A nation-wide study for the occurrence of PPD antioxidants and 6PPD-quinone in road dusts of China.

N,N'-substituted p-phenylenediamines (PPDs) are widely used antioxidants in rubber tires, which could be released and accumulated in road dusts with rubber tires wear. As ozonation product of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), 6PPD-quinone (6PPD-Q) exhibited higher toxicity to coho salmon. However, studies on their environmental behaviors are still limited. Road dust is the major medium PPDs exist, which significantly affects the levels of PPDs in other mediums, especially surface water and particulate matter. In this study, road dust samples were collected in 55 major cities of China to explore the distribution characteristics of PPDs and 6PPD-Q. The concentrations of total PPDs (ΣPPDs) and 6PPD-Q in urban trunk road dust samples were in the ranges of 7.90-727 and 3.00-349 ng/g, with median concentrations of 68 and 49 ng/g, respectively. 6PPD and 6PPD-Q are the dominant components in most road dusts. The functional region-dependent pollution characteristics of PPDs and 6PPD-Q give the first finding that urban tunnel road was the highly polluted region, followed by urban trunk roads. Suburban road dusts had a lower pollution level. Moreover, the estimated daily intake (EDI) of PPDs and 6PPD-Q for children was much higher than adults.

[New pretreatment method for detecting petroleum hydrocarbons in soil: silica-gel dehydration and cyclohexane extraction].

Oil is a primary source of energy worldwide. However, the use of oil produces large amounts of pollutants, which are detrimental to the environment. The presence of petroleum hydrocarbons in soil is a critical marker of environmental pollution and safety. Rapid on-site detection technology has been broadly used in emergency tracking, offering critical information support for effective reactions to environmental emergencies. Thus, it is expected to play an increasingly critical role in environmental remediation efforts. The current approach for petroleum hydrocarbon detection in soil mainly involves Soxhlet extraction with a combination of solvents, including acetone and n-hexane. The samples are then analyzed after rotary evaporation, dehydration with anhydrous sodium sulfate, and purification using a magnesium silica-type adsorbent. Unfortunately, this approach requires sample analysis to be performed in the laboratory, which is tedious and time consuming, and consumes large amounts of solvents. Moreover, the rotary evaporator is not portable. Therefore, this method is not appropriate for the rapid on-site detection of petroleum hydrocarbons. In this study, a rapid on-site detection method based on silica-gel dehydration and cyclohexane extraction was developed for the extraction and pretreatment of petroleum hydrocarbons (C10-C40) in soil. First, an appropriate amount of silica gel was added to the soil, and the mixture was completely ground to eliminate moisture. Next, petroleum hydrocarbons were extracted with 40 mL of cyclohexane, and the extract was cleaned by Florisil solid-phase extraction (SPE) column elution. Finally, the samples were analyzed by gas chromatography (GC) to evaluate the above method. The silica gel exhibited optimal adsorption properties compared with anhydrous sodium sulfate, calcium oxide, and molecular sieves, with recovery of 87.5%. The effects of different soil water content (5%, 10%, and 20%) and silica gel (1, 3, 5, and 10 times the moisture content) dosage on the extraction of petroleum hydrocarbons were investigated. The recoveries of petroleum hydrocarbons increased from 74.0% to 103.8% after 15 min of invasive extraction (relative standard deviation, RSD, <10.1%) when silica gel amounting to 10 times the moisture content was used. Five types of silica gels with different properties were purchased from four manufacturers, and the effects of these silica gels on the dehydration and extraction efficiency of petroleum hydrocarbons in soil were assessed. The results showed that amorphous silica gel led to low recoveries (<60%), spherical silica gel achieved extraction efficiencies of approximately 70%-90%, and alkaline silica gel produced recoveries with poor precision. Therefore, neutral spherical silica gel was used for further experiments. The fingerprints of petroleum hydrocarbons with different carbon numbers are an important reference for identifying pollution sources. Thus, ensuring good recoveries throughout the entire carbon range is necessary to ensure the accuracy of the fingerprint analysis results. The proposed method showed good recoveries for petroleum hydrocarbons of all carbon numbers (75%-101%). The findings above indicate that the developed method could be an efficient means to extract petroleum hydrocarbons from soil for both total quantity and fingerprint analyses. Compared with standard methods, the proposed method requires lower solvent dosages and features simpler processing steps. Another advantage of this method is that it does not require the use of highly toxic halogenated solvents; thus, it does not contribute to environmental pollution. It can be applied to the laboratory analysis of soil petroleum hydrocarbons and coupled with other rapid on-site detection techniques for soil petroleum hydrocarbons, such as infrared spectroscopy and portable GC. However, because it does not include a concentration process, the developed method exhibits relatively low sensitivity. In the future, we plan to develop a simple and flexible on-site sample-concentration system to further improve various indicators of this method.

