Pressurised liquid extraction and quantification of fat-oil in bread and derivatives products

A pressurised liquid extraction (PLE) method for extraction and quantification of total fat and oil in bread and derivatives products has been proposed. Parameters implied in the extraction process; such us temperature, static time, number of extraction cycles, purge time and flush volume; have been optimised using a formal methodology based on statistical experimental design in order to obtain the best results. Moreover, this method has been validated using homemade bread elaborated in the laboratory which contained 9.64 g of olive oil in 100 g dry weight. The production and use of an “ad hoc” in-house reference material is just one of the most relevant aspects of this study. The uncertainty estimation has been carried out taking into account all the uncertainty components of the process and it was stated as 4.2%. Finally, the proposed method has been applied to six different Spanish bread derivatives products with different olive oil contents (5-20%) to determine the fat content.     

Determination of N-nitrosamines by HPTLC with Fluorescence Detection — Use of Non-Ionic Surfactants as Enhancing Agents

JPC – Journal of Planar Chromatography – Modern TLC - The dansyl derivatives of N-nitrosodimethylamine, N-nitrosodi-ethylamine, and N-nitrosodibuthylamine have been separated by HPTLC...     

Diverse evolution of [[Ph(2)P(CH(2))(n)PPh(2)]Pt(mu-S)(2)Pt[Ph(2)P(CH(2))(n)PPh(2)]] (n = 2, 3) metalloligands in CH(2)Cl(2)

The nucleophilicity of the [Pt(2)S(2)] core in [[Ph(2)P(CH(2))(n)PPh(2)]Pt(mu-S)(2)Pt[Ph(2)P(CH(2))(n)PPh(2)]] (n = 3, dppp (1); n = 2, dppe (2)) metalloligands toward the CH(2)Cl(2) solvent has been thoroughly studied. Complex 1, which has been obtained and characterized by X-ray diffraction, is structurally related to 2 and consists of dinuclear molecules with a hinged [Pt(2)S(2)] central ring. The reaction of 1 and 2 with CH(2)Cl(2) has been followed by means of (31)P, (1)H, and (13)C NMR, electrospray ionization mass spectrometry, and X-ray data. Although both reactions proceed at different rates, the first steps are common and lead to a mixture of the corresponding mononuclear complexes [Pt[Ph(2)P(CH(2))(n)PPh(2)](S(2)CH(2))], n = 3 (7), 2 (8), and [Pt[Ph(2)P(CH(2))(n)PPh(2)]Cl(2)], n = 3 (9), 2 (10). Theoretical calculations give support to the proposed pathway for the disintegration process of the [Pt(2)S(2)] ring. Only in the case of 1, the reaction proceeds further yielding [Pt(2)(dppp)(2)[mu-(SCH(2)SCH(2)S)-S,S']]Cl(2) (11). To confirm the sequence of the reactions leading from 1 and 2 to the final products 9 and 11 or 8 and 10, respectively, complexes 7, 8, and 11 have been synthesized and structurally characterized. Additional experiments have allowed elucidation of the reaction mechanism involved from 7 to 11, and thus, the origin of the CH(2) groups that participate in the expansion of the (SCH(2)S)(2-) ligand in 7 to afford the bridging (SCH(2)SCH(2)S)(2-) ligand in 11 has been established. The X-ray structure of 11 is totally unprecedented and consists of a hinged [(dppp)Pt(mu-S)(2)Pt(dppp)] core capped by a CH(2)SCH(2) fragment.     

Intramolecular "Aryl-metal chelate ring" pi,pi-interactions as structural evidence for metalloaromaticity in (aromatic alpha,alpha'-diimine)-copper(II) chelates: molecular and crystal structure of aqua(1,10-phenanthroline)(2-benzylmalonato)copper(II) three-hydrate

By reaction of Cu(2)CO(3)(OH)(2), 2-benzylmalonic acid (H(2)Bzmal), and 1,10-phenanthroline (phen), [Cu(Bzmal)(phen)(H(2)O)] x 3H(2)O (compound 1) has been obtained and characterized by thermal, spectral, magnetic, and X-ray diffraction methods. The molecular structure of 1 is remarkably similar to that of [Cu(Bzmal)(bipy)(H(2)O)] x 2H(2)O (compound 2, bipy = 2,2'-bipyridine). In both complexes, the aryl(Bzmal) ring produces an unexpected pi,pi-stacking interaction with the Cu(II)-(aromatic alpha,alpha'-diimine) chelate ring, at an average distance d(pi)(-)(pi) of 3.40 A, involving roughly parallel and smoothly slipped rings. This insight is discussed as new structural evidence for metalloaromaticity of Cu(II)-(aromatic alpha,alpha'-diimine) chelate rings. Interestingly, 1 recognizes itself by a weak intermolecular pi,pi-stacking interaction between aryl(Bzmal) ligands to give pairs of complex molecules. In contrast, there is an intermolecular pyridyl-pyridyl pi,pi-stacking interaction also forming pairs of complex molecules in 2.     

