured in surface soils of Datuo karst Tiankeng (large sinkholes) in South China with the use of a gas chromatography–mass spectroscopy (GC–MS) system. This paper provides data on the levels and distribution of PAHs from the top to the bottom of the Datuo karst Tiankeng. The results showed that the sum of the 16 EPA priority PAHs from the sampled locations from top to bottom had a relative increment in PAHs concentration. ∑PAHs ranged from 16.93 ng/g to 68.07 ng/g with a mean concentration of 42.15 ng/g. The correlated results showed the bottom of the large sinkhole, which accounts for the higher concentrations, probably acts like a trap for the PAHs. Thus, the low evaporation rate at the bottom may play a key role in controlling the high concentration of PAHs at the bottom. [ABSTRACT FROM AUTHOR]

Hexachlorocyclohexane (HCH) has a history of use in China. This paper presents the result of an investigation of HCH residue isomers and their distribution characteristics in soils near Tianjin, China. One hundred eighty-eight soil samples were collected from the Tianjin area. Four HCH isomers—α-HCH, β-HCH, γ-HCH, and δ-HCH—were detected using gas chromatography for all samples. Concentrations of the ∑HCH ranged from 1.3 to 1095 ng g-1, among which β-HCH accounted for 52.5%. In addition, residues of HCH within Tianjin's urban areas were found to be higher. No significant differences were found between the residues of HCH in soils from waste irrigation areas and those in other areas. Total organic carbon content was determined to impact the residue levels of HCH in soils, while pH value and clay content were not related to concentrations of HCH. In general, all HCH isomers in soil samples had abnormally high residue levels, possibly the result of continuous use of HCH in this area. [ABSTRACT FROM AUTHOR]

To understand variations in geochemistry, organic petrology, and chemical composition of crude oil and byproducts, an immature sample from the Cretaceous Qingshankou Formation in the Songliao Basin, China, was analyzed by anhydrous and hydrous pyrolysis (AHP/HP) at a wide range of temperatures ranging from 300 °C to 450 °C. The geochemical parameters: TOC, S2, HI, and Tmax obtained from Rock–Eval pyrolysis showed both a decrease and an increase as thermal maturity progressed under HP and AHP conditions. Gas chromatography (GC) analysis showed the presence of n-alkanes in the C14 to C36 range in both expelled and residual byproducts, a Delta-shaped configuration although many samples had a gradually reducing (tapering) trend toward the high range. Gas chromatography-mass spectrometry (GC–MS) analysis revealed both an increase and a decrease in biomarker and very small changes in aromatic compound variations with increasing temperature during pyrolysis. To be more specific, C29Ts biomarker increased with temperature for the expelled byproduct, while the opposite trend was observed for the residual one. Next, The Ts/Tm ratio initially increased and then decreased with temperature while the C29H/C30H ratio fluctuated for the expelled byproduct but increased for the residual. Moreover, the GI and C30 rearranged hopane to C30 hopane ratio remained unchanged whereas the C23 tricyclic terpane/C24 tetracyclic terpane ratio and the C23/C24 tricyclic terpane ratio showed varying trends with maturity alike the C19/C23 and C20/C23 tricyclic terpane. Ultimately, based on organic petrography observations, increasing the temperature resulted in higher bitumen reflectance (%Bro, r) and optical and structural alterations in the macerals. The findings of this study provide valuable insights for future exploration endeavors in the studied region. Moreover, they contribute to our understanding of the significant role of water in the generation and expulsion of petroleum and associated byproducts, thereby facilitating the development of updated models in this field. [ABSTRACT FROM AUTHOR]