Internal exposure of Chinese children from a typical coastal city to bisphenols and possible association with thyroid hormone levels.

Bisphenols (BPs) are widely used in consumer products, and human exposure to BPs is nearly ubiquitous. However, human biomonitoring data are scarce, especially for children. In this study, we quantified eight BPs in the serum of 345 children from a typical coastal city in China. Bisphenol A (BPA), bisphenol F (BPF), and bisphenol S (BPS) were frequently detected (63% BPA, 68% BPF, 43% BPS), with geometric mean (GM) concentrations of 1.6, 0.08, and 0.04 ng/mL, respectively. The other five BPs had low detection frequencies (<5%). The distribution of BPA, BPF, and BPS in children's serum samples was independent of sex whereas the concentrations of BPS and BPF both significantly increased with age (P < 0.01). The GM values of estimated daily intake for BPA and BPS were 0.61 and 0.014 µg/kg body weight (bw)/day, respectively, indicating a relatively higher exposure risk of BPA in comparison with BPS. Compared with the population with euthyroid or nonhyperthyroid thyroid dysfunction, children with hyperthyroidism suffered higher exposure to BPA. By multiple linear regression analysis, thyroid-stimulating hormone showed a significantly negative relationship with log10-BPA concentration for euthyroid children (R2 = 0.477, P < 0.001), whereas a significantly positive correlation (R2 = 0.753, P = 0.033) was found for hyperthyroid children.

[Evaluation of thermal adsorption and desorption properties of dioxins on 11 adsorbents].

The key to the online thermal capture of dioxins is the appropriate choice of adsorbent for efficient capture at low temperatures and rapid desorption at high temperatures. Efficient adsorbents can allow for capture and separation during the online monitoring of dioxins or during offline dioxin tests. In this study, 1,2,3,4-tetrachlorodibenzo-p-dioxin (1,2,3,4-TCDD) and pentachlorodibenzofuran (1,2,3,8,9-PCDF) were used as model compounds for dioxin monomers, and an electron capture detector (ECD) was used to detect the dioxin signals. The retention volumes of 1,2,3,4-TCDD and 1,2,3,8,9-PCDF on 11 types of adsorbents were determined using a packed-column gas chromatography system. Then, the corresponding van der Hoff equation was established, and these adsorbents were evaluated for the thermal trapping of dioxin. The linear coefficients of determination (R2) of these adsorbents were greater than 0.96, which indicated a strong correlation between the adsorption capacity and 1/T (T: temperature). The gas-solid partition coefficients (KSA) of the adsorbent at 120, 150 and 180 ℃ were predicted according to the van der Hoff equation, which was obtained in an earlier study. Among the 11 adsorbents, florite had the largest adsorption capacity at 120, 150, and 180 ℃, especially at 120 ℃; the KSA values for 1,2,3,4-TCDD and 1,2,3,8,9-PCDF on florite were as high as 1.82×108 m3/g and 1.46×1013 m3/g, respectively. Carbon-based adsorbents of the Chinese stilbene polymer porous microspheres GDX series, GDX-101, GDX-102, GDX-103, GDX-105, and GDX-203, can facilitate thermal desorption below 270 ℃, which is the maximum tolerance temperature for series 1 and 2, thus providing evidence for the feasibility of using these adsorbents for the thermal adsorption/desorption of dioxins. When the detection temperature is less than 310 ℃, 1,2,3,4-TCDD is thermally desorbed from mordenite, but 1,2,3,8,9-PCDF is not; this indicates the selective adsorption of dioxin monomers on zeolite. However, diatomite and montmorillonite have poor adsorption capacity for dioxins in the gas phase, thus being unsuitable for the thermal trapping of dioxins. Florite, silica gel, alumina, GDX-102, GDX-103, and GDX-203, which have strong adsorption capacities, were selected as possible absorbents for the next evaluation. Comparison of the lnKSA values of dioxin monomers on the same adsorbent at 120 ℃ and 270 ℃ revealed that the retention volume of florite was the largest at both temperatures. When the thermal trapping performance of dioxin at low temperatures is considered, florite is thought to be the best among the 11 adsorbents for capturing dioxins. However, when the desorption performance at high temperatures is considered, GDX-102 is the best adsorbent for the thermal desorption of dioxins, and its lnKSA,270 ℃ is the smallest among those for the aforementioned six adsorbents. The lnKSA,120 ℃ and lnKSA,270 ℃ values of silica gel, GDX-103, and GDX-203 are similar to those of GDX-102, and hence, they can also be used as rapid thermal adsorption/desorption materials. In this study, the thermal adsorption/desorption properties of 1,2,3,4-TCDD and 1,2,3,7,8-PCDF on 11 adsorbents were systematically evaluated to obtain a new solution for the sampling and preparation of dioxins and to provide technical support for the thermal capture of dioxins. It should be noted that these results were obtained under ideal conditions of nitrogen, without considering the influence of the complex conditions of flue gas (such as moisture and CO2) on the thermal capture. To achieve the thermal capture of dioxins in incineration flue gas, it is necessary to carry out the relevant evaluation and test research in a flue gas atmosphere.

