An efficient and reusable quaternary ammonium fabric adsorbent prepared by radiation grafting for removal of Cr(VI) from wastewater.

A novel quaternary ammonium polyethylene nonwoven fabric for removing chromium ions from water was prepared via radiation-induced grafting of glycidyl methacrylate and further modification with N,N'-dimethylethylenediamine. The structural and morphological characteristics of the adsorbent were analyzed using Fourier transform infrared spectroscopy (FTIR), thermogravimetry and differential thermogravimetry (TG/DTG), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The influences of several principal factors, including pH value, initial Cr(VI) concentration, contact time, and coexisting anions (including SO42-, CO32-, NO3-, PO43-, and Cl-), on adsorption performance were investigated via batch tests. The results showed that the optimum removal efficiency was 99.2% at pH 3 and the maximum adsorption quantity for Cr(VI) at 25 °C was 336 mg/g. The adsorption kinetic parameters were better fitted with the pseudo-second-order kinetic model, and the equilibrium data were described very well by the Freundlich isotherm model. Furthermore, the as-synthesized adsorbent exhibited excellent regeneration and recyclability while maintaining high adsorption performance after five adsorption/desorption cycles.

Research progress of stoichiogenomics.

Stoichiogenomics is a newly arisen research field, which concerns the element usage biases of biological macromolecules at genome, transcriptome, proteome, metabonome levels. Different biological macromolecules have different element compositions and contents. When the supply of some elements was constrained, natural selection might bias the usage of the monomers (amino acid or nucleotide) to reduce constrained element costs in the synthesis of biological macromolecules. This field is flourishing with the intensive applications of high throughput sequencing and assembly technologies, more and more available metagenomic and metatranscriptomic data, and the applications of new analysis strategies. As a newly emerged cross discipline field, stoichiogenomics integrates stoichiometry, ecology, evolutionary biology, genomics and bioinformatics to provide a whole new perspective for investigating the interactions of the macromolecular evolution and ecosystem, and data mining in the post genomic era. In this review, we summarize the latest research progress of stoichiogenomics from the aspect of the element usage biases in proteins and nucleic acids. Furthermore, new research directions are discussed to provide some valuable references for the research and application of stoichiogenomics.

[Determination of avermectin and ivermectin in swine muscular tissues using high performance liquid chromatography-tandem mass spectrometry].

OBJECTIVE: To develop a method for simultaneous determination of avermectin (AVM) and ivermectin (IVM) in swine muscular tissues using high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). METHODS: The AVM and IVM were extracted with acetonitrile, cleaned with basic alumina solid phase extraction cartridges, separated through C8 column, and then detected by mass spectrometry in positive ion mode with multiple reaction monitoring (MRM) using an electrospray ionization interface, with quantitative ion pair of 890.4/305.3 and 892.5/307.3 for AVM and IVM, respectively. RESULTS: The linear ranges for both AVM and IVM were between 5 microg/L and 100 microg/L, with a correlation coefficient of 0.9999. The detection limit was 2.0 microg/kg. The recoveries at the spiked concentration of 2 microg/kg, 10 microg/kg and 20 microg/kg ranged from 77.4% to 83.1% for AVM and 77.2% to 84.8% for IVM, with relative standard deviation (RSD) ranging from 8.7% to 11.7% for AVM and 6.3% to 10.3% for IVM, respectively. No AVM and IVM residues were detected in samples taken from Chengdu markets. CONCLUSION: A HPLC-MS/MS method was successfully developed for determining AVM and IVM in swine muscular tissues, which is simple, sensitive and precise and can meet both domestic and international requirements.

[Determination of trace thallium by platform-GFAAS after preconcentration with polyurethane foam].

OBJECTIVE: To develop a method for trace thallium determination. METHODS: Thallium (L) was oxidized to thallium (III) by bromine water and the thallium (III) was complexed to [TlCl4]- in 20 mL/100 mL HCI and absorbed by polyurethane foam. The adsorbed thallium was eluted by a boiling water bath and determined by platform-GFAAS. Tl (III) could be analyzed directly and the total Tl be analyzed after oxidation, so speciation could be achieved. RESULTS: In the range of 5-100 ng/mL the linear equation was y = 0.013x + 0. 012 with the regression coefficient 0.996. The relative standard deviation was 4.7% for the standard solution of 5.00 ng/mL and the recoveries of water samples were in the range of 95.7%-104.5%. CONCLUSION: The proposed method could determine trace thallium as low as 0.02 ng/mL.