The reverse transcription-quantitative polymerase chain reaction (RT-qPCR) approach has been widely used to detect the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, instead of using it alone, clinicians often prefer to diagnose the coronavirus disease 2019 (COVID-19) by utilizing a combination of clinical signs and symptoms, laboratory test, imaging measurement (e.g., chest computed tomography scan), and multivariable clinical prediction models, including the electronic nose. Here, we report on the development and use of a low cost, noninvasive method to rapidly sniff out COVID-19 based on a portable electronic nose (GeNose C19) integrating an array of metal oxide semiconductor gas sensors, optimized feature extraction, and machine learning models. This approach was evaluated in profiling tests involving a total of 615 breath samples composed of 333 positive and 282 negative samples. The samples were obtained from 43 positive and 40 negative COVID-19 patients, respectively, and confirmed with RT-qPCR at two hospitals located in the Special Region of Yogyakarta, Indonesia. Four different machine learning algorithms (i.e., linear discriminant analysis, support vector machine, stacked multilayer perceptron, and deep neural network) were utilized to identify the top-performing pattern recognition methods and to obtain a high system detection accuracy (88–95%), sensitivity (86–94%), and specificity (88–95%) levels from the testing datasets. Our results suggest that GeNose C19 can be considered a highly potential breathalyzer for fast COVID-19 screening. [ABSTRACT FROM AUTHOR]

Oxadiargyl is a commonly used herbicide in China. We developed a simple, fast, and high-throughput method employing gas chromatography with electron capture detector to determine oxadiargyl residues in food samples (rice, straws) and environmental samples (soil, water). Samples were prepared by a modified QuEChERS procedure. In this method, acetonitrile was used as the extracting solvent. The purifying step was omitted when the chromatographic conditions were optimized. Recoveries ranged from 82.9 to 112.0% for oxadiargyl in all samples, with relative standard deviation values lower than 6.2% at 0.01 mg/kg fortified concentration level. [ABSTRACT FROM AUTHOR]

A high-efficient method for determining the total petroleum hydrocarbon (TPH) was established by gas chromatography-flame ionization detection, coupled with an efficient 10 m short chromatographic column; the analyzing period was narrowed to 5 mins. The limits of detection of the method included 1.47, 4.02, and 0.69 mg/kg, and the corresponding limits of quantification reached 4.45, 12.2, and 2.10 mg/kg for the three fractions C10–C16, C17–C34, and C35–C40, respectively. The method was employed to real samples to achieve the routine environmental monitoring of TPH in polluted sites from Fushan oilfield, China. As revealed from the analysis of 30 soil samples in the study area, a wide range of TPH concentrations were achieved: 61.6–7300 mg/kg (average, 1055 mg/kg) for ΣC10–C16, 438–14,280 mg/kg (average, 4544 mg/kg) for ΣC17–C34, 25.4–638 mg/kg (average, 250 mg/kg) for ΣC35–C40, and 617–15,348 (average, 5848 mg/kg) for ΣC10–C40, respectively. According to the Nemerow integrated pollution index, the Fushan oilfield has been slightly polluted by TPH. As suggested from the distribution of TPH concentrations, the main sources of TPH in soil samples of Fushan oilfield included oil spills during temporary storage, transportation, and oil exploitation. Adopting the developed method to delve into oilfield soil samples further verifies the effectiveness of the method, indicating that the method can well meet the growing demand of regulatory guidelines for related risk assessment and environmental monitoring and remediation strategy formulation. [ABSTRACT FROM AUTHOR]