The dose effect of dansyl chloride on the derivative products of bisphenols and its application for the determination of bisphenols in human serum by high-performance liquid chromatography-tandem mass spectrometry.

Human exposure to bisphenols has rarely been reported. The most important challenges in this regard are the sensitivity and accuracy of the analytical methods employed. Dansyl chloride derivatization prior to high-performance liquid chromatography-tandem mass spectrometry has been prevalently employed to improve sensitivity. However, the dose effect of the derivatization reagent on the reaction products is not well understood, especially for reactants with two or more active groups. This study investigated the mass ratio of dansyl chloride to bisphenols and found the mass ratio played a vital role in changing the composition of derivatives; further, the optimal ratio for obtaining di-substituted derivatives was confirmed. Under optimal conditions, solid-phase extraction followed by dansyl chloride derivatization coupled with high-performance liquid chromatography-tandem mass spectrometry was used to detect eight bisphenols in human serum samples. The method detection limits of the eight bisphenols were 0.025-0.28 ng/mL, and the recoveries were 72.9-121.7% by spiking bisphenols (2, 5, and 20 ng/mL) into bovine serum. The detection frequencies of bisphenol A and bisphenol F in 73 serum samples obtained from children from Guangzhou were 41.1% and 71.2%, respectively, while the detection frequencies of other bisphenols were below 20%. The concentrations of bisphenol A and bisphenol F were < 0.28-8.0 ng/mL and < 0.028-7.6 ng/mL, respectively.

Biosynthetic L-tert-leucine using Escherichia coli co-expressing a novel NADH-dependent leucine dehydrogenase and a formate dehydrogenase

BACKGROUND: L-tert-Leucine has been widely used in pharmaceutical, chemical, and other industries as a vital chiral intermediate. Compared with chemical methods, enzymatic methods to produce L-tert-leucine have unparalleled advantages. Previously, we found a novel leucine dehydrogenase from the halophilic thermophile Laceyella sacchari (LsLeuDH) that showed good thermostability and great potential for the synthesis of L-tertleucine in the preliminary study. Hence, we manage to use the LsLeuDH coupling with a formate dehydrogenase from Candida boidinii (CbFDH) in the biosynthesis of L-tert-leucine through reductive amination in the present study. RESULT: The double-plasmid recombinant strain exhibited higher conversion than the single-plasmid recombinant strain when resting cells cultivated in shake flask for 22 h were used. Under the optimized conditions, the double-plasmid recombinant E. coli BL21 (pETDute-FDH-LDH, pACYCDute-FDH) transformed 1 mol·L-1 trimethylpyruvate (TMP) completely into L-tert-leucine with greater than 99.9% ee within 8 h. CONCLUSIONS: The LsLeuDH showed great ability to biosynthesize L-tert-leucine. In addition, it provided a new option for the biosynthesis of L-tert-leucine.

Monitoring gas- and particulate-phase short-chain polychlorinated paraffins in the urban air of Dalian by a self-developed passive sampler.

