A New Method of Synthesis of Azo Schiff Base Ligands with Azo and Azomethine Donors： Synthesis of N-4-Methoxybenzylidene-2-（3-hydroxyphenylazo）-5-hydroxyaniline and Its Nickel（Ⅱ） Complex

A new method for the synthesis of azo Schiff an base ligand in which the azo and azomethine groups are coordination sites was developed through a Schiff base precursor. The precursor, N-4-methoxybenzylidene-3-hydroxyphenylamine （SB） derived from 3-aminophenol was regioselectively coupled with a diazonium ion para to the hydroxyl group of the amine component of the Schiff base. The para selectivity was controlled by the directing effect of the hydroxyl group. The ligand and its nickel（Ⅱ） complex were characterized by elemental analyses, IR and UV-Vis spectroscopy. The analytical and spectral data supported the mononuclear formulation of the complex with metal to ligand ratio （M ： L = 1 ： 2） and suggested a square planar geometry for the complex.     

Adsorption of the Ternary Liquid Mixture Ethanol/n-Octane/n-Hexadecane onto Activated Carbon: I. The Adsorption Excess of the Ternary Mixture and of Its Binary Combinations

The adsorption isotherms of the binary mixtures of ethanol/n-Octane, ethanol/n-hexadecane and n-octane/n-hexadecane onto the activated carbon TA 95 were measured at 278 K, 288 K, 298 K and 308 K and described with mathematical functions. About 300 experimental values of the adsorption excess of the ternary mixture ethanol/n-octane/n-hexadecane onto activated carbon TA 95 at 298 K were measured by gas chromatography inside the ternary triangle. The ternary miscibility gap was determined at three temperatures. A good representation of the ternary data and the calculated activity coefficients (using the UNIFAC model) in three-dimensional space was possible with the help of transformation of coordinates. It was possible, too, by utilization of the conception of the quasi two-component representation of the mole fractions with and without miscibility gap. Several influencing factors on ternary adsorption isotherms were discussed for the system ethanol/n-octane/n-hexadecane/TA 95.     

Liner as the Key of Injection Optimization in Pesticide Analysis

Regulations for pesticide residue analysis in food require very low detection limits; thus requiring maximum sensitivity in the gas chromatographic determination. This is accomplished by an overall method optimisation, which includes optimisation of injector parameters. Here we study the effect of the inlet liner design on the optimisation by comparing five liner designs in splitless and pulsed splitless injection modes, using a test mixture of fifteen pesticides analyzed by GC-ECD. Possible links between the injection parameters and liner types were evaluated, with the result that, accurate choice of inlet liner and injection parameters can reduce detection limits by up to 300%. Revised: 25 October 2005 and 9 January 2006     

The assessment of compliance with legal limits. Part 2. How to consider both type I and type II errors when working in the concentration domain

Considering the uncertainty of measurement when assessing compliance with reference values given in compositional specifications and statutory limits is still a controversial matter. In theory, assessing compliance requires considering both type I (false positive) and type II (false negative) errors. The more the concentration of the analyte in the sample under investigation is close to the allowed concentration limit, the more critical it is to consider both types of errors. This paper describes how this could be done. The matter is discussed in the light of the most recent literature information.     

Determination of Aldehydes and Ketones in Fuel Ethanol by High-Performance Liquid Chromatography with Electrochemical Detection