Purpose: Previous studies have shown that high-dose supplementation with n-3 polyunsaturated fatty acids (PUFAs) may benefit patients with nonalcoholic fatty liver disease (NAFLD), but the association of n-3 PUFAs with NAFLD among individuals with normal diets is only speculative. We investigated the cross-sectional and prospective associations between n-3 PUFAs and NAFLD in Chinese adults. Methods: This community-based prospective study included 3049 men and women (40–75 years) in Guangzhou, China, whose participants completed an NAFLD ultrasound evaluation and erythrocyte PUFA tests. A total of 2660 participants underwent the second NAFLD evaluation approximately 3 years later. α-Linolenic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in erythrocytes were measured by gas chromatography. Results: After adjusting for potential confounders, we observed inverse associations between DHA, DHA + EPA, total n-3 PUFAs and the presence of NAFLD in the cross-sectional analysis. The adjusted odds ratios (95% confidence interval) of NAFLD for the highest (vs. lowest) tertile were 0.74 (0.61, 0.90) for DHA, 0.82 (0.67, 1.00) for EPA, 0.73 (0.60, 0.88) for DHA + EPA and 0.74 (0.61, 0.91) for total n-3 PUFAs (all P values≤0.05). Over the average 3.12 years of follow-up, higher levels of DHA was associated with an improvement of NAFLD. The hazard ratio of improved NAFLD for the highest tertile was 1.18 (95% CI 1.09, 1.33) for DHA. Pathway analyses showed that favorable associations may be mediated by improvements in inflammatory markers (e.g., interleukin 1 beta and tumor necrosis factor alpha-like). Conclusions: Erythrocyte membrane n-3 PUFAs are inversely associated with the presence and progression of NAFLD in Chinese adults. Trial registrations: ClinicalTrials.gov NCT03179657. [ABSTRACT FROM AUTHOR]

The semi-volatile organic compounds in Lhasa River were determined qualitatively and quantitatively by gas chromatography method with mass spectrometric detection. Total concentrations of 23 organic pollutants in samples from five sites ranged from 1.56 to 2.78 μg/L. The average concentrations for ΣPAEs, ΣPAHs and ΣBTEXs obtained in this study were 1.53, 0.33 and 0.51 μg/L, respectively. Moreover, the results of analysis of variable showed that there were significant differences ( P < 0.05) among the sites for levels of ΣPAHs, ΣPAEs and ΣBTEXs. Cluster analysis was applied to detect spatial similarity for grouping of sites under the monitoring network. The results indicated that the five sites in this study could be divided into two significant groups, i.e. low and high pollutant groups. Health risk assessment was conducted by multimedia environmental goals (MEG), risk quotient (RQ) for each pollutant and hazard quotient (HQ) approach from USA ecological risk assessment (ERA) for screening stage. Calculated both total ambient severity and RQ were less than 1 and therefore minimal risk to human and ecological health. For analysis results of HQ, whether for the ingestion exposure or dermal adsorption pathway were all less than 1, the results also agreed with the RQ model and MEG model for evaluating the potential for adverse health effects due to exposure semi-volatile organic compounds from surface water. Therefore, SVOCs in Lhasa River posed little or no threat to the health of local consumers and ecological environment. [ABSTRACT FROM AUTHOR]

Surface soil samples were collected in two karst Tiankengs, Dashiwei and Datuo, situated within the Dashiwei Tiankeng group, located in Leye County of Guangxi province, South China. The soil samples were analyzed for 23 kinds of organochlorine pesticides (OCPs) using a gas chromatography electron capture detector device. The results showed that the concentrations of OCPs in soils of Dashiwei Tiankeng ranged from 0.03 to 5.13 ng/g for total OCPs, not detectable (ND) to 0.22 ng/g for Hexachlorocyclohexane (HCHs), and 0.01 to 3.61 ng/g for Dichlorodiphenyltrichloroethane and metabolites (DDTs). Concentration of the total OCPs in soils of Datuo Tiankeng ranged from 0.13 to 14.36 ng/g, ND to 0.39 ng/g for HCHs, and 0.01 to 3.28 ng/g for DDTs. These concentrations indicated that there could be new inputs of HCHs and DDTs from recent application of lindane and dicofol in this area. Further analysis also revealed that the concentration of OCPs at the bottom of both Tiankengs was higher than the top. The variability in concentrations between the top and the bottom was attributed to the 'cold trapping effect' for persistent organic pollutants (POPs) in karst Tiankeng topography. The difference in temperature between the top and bottom of Tiankeng is a predominating factor which can cause a POPs 'cold trapping effect.' Other environmental factors are proposed to explain the difference in concentration such as humidity, topography (or slope), wind speed, wind direction, solar radiation, vegetation cover, and soil organic matter. The environmental condition of Dashiwei Tiankeng appears to favor the accumulation of OCPs than that of Datuo Tiankeng because Dashiwei Tiankeng is a matured Tiankeng but Datuo Tiankeng is a degraded one. Thus, there is the need for further studies on the environmental factors influencing distribution of OCPs in karst Tiankeng. [ABSTRACT FROM AUTHOR]

