The residues of atrazine in surface and ground water will cause harm to human health as they are slowly biodegraded microbiologically. In this work, density functional theory (DFT) and the polarizable continuum model (PCM) were used to investigate the degradation of atrazine in an aqueous medium by Fenton oxidation technology. The results show that H atom abstraction pathways are more probable than both OH radical addition and Cl atom substitution pathways. Moreover, the H atom abstraction from the –CH– of –CH(CH3)2 group and –CH2– of –CH2CH3 group are expected to occur more easily. New dealkylation and alkyl oxidation mechanisms are proposed, in which water can act as a catalyst to reduce the reaction barrier dramatically. The stable intermediates and products: CH3COCH3, DEDIA, DIA, DEA, CAFT, CDAT, CDET, CDFT and CFIT, have been identified with LC/MS analysis. This study offers a cost-effective way to probe the degradation mechanism of atrazine in an aqueous medium by Fenton oxidation technology.

•An integrated microsampling system was used for atmospheric study.•Theoretical and experimental verification confirmed the feasibility of this integrated microsampling system.•The integrated microsampling system performed very well when applied to ambient aerosol sampling.•The system is a simple, rapid, reusable, and cost-effective screening tool.An integrated microsampling approach based on active microextraction was developed to study semivolatile organic compounds (SVOCs). This microsampling system included an in-tube hollow-fiber solid-phase microextraction device in combination with a sorbent tube that can be applied in parallel to collect gas- and particle-phase SVOCs. The preparation procedure, theory, and application of two devices were characterized and validated by the single fiber theory and scanning mobility particle sizer experiments. The influence of the optimization parameters (sampling time, flow rate, and breakthrough volume) on the extraction process was studied in detail. The performance of the system was tested via simultaneous collection of a range of gas and particle samples of ethylbenzene, xylenes, n-alkanes, polycyclic aromatic hydrocarbons, and monoterpenes. The collection efficiencies of the two devices were more than 90% for most target compounds. Typically, relative standard deviation values in the range 2–6% were obtained, depending on the compound. The calibration curves for each compound were reproducible and linear over the concentration ranges normally found in atmospheric samples. Both devices were used to collect ambient air samples during a haze period and performed well in the extraction of both gas- and particle-phase SVOCs at the ng m−3 levels. The results from phase studies were used for further evaluation of the gas/particle partitioning of SVOCs. Application of this integrated microsampling system in the field validated its use as a simple, rapid, reusable, and cost-effective screening tool.

This paper reports the use of chromatographic profiles of breath volatiles to determine disease markers in lung cancer patients and healthy volunteers. The volatile fraction was isolated by headspace solid-phase microextraction (HS-SPME) and analyzed by flow-modulated comprehensive two-dimensional gas chromatography and flame ionization (GC × GC-FID). Following the experiments, collected data were transformed, and partial least-squares discriminant analysis (PLS-DA) as well as Mann–Whitney Test were carried out to model the data and discover breath metabolites with a significant concentration difference between patients and healthy subjects. Using the abovementioned method, lung cancer patients and healthy controls could be correctly distinguished based on metabolic VOCs abnormality in human breath. Five potential target compounds including acetone, isoprene, methanol, pentane and propanol were identified. Lung cancer patients show higher concentrations of propanol (7415.3 ng L−1), acetone (1811.6 ng L−1) and methanol (225 ng L−1) compared with those of healthy volunteers (1975.3 ng L−1, 579.9 ng L−1, 76.8 ng L−1, respectively). In addition, there is no significant relationship between breath VOCs and gender or body mass index (BMI). This approach will facilitate the comparison of complex breath VOC profiles and diseases. These findings may offer valuable and reliable information for the early diagnosis and prognosis of lung cancer.

In this study a differential optical absorption spectroscopy (DOAS) method was used to monitor formaldehyde (HCHO) concentrations in Shanghai ambient air at a research station in Fudan University. The measurements were carried out during April 2010–April 2011 and a total of 120940 recorded data points were obtained. The average HCHO concentration was found to be the highest (10.0 ppbv) during August 2010 and the lowest (2.0 ppbv) during April 2010. The diurnal variation of HCHO and O3 followed very similar trends in all the seasons. This was evident from the fact that HCHO had a strong positive correlation with O3. Both peaked once in the morning (07:00–09:00 local time), and once in the night (16:00–19:00 local time). The peak concentrations varied from season to season, which could be attributed to the seasonal variation in anthropogenic activity, traffic movement and atmospheric boundary layer conditions. The background HCHO concentration in 2011 winter (similar to 12.0 ppbv) was an order of magnitude higher than that observed in 2010 spring (similar to 2.0 ppbv); corresponding with the results of several pollution controls adopted by the Shanghai administrative government before and after the EXPO 2010 period (May 1, 2010–Oct. 31 2010). This study contributed the basic information for understanding the concentration level and the chemical processes of atmospheric HCHO in a major metropolitan area.