The concentration of short-chain polychlorinated paraffins (SCCPs) in the urban air of Dalian, China was monitored from September 2016 to August 2017 with a self-developed passive sampler (PAS1) and an active high-volume sampler, simultaneously. PAS1 successfully collected the entire target SCCPs in the ambient air. Air SCCPs sampled by PAS1 were found be in the linear uptake stage during 181 days of sampling. Passive and active samples showed comparable congener profiles, and the dominant contributors of SCCPs in the two kinds of samples were similar. A significant linear correlation was observed between the total concentration of SCCPs sampled by PAS1 and active sampler in the four seasons. The passive sampling rates of the PAS1 for the gas and particulate phases of SCCPs were measured. The quantitative structure-property relationship of the sampling rate of PAS1 (Rair) for gas-phase SCCPs was studied. From the molecular point of view, Rair was mainly affected by the molecular weight and sub-cooled liquid vapor pressure of SCCPs. In general, SCCPs in the urban air of Dalian mainly existed in gas phase, lower molecular weight SCCPs primarily occurred in the gas phase, whereas higher molecular weight SCCPs were predominately adsorbed or absorbed on airborne particles. The air concentration of SCCPs in the four seasons were different, the correlation of the concentration of SCCPs in the air with the meteorology parameters was conducted. The exposure risk by intake air SCCPs of the residents around the sampling sites was evaluated according to the European risk assessment standards.

Hyperbranched mixed-mode anion-exchange polymeric sorbent for highly selective extraction of nine acidic non-steroidal anti-inflammatory drugs from human urine.

This paper describes the poly(divinylbenzene) (PDVB) supported synthesis of quaternized hyperbranched macromolecules (QHMs) and its use as a highly selective, high-capacity mixed-mode anion-exchange (MAX) sorbent. In detail, the aminated PDVB support was firstly synthesized by copolymerization of divinylbenzene and 2-(diethylamino)ethyl methacrylate via Pickering emulsion polymerization. The QHMs were then grafted on PDVB by a divergent synthesis involving consecutive reactions of resorcinol diglycidyl ether with methylamine (N, N-dimethylethanolamine for terminal epoxides), which brought in a high density of quaternary ammonium functionalities. The changes of specific surface area (SBET), pore volume and ion exchange capacity (IEC) with generation number reveal that the QHMs have been grown successfully within the large meso-channels of the porous aminated PDVB. The best compromise between the SBET, pore volume and IEC was obtained at the 4th generation (G4). Due to the highest IEC (0.47 meq/g), the G4-QHMs was successfully applied for mixed-mode solid phase extraction (SPE) of acidic non-steroidal anti-inflammatory drugs (NSAIDs). An efficient approach based on the mixed-mode SPE coupled with HPLC-UV was developed for highly selective extraction and cleanup of nine NSAIDs (tolmetin, TLM; ketoprofen, KEP; naproxen, NAP; flurbiprofen, FLB; diclofenac, DIC; indomethacin, INM; ibuprofen, IBP; mefenamic acid, MFA; tolfenamic acid, TFA) in human urine samples. Under the optimized conditions, the method exhibited satisfactory recoveries ranging from 81.9% to 104.0% with relative standard deviation (RSD) values below 8.5%, good sensitivity (0.004-0.009 µg mL-1 limit of detection) and good linearity (coefficient of determination, R2 > 0.997, 0.01-0.2 µg mL-1 for NAP, 0.05-1.0 µg mL-1 for FLB, DIC, INM, MFA, TFA, 0.1-2.0 µg mL-1 for TLM, KEP, IBP). The hyperbranched MAX sorbent is superior to Oasis HLB and comparable to Oasis MAX in obtaining clean chromatographic profiles. Our results demonstrate the potential application of the hyperbranched MAX for complex sample analysis.

Levels and gas-particle partitioning of hexabromocyclododecanes in the urban air of Dalian, China.

