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Two Zn(II) complexes of captopril were prepared and characterized with different analytical methods: IR, NMR and XPS. Captopril is a molecule which has been proven to be very effective in reducing blood pressure. The ligand chelates via the OCO group to a zinc ion and via S and amidic oxygen atoms to another zinc ion when the ZnL complex is obtained. The sulphur atom and the amidic CO group are the only atoms involved in the coordination when the sodium—zinc complex, Na 2 ZnL 2 , is synthesized.

With regard to single step reactions, a new approach to the processing of DTA/DSC curves is presented, taking into account the heat transfer into the instrument. It is an extension of a previous physical model, that allowed the calculation of true kinetic parameters from TG curves. The peak area can be properly calculated as well as the degree of reaction, this also being suitable for kinetic parameters calculation. Through numerical simulations, other methods for DTA/DSC curve processing are discussed with respect to that proposed. By TG and DTA, the true kinetic parameters have been finally determined for the second and third steps of the thermal decomposition of CaC204sdH2O, to complete previously reported data for the first dehydration step. The agreement of the results with isothermal experiments seems to indicate a way to escape from the dichotomy between isothermal and non-isothermal kinetics. Several other approaches to non isothermal kinetics are reviewed and discussed. The software developed is also briefly described.

Six Japonica and three Indica rice samples were considered in this study. Total amino acid composition and protein digestibility were studied in relation to protein component while, amylose content, resistant and damaged starch were considered to assess starch characteristics. Results showed a comparable amino acid pattern and carbohydrate but different protein and starch digestibility. Due to the different botanical origin of samples, the amylose content raged between 15.5 and 25.2 g/100 g d. b. to whom corresponded a wide range of pasting temperatures determined by means of Differential Scanning Calorimetry. Principal Component Analysis, used to perform an exploratory data analysis, evidenced the contribution of some amino acids in recognising samples and this evidence could be usefully employed in breeding programs.

Enantiomers are isomers that are the mirror image of one another and that, except for the property of rotating the plane-polarized light in opposite direction, share common physical and chemical properties. However, quite often it can happen that their pharmacological properties are significantly different so that one enantiomer is active while the other one doesn't produce any effect or, in some cases, can result even noxious. It is evident, therefore, that the possibility of determining the excess of the most abundant enantiomer in a mixture (enantiomeric excess) is of capital importance, especially in the quality control of drugs. In this paper, the possibility of quantifying the enantiomeric excess in mixtures of two pharmacologically important active principles (namely mandelic acid and ketoprofen) by means of multivariate calibration of IR data is explored. Since the measurements are carried out on KBr pellets, different background correction and data pre-treatment techniques have been used. Pretreated data have then been analyzed by Partial Least Squares Regression (PLS) and Multivariate Curve Resolution (MCR), considering at first the whole spectrum and later just a more limited spectral region selected by a sequential application of backward interval PLS and genetic algorithms (bi-PLS-GA). Results have proved to be significantly accurate both by internal and external validation.

Complex formation by chromium(III) with diethylentriaminepentaacetic acid (DTPA) has been studied by potentiometry and spectrophotometry. In equimolar solutions or with a ligand excess, complexation is practically complete at pH > 1 and protonation equilibria have been calculated. Molar absorbtivities of the different species have been evaluated. Equilibrium constants for complex formation have been calculated in 1 mol dm−3 (Na,H)ClO4 at 20°C.

The thermal properties of some mixed complexes of Co(III) with o-phenanthroline and several amino acids were determined by thermogravimetry (TG) and differential thermal analysis (DTA). The thermal stability derived from decomposition temperatures is discussed in terms of the molecular properties of the amino acids which affect the distribution of the intermolecular bonds in the solid lattice. With reference to the weight losses and IR spectra of the heated compounds, the thermal decomposition pathways of these complexes were also determined. Modifications to the methods of preparation cited in the literature were also proposed to increase the yields and to simplify operating procedures.

The possibility of using two different artificial neural networks architectures (multi-layer feed-forward, MLF-NN, and counterpropagation, CP-NN) for the classification of 255 durum wheat samples from Sicily (Italy) was investigated and the performances of the optimal models were compared both among each others and to those resulting from the application of traditional chemometric pattern recognition techniques. When considering predictive ability over an independent test set, counterpropagation NN performed best, being able to correctly predict about 82% of the external validation samples (the corresponding predictive ability for MLF-NN, LDA and QDA was 72.0%, 50.9% and 52.7%, respectively.

Captopril (H2L) reacts with cobalt(II) in aqueous solution at a neutral pH forming a deep red complex. The reaction rate depends on the temperature, pH, metal ion and ligand concentrations. A solid compound precipitates by acidification of the solution. The chemical, potentiometric, and spectroscopic analyses of the solid complex give the simplest formula, Co(HL)2·H2O, and suggest that the sequence of the bonds is S-Co-S, with the carboxylic group of the ligand remaining uncoordinated. The thermal behaviour of the captopril and its cobalt complex was studied by thermogravimetry, differential thermal analysis and differental scanning calorimetry in dynamic nitrogen and oxygen atmospheres.