A new methodology was developed for analysis of aldehydes and ketones in fuel ethanol by high-performance liquid chromatography (HPLC) coupled to electrochemical detection. The electrochemical oxidation of 5-hydroxymethylfurfural, 2-furfuraldehyde, butyraldehyde, acetone and methyl ethyl ketone derivatized with 2,4-dinitrophenylhydrazine (DNPH) at glassy carbon electrode present a well defined wave at +0.94 V; +0.99 V; +1.29 V; +1.15 V and +1.18 V, respectively which are the basis for its determination on electrochemical detector. The carbonyl compounds derivatized were separated by a reverse-phase column under isocratic conditions with a mobile phase containing a binary mixture of methanol / LiClO_4(aq) at a concentration of 1.0 × 10⁻³ mol L⁻¹ (80:20 v/v) and a flow-rate of 1.1mL min⁻¹ . The optimum potential for the electrochemical detection of aldehydes-DNPH and ketones-DNPH was +1.0 V vs. Ag/AgCl. The analytical curve of aldehydes-DNPH and ketones-DNPH presented linearity over the range 5.0 to 400.0 ng mL⁻¹, with detection limits of 1.7 to 2.0 ng mL⁻¹ and quantification limits from 5.0 to 6.2 ng mL⁻¹, using injection volume of 20 μL. The proposed methodology was simple, low time-consuming (15 min/analysis) and presented analytical recovery higher than 95%.     

Solid products and rate-limiting step in the thermal half decomposition of natural dolomite in a CO2 (g) atmosphere

Natural dolomite powders obtained from caves which give unusual high resistance building materials, have been decomposed in a Knudsen cell at high CO₂ pressures in the temperature range of 913-973 K. XRD traces for the final solid products, after the first half thermal decomposition, have shown, that beside the XRD patterns for the calcite and MgO, the existence of a new structure with major peaks at 2θ equal to 38.5 and 65°. This finding has been ascribed to a solid solution of MgO in calcite. The kinetic analysis of the TG curves yield a total apparent enthalpy (ΔH^∗) for the decomposition equal to 440±10 kJ mol⁻¹ for a range of fraction decomposed (α) varying between 0.2 and 0.7. This value is much closer to the theoretical expected at 950 K value ΔH=486 kJ mol⁻¹ for the dolomite decomposition in CO₂ environment, where CaO, MgO and oxides of solid solution can be the solid reaction products. The rate determining step is the transport of CO₂ across the reacting interface through an high activated thermal process due to solid state diffusion of CO₃²⁻ in the bulk and/or the grain boundaries phases of CaCO₃ and/or of the solid solution. The microstructure evolution of the solid products follows a shear-transformation mechanism. At temperatures below 943 K, porous product particles are characterized by a monomodal narrow pore size distribution around 0.05 μm. At higher temperatures, a critical level of tensions inside the particles is reached and a bimodal pore size distribution around 1 and 0.05 μm is formed.     

Reaktive E = C(p-p)π-Systeme. XLII [1]. Neue Koordinationsverbindungen des 2-(Diisopropylamino)-1-phosphaethins: [{η4-(iPr2NCP)2}Ni{η2-(iPr2NCP)}], [(Ph3P)2Pt{η2-(iPr2NCP)}] und [Co2(CO)6{η2-η2-(iPr2NCP)}]