The concentrations of α-, ß-, and γ-hexabromocyclododecane diastereomers (HBCDs) in gas phase and particulate phase of Dalian urban air, China, were monitored from September 2016 to August 2017 with high-volume active sampler. The total concentration of ∑HBCDs (gas phase + particulate phase) ranged from 15.47 to 43.57 pg m-3, with an average of 27.07 pg m-3, and 73.39-96.76% of the total HBCDs were found in the particulate phase. No matter in gas phase or in particulate phase, α-HBCD was the predominant component in all, and there was a good negative correlation between the relative contribution of α-HBCD to ∑HBCDs and that of γ-HBCD to ∑HBCDs. The average ratios of the air concentration of α-HBCD to γ-HBCD were comparable with those found in decorative polystyrene, which indicated that HBCDs in outdoor air of Dalian probably came from indoor air and ventilation air from inside of buildings coupled with the already present contamination in background air. There were clear seasonal differences in the HBCD concentrations. Spearman's rank correlation analysis between the concentrations of HBCDs with meteorological parameters was conducted. The exposure risk of HBCDs was evaluated, which illustrated that the estimated exposure of HBCDs via the outdoor air in Dalian was well below the reference doses (200 ng kg-1 bw day-1) derived by the US National Research Council.

Ammonium hydroxide enhancing electrospray response and boosting sensitivity of bisphenol A and its analogs.

As one of the most important analytical techniques for accurate quantification of bisphenol compounds, liquid chromatography coupled to online electrospray ionization (ESI) tandem mass spectrometry exhibits relative weak ESI response in negative mode, which greatly reduces their sensitivity and limits their detection at trace levels, especially in complex samples such as blood. Based on the facilitated deprotonation of bisphenol molecule under alkaline condition, post-column injection of ammonium hydroxide (NH3·H2O) to mass spectrometer was explored to enhance the ionization efficiency of BPA and its eight analogs and improve their analytical sensitivity. Parameters effecting response intensity and stability were investigated, including mass concentration and flow rate of NH3·H2O. Under the optimal conditions with the addition of 2% (w/w) of NH3·H2O at 4 µL min-1, the instrument detection limits for bisphenol compounds were greatly lowered to 0.001-0.04 ng mL-1, which were 2-28.6 times lower than the result obtained without injecting NH3·H2O, except TBBPA (0.03 ng mL-1 in either case). The relative standard deviations (RSDs) for instrument repeatability of BPA and its analogs at three different concentration levels were in a range of 1.2-20%. Furthermore, a decreased matrix effects (90-111%) for bisphenols (except TBBPA) analysis in serum extracts were found compared with the result obtained without NH3·H2O injection (43-111%). The results demonstrated that the improved instrumental method coupled with suitable pretreatment techniques is more feasible to analyze bisphenol compounds in complex bio-samples.

Multiresidue determination and potential risks of emerging pesticides in aquatic products from Northeast China by LC-MS/MS.

A simple method for determining 33 pesticides with a wide polarity range (logKow 0.6-4.5) in aquatic products was developed based on LC-MS/MS. The target analytes included three types of widely used pesticides: insecticides, fungicides and herbicides. Based on the optimization of ultrasonic assisted extraction and GPC clean-up procedures, the matrix effect, extraction recoveries and LOD were improved distinctively. LOQ of this method was below 0.5ng/g for all pesticides, which is superior to values in the literature, and the matrix effect was reduced effectively (-14.7% to 7.5%). The method was successfully applied to investigate the pesticide residue levels of twenty-five samples including seven common kinds of fishes from Northeast China. The results showed that all targeted pesticides were present in the fish samples; however, their levels were low, except for atrazine, linuron, ethoprophos, tetrachlorvinphos, acetochlor and fenthion. Atrazine and linuron caught our attention because the concentrations of atrazine in fish samples from Liaoning province were in the range of 0.5-8ng/g (w/w) with mean concentration of 2.3ng/g, which were far above those of other pesticides. The levels of linuron were in the range of 0.6-6ng/g (mean concentration 2.8ng/g), which were the highest among all targeted pesticides in the Inner Mongolia. This is the first systematic investigation on the characteristics and levels of these pesticides in aquatic products from northeast China. Considering their toxicity and bioaccumulation, the potential risk of atrazine and linuron from consuming aquatic products should be paid more attention.

[Determination of hexabromocyclododecanes in ambient air by high performance liquid chromatography- electrospray ionization-mass spectrometry].