Fourteen surface water and nine surface sediment samples were collected from the Peacock River and analyzed for organochlorine pesticides (OCPs) by gas chromatograph-electron capture detector (GC-ECD). All the analyzed organochlorine pesticides, except o,p-DDT, were detected in sediments from the Peacock River; but in the water samples, only β-HCH, HCB, p,p-DDD, and p,p-DDT were detected at some sites. The ranges for total OCPs in the water and sediments were from N.D. to 195 ng l and from 1.36 to 24.60 ng g, respectively. The only existing HCH isomer in the water, β-HCH, suggested that the contamination by HCHs could be attributed to erosion of the weathered agricultural soils containing HCHs compounds. Composition analyses showed that no technical HCH, technical DDT, technical chlordanes, endosulfans, and HCB had been recently used in this region. However, there was new input of γ-HCH (lindane) into the Peacock River. The most probable source was water flowing from Bosten Lake and/or agricultural tailing water that was returned directly into the Peacock River. DDT compounds in the sediments may be derived mainly from DDT-treated aged and weathered agricultural soils, the degradation condition was aerobic and the main product was DDE. HCB in the sediment might be due to the input from Bosten Lake and the lake may act as an atmospheric deposition zone. There was no significant correlation between the concentrations of OCPs (including ∑HCH, ∑DDT, chlordanes, endosulfans, HCB and total OCPs) and the content of fine particles (<63 μm). The concentrations of OCPs were affected by salinity. [ABSTRACT FROM AUTHOR]

Nitroaromatic compounds are known to be hazardous to ecological and human health. To assess the status of nitroaromatic compounds contamination in the main rivers in the important industrial bases of the northeastern China, we collected water, suspended particulate matter (SPM) and sediment samples from 28 sites in the Daliao River watershed and analysed them for eight nitroaromatic compounds by gas chromatography. The total concentrations of eight nitrobenzenes in the water column including aqueous and SPM phases ranged from 740 to 15,828 ng L, with a mean concentration of 3,460 ng L. The total concentrations of eight nitrobenzenes in the sediment were 7.47 to 8,185.76 ng g, with a mean concentration of 921.98 ng g, and several times higher than those found from the Yellow River in China. 4-Nitrotoluene was the predominant contaminant in the water and sediment of the three rivers of the Daliao River watershed. 2,6-Dichloro-4-nitroaniline was generally dominant in the SPM. The levels of nitroaromatic compounds were different among different sites in the Daliao River watershed, mainly caused by the distribution of pollution sources. No obvious correlation was found between the total concentrations of eight nitrobenzenes concentrations and TOC or the slit-clay content of the sediments. [ABSTRACT FROM AUTHOR]

Forty-six crude oil samples were selected from the Ordovician in the northwestern part of the Tahe oilfield for detailed molecular geochemical and isotopic analysis, including group compositions, carbon-hydrogen isotopes and gas chromatograms of saturated hydrocarbons, as well as the characteristics of terpane, sterane and other biomarkers, indicating that crude oils are of the same origin from different districts in the Tahe oilfield and were derived from the same source kitchen (or oil source formation), i.e., mainly stemming from marine hydrocarbons. Detailed studies of oil physical properties of 25-honpane revealed that such oils have heavy or thick oil qualities due to biodegradation. Comprehensive assessment in terms of five maturity parameters shows that the oils from the Ordovician with R values varying from 0.80% to 1.59% are widely distributed in the northwest of the Tahe oilfield. [ABSTRACT FROM AUTHOR]

Comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GCxGC-TOFMS) is commercially available in the 1990s, with the characteristics of large peak capacity, high resolution, high sensitivity, etc. However, its application to the petroleum and geological analyses is just emerging in China and overseas. In this research, the analytical method for petroleum aromatic fraction using GCxGC-TOFMS is set up, via the choice of the column system and optimization of setting parameters, such as temperature programming, modulation time, hot pulse time, flow rate of carrier gas, data acquisition rate and data processing. The results indicate that different polar compounds of aromatic fraction distribute as bands on structured GCxGC chromatogram. Within each band, homologous compounds appear as a roof-tile structure based on the number of substituent residues. The aromatic compounds are identified and characterized according to the GCxGC chromatogram and mass spectra. According to the polarity and the number of rings, aromatic compounds are spatially present on one chromatogram, which directly reflects the distribution characteristics of complex compounds of aromatic hydrocarbons. In addition, quantitative analysis is favored as some overlapped peaks on traditional GC-MS chromatogram have been separated completely on GCxGC. Some heterocyclic atom aromatic compounds at trace level can be clearly identified using this method, for polarity differences from other interfered aromatic compounds. The development of this method and chromatogram recognition offer petroleum geologists a practical example for the application performance of GCxGC-TOFMS. [ABSTRACT FROM AUTHOR]

Abstract  The sex pheromone of the chrysanthemum gall midge, Rhopalomyia longicauda (Diptera: Cecidomyiidae), the most important insect pest in commercial plantations of chrysanthemum, Dendranthema morifolium (Ramat.) Tzvel., in China, was identified, synthesized, and field-tested. Volatile chemicals from virgin females and males were collected on Porapak in China and sent to the United Kingdom for analysis. Coupled gas chromatographic–electroantennographic detection (GC-EAG) analysis of volatile collections from females revealed two compounds that elicited responses from antennae of males. These compounds were not present in collections from males. The major EAG-active compound was identified as 2-butyroxy-8-heptadecene by gas chromatographic (GC) retention indices, mass spectra, in both electron impact and chemical ionization modes, hydrogenation, epoxidation, and derivatization with dimethyldisulfide. The lesser EAG-active compound was identified as the corresponding alcohol. The ratio of butyrate to alcohol in the collections was 1:0.26. Racemic (Z)-8-heptadecen-2-ol and the corresponding butyrate ester were synthesized from (Z)-7-hexadecenyl acetate, and the synthetic compounds found to have identical GC retention indices and mass spectra to those of the natural, female-specific components. Analysis of the volatile collections on an enantioselective cyclodextrin GC column showed the natural pheromone contained (2S,8Z)-2-butyroxy-8-heptadecene. Field tests showed that rubber septa containing racemic (Z)-2-butyroxy-8-heptadecene were attractive to R. longicauda males. The (naturally occurring) S-enantiomer was equally as attractive as the racemate, while the R-enantiomer was not attractive to males, and did not inhibit the activity of the S-enantiomer. The attractiveness of the butyrate was significantly reduced by the presence of even small amounts of the corresponding alcohol. [ABSTRACT FROM AUTHOR]

The Linnan subsag is the main oil producer of the Linpan oil zone. Based on the oil group composition, gas chromatography data and biomarker analysis, it was indicated that crude oils from different oilfields varied greatly in group composition and showed obvious heterogeneities in the aspects of precursor type, crude oil maturity and hydrocarbon depositional environment. According to the characteristics of source rocks, three oil populations can be distinguished, i.e., the southern, northern and transitional oil populations. Furthermore, on the basis of post-reservoir reworking processes, the medium conditions of hydrocarbon-generating environment and differences in maturity, six oil families and twelve sub-families were distinquished. An integrated study suggested that the factors leading to such heterogeneities in crude oil composition mainly include different source rocks, multi-stage oil/gas charging, geo-chromatographic effects during oil/gas migration, reservoir heterogeneities and various post-reservoir secondary alterations. [ABSTRACT FROM AUTHOR]

