Huixiong Lü

Determination of carbonyl compounds in the atmosphere by DNPH derivatization and LC-ESI-MS/MS detection

A method of determination of 32 carbonyl compounds by high performance liquid chromatography (HPLC) and electrospray ionization (ESI) tandem mass spectrometry (MS/MS) after derivatization with 2,4-dinitrophenylhydrazine (DNPH) was developed and successfully applied to the atmosphere sample of a residential area of Liwan District (S1) and a research institute of Tianhe District (S2) in Guangzhou, China. Some operation conditions of ESI-MS/MS in the negative ion mode including selection of parent and daughter ions, declustering potential (DP), entrance potential (EP), collision energy (CE), collision cell exit potential (CXP) and effect of buffer in ESI-MS/MS process were optimized. The regression coefficient of the calibration curves (R(2)), recovery, reproducibility (R.S.D., n=5) and limit of detection (LOD) were in the range of 0.9938-0.9999, 90-104%, 1.7-11% and 0.4-9.4ng/m(3), respectively. Among most of the samples, acetone was the most abundant carbonyl in two sampling sites and formaldehyde, acetaldehyde and butyraldehyde/2-butanone were also abundant carbonyls. In contrast to LC-UV method, the LOD, the separation of some co-eluting compounds and the precision (mainly to higher molecular weight carbonyls) are all improved by LC-ESI-MS/MS.

Levels of Organic Pollutants in Vegetables and Human Exposure Through Diet: A Review

The authors summarize the scientific literature on toxic organic microcontaminants in vegetables published during the last 15 years. A wide range of persistent, bioaccumulative, and toxic organic pollutants have been studied, namely polycyclic aromatic hydrocarbons (PAHs), polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), phthalic acid esters (PAEs), and perfluorinated substances. The available literature data covers the occurrence of organic contaminants in vegetables and the subsequent human exposure, through ingestion. Benzo[a]pyrene equivalents (BaPeq) were calculated following the concentrations of individual PAH in the literature and then compared. This review also summarizes Toxic Equivalent Concentrations (TEQ) and daily intake of PCDD/Fs, PCBs, and PBDEs through vegetable consumption. Temporal and spatial variations in contaminants concentrations are discussed. The existing scientific literature is critically evaluated regarding gaps, implications, and needs for future research.

Carbonyl compounds and BTEX in the special rooms of hospital in Guangzhou, China

The occurrence of carbonyl compounds and benzene, toluene, ethylbenzene and xylenes (BTEXs) was assessed in the indoor and outdoor air of a hospital in Guangzhou, China. The pharmacy room, the preparing traditional Chinese medicine room, the supply room (where the medical appliances are disinfected), the laundry and the garbage room were selected as sampling sites. Acetaldehyde (ranging from 4.56 to 66.8 microg m(-3)) was in all samples the most abundant among the 18 carbonyls detected, and toluene (ranging from 33.5 to 264 microg m(-3)) among the BTEXs. The indoor/outdoor (I/O) concentration ratios of BTEXs in the morning were always >1.0, and close to 1.0 or slightly <1.0 in the afternoon, while the concentration ratios of carbonyls in the afternoon showed large variation. These ratios demonstrate the significance of outdoor emissions that deteriorate the indoor air quality at the various rooms of the hospital. The possible sources of BTEXs and carbonyls in these rooms are discussed with the use of specific ratios and with the use of statistical methods, like principal components analysis.

Effect of composting on the removal of semivolatile organic chemicals (SVOCs) from sewage sludge.

In order to investigate the occurrence and removal of semivolatile organic chemicals (SVOCs) in the compost of sewage sludge, three different composting treatments, including manual turned compost (MTC), intermittent aerated compost (IAC), and naturally aerated compost (NAC) were conducted. Thirty SVOCs in composts were Soxhlet-extracted and analyzed by GC/MS. After 56 days of composting, the total concentrations of 16 polycyclic aromatic hydrocarbons (∑PAHs) ranged from 0.55 to 8.20 mg kg(-1) dry weight, decreasing in order of IAC>MTC>NAC. The total concentrations of six phthalic acid esters (∑PAEs), five chlorobenzenes or three nitroaromatic compounds were less than 5.0 mg kg(-1). Compared with the initial concentrations in sewage sludge, a significant reduction of ∑PAHs, ∑PAEs and chlorobenzenes was observed. The removal rates of ∑PAHs and ∑PAEs ranged from 54.6% to 75.9% and from 58.3% to 90.6%, respectively. Compared with different composting processes, MTC showed the highest potential for removal of SVOCs.

Soil contamination and sources of phthalates and its health risk in China: A review

&NA; Phthalates (PAEs) are extensively used as plasticizers and constitute one of the most frequently detected organic contaminants in the environment. With the deterioration of eco‐environment in China during the past three decades, many studies on PAE occurrence in soils and their risk assessments have been conducted which allow us to carry out a fairly comprehensive assessment of soil PAE contamination on a nation‐wide scale. This review combines the updated information available associated with PAE current levels, distribution patterns (including urban soil, rural or agricultural soil, seasonal and vertical variations), potential sources, and human health exposure. The levels of PAEs in soils of China are generally at the high end of the global range, and higher than the grade II limits of the Environmental Quality Standard for soil in China. The most abundant compounds, di‐n‐butyl phthalate (DBP) and di‐(2‐ethylhexyl) phthalate (DEHP), display obvious spatial distribution in different provinces. It is noted that urbanization and industrialization, application of plastic film (especially plastic film mulching in agricultural soil) and fertilizer are the major sources of PAEs in soil. Uptake of PAEs by crops, and human exposure to PAEs via ingestion of soil and vegetables are reviewed, with scientific gaps highlighted. Graphical abstract Figure. No Caption available. HighlightsPAE levels in soils of China were generally higher than the other countries.DBP and DEHP are the dominant compounds in soil with obvious spatial distribution.Urbanization and industrialization, application of plastic film and fertilizer are the major sources of PAEs in soil.Uptake of PAEs by crops and human exposure to PAEs are reviewed.

A conductive scanning study of La0.67Sr0.33MnO3/Nb:SrTiO3 hetero-junction

Basing on conductive atomic force microscopy, we presented a direct conductance mapping for the interface of the La0.67Sr0.33MnO3/Nb:SrTiO3 hetero-junction. The most remarkable observation is the presence of an interfacial layer in Nb:SrTiO3 adjacent to the manganite film. Within this layer, the AFM tip/Nb:SrTiO3 contact shows a current-voltage dependence that strongly deviates from Shockley equation, unlike a Schottky diode. Spatial extension of this layer is explored and possible transport mechanism in or outside this interfacial layer is discussed. The present work gives a direct intuitional image on the interface of manganite junction. The principle proven here can be extended to other complex oxide interfaces.