A high performance liquid chromatography-electrospray ionization-mass spectrometry (HPLC-ESI-MS) method was developed for the determination of hexabromocyclododecanes (HBCDs) in ambient air samples. The samples were extracted by Soxhlet extractor with hexane, then purified on the composite gel column. At first, the interfering substances were rinsed with 50 mL hexane and 100 mL hexane-dichloromethane (9:1, v/v), then 180 mL hexane -dichloromethane (4:1, v/v) was used to elute the targets. The compounds were separated by gradient elution with acetonitrile-methanol-water as mobile phases on a UF-ODS column (150 mm×2.1 mm, 3.0 µm). Electrospray ionization negative ion source and selective ion monitoring (SIM) mode were adopted in MS detection. The results showed that α -HBCD, ß -HBCD and γ -HBCD could be well separated, and the chromatographic peak area ratio of α -HBCD, ß -HBCD and γ -HBCD to internal standard D18- γ -HBCD with their concentrations had a good linear relationship, with the correlation coefficients (R) ≥ 0.9988. The limits of detection (LODs, S/N=3) of α -HBCD, ß -HBCD and γ -HBCD were 0.4, 0.5 and 0.4 µg/L, respectively. The limits of quantification (LOQs, S/N=10) were 1.4, 1.6 and 1.3 µg/L, respectively. The method detection limits (MDL) were 0.13, 0.17 and 0.13 pg/m3 (n=5), respectively. The recoveries of HBCDs spiked in the actual air samples were in the range of 74.8%-95.8%. It is demonstrated that the method has high sensitivity and good selectivity, and can meet the requirement of monitoring and analyzing HBCDs in air samples.

Concentrations and inhalation risk assessment of short-chain polychlorinated paraffins in the urban air of Dalian, China.

The concentrations of short-chain polychlorinated paraffins (SCCPs) in the urban air of Dalian, China, were monitored from March to October 2010 and from September to October 2016 with active high-volume sampler. The total concentration of SCCPs (particulate phase + gas phase) ranged from 15.12 to 66.44 ng m-3, with an average of 30.26 ng m-3 in 2010, and 65.30 to 91.00 ng m-3, with an average of 78.15 ng m-3 in 2016. Hexa-chlorinated dodecane and hexa-chlorinated undecane are the predominant components in the gas phase, while octa-chlorinated undecane and hepta-chlorinated tridecane are dominant in the particulate phase. In 2010, 82.57-97.16% of the total SCCPs were found in the gas phase, except that in winter, where 63.11% of the total SCCPs were in the particulate phase; the air concentrations of SCCPs in gas phase were summer > autumn > spring > winter, which was positively correlated with the change of the average ambient temperature, while it was the contrary in particulate phase. In autumn, the gas phase and the total air concentration of SCCPs in 2016 were 2.57 times more than that in 2010, while the congener group patterns of SCCPs were similar. Spearman's rank correlation analysis between the concentrations of SCCPs with meteorological parameters was conducted. The gas-particle distribution was examined through the relationship of the logarithm of the gas-particle partition coefficient with that of the subcooled vapor pressure and the octanol-air partitioning coefficient of SCCPs. Results indicated that the absorption mechanisms contributed more to the partitioning process. The exposure risk of SCCPs was evaluated, which illustrated that the estimated exposure of SCCPs via the outdoor environment in Dalian did not exceed the health concern threshold of the European risk assessment.

Hexabromocyclododecane and tetrabromobisphenol A in sediments and paddy soils from Liaohe River Basin, China: Levels, distribution and mass inventory.

Hexabromocyclododecane (HBCD) and tetrabromobisphenol A (TBBPA) are two kinds of brominated flame retardants and widely present in the environment and biota. The levels, spatial distributions and mass inventories of HBCD and TBBPA were investigated in sediments and paddy soils from the Liaohe River Basin in northeast China. The concentrations of ΣHBCD and TBBPA were in the range of not detected (nd) to 4.02ng/g dry weight (dw) and 0.03 to 4.06ng/g dw, respectively. γ-HBCD was dominated in sediments, while the abundance of α-HBCD was relatively high in paddy soils. The spatial distributions of HBCD and TBBPA in surface sediments and paddy soils indicated that the local point-input was their major source. The significant correlation between total organic carbon (TOC) contents and the HBCD levels suggested that TOC content also exerted an influence on the distribution of HBCD in sediments. Meanwhile, it was found that the irrigation with river water was not the major transportation pathway of HBCD and TBBPA in paddy soils. Based on the study, it was estimated that there were about 1.67tons HBCD and 2.20tons TBBPA deposited into sediments of the Liaohe River system every year. The total mass inventories of HBCD and TBBPA in sediments were far higher than that in paddy soils.

