LC Determination of 4-Bromoaniline in Green Algae Chlamydomonas reinhardtii After Continuous-Flow Microextraction

In this study, the determination of 4-Bromoaniline (4-BA) in green algae Chlamydomonas reinhardtii (C. reinhardtii) was investigated by applying continuous-flow microextraction (CFME) combined with high-performance liquid chromatography (HPLC). Continuous-flow microextraction was conducted in a homemade glass chamber, i.e. the sample solution flowed through a constant volume drop of solvent in the chamber at a constant flow rate. The effects of different factors on extraction efficiencies were also investigated and these factors included the kind of extraction solvent, solvent drop volume, sample flow rate, extraction time and addition amount of salt. Under the optimum extraction conditions (extraction solvent, carbon tetrachloride; solvent drop volume, 3.5 μL; sample flow rate, 1.0 mL min⁻¹; extraction time, 10 min; no addition of salt), the calibration plot was set up by plotting peak area against a series of 4-Bromoaniline concentrations (0.01–10 μg mL⁻¹) in aqueous solution. The correlation coefficient (r) was 0.9990. The limit of detection (LOD) was 0.6 ng mL⁻¹. The precision of this method was obtained by successive five time analyses of 100-ng mL⁻¹ standard solution of 4-Bromoaniline, and the relative standard deviation (RSD) was 3.5%. The concentration factor was calculated by the ratio of peak area of the analyte obtained after and before extraction and found to be 10.6. 4-Bromoaniline residues in Chlamydomonas. reinhardtii cells and tap water samples were satisfactorily analyzed according to the method described above.     

A simple and efficient colorimetric anion receptor for H(2)PO(4)(-)

A novel and neutral anion sensor bearing a urea group as binding sites and 2,4-di nitrophenylhydrazine unit as a molecular architecture and a chromophore was synthesized and the visible color changes, the UV-vis and (1)H NMR spectral responses toward anions were assessed.     

UV-visible spectroscopic study of the salicyladehyde benzoylhydrazone and its cobalt complexes

Salicyladehyde benzoylhydrazone (SBH) has three groups suitable for forming coordination bond with transition metal. The UV-vis absorption spectra of SBH and its Co(II) complexes in various media were studied by using the deconvolution method. It is found that the structure of complex in solution is different from those in solid crystals. The nature of complexes in solution depends on acidity of the phenolic proton of SBH and on the medium. In neutral or slightly acid medium, the SBH is a non-charged bidentate ligand. And the "free" hydroxyl group on the SBH molecule makes it possible to form hydrogen bonds in solution. In basic medium, the SBH is a mono, negatively charged tridentates ligand.     

Simultaneous determination of cations, zwitterions and neutral compounds using mixed-mode reversed-phase and cation-exchange high-performance liquid chromatography

A novel mixed-mode reversed-phase and cation-exchange high-performance liquid chromatography (HPLC) method is described to simultaneously determine four related impurities of cations, zwitterions and neutral compounds in developmental Drug A. The commercial column is Primesep 200 containing hydrophobic alkyl chains with embedded acidic groups in H(+) form on a silica support. The mobile phase variables of acid additives, contents of acetonitrile and concentrations of potassium chloride have been thoroughly investigated to optimize the separation. The retention factors as a function of the concentrations of potassium chloride and the percentages of acetonitrile in the mobile phases are investigated to get an insight into the retention and separation mechanisms of each related impurity and Drug A. Furthermore, the elution orders of the related impurities and Drug A in an ion-pair chromatography (IPC) are compared to those in the mixed-mode HPLC to further understand the chromatographic retention behaviors of each related impurity and Drug A. The study found that the positively charged Degradant 1, Degradant 2 and Drug A were retained by both ion-exchange and reversed-phase partitioning mechanisms. RI2, a small ionic compound, was primarily retained by ion-exchange. RI4, a neutral compound, was retained through reversed-phase partitioning without ion-exchange. Moreover, the method performance characteristics of selectivity, sensitivity and accuracy have been demonstrated to be suitable to determine the related impurities in the capsules of Drug A.     

Solid-phase synthesis of azidomethylene inhibitors targeting cysteine proteases

An efficient strategy for the solid-phase synthesis of azidomethylene inhibitors targeting cysteine proteases is described. The method is highlighted by its compatibility with readily available building blocks, as well as its ability to accommodate different functional groups. A 249-member library has thus far been successfully synthesized, characterized, and screened against Caspase-1, -3 and -7.     

Karman vortex street assisted patterning in the growth of silicon nanowires

A Karman vortex street was employed to pattern catalysts and grow nanomaterial arrays, which were made of a disk-like superstructure built of silicon nanowires; there also existed nanowires connected with the disks.     

Modeling of radionickel sorption on MX-80 bentonite as a function of pH and ionic strength

MX-80 bentonite was detected using acid-based titration, XRD and FTIR in detail. The sorption behavior of 63Ni(Ⅱ) from aqueous solution to MX-80 bentonite was investigated as a function of solid content, ionic strength and pH by using batch technique. The experimental data of 63Ni(Ⅱ) sorption on MX-80 bentonite was obtained using the diffuse layer model (DLM) with the aid of FITEQL 3.1 program. The results indicated that the sorption of 63Ni(Ⅱ) on MX-80 bentonite was mainly dominated by surface complexation...     

A simple and efficient colorimetric anion sensor based on a thiourea group in DMSO and DMSO-water and its real-life application

An efficient colorimetric sensor with a thiourea moiety as binding sites and p-nitrophenylhydrazine as a signaling unit has been synthesized by only one single-step procedure. Selectivity for anions with the distinct geometry (tetrahedral, trigonal planar and spherical) has been investigated in dry DMSO and even in DMSO/H(2)O (95:5, v/v) solutions through the naked-eye experiment, UV-vis titration and (1)H NMR titration techniques. In particular, the fluoride of toothpaste can be detected qualitatively by the sensor 1.     

Synthesis and Structure of an Extremely Air‐Stable Binuclear Hafnocene Perfluorooctanesulfonate Complex and Its Use in Lewis Acid‐Catalyzed Reactions

Stable complexes : An extremely air‐stable μ²‐hydroxy‐bridged binuclear hafonocene perfluorooctanesulfoante complex shows high catalytic efficiency in Lewis acid‐catalyzed reactions, such as esterification, Friedel–Crafts acylation, the Mukaiyama aldol reation, and the allylation of aldehyde (see scheme).