Nutritional parameters of commercially available milk samples by FTIR and chemometric techniques

A chemometric study on the prediction of the main nutritional aspects of milk has been carried out by using fourier transform infrared spectroscopy (FTIR) attenuated total reflectance (ATR) measurements of commercially available milk samples of different types. Whole, semi and skimmed milks, enriched or not with calcium, vitamins or modified by alteration of lipid or sugar composition were considered. After evaluating different strategies for data acquisition and ATR cleaning between samples, hierarchical cluster analysis (HCA) was carried out for classification of samples in order to choose the calibration set. The prediction capabilities of partial least squares (PLS) data treatment were evaluated in order to obtain information about total fat, total protein, total carbohydrates (CH), calories and calcium. On using the mean square error of cross-validation and prediction as control variables, a critical evaluation were made about the calibration set to be used, the spectral range to be considered and the data treatment (PLS-1 or PLS-2) to be performed. By selecting a calibration set of 33 samples the properties of 48 samples were predicted with relative precision of triplicates of 0.062, 0.040 and 0.039% w/v for total fat, protein and carbohydrates, and 0.66 kcal/100 ml for calories, and 2.1 mg of Ca/100 ml. The mean difference (d_x−y) between predicted and actual values and standard deviation of mean differences (s_x−y), were of 0.06 (0.38), 0.03 (0.18) and −0.15 (0.41), being s_x−y values between brackets, for total fat, proteins and carbohydrates, 0.06 (3.8) kcal/100 ml for calories and −4.5 (9) mg/100 ml for calcium.The sensitivity and selectivity of the methodology developed were evaluated on terms of the net analyte signal. Selectivity factors ranging from 2 to 7.6% have been calculated for the five parameters considered.     

New [Mo(eta3-allyl)(CO)2L3]+ complexes with monodentate or tridentate nitrogen-donor ligands

Cationic complexes [Mo(eta(3)-allyl)(CO)2L3]+ (L3 = either nitrogen-donor tridentate ligand or three monodentate ligands) were prepared in high yield and under mild conditions using as precursors either the triflato complex [Mo(eta(3)-allyl)(OTf)(CO)2(NCMe)2] or the combination of the chloro complex [Mo(eta(3)-allyl)Cl(CO)2(NCMe)2] and the salt NaBAr'(4)(Ar'= 3,5-bis(trifluoromethyl)phenyl). The tridentate ligands employed were 2,2':6',2'-terpyridine (terpy) and cis,cis-1,3,5-cyclohexanetriamine (CHTA), whereas the monodentate ligands imidazole (im) and 3,5-dimethylpyrazole (dmpz) were chosen. In order to stabilize the labile intermediates, an excess of acetonitrile was used in most of the syntheses. However, the pyrazole complex was prepared through a nitrile-free route to avoid reactions at the coordinated nitrile. The solid state structures of [Mo(eta(3)-methallyl)(CO)2(terpy)]OTf (2), [Mo(eta(3)-methallyl)(CO)2(CHTA)]BAr'4 (3), [Mo(eta(3)-methallyl)(CO)2(NCMe)3]BAr'4 (4), [Mo(eta(3)-allyl)(CO)2(im)3]OTf (5) and [Mo(eta(3)-allyl)(CO)2(dmpz)3]BAr'4 (6) were determined by means of single-crystal X-ray diffraction.     

Identifying acetylated lignin units in non-wood fibers using pyrolysis-gas chromatography/mass spectrometry

A series of non-wood plant fibers, namely kenaf, jute, sisal and abaca, have been analyzed upon pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) of the whole material. The pyrolysis products mainly arise from the carbohydrate and lignin moieties of the fibers. The lignin-derived phenols belonged to the p-hydroxyphenylpropanoid (H), guaiacylpropanoid (G) and syringylpropanoid (S) structures, and showed a high S/G ratio of between 2.0 and 5.4, the highest corresponding to kenaf. Among the lignin-derived phenols released, small amounts of sinapyl and coniferyl acetates (in both cis- and trans-forms) were identified for the first time upon Py-GC/MS of lignocellulosic materials. Acetylation of the sinapyl and coniferyl alcohols was at the gamma-position of the side chain. The release of these alcohols derived from intact acetylated lignin units upon pyrolysis seems to indicate that the native lignin in the fibers selected for this study is at least partially acetylated. Sinapyl (and coniferyl) acetates have recently been suggested to be authentic lignin precursors involved in the polymerization of lignin along with the normal sinapyl and coniferyl alcohols. Py-GC/MS will offer a convenient and rapid tool for analyzing naturally acetylated lignins, as well as to screen plant materials for the presence of acetylated units in lignin.     