Dendrimer-functionalized mesoporous silica as a reversed-phase/anion-exchange mixed-mode sorbent for solid phase extraction of acid drugs in human urine.

A new dendrimer-functionalized mesoporous silica material based on large-pore 3D cubic Korea Advanced Institute of Science and Technology-6 (KIT-6) was synthesized by the growing of dendritic branches inside the mesopores of aminopropyl functionalized KIT-6. Detailed physical characterizations using transmission electron microscopy, nitrogen adsorption-desorption measurements, Fourier transform infrared (FTIR) spectroscopy, and elemental analysis reveal that the multifunctional dendrimers have been grown successfully within the confined spaces of mesopores. Although the 3D ordered mesoporous architecture of KIT-6 was well preserved, there was a significant and continuous decrease in pore size, specific surface area (SBET) and pore volume when increasing dendrimer generation up to six. In order to get a compromise between the SBET, pore size and density of functionalities, the dendrimer-functionalized KIT-6 (DF-KIT-6) for generation 2 (SBET, 314.2 m(2) g(-1); pore size, 7.9 nm; carbon and nitrogen contents, 19.80% and 1.92%) was selected for solid phase extraction (SPE) applications. The DF-KIT-6 was then evaluated as a reversed-phase/anion-exchange mixed-mode sorbent for extraction of the selected acidic drugs (ketoprofen, KEP; naproxen, NAP; and ibuprofen, IBU), since the dendrimers contained both hydrocarbonaceous and amine functionalities. The effective parameters on extraction efficiency such as sample pH and volume, type and volume of eluent and wash solvents were optimized. Under the optimized experimental conditions, the DF-KIT-6 based SPE coupled with HPLC-UV method demonstrated good sensitivity (0.4-4.6 ng mL(-1) detection of limits) and linearity (R(2)>0.990 for 10-2000 ng mL(-1) of KEP and IBU, and 1-200 ng mL(-1) of NAP). The potential use of DF-KIT-6 sorbent for preconcentration and cleanup of acid drugs in human urine samples was also demonstrated. Satisfactory recoveries at two spiking levels (30 and 300 ng mL(-1) for KEP and IBU, 3 and 30 ng mL(-1) for NAP) were obtained in the range of 85.7-113.9% with RSD values below 9.3% (n=3).

[Non-target screening of organic pollutants in sediments and sludges using gas chromatography-mass spectrometry and automated mass spectral deconvolution].

A screening method in the combination of ultrasonic extraction, gas chromatography-mass spectrometry detection and automated mass spectrometry deconvolution technique was developed for non-target screening of non-polar and weak polar pollutants in sediments and sludges. The samples were extracted by ultrasonication for 20 min using dichloromethane for three times. The extraction solutions were cleaned-up by gel permeation chromatography and a silica gel column, and then 3 g of copper powder was used to remove the sulfur by ultrasonication for 10 min. Parallel experiments were carried out for 5 times and the RSDs were ranged from 5.8% to 14.9%. Automated mass spectral deconvolution & identification system (AMDIS) would improve the resolution of overlapping peaks, and identify the pure mass spectrum of the analytes in the cases of stronger background interference and co-extracted substances covering. Standard spectrum databases, such as NISTDRUG, NISTEPA, NISTFDA, Mass Spectral Library, etc, would qualitatively identify the organic pollutants in the samples. As a result, a total of 290 organic pollutants were identified, of which 190 and 153 pollutants were found in sediments and sludges, respectively. The identified pollutants included the Environmental Protection Agency (EPA) priority pollutants, pharmaceuticals, herbicides, antioxidants, intermediates, organic solvents and chemical raw materials. The proposed method is proved to be a promising one for non-target screening of complex matrix samples with the advantages of higher sensitivity and better repeatability.

New reversed-phase/anion-exchange/hydrophilic interaction mixed-mode stationary phase based on dendritic polymer-modified porous silica.