Carbonaceous particles concentrations of OC and EC are determined using a two-step gas chromatography system in Muztagh Ata ice core covering the time period of 1955-2000. Over the period represented by the core, OC and EC concentrations appear to have changed significantly, varied in the range of 17.7-216.7 and 6.5-124.6, and averaged 61.8, 32.9 ng·g-1, respectively. The average concentration of EC in Muztagh Ata ice core is much lower than that in an Alpine ice core record (100-300 ng·g-1) during the same period, but it is a factor of 14 in Greenland ice core (2.3 ng·g-1), this may induce a strong impact on the snow albedo in the last 46 years in our study area. Observations indicate two periods with obviously high deposition concentrations (1955-1965 and 1974-1989) and two periods with low concentrations (1966-1973 and 1990-1995), as well as a recent increasing trend. By com- paring EC and SO42- concentration variations and deciphering OC/EC ratios recorded in the same ice core, we can judge roughly that the carbonaceous particles deposited in Muztagh Ate ice core were attributed to fossil fuel combustion sources. [ABSTRACT FROM AUTHOR]

A method to effectively remove pigments in fresh vegetables using activated carbon followed cleanup through solid phase extraction (SPE) cartridge to further reduce matrix interference and contamination, was established to determine eight organophosphorous pesticides (OPPs) by gas chromatography (GC) with nitrogen–phosphorus detection (NPD) in this study, and it has been successfully applied for the determination of eight OPPs in various fresh vegetables with the recoveries ranging from 61.8% to 107%. To evaluate eight OPPs residue level, some fresh vegetables retailed at three agricultural product markets (APM) of Nanjing in China were detected, the results showed that phorate in Shanghai green (0.0257 μg g−1) and Chinese cabbage (0.0398 μg g−1), dimethoate in Shanghai green (0.0466–0.0810 μg g−1), Chinese cabbage (0.077 μg g−1), and spinach (0.118–0.124 μg g−1), methyl-parathion in Shanghai green (0.0903 μg g−1), Chinese cabbage (0.157 μg g−1), and spinach (0.0924 μg g−1), malathion in Shanghai green (0.0342–0.0526 μg g−1), chorpyrifos in spinach (0.106–0.204 μg g−1), and Chinese cabbage (0.149 μg g−1), chlorfenvinfos in carrot (0.094–0.131 μg g−1), were found. However, fonofos and fenthion were not detected in all the collected vegetable samples. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons (PAHs) in total suspended particulates (TSP) collected at six rural and urban stations in Hong Kong from 1993–1995 using high volume air samplers were identified using GC-MS (gas chromatography-mass spectrometry). The results showed that the PAHs exhibited distinct spatial and seasonal variability. The total PAH content (ΣPAH) in the samples ranged from 0.41 to 48 ng m$^-3$. The unsubstituted analogs are the characteristic products of high temperature combustion processes. The highest average ΣPAH was measured at the street-level station in Mong Kok indicating that vehicles were high PAHs contributors. The rural station at Hok Tsui exhibited the lowest PAH level, however; influences of city plumes could be seen when northerly or northeasterly winds prevailed in the winter. All stations experienced the highest loading of PAHs in autumn and the lowest in summer; the former was 2.8 times greater than the latter. This seasonal variability is due to the Asian monsoon system, precipitation, micrometeorology, and the rate of photodegradation. In summer, Hong Kong experiences relatively clean oceanic air and high rates of precipitation and photodegradation, while upon the onset of the winter monsoon, local air mass is replaced by polluted air streams from the Asian continent. Benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(e)pyrene, indeno(1,2,3-cd)pyrene and benzo(ghi)perylene were the dominant species in the samples. The PAH distribution patterns at different stations were similar within each season. However, seasonal variations existed. For example, phenanthrene contributed up to 14% of the total PAH in summer, while the dominance of benzo(b)fluoranthene, benzo(k)fluoranthene was more significant in autumn and winter. [ABSTRACT FROM AUTHOR]