Simple and rapid micellar electrokinetic capillary chromatographic method for simultaneous determination of four antiepileptics in human serum

A very rapid and simple MEKC method was developed for the simultaneous determination of four antiepileptic drugs, ethosuximide (Etho), primidone (Pri), phenytoin (Pht) and carbamazepine (Cbz) in human serum. Sample analysis required only 100 microL of human serum which only needed to be centrifuged, decanted and combined with the running buffer [5.3 mM Na(2)HPO(4)/3.2 mM borax buffer (pH 9.5) containing 55 mM SDS and 3.5% (v/v) acetone]. The analysis was performed in only 10 min into fused-silica capillaries (57 cm total length with 50 microm i.d. and 50 cm to the detector) using the MEKC methodology with diode-array detection at 220 nm. The calibration graphs were established for ethoximide, primidone, phenytoin and carbamazepine between 0 and 20 mg/L. Recoveries were between 85 and 87%. The simplicity of the proposed methodology makes it suitable for routine clinical use, especially for epileptic patients on polytherapy.     

Multicommutation as an environmentally friendly analytical tool in the hydride generation atomic fluorescence determination of tellurium in milk

The aim of this study is to show the advantages of the emerging multicommutation methodology based on the use of solenoid valves for Te determination in milk by hydride generation atomic fluorescence spectrometry (HG-AFS). The delivery of a series of alternating sequential insertions of small volumes of samples and reagents gives rise to new hydrodynamic processes and exciting analytical potentials by controlling the time of flow through the on/off-switched solenoid valves. This drastically reduces the reagent consumption by a factor of 4 and the generation of effluents (590 mL h^–1 instead of 750 mL h^–1 generated by the continuous-mode measurement) and also provides an improvement in the laboratory productivity by an increase of the sample throughput (85 h^–1 compared to 20 h^–1 found in the continuous mode). So, multicommutation is an environmentally and economically sustainable alternative to the methodology based on continuous measurements. The multicommutation-based method developed was applied to tellurium determination in commercially available milk samples; a calibration range of 0.0–0.5 ng mL^–1 and a detection limit of 0.20 ng L^–1 with average relative standard deviation of 2.1% were found. Comparable results were obtained for a series of samples using both continuous and multicommutation HG-AFS modes.     

Electronic structure and properties of isoreticular metal-organic frameworks: the case of M-IRMOF1 (M = Zn, Cd, Be, Mg, and Ca)

We investigate the possibility of tailoring the electronic properties of isoreticular metal-organic materials by replacing the metal atom in the metal-organic cluster and by doping. The electronic structure of M-IRMOF1, where IRMOF1 stands for isoreticular metal-organic framework 1 and M = Be, Mg, Ca, Zn, and Cd, was examined using density-functional theory. The results show that these materials have similar band gaps (ca. 3.5 eV) and a conduction band that is split into two bands, the lower of which has a width that varies with metal substitution. This variation prompted us to investigate whether doping with Al or Li could be used to tailor the electronic properties of the Zn-IRMOF1 and Be-IRMOF1 materials. It is shown that replacing one metal atom with Al can effectively be used to create IRMOFs with different metallic properties. On the other hand, adding Li produces structural changes that render this approach less suitable.     

