Rapid Analysis of Seven Polyamines in Nephotettix cincticeps by Using Ultra-Performance Liquid Chromatography-Triple Quadrupole Mass Spectrometry.

A fast, simple, and sensitive method for the simultaneous determination of seven polyamines in Nephotettix cincticeps was developed based on ultra-performance liquid chromatography-triple quadrupole mass spectrometry (UPLC-3Q-MS) together with liquid phase extraction. Polyamines in insect samples were extracted with HClO4 solution and then were separated and detected by UPLC-3Q-MS, which was equipped with a hydrophilic interaction liquid chromatography column, within 5 min without any derivatization procedure. The method has been successfully used to detect 7 polyamines in healthy and difluormethylornithine-treated adults of Nephotettix cincticeps with a method limit of detection and the method limit of quantitation of 24-139 pg/mg and 82-464 pg/mg, respectively, an intraday and interday relative standard deviation (RSD, n = 5) of 1.97-6.00% and 2.08-5.92% respectively, and a recovery of 86-115%. The success of this study provided a reliable method for the rapid and high-throughput detection of polyamines in the insect sample.

Ecosystem health of the Beiyun River basin (Beijing, China) as evaluated by the method of combination of AHP and PCA.

Ecosystem services provided by river ecosystems rely on healthy ecosystem structure and ecological processes. The Beijing-Tianjin-Hebei urban is a typical water-deficient area. As an important part of the urban-rural integration construction, evaluating the health status of the Beiyun River Basin and discovering the weak links in the water environment are the basis for improving the health of the basin. In this study, analytic hierarchy process (AHP) was used to establish an evaluation index system for the Beiyun River Basin from 5 aspects including water quality, biology, ecology, hydrology, and social functions, and the principal component analysis (PCA) was then used to assign weights to the index layer. The evaluation results showed that the health evaluation results of the Beiyun River Basin in 2019 are "sub-healthy," and the overall health status is getting worse from northwest to southeast. In the middle reaches of the region, the evaluation result is "healthy," followed by the upstream, and the downstream is the worst. The results showed that areas with less human interference or orderly intervention are in better health. High eutrophication level, low bio-diversity, and low vegetation coverage are the main indicators that leads to poor ecosystem health in the Beiyun River Basin. For the comprehensive management of the Beiyun River, the improvement of water quality and habitat ecological restoration are key actions to the health of the upstream ecosystem. The improvement of the health status of the downstream should focus on equal emphasis on water quality and quantity, restoration of biodiversity, and improvement of the quality of the riparian ecological environment.

Evaluating surface water quality using water quality index in Beiyun River, China.

The Beijing-Tianjin-Hebei urban agglomeration is one of the most water-scarce regions in China, because of the frequent human activities. Water scarcity and pollution have weakened the service functions of water ecosystems and hindered the regional economic development. As the "lifeline" of the economic development of Beijing-Tianjin-Hebei region, the water quality of Beiyun River has been widely concerned. River water quality assessment is one of the most important aspects to enhance water resources management plans. Water quality index (WQI), as one of the most frequently used evaluation tools, was used to comprehensively analyze the water quality in the Beiyun River. Between January 2017 and October 2018, we collected samples from 16 typical sampling sites along the main rivers of the watershed, covering four seasons. Seventeen water quality parameters, including temperature, pH, conductivity, dissolved oxygen (DO), chemical oxygen demand (COD), biochemical oxygen demand (BOD5), ammonia nitrogen (NH3-N), total phosphorus (TP), oil, volatile phenol (VP), fluoride, sulfide, surfactant, lead (Pb), copper (Cu), zinc (Zn), and arsenic (As), were used to calculate WQI. The average WQI values of Beiyun River in winter, spring, summer, and autumn were 88.15, 71.70, 78.92, and 90.12, respectively, explaining the water quality was "good" generally. There were significant differences in the spatial distribution of WQI values from Beiyun River, and water quality of upstream and downstream was better than that of midstream. In addition, correlation analysis was applied to explore the correlation between land use types and water quality. Water quality was significant negatively correlated with agriculture land and rural residential land, and a positive relationship between urban land and water quality. Generally, we believe that people's related activities on different land use are major elements impacting the water quality. Water environment improvement ought to increase the wastewater collection rate and sewage treatment capacity in rural areas, especially in the midstream of the Beiyun River. Graphical abstract.

Aqueous synthesis of Cu-doped ZnCdS/ZnS core/shell nanocrystals with a new and highly reactive sulfur source.

A new sulfur precursor with a highly reactive chemical nature was prepared with S powder and NaBH4 at the high temperature of 180 °C in a closed autoclave and made it possible to carry out the synthesis of high quality metal sulfide nanocrystals (NCs) with diverse composition and structure. Using this new sulfur source, we demonstrated aqueous synthesis of colloidal Cu-doped ZnCdS NCs (d-dots) with pure, color-tunable photoluminescence (PL) in a wide spectral range (from 517 to 650 nm) based on the 'co-nucleation doping' strategy. The influences of the various experimental variables, including Cd/Zn ratio, Cu-doping concentration, pH value and amount of mercaptopropionic acid (MPA), on the optical properties of Cu-doped ZnCdS NCs were systematically investigated. Furthermore, highly efficient and stable dopant emission from Cu:ZnCdS/ZnS core/shell d-dots with PL quantum yield as high as 40% was achieved by the deposition of a ZnS shell around the bare Cu:ZnCdS cores; this is the highest reported to date for aqueous doped NCs. The optical properties and structure of the d-dots were characterized by UV-vis absorption spectra, PL spectra, x-ray photoelectron spectroscopy, powder x-ray diffraction, and transmission electron microscopy. The experimental results indicated that this facile synthesis route would provide a versatile approach for the preparation of other water-soluble sulfide NCs.