Interligand interactions controlling the mu-N7,N9-metal bonding of adenine (AdeH) to the N-benzyliminodiacetato(2-) copper(II) chelate and promoting the N9 versus N3 tautomeric proton transfer: molecular and crystal structure of [Cu2(NBzIDA)(2)(H2O)(2)(mu-N7,N9-Ade(N3)H)].(3)H2O

The reaction in water of the N-benzyliminodiacetate-copper(II) chelate ([Cu(NBzIDA)]) and the adenine:thymine base pair complex (AdeH:ThyH) with a Cu/NBzIDA/AdeH/ThyH molar ratio of 2:2:1:1 yields [Cu(2)(NBzIDA)(2)(H(2)O)(2)(mu-N7,N9-Ade(N3)H)].3H(2)O and free ThyH. The compound has been studied by thermal, spectral, and X-ray diffraction methods. In the asymmetric dinuclear complex units both Cu(II) atoms exhibit a square pyramidal coordination, where the four closest donors are supplied by NBzIDA in a mer-tridentate conformation and the N7 or N9 donors of AdeH, which is protonated at N3. The mu-N7,N9 bridge represents a new coordination mode for nonsubstituted AdeH, except for some adeninate(1-)-[methylmercury(II)] derivatives studied earlier. The dinuclear complex is stabilized by the Cu-N7 and Cu-N9 bonds and N6-H(exocyclic)...O(carboxyl) and N3-H(heterocyclic)...O(carboxyl) interligand interactions, respectively. The structure of the new compound differs from that of the mononuclear compound [Cu(NBzIDA)(Ade(N9)H)(H(2)O)].H(2)O, in which the unusual Cu-N3(AdeH) bond is stabilized by a N9-H...O(carboxyl) interligand interaction and where alternating benzyl-AdeH intermolecular pi,pi-stacking interactions produce infinite stacked chains. The possibility for ThyH to be involved in the molecular recognition between [Cu(NBzIDA)] and the AdeH:ThyH base pair is proposed.     

Monitoring of the metal displacement from the recombinant mouse liver metallothionein Zn(7)-complex by capillary zone electrophoresis with electrospray MS detection

A solution of a Zn-complex of recombinant mouse MT-1 isoform (Zn(7)-MT-1) was prepared and titrated with Cd(2+) ions. A method based on the coupling of capillary zone electrophoresis (CZE) with electrospray MS detection was developed for the analysis of the stoichiometry of the species formed during the titration. The method offered the possibility of the on-line removal of up to 100 mM Tris or phosphate buffer solutions that would otherwise suppress the electrospray signal. By allowing the determination of the metal stoichiometry of the complex species present in solution the method was shown to be complementary to circular dichroism and UV-VIS spectrophotometry conventionally used for similar studies. The titration of the Zn(7)-MT complex with Cd(II) showed the sequential displacement of the Zn by Cd. The unusually high stability of the Cd(6)Zn(1)-MT species was observed which suggests a structural role of the remaining Zn(II) ion.     

On the Role of the Electronic Structure of the Heteronuclear Oxide Cluster [Ga2Mg2O5].+ in the Thermal Activation of Methane and Ethane: An Unusual Doping Effect

The reactivity of the heteronuclear oxide cluster [Ga₂Mg₂O₅]^.+, bearing an unpaired electron at a bridging oxygen atom (O_b^.?), towards methane and ethane has been studied using Fourier transform ion cyclotron resonance mass spectrometry (FT‐ICR‐MS). Hydrogen‐atom transfer (HAT) from both methane and ethane to the cluster ion is identified experimentally. The reaction mechanisms of these reactions are elucidated by state‐of‐the‐art quantum chemical calculations. The roles of spin density and charge distributions in HAT processes, as revealed by theory, not only deepen our mechanistic understanding of C? H bond activation but also provide important guidance for the rational design of catalysts by pointing to the particular role of doping effects.     

Covalent Grafting of Coordination Polymers on Surfaces: The Case of Hybrid Valence Tautomeric Interphases

We have developed a novel approach for grafting coordination polymers, structured as nanoparticles bearing surface reactive carboxylic groups, to amino‐functionalized surfaces through a simple carbodiimide‐mediated coupling reaction. As a proof‐of‐concept to validate our approach, and on the quest for novel hybrid interphases with potential technological applications, we have used valence tautomeric nanoparticles exhibiting spin transition at or around room temperature. SEM and AFM characterization reveal that the nanoparticles were organized chiefly into a single monolayer while X‐ray photoelectron spectroscopy (XPS) measurements confirm that the nanoparticles retain a temperature‐induced electronic redistribution upon surface anchorage. Our results represent an effective approach towards the challenging manufacture of coordination polymers.     

Experimental methodology for precise determination of density of RTILs as a function of temperature and pressure using vibrating tube densimeters

A specific calibration procedure that allows the accurate determination of densities of room temperature ionic liquids, RTILs, as a function of temperature and pressure using vibrating tube densimeters is presented. This methodology overcomes the problems of common calibration methods when they are used to determine the densities of high density and high viscosity fluids such as RTILs. The methodology is applied for the precise density determination of RTILs 1-ethyl-3-methylimidazolium tetrafluoroborate [Emim][BF₄], 1-butyl-3-methylimidazolium tetrafluoroborate [Bmim][BF₄], 1-hexyl-3-methylimidazolium tetrafluoroborate [Hmim][BF₄], and 1-octyl-3-methylimidazolium tetrafluoroborate [Omim][BF₄] in the temperature and pressure intervals (283.15 to 323.15) K and (0.1 to 60) MPa, respectively. The viscosities of these substances, needed for the estimation of the viscosity-induced errors, were estimated at the same conditions from the experimental measurements in the intervals (283.15 to 323.15) K and (0.1 to 14) MPa and from a specific extrapolation procedure. The uncertainty in the density measurements was estimated in ±0.30 kg · m^?3 which is an excellent value in the working intervals. The results of these RTILs have demonstrated that viscosity-induced errors are relevant and they must be taken into account for a precise density determination. Finally, an alternative tool for a simpler application of this procedure is presented.