Atmospheric polycyclic aromatic hydrocarbons (PAHs) mainly originate from incomplete combustion or pyrolysis of materials containing carbon and hydrogen. They exist in gas and particle phases, as well as dissolved or suspended in precipitation (fog or rain). Current studies in atmospheric PAHs are predominantly focused on fog and rainwater samples. Some sampling difficulties are associated with fog samples. This study presented the first observation of the characteristics of PAHs in fog samples using a solid phase microextraction (SPME) technique. Eighteen fog samples were collected during ten fog events from March to December 2009 in the Shanghai area. PAHs were extracted by SPME and analyzed by gas chromatography-mass spectrometry (GC-MS). As the compounds were partially soluble in water, with solubility decreasing with increasing molecular weight, low molecular weight (LMW) PAH compounds were universally found in the fog water samples. Naphthalene (NaP), phenanthrene (Phe), anthracene (Ant) and fluoranthene (Flo) were dominant compounds in fog water. The total PAH concentration in fog water ranged from 0.03 to 6.67 μg L−1 (mean of 1.06 μg L−1), and was much higher in winter than in summer. The concentration of PAHs in fog or rain water decreased after undergoing a pre-rain or pre-fog wash. The average concentration of PAHs was higher in fog than in rain. Diagnostic ratio analysis suggested that petroleum and combustion were the dominant contributors to PAHs in urban Shanghai. Backward trajectories were calculated to determine the origin of the air masses, showing that air masses were mostly from the northeast territory.

Previous aerosol studies utilizing solid-phase microextraction (SPME) predominantly focused on volatile and semivolatile compounds in the gaseous phase. Difficulties were associated with quantitative analysis of these compounds when they were associated with atmospheric particles. The present study combines SPME technology with that of carboxen packed needles (needle trap, NT) for analysis of gaseous and particle-bound compounds in atmospheric samples. The NT device is constructed as a micro trap by placing some small sorbents in a needle. Aerosol samples are collected by drawing air through the NT device with a pump. The trapped components contain both gaseous chemical compounds as well as particulate matter present in the sample. The total concentration of analytes in an aerosol sample can be obtained on the basis of the exhaustive sampling mode of the NT device. Direct SPME is simultaneously used to determine gaseous compound in the aerosol sample. As a result, the SPME and NT devices, when used together, can provide a complete solution to highly efficient and accurate aerosol studies. The theoretical considerations of SPME and NT devices for aerosol sampling are validated by sampling seasalt aerosol, barbecue, and cigarette smoke. The concentrations of PAHs in the different phases of the samples are few ng/L. Result analysis shows that SPME and the NT device demonstrate several important advantages such as simplicity, convenience, and low costs under laboratory and on-site field sampling conditions.

Current direct analysis methods in mass spectrometry (MS) are predominantly focused on desorbing and ionizing samples in the solid phase. Some sampling difficulties are associated with liquid (solution) or gas samples. The present study has expanded direct MS analysis to solution samples by using the desorption corona beam ionization (DCBI) technique in combination with poly(dimethylsiloxane) (PDMS) substrate sampling. Typically, the PDMS substrate is dipped in water for microextraction of pesticide compounds and then is transferred to an MS ion source for desorption and ionization. This approach improves the detection limit for DCBI and allows more organic compounds in complex mixtures to be identified within seconds. The practical application of this device is demonstrated by identifying five pesticides (acephate, isoprocarb, dimethoate, dichlorvos, and dicofol) in water. The obtained detection limits of pesticides are 1 μg/L, the measured dynamic ranges are 3 orders of magnitude, the calculated correlation coefficients are between 0.939 and 0.979 at concentration levels of 5−5000 μg/L, and the repeatabilities defined as a relative standard deviation of five successive injections are in the range of 13−17%. The results indicate that the DCBI technique coupled with PDMS sampling is an excellent method for the analysis of organic pesticides in solution, and it also opens up a new avenue for direct MS studies of solution samples with general importance.

The efficiency of polythiophene (PTh) was investigated as a new fiber for solid-phase microextraction (SPME). The PTh film was directly electrodeposited on the surface of a stainless steel wire in boron trifluoride diethyl etherate (BFEE) solution using cyclic voltammetry (CV) technique. PTh fibers were used for the extraction of some organochlorine pesticides (OCPs) from water samples. The extracted analytes were transferred to an injection port of gas chromatography using a laboratory-designed SPME device. The results obtained prove the ability of PTh material as a new fiber for sampling of organic compounds from water samples. This behavior is due most probably to the granulated surface of PTh film, which produces large surface areas. In this work, the optimum conditions for the preparation and conditioning of fibers and the extraction of analytes from water samples were obtained. In the optimum conditions, the limit of detection of the proposed method is 0.5–10 ng L−1 for analysis of OCPs from aqueous samples, and the calibration graphs were linear in a concentration range of 10–10,000 ng L−1 (R2 > 0.982) for most of organochlorine pesticides. Single fiber repeatability and fiber-to-fiber reproducibility were less than 12 and 18% (n = 5), respectively. The PTh fiber was used to monitor the OCPs in real water samples, and the results compared favorably with the data determined by commercially available carbowax/divinylbenzene (CW/DVB) fiber.