A novel dendritic polymer-modified silica (DPS) stationary phase was prepared by a divergent synthesis scheme starting from propylamine on silica by consecutive amine-epoxy reactions with 1,4-butanedioldiglycidyl ether and aniline. Both elemental analysis and infrared spectra data shows the successful growth of dendritic polymer on silica particles. The carbon and nitrogen contents increased with an increasing number of reaction cycles and achieved 25.2% and 2.1% (w/w) after 11 reaction cycles. The combination of a phenyl ring with a quaternary ammonium, or a tertiary amine at the branch point along with embedded polar functionalities (including ether and hydroxyl groups) in the branch, generated hydrophobic, electrostatic, as well as hydrophilic interactive domains. Depending on solute structure and mobile phase composition, the DPS stationary phase provided multiple retention mechanisms, including reversed phase (RP), anion-exchange (AEX), and hydrophilic interactions. The RP capability achieved separation of polycyclic aromatic hydrocarbons. Basic, neutral and acidic molecules were well separated under RP/AEX mixed mode. Effective separation of small polar compounds (such as nucleobases and nucleosides) was also obtained under hydrophilic interaction liquid chromatography (HILIC) mode.

Comprehensive screening and priority ranking of volatile organic compounds in Daliao River, China.

An analytical strategy for comprehensive screening of target and non-target volatile organic compounds (VOCs) in surface water was developed, and it was applied to the analysis of VOCs in water samples from Daliao River. The target VOCs were quantified using purge and trap-gas chromatography-mass spectrometry (P&T-GC/MS). Among 20 water samples, 34 VOCs were detected at least once. For the screening of non-target VOCs, the double distillation apparatus was used for the pre-concentration of VOCs prior to P&T-GC/MS analysis. Subsequently, deconvolution software and NIST mass spectral library were applied for the identification of the non-target compounds. A total of 17 non-target VOCs were identified. The most frequently detected VOCs (detection frequencies >80 %) included toluene, benzene, naphthalene, 1,2-dichloroethane, 1,1,2-trichloroethane, and methyl tert-butyl ether. The distribution of VOCs obviously varied according to the sampling sites. The total concentrations of VOCs in water samples collected from the heavily industrialized cities (Anshan and Liaoyang) and the busy port city (Yingkou) were relatively high. The top ten priority VOCs, including naphthalene, 1,2-dichloroethane, o-xylene, 1,3-dichlorobenzene, tetrachloroethene, 1,2-dichlorobenzene, 1,2,4-trichlorobenzene, ethylbenzene, m-xylene, and p-xylene, were obtained by the ranking of the detected VOCs according to their occurrence and ecological effects. These compounds should be given more attention in monitoring and drainage control strategies.

[Determination of undecanoic acid and 13-methyl-tetradecanoic acid connected to the glyceride with internal standard method and its application to the identification of adulteration of illegal cooking oil].

On the basis of the source of illegal cooking oil (heated vegetable oil and animal oil) and the important referents reflecting their sources, namely, undecanoic acid and 13-methyl-tetradecanoic acid connected to the glyceride, their corresponding ramifications in edible oil were detected with internal standard method. The sensitivity and selectivity of this method were improved by the on-line cleanup and preconcentration. The detection limits of the method were 0.070 mg/kg for undecanoic acid and 0.006 mg/kg for 13-methyl-tetradecanoic acid. Additionally, most of the normal vegetable oils have lower levels of both fatty acids than illegal cooking oils. It was suggested to evaluate the quality of edible oils to some extent on the basis of the contents of undecanoic acid and 13-methyl-tetradecanoic acid.

Bioaccumulation and trophic transfer of polybrominated diphenyl ethers (PBDEs) in a marine food web from Liaodong Bay, North China.

The concentrations of 21 polybrominated diphenyl ethers (PBDEs) congeners were analyzed in organisms within a marine food web collected from the Liaodong Bay, North China. The total concentrations of PBDEs in all samples ranged from 0.87 to 91.4 ng g(-1) lipid weight (lw). BDE-47 was the predominant congener and had a concentration ranging from 0.30 to 36.1 ng g(-1) lw. The trophic magnification factors (TMF) of the PBDEs were calculated using the trophic levels obtained from the stable nitrogen isotope ratios. The TMF value of ∑PBDEs was 3.50 for the entire food web and 2.21 for the food web excluding seabirds. Four concentration ratios, BDE-99/BDE-100, BDE-99/BDE-47, BDE-153/BDE-154 and BDE-183/BDE-154, decreased linearly with the increase of the trophic levels in the invertebrates and the fishes (p<0.01). The results suggested that the PBDEs were steadily metabolized in the trophic transfer process along the food chain.