Evaluation of new pregnane derivatives as 5alpha-reductase inhibitor

The objective of this study was to synthesize several new pregnane derivatives and evaluate them as antiandrogens. From the commercially available 16-dehydropregnenolone acetate (7), two new steroidal compounds were synthesized: 17alpha-hydroxy-17beta-methyl-16beta-phenyl-D-homoandrosta-1,4,6-triene-3,20-dione (18) and 17alpha-acetoxy-17beta-methyl-16beta-phenyl-D-homoandrosta-1,4,6-triene-3,20-dione (19). The 5alpha-reductase inhibitory effect of the new compounds 18 and 19 together with the previously synthesized intermediates 7, 8, 13, 16, and 17 was determined in three different models: gonadectomized hamster flank organs diameter size, incorporation of [1,2-(14)C]sodium acetate into lipids in flank organs and conversion of [3H]testosterone (T) to [3H]dihydrotestosterone (DHT) by Penicillium crustosum. The evaluation of these steroids was carried out with three different controls: one group was treated with vehicle, the second with T and the third group with T plus finasteride. The pharmacological results from this work demonstrated that T significantly increases the diameter of the pigmented spot on the flank organs (p<0.05) as well as the incorporation of labeled sodium acetate into lipids in gonadectomized hamster flank organs (from 0.125 to 0.255 nmol per gland). In this study we also observed that broth of Penicillium crustosum converted [3H]T to [3H]DHT in a manner comparable to that of the flank organs. All experiments indicated that finasteride as well as steroids 7, 8, 13, 16-19 reduced significantly the conversion of T to DHT in P. crustosum. These compounds also decrease the size of the pigmented spot in the flank organs as well as reducing the incorporation of radiolabeled sodium acetate into lipids; T and the control sample (treated with vehicle only) were used for comparison. Apparently the presence of the 4,6-diene-3,20-dione moiety and also the C-17 ester group produce a higher inhibitory effect on the parameters used. PPThe data from this study indicated also that the three models used for the pharmacological evaluation exhibited comparable results.     

Human serum albumin-mediated stereodifferentiation in the triplet state behavior of (S)- and (R)-carprofen

A remarkable stereodifferentiation has been observed in the interaction between the excited triplet state of carprofen (CP) and human serum albumin (HSA). Time-resolved measurements using laser flash photolysis reveal the presence of two components with different lifetimes in triplet decay. This is explained by complexation of CP to the two possible HSA binding sites. The shorter-lived components are ascribed to the CP/HSA complexes in site I, where stereodifferentiation is more important (tauR/tauS ca. 4). This is correlated with formation of a dehalogenated photoproduct upon steady-state photolysis.     

Ethylenediamine effect on Co2+ uptake by zeolite Y

Co²⁺ ion exchange, at room temperature, from aqueous cobalt — sodium chloride solutions with NaY zeolite has been studied. The effect of contact time on the shape of the sorption curves of Co²⁺ using zeolite Y dehydrated at 600°C is similar to the one found in our previous work with a zeolite dehydrated at 150 °C. A fast sorption uptake is observed in which 1.8 meq of Na⁺ ions/g of zeolite are replaced by cobalt ions followed by a desorption process where the uptake decreases to 1.2 meq/g zeolite. The Co²⁺ sorption using zeolite Y dehydrated at 600 °C is increased when ethylenediamine solution is passed through the zeolite. The Co²⁺ sorption uptake, initially 2.0 meq/g, incrases to 2.8 meq/g of zeolite. This behavior is explained by the location and coordination of cobalt in zeolite Y sites. It is suggested that the highest uptake process is due to the blocking of zeolite sites by a Co complex compound.     

From nitrides to carbides: topotactic synthesis of the eta-carbides Fe3Mo3C and Co3Mo3C

The molybdenum bimetallic interstitial carbides Fe(3)Mo(3)C and Co(3)Mo(3)C have been synthesized by temperature-programmed reaction (TPR) between the molybdenum bimetallic interstitial nitrides Fe(3)Mo(3)N and Co(3)Mo(3)N and a flowing mixture of CH(4) and H(2) diluted in Ar. These compounds have been characterized by X-ray diffraction, laser Raman spectroscopy, elemental analysis, energy dispersive analysis of X rays, thermal analysis (in air) and scanning electron microscopy (field emission). Their structures have been refined from X-ray powder diffraction data. These carbides crystallize in the cubic system, space group Fd3m[a= 11.11376(6) and 11.0697(3)[Angstrom] for Fe and Co compounds, respectively].