•Particle-bound trace elements were measured in a city affected by non-ferrous metal smelting during winter haze episodes.•Regional deposition fluxes of trace elements were size-dependent.•Fine mode particles contributed the most to inhalation cancer risk.•Residents living in study sites are subject to potential health risk.This study examines size-resolved heavy metal data for particles sampled near an urban site affected by non-ferrous metal smelting in China with a focus on how particle sizes impact regional respiratory deposition behavior. Particles with aerodynamic diameters between 0.43 and 9 μm were collected during winter haze episodes from December 2011 to January 2012. The results showed that concentrations of individual trace elements ranged from ∼10−2–∼104 ng/m3. Mass size distributions exhibit that Cu, Zn, As, Se, Ag, Cd, TI, and Pb have unimodal peak in fine particles range (<2.1 μm); Al, Ti, Fe, Sr, Cr, Co, Ni, Mo, and U have unimodal peak in coarse range (>2.1 μm), and Be, Na, Mg, Ca, Ba, Th, V, Mn, Sn, Sb, and K have bimodal profiles with a dominant peak in the fine range and a smaller peak in the coarse range. The total deposition fluxes of trace elements were estimated at 2.1 × 10−2 – 4.1 × 103 ng/h by the MPPD model, and the region with the highest contribution was the head region (42% ± 13%), followed by the tracheobronchial region (11% ± 3%) and pulmonary region (6% ± 1%). The daily intake of individual element for humans occurs via three main exposure pathways: ingestion (2.3 × 10−4 mg/kg/day), dermal contact (2.3 × 10−5 mg/kg/day), and inhalation (9.0 × 10−6 mg/kg/day). A further health risk assessment revealed that the risk values for humans were all above the guidelines of the hazard quotient (1) and cancer risk (10−6), indicating that there are potential non-cancer effects and cancer risks in this area.Download high-res image (368KB)Download full-size image

Atmospheric polycyclic aromatic hydrocarbons (PAHs) mainly originate from incomplete combustion or pyrolysis of materials containing carbon and hydrogen. They exist in gas and particle phases, as well as dissolved or suspended in precipitation (fog or rain). Current studies in atmospheric PAHs are predominantly focused on fog and rainwater samples. Some sampling difficulties are associated with fog samples. This study presented the first observation of the characteristics of PAHs in fog samples using a solid phase microextraction (SPME) technique. Eighteen fog samples were collected during ten fog events from March to December 2009 in the Shanghai area. PAHs were extracted by SPME and analyzed by gas chromatography-mass spectrometry (GC-MS). As the compounds were partially soluble in water, with solubility decreasing with increasing molecular weight, low molecular weight (LMW) PAH compounds were universally found in the fog water samples. Naphthalene (NaP), phenanthrene (Phe), anthracene (Ant) and fluoranthene (Flo) were dominant compounds in fog water. The total PAH concentration in fog water ranged from 0.03 to 6.67 μg L−1 (mean of 1.06 μg L−1), and was much higher in winter than in summer. The concentration of PAHs in fog or rain water decreased after undergoing a pre-rain or pre-fog wash. The average concentration of PAHs was higher in fog than in rain. Diagnostic ratio analysis suggested that petroleum and combustion were the dominant contributors to PAHs in urban Shanghai. Backward trajectories were calculated to determine the origin of the air masses, showing that air masses were mostly from the northeast territory.

This paper reports the use of chromatographic profiles of breath volatiles to determine disease markers in lung cancer patients and healthy volunteers. The volatile fraction was isolated by headspace solid-phase microextraction (HS-SPME) and analyzed by flow-modulated comprehensive two-dimensional gas chromatography and flame ionization (GC × GC-FID). Following the experiments, collected data were transformed, and partial least-squares discriminant analysis (PLS-DA) as well as Mann–Whitney Test were carried out to model the data and discover breath metabolites with a significant concentration difference between patients and healthy subjects. Using the abovementioned method, lung cancer patients and healthy controls could be correctly distinguished based on metabolic VOCs abnormality in human breath. Five potential target compounds including acetone, isoprene, methanol, pentane and propanol were identified. Lung cancer patients show higher concentrations of propanol (7415.3 ng L−1), acetone (1811.6 ng L−1) and methanol (225 ng L−1) compared with those of healthy volunteers (1975.3 ng L−1, 579.9 ng L−1, 76.8 ng L−1, respectively). In addition, there is no significant relationship between breath VOCs and gender or body mass index (BMI). This approach will facilitate the comparison of complex breath VOC profiles and diseases. These findings may offer valuable and reliable information for the early diagnosis and prognosis of lung cancer.