Speciation analysis of mercury in natural water and fish samples by using capillary electrophoresis-inductively coupled plasma mass spectrometry.

A environment-friendly microwave-assisted extraction used to extract trace mercury compounds from fish samples, and a ultra-sensitive method for the analysis of Hg(II), methylmercury (MeHg) and ethylmercury (EtHg) by using capillary electrophoresis-inductively coupled plasma mass spectrometry (CE-ICP-MS) were described in this study. The extraction method is environment-friendly, simple, effective, and can be used to extract trace mercury compounds in fish samples with a satisfied recovery within several minutes. The CE-ICP-MS analytical method has a detection limit as lower as 0.021-0.032 ng Hg/mL for MeHg, EtHg and Hg(II), and can be used to determined ultratrace MeHg, EtHg and Hg(II) in natural water and fish samples directly without any preconcentration. With the help of the above methods, we have successfully determined MeHg, EtHg and Hg(II) in dried fish (Tapertail anchovy) muscle and natural water within 25 min with a RSD (relative standard deviation, n=6) <5% and a recovery of 94-103%. Our results showed that dried muscle of T. anchovy contained only one species of mercury, MeHg, indicating that MeHg is easier to be accumulated by aquatic organisms.

Speciation analysis and characterisation of arsenic in lavers collected from coastal waters of Fujian, south-eastern China.

Laver samples (Porphyra haitanensis) were collected from the coastal waters of Fujian province, south-eastern China and then the speciation characteristics of arsenic in the samples were studied in detail. These laver samples contained five arsenical species, namely arsenobetaine, monomethylarsonic acid, As(V) and two kinds of arsenic-containing ribosides (arsenosugars), with a relatively high concentration of total arsenic in the range of 28.85-63.03µgAs/g dried weight. DMAsSugarMethoxy was found to be the predominant species of arsenic in lavers, accounting for 90-98% of total arsenic. As3+ was not detected and the level of inorganic arsenic was much lower than the national tolerable average residue level (TARL), suggesting that the lavers are safe for consumption.

Facile synthesis of Mn-doped ZnS nanocrystals and determination of critical temperature for lattice diffusion process.

High-quality Mn:ZnS doped nanocrystals (d-dots) with photoluminescence (PL) quantum yield (QY) of 50-70% have been synthesized based on nucleation-doping strategy by choosing 1-dodecanethiol (DDT) as the capping ligand. Controlling the growth of small-sized MnS core nanoclusters was successfully achieved by changing the injection temperature of sulfur precursor, the growth time of MnS nuclei, and the amount of DDT. Furthermore, MnS/ZnS core/shell d-dots with a diffusion layer at the interface between the MnS core and the ZnS shell were fabricated through an overcoating of the ZnS shell layer on the presynthesized MnS core nanoclusters. The resulting monodisperse d-dots exhibited spherical shape with a zinc-blende crystal structure. The critical temperature for lattice diffusion of Mn ions in the ZnS host lattice was determined to be about 260 degrees C by annealing the presynthesized and purified Mn:ZnS d-dots.

[Speciation analysis of arsenic in seaweeds by capillary electrophoresis-inductively coupled plasma mass spectrometry].

A method for the detection of trace As (III), As (V), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), arsenocholine (AsC) and arsenobetaine (AsB) in seaweeds by capillary electrophoresis-inductively coupled plasma mass spectrometry (CE-ICP-MS) was developed. The optimized conditions of CE including chemical component, pH and concentration of the buffer, separation voltage and injection time were studied in detail. The results showed that the above six species of arsenic were baseline separated within 25 min under the optimized conditions. The relative standard deviations (n = 6) of the peak areas were smaller than 5%, and the detection limits (calculated as As) (S/N = 3) were 0.08 - 0.12 microg/L for all the above six species of arsenic. The method has been successfully applied to the determination of the species of arsenic in kelp samples. The recoveries were 90% - 103%. The method has good reproducibility, high sensitivity, short analytical time and strong resistance to complex matrix, and can be used for the speciation analysis of arsenic in real seafood samples.

Speciation analysis of selenium in rice samples by using capillary electrophoresis-inductively coupled plasma mass spectrometry.

An enzyme-assisted extraction used to extract all species of selenium in rice sample and a sensitive analytical method for the determination of ultratrace Se(VI), Se(IV), SeCys(2) (selenocystine) and SeMet (selenomethionine) with capillary electrophoresis-inductively coupled plasma mass spectrometry were firstly described in this study. The extraction method is simple, effective and can be used to extract trace selenium compounds in rice with high extraction efficiency and no altering its species. The analytical method has a detection limit of 0.1-0.9 ng Se/mL, and can be used to determine trace Se(VI), Se(IV), SeCys(2) and SeMet in rice directly without any derivatization and pre-concentration. With the help of above methods, we have successfully determined Se(VI), Se(IV), SeCys(2) and SeMet in selenium-enriched rice within 18 min with a recovery of 90-103% and a RSD (relative standard deviation, n=6) of 3-7%. Our results indicated that selenium-enriched rice contained only one species of selenium, SeMet, and its concentration is in range of 0.136-0.143 µg Se/g dried weight. The proposed method providing a realistic approach for the nutritional and toxical evaluation of different selenium compounds in nutritional supplements.