Retention behavior and solvent optimization of organochlorine pesticides in solid-phase extraction

Summary Plots of capacity factor and retention time vs. elution solvent composition were proved to be useful to interpret the retention behavior of Kepone and its metabolites in a reversed-phase solid-phase extraction and to optimize the elution solvent. The percent recovery of Kepone was largely improved when the solvent was optimized. The standard deviations of the results of extractions were also improved upon the optimization of the solvent.     

Preparation and Crystal Structure of PrNb_5O_(14)

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磷钼酸四氢三铵的制备及其交换性能

磷钼酸四氢三铵的制备及其交换性能臧二乐，梁树权（北京农业大学应用化学系北京１０００９４）（中国院学院化学研究所北京）关键词磷钼酸四氢三铵，制备，离子交换性能通式为Ｍ＿ｎＸＹ＿（１２）Ｏ＿（４０）·ｐＨ＿２Ｏ（其中Ｍ为一价阳离子；Ｘ为Ｐ、Ａｓ、Ｓｉ、Ｇ...     

Na2B2Se7, K2B2S7 und K2B2Se7: Drei Perchalkogenoborate mit neuem polymeren Anionengerüst

Na₂B₂Se₇, K₂B₂S₇, and K₂B₂Se₇: Three Perchalcogenoborates with a Novel Polymeric Anion Network Na₂B₂Se₇ (I 2/a; a = 11.863(4) Å, b = 6.703(2) Å, c = 13.811(6) Å, β = 109.41(2)°; Z = 4), K₂B₂S₇ (I 2/a; a = 11.660(2) Å, β = 6.827(1) Å, c = 12.992(3) Å, β = 106.78(3)°; Z = 4), and K₂B₂Se₇ (I 2/a; a = 12.092(4) Å, b = 7.054(2) Å, c = 13.991(5) Å, β = 107.79(3)°; Z = 4) were prepared by reaction of stoichiometric amounts of sodium selenide (potassium sulfide) with boron and sulfur or of potassium selenide and boron diselenide, respectively, at 600°C with subsequent annealing. The crystal structures consist of polymeric anion chains of composition ([B₂S₇]^2?)_n or ([B₂Se₇]^2?)_n formed by spirocyclically connected five-membered B₂S₃ (B₂Se₃) rings and six-membered B₂S₄ (B₂Se₄) rings. The nine-coordinate alkaline metal cations are situated in between.     

A novel composite chitosan membrane for the separation of alcohol-water mixtures

A novel alcohol dehydration membrane with a three layer structure has been prepared. The top layer is a thin dense film of chitosan (CS), and the support layer is made of microporous polyacrylonitrile (PAN). Between the dense and microporous layer, there is an intermolecular cross-linking layer. This novel composite membrane has a high separation factor of more than 8000 and a good permeation rate of 0.26 kg/m² h for the pervaporation of 90 wt% ethanol aqueous solution at 60°C, 0.8 kg/m² h flux for a n-PrOH/water system and around 1 kg/m² h flux for an i-PrOH/water system using 80 wt% alcohol concentration at 60°C. The separation factor for both cases is more than 10⁵. The separation performance varies with feed composition, operating temperature and conditions of membrane preparation. The results show that the separation factor and flux of this membrane increase with raising the operating temperature. At the same time, the crosslinking layer improves durability of the composite membrane, and the pervaporation performance can be adjusted by changing the structure of the cross-linking layer. The cross section of the composite membrane has been examined by SEM.     

Darstellung und schwingungsspektroskopische Untersuchung von [H3B?Se?Se?BH3]2− und [H3B-μ2-Se(B2H5)]− Kristallstruktur und theoretische Untersuchung der Molekülstruktur von [H3B-μ2-Se(B2H5)]−

Synthesis and Vibrational Spectroscopic Investigation of [H₃B? Se? Se? BH₃]^2? and [H₃B-μ₂-Se(B₂H₅)]^? Crystal Structure and Theoretical Investigation of the Molecular Structure of [H₃B-μ₂-Se(B₂H₅)]^? M₂[H₃B? Se? Se? BH₃] 1 is produced by the reaction between elemental selenium and MBH₄ (1 : 1) in triglyme (diglyme), under dehydrogenation. 1 reacts with an excess of B₂H₆ to give M[H₃B-μ₂-Se(B₂H₅)] 2 which is also formed in the reaction of THF · BH₃ with 1 . These reactions proceed under cleavage of the Se? Se bond and hydrogen evolution. [(C₆H₅)₄]Br reacts with Na · 2 to form [(C₆H₅)₄P] · 2 which crystallizes in the tetragonal space group I4 (Nr. 82). An X-ray structure determination failed because of disordering of the cation and anion. ¹¹B, ⁷⁷Se NMR shifts and ¹J(¹¹B¹H) coupling constants as well as IR- and Raman spectroscopic investigations convey further structural information. Structural data of 2 have been calculated by SCF methods. The anion of 2 may be viewed either as an adduct of Se with B₃H₈^?, or as a bridge substituted selena derivative of B₂H₆.     

