Quantitative determination of glyphosate in human serum by 1H NMR spectroscopy

The determination and quantification of glyphosate in serum using (1)H NMR spectroscopy is reported. This method permitted serum samples to be analysed without derivatization or any other sample pre-treatment, using 3-trimethylsilyl 2,2',3,3'-tetradeuteropropionic acid (TSP-d(4)) as a qualitative and quantitative standard. Characterization of the herbicide N-(phosphonomethyl)glycine was performed by analysing chemical shifts and coupling constant patterns. Quantification was performed by relative integration of CH(2)-P protons to the TSP-d(4) resonance peak. The method was tested for repeatability (n=5) and yielded coefficients of variation of 1% and 3%, respectively: detection and quantification limits were also determined and were 0.03 and 0.1mmol/L, respectively. The method was applied to the quantification of glyphosate in a case of acute poisoning.     

Capillary electrophoresis analysis of inorganic cations in post-blast residue extracts applying a guanidinium-based electrolyte and bilayer-coated capillaries

A new CE method was developed for the identification and quantitation of inorganic cations in post‐blast residues. The simultaneous analysis in 20 min total runtime of eight cations in post‐blast residues (ammonium, potassium, monomethylammonium, calcium, sodium, magnesium, strontium), plus lithium cation as the internal reference, was carried out with a BGE involving a non‐CMR (carcinogenic, mutagenic, and harmful to reproduction) chromophore (guanidinium cation) and a double‐layer modified capillary (hexadimethrine bromide/polyvinylsulfonate). A study of UV detection conditions using guanidinium ion as the probe led us to set the analysis and reference wavelengths and their associated bandwidths as well as the probe concentration fixed at 15 mM. The successive multiple ionic‐polymer layer approach limited the cation adsorption on capillary wall and improved the EOF stability. These caused a significant improvement in method repeatability. Intermediate precisions were 2.4% for corrected areas and 1.3% for normalized migration times. Limits of detection close to 1 mg/L for all cations were obtained. The matrix effects were studied with chemometric approach for different matrices representative of those collected after explosion. Tests with blank matrix extracts of soil, cloth, and with simulated matrix extract containing 800 mg/L Ca²⁺ and 500 mg/L Fe²⁺ were carried out and no significant matrix effects were observed. Finally, analyses of real residues collected after cash dispenser and homemade firework explosions demonstrate excellent correlation between the CE results and those obtained with the ion chromatography method used routinely.     

Adventitious formation of a new oxopentadienyl Mn(I) tricarbonyl complex: Structural study and bonding investigation of (η-CH2C(Fc)CHC(Fc)O)Mn(CO)3

A Mn(I) tricarbonyl complex of a 1,3-diferrocenyl-1-oxopentadienyl ligand was synthesised adventitiously by what seems to be an in-situ aldol-like condensation of two acetylferrocene units promoted by benzyl-Mn(CO)₅. X-ray structural analysis of this unexpected product confirms the η⁵ coordination of the 1,3-diferrocenyl-1-oxopentadienyl ligand to the Mn(CO)₃ moiety. The nature of the metal-ligand bonding relationship was studied by theoretical calculations; it outlines the charge unbalance (polarisation) at the oxopentadienyl moiety as well as the lack of ketone character of the latter Mn-bound ligand.     

Hierarchical structure in polymer‐based drug delivery systems as probed by calorimetric measurements

Thermoporosimetry (TPM), a differential scanning calorimetry technique that relies on the shift of transition temperatures caused by the confinement of liquids, was applied to elucidate the complex morphology of drug‐loaded polymeric microcapsules prepared by the emulsion solvent evaporation method. For the very first time, TPM has been applied simultaneously with two liquids as structural probes. It was found that Miglyol, which dissolves the selected drug (Ibuprofen), is confined inside vesicles having a mean radius of 26.3 nm, whereas water, which is the continuous phase, is trapped inside a swollen polymeric network of Eudragit with an average mesh radius of 1.7 nm. A proposed hierarchical structure is given, which predicts that Eudragit microcapsules are formed from a collection of inert oil vesicles partitioned by polymeric Eudragit membranes swollen by water. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1939–1945, 2010     

Possible use of DFT approaches for the determination of double exchange interactions

DFT calculations are performed on a model mixed-valence system presenting a double exchange phenomenon. Due to the intrinsic multireference character of the lowest Ms components of the spin states, it is shown that the interactions involved in the double-exchange model cannot be simply extracted from the DFT energies as it is sometimes done. It is, however, possible to extract from different DFT single determinant energies the interactions of a generalized Hubbard Hamiltonian, from which, in a second step, the double-exchange spectrum may be evaluated. The problems generated by the charge and spin polarization are discussed in both symmetric and non symmetric geometries, and the sensitivity of the results to the choice of the density functional is illustrated.     

A Cox Process Involved in the Bose–Einstein Condensation

The point process corresponding to the configurations of bosons in standard conditions is a Cox process driven by the square norm of a centered Gaussian process. This point process is infinitely divisible. We point out the fact that this property is preserved by the Bose–Einstein condensation phenomenon and show that the obtained point process after such a condensation occured, is still a Cox process but driven by the square norm of a shifted Gaussian process, the shift depending on the density of the particles. This law provides an illustration of a “super”- Isomorphism Theorem existing above the usual Isomorphism Theorem of Dynkin available for Gaussian processes. Submitted: February 8, 2008. Accepted: March 5, 2008.     

A serendipitous conversion of enaminolactone nitriles with primary amines: a new synthesis of substituted 2-aminopyridine derivatives

In the course of our studies on Cerpegin analogues synthesis, a serendipitous reactivity of enaminolactone nitrile has been observed. Instead of expecting iminocerpegins, we have gained new class of substituted 2-aminopyridines. The methodology has been applied on a wide range of primary amines, as aliphatic, aromatic, heteroaromatic and also, diamines, hydrazines and chiral amines.     

Bacteria encapsulation in colloidal inorganic matrices: Is it a general method?

Zirconium oxyhydroxide nanoparticles prepared by an aqueous route were evaluated for Escherichia coli bacteria encapsulation. A low viability rate was measured 24 hours after immobilization that could be attributed to nanoparticle cytotoxicity. Moreover, the presence of glycerol, a long-term cell-preserving molecule, hindered gel formation, probably due to its adsorption on the nanoparticle surface. A comparison with boehmite and ferrihydrite gels previously synthesized following a similar aqueous colloidal route suggests that the generalization of this method will rely on a careful control of the nanoparticle surface reactivity and may require surface chemical modification.