Reactive E = C(pp)π-Systems. XLII [1]. Novel Coordination Compounds of 2-(Diisopropylamino)-1-phosphaethyne: [{η⁴-(iPr₂NCP)₂}Ni{η²-(iPr₂NCP)}], [(Ph₃P)₂Pt{η²-(iPr₂NCP)}], and [Co₂(CO)₆{η²-μ²-(iPr₂NCP)}] 2-(Diisopropylamino)-phosphaethyne iPr₂N? C?P ( 2 ) reacts with the Ni(0)-complexes [Ni(1,5-cyclooctadiene)₂] and [Ni(CO)₃(1-azabicyclo[2.2.2]octane)], respectively, to give the novel complex [{η⁴-(iPr₂NCP)₂}Ni{η²-(iPr₂NCP)}] ( 5 ), with the 1,3-diphosphacyclobutadiene derivative and 2 (side-on) as π-ligands. The molecular structure of 5 determined by X-ray diffraction on single crystals proves the spin systems and rotational barriers deduced from NMR-data (¹H, ¹³C-, ³¹P). The PC distances of the four-membered ring of 1.817(2) and 1.818(2) Å – as expected – are considerably longer than the PC bond of the η²-coordinated phosphaalkyne 2 [1.671(2) Å]. – In the reactions of 2 with [(Ph₃P)₂Pt(C₂H₄)] or [Co₂(CO)₈] the ligand properties of 2 resemble those of alkynes affording the complexes [(Ph₃P)₂Pt{η²-(iPr₂NCP)}] ( 7 ) with side-on coordinated 2 and [Co₂(CO)₆{η²-μ²-(iPr₂NCP)}] with 2 acting as a 4e donor bridge in quantitative yield. In attempts to prepare copper(I) complexes of the aminophosphaalkyne 2 by reaction with CuCl or CuI the only isolable product formed in reasonable amounts under the influence of air and moisture is the 1 λ³, 3 λ⁵-diphosphetene (iPr₂N) ( 10 ) (isolated yield: ca. 20%). The crystal structure analysis of 10 indicates a strong structural relationship to the diamino-2-phosphaallyl cation [Me(iPr₂N)]⁺ ( 12 ), the 1,3-diphosphacyclobutadiene ligand (iPr₂NCP)₂ in the binuclear complex [{η¹, μ²-(iPr₂NCP)₂}Ni₂(CO)₆] ( 3a ) as well as to the heterocycles (dme)₂LiOE₂′ (E′ = S, 11a ; E′ = Se, 11b ) prepared by Becker et al. [11b, 35].     

ImmobilizedE. coli Alkaline Phosphatase

We have immobilized E.coli alkaline phosphatase (EC 3.1.3.1) by linking it covalently to sepharose 4B. This preparation has several advantages over the soluble enzyme. The immobilized enzyme is easily separable from other constituents in incubation mixtures. The immobilized enzyme can be reused repeatedly and is more stable than the soluble enzyme to heat treatment in the presence of 10 mM Mg²⁺. The insoluble and soluble phosphatases removed 75 and77%, respectively, of the inorganic phosphorus from casein. The immobilized enzyme inactivated two enzymes believed to be active in the phosphorylated state, acyl-CoA : cholesterol acyltransferase (ACAT) by 39% and NADPH-cytochrome P-450 reductase by 89%. The utility of immobilized alkaline phosphatase for studying the phosphorylation and dephosphorylation of soluble or membrane-bound enzymes and proteins is discussed.     

High performance liquid chromatographic determination of metoclopramide in plasma and urine and its application to biopharmaceutical investigations

An optimized HPLC method for the quantification of metoclopramide (MCP) in human plasma and urine is described. MCP and internal standard are extracted from alkalinized substrate into diethyl ether and back-extracted into dilute acid. The analytes are separated with a ternary mobile phase at cyanopropyl-silica and detected at 312 nm (UV detection). The lower limit of quantification is 0.5 ng/ml in plasma and 50 ng/ml in urine. Optimization of extraction, chromatography, and detection is discussed. The method is selective to numerous common drug substances with excellent accuracy and precision data. After validation, the method is applied to the samples of a pharmacokinetic study. Pharmacokinetic parameters indicate the need for a sophisticated method as tool for optimization of metoclopramide formulations.     

Coordination around thorium(IV) in aqueous perchlorate,chloride and nitrate solutions

The coordination around the thorium(IV) ion in aqueous perchlorate, chloride and nitrate solutions has been determined from large angle X-ray scattering measurements. In perchlorate solutions, where inner-sphere complexes are not formed, the first coordination sphere contains 8.0±0.5 water molecules with Th-H₂O bond lengths of 2.48₅ Å. In chloride solutions inner-sphere complexes are formed, which lead to an increase in the coordination number. In nitrate solutions the nitrate ions are bonded as bidentate ligands to the thorium ion. The bond lengths are similar to those found in crystalline hydrates of thorium nitrate. The coordination numbers found for thorium(IV) in solution are compared with previously reported values for lower charged ions of similar size.On leave from Department of Inorganic Chemistry Royal Institute of Technology S-10044 Stockholm Sweden