Automated sample preparation method for suspension arrays using renewable surface separations with multiplexed flow cytometry fluorescence detection

In this paper, we describe a new method of automated sample preparation for multiplexed biological analysis systems that use flow cytometry fluorescence detection. In this approach, color-encoded microspheres derivatized to capture particular biomolecules are temporarily trapped in a renewable surface separation column to enable perfusion with sample and reagents prior to delivery to the detector. This method provides for separation of the biomolecules of interest from other sample matrix components as well as from labeling solutions. After sample preparation, the beads can be released from the renewable surface column and delivered to a flow cytometer for direct on-bead analysis one bead at a time. Using mixtures of color-encoded beads derivatized for various analytes yields suspension arrays for multiplexed analysis. Development of this approach required a new technique for automated capture and release of the color-encoded microspheres within a fluidic system. We developed a method for forming a renewable filter and demonstrate its use for capturing microspheres that are too small to be easily captured in previous flow cells for renewable separation columns. The renewable filter is created by first trapping larger beads in the flow cell, and then smaller beads are captured either within or on top of the bed of larger beads. Both the selective microspheres and filter bed are automatically emplaced and discarded for each sample. A renewable filter created with 19.9 μm beads was used to trap 5.6 μm optically encoded beads with trapping efficiencies of 99%. The larger beads forming the renewable filter did not interfere with the detection of color-encoded 5.6 μm beads by the flow cytometer fluorescence detector. The use of this method was demonstrated with model reactions for a variety of bioanalytical assay types including a one-step capture of a biotinylated label on Lumavidin beads, a two-step sandwich immunoassay, and a one-step DNA binding assay. A preliminary demonstration of multiplexed detection of two analytes using color-encoded beads was also demonstrated. The renewable filter for creating separation columns containing optically encoded beads provides a general platform for coupling renewable surface methods for sample preparation and analyte labeling with flow cytometry detectors for suspension array multiplexed analyses.     

A High－efficiency Preparation, Properties and Structure of （R, S ）－and （ S, S）－Pyrrolidine－2－carboxylic Acid 3,5－Dioxa－4－boracvclo.hepta [ 2,1－α; 3,4－α′] dinaphthalen－4－yl Esters

A highly-efficient preparative procedure for ( R, S )- and ( S, S)-pyrroHdine-2-carboxyHc acid 3,5-dioxa-4-boracyclohepta[2, 1-α ; 3,4-α′] dlnaphthalen-4-yl esters [ namely ( R, S )-BNBAP and (S, S )-BNBAP] is described and the crystal structure of (R, S )-BNBAP was obtained. The data indicate that ( R, S )-BNBAP is a spirocyclic inner borate salt with almost normal te-trahedral configuration. This structural form may be the basic reason for their high chemical, optical and thermodynamic sta-bility.     

19F-NMR-spektroskopischer Nachweis und Berechnung der statistischen Bildung der gemischten Clusteranionen [(Mo6BrCl)F]2−, n = 0 – 8

¹⁹F NMR Spectroscopic Evidence and Calculation of the Statistical Formation of Mixed Cluster Anions [(Mo₆Br Cl )F ]^2?, n = 0 – 8 The complete system of the innersphere mixed clusters (Mo₆BrCl)⁴⁺ is formed by exchange of innersphere bound Clⁱ against outersphere bound Br^a on tempering the solid [(Mo₆Cl)Br] at 500°C for 16 h. After conversion with conc. HCl into (H₃O)₂[(Mo₆BrCl)Cl] and precipitation of the outer Cl^a with AgBF₄ in ethanol, treatment with tetrabutylammonium(TBA)fluoride yields (TBA)₂ [(Mo₆BrCl)F], a mixture of 22 different species. According to the sets of chemical equivalent fluorine atoms in total 55 ¹⁹F nmr signals are expected, which are really observed in the high resolution 1D-¹⁹F-nmr spectrum. Using increments of chemical shifts, peak intensities and multiplet structures as well as the 2D-¹⁹F/¹⁹F-COSY spectrum the complete and unambiguous assignment of all resonances is achieved. From the measured integral intensities the distribution of the different compounds is determined, revealing statistical formation of the geometrical isomers.     

Die Perthioborate RbBS3, TIBS3 und TI3B3S10

The Perthioborates RbBS₃, TIBS₃, and Tl₃B₃S₁₀ . RbBS₃ (P2₁/c, a=7.082(2) Å, b=11.863(4) Å, c=5.794(2) Å, β=106.54(2)°) was prepared as colourless, plate-shaped crystals by reaction of stoichiometric amounts of rubidium sulfide, boron, and sulfur at 600°C and subsequent annealing. TlBS₃ (P2₁/c, a=6.874(3) Å, b=11.739(3) Å, c=5.775(2) Å, β=113.08(2)°) which is isotypic with RbBS₃ was synthesized from a sample of the composition Tl₂S · 2 B₂S₃. The glassy product which was obtained after 7 h at 850°C was annealed in a two zone furnace for 400 h at 400→350°C. Yellow crystals of TlBS₃ formed at the warmer side of the furnace. Tl₃B₃S₁₀ (P1 , a=6.828(2) Å, b=7.713(2) Å, c=13.769(5) Å, α=104.32(2)°, β=94.03(3)°, γ=94.69(2)°) was prepared as yellow plates from stoichiometric amounts of thallium sulfide, boron, and sulfur at 850°C and subsequent annealing. All compounds contain tetrahedrally coordinated boron. The crystal structures consist of polymeric anion chains. In the case of RbBS₃ and TlBS₃ nonplanar five-membered B₂S₃ rings are spirocyclically connected via the boron atoms. To obtain the anionic structure of Tl₃B₃S₁₀ every third B₂S₃ ring of the polymeric chains of MBS₃ is to be substituted by a six-membered B(S₂)₂B ring.