Sources of misunderstandings when evaluating kinetic parameters from thermogravimetric (TG) curves are discussed. A simple method for calculating Arrhenius parameters, suitable for implementation on a PC connected to the TG apparatus, is presented. The results obtained with calcium oxalate are discussed with respect to their ability to predict thermal behaviour in several experimental conditions: agreement with experimental data is satisfactory. This is not so when using some literature-cited kinetic parameters, which fail to represent the same TG curves from which they are extracted. Suggestions are derived for design of a modern TG apparatus connected to a PC.

The problem of authenticating extra virgin olive oil varieties is particularly important from the standpoint of quality control. After having shown in our previous works the possibility of discriminating oils from a single variety using chemometrics, in this study a combination of two different neural networks architectures was employed for the resolution of simulated binary blends of oils from different cultivars. In particular, a Kohonen self-organizing map was used to select the samples to include in the training, test and validation sets, needed to operate the successive calibration stage, which has been carried out by means of several multilayer feed-forward neural networks. The optimal model resulted in a validation Q 2 in the range 0.91–0.96 (10 data sets), corresponding to an average prediction error of about 5–7.5%, which appeared significantly better than in the case of random or Kennard–Stone selection.

A simple, fast and relatively inexpensive spectrophotometric method for the identification and the quantification of the individual components of the Italian general denaturant in alcohol samples is proposed. In particular, it is shown that bitrex (a quaternary ammonium salt), whose UV spectrum is completely masked by those of the other denaturant components, can be identified using its reaction with disulphine blue VN-150 (an anionic dye indicator), which leads to the formation of an intensely colored ion-association complex (mole ratio 1:1), easily extractable in chloroform. As far as the quantitative detection is involved, it is however necessary to shake the chloroform phase in the presence of 1 mol L(-1) NaClO(4) aqueous solution because of the fast adsorption of the ion pair on the walls of the glass cell. Perchlorate anion, due to mass action, substitutes the anionic dye indicator in the association complex: as a consequence, disulphine blue passes to the aqueous phase, where its absorbance at lambda=640 nm is measured. On the other hand, C.I. Reactive Red 24 dye is easily identifiable from the visible spectrum of the product without any further pretreatment: its concentration can be determined measuring the absorbance at lambda=542 nm. Thiophene, being significantly more concentrated than the other components, can be identified from the UV spectrum of a 1:100 diluted solution of the alcohol sample and quantitatively determined measuring the absorbance at lambda=230 nm. Lastly, methyl ethyl ketone (MEK) can be identified from the UV spectrum of a 1:5 diluted solution of the alcohol sample and quantitatively determined measuring the absorbance at lambda=273 nm. However, more accurate results can be obtained using a multiwavelength analysis in the range 220-250 and 250-310 nm for the determination of thiophene and MEK, respectively. Validation on standard denatured alcohol samples has proven the method to be both accurate and sufficiently precise (within- and between-days repeatability

Two chemometric class-modeling techniques (SIMCA and UNEQ) have been used to authenticate the origin of CDO wine samples from Italy. While SIMCA modeling was performed using all variables, UNEQ requires a preliminary variable selection, leading to 4 variables only (Cu, Zn, antocyans and SO 2 ) being included in the models. Both techniques provided highly sensitive and specific category models and resulted also in a very reliable classification of samples (only one or two samples misclassified in SIMCA and UNEQ, respectively). A further investigation on the stability of the models with respect to the wine production year was carried out, showing that while SIMCA models failed to classify most of the samples produced in years different from those used in the modeling phase, quite all of the same samples were accepted by the corresponding UNEQ models. However, when SIMCA modeling was repeated using only the same 4 variables than UNEQ, comparable results were obtained, suggesting an effect of the choice of the experimental variables in the classification outcomes.

The thermal decomposition of iminodiacetic, oxydiacetic, and thiodiacetic acids in helium atmosphere has been studied by means of thermogravimetry (TG), differential thermal analysis (DTA) and temperature-programmed pyrolysis directly coupled with mass spectrometry (TPPy-MS). Evolved gas analysis (EGA) profiles of iminodiacetic and oxydiacetic acids were obtained and compared with TG and DTA profiles. The decomposition of iminodiacetic acid forms water, CO, CO2, CH3CN, HCN and some hydrocarbons. After water evolution a cyclic anhydride is formed, as well as for oxydiacetic acid. Thiodiacetic acid vaporizes without decomposition.

A comparison of the results obtained by applying three spectrophotometric methods (at fixed wavelength, second-derivative and multicomponent analysis) to the determination of gamma-oryzanol in rice bran oil is reported. At fixed wavelength the results are more accurate when using isopropyl alcohol, rather than n-heptane, to dilute the oil samples, because the absorption bands of gamma-oryzanol are red-shifted and the absorbance, measured at lambda(max)=327 nm, is less affected by the interference of the oil "matrix" (lambda(max)=314 nm in n-heptane).However, to obtain accurate results also in oils with a low content of gamma-oryzanol, it is necessary to perform the analysis using second-derivative ((2)D330.365) or multicomponent (lambda=310-360 nm) methods. The first one fully removes the interference of oil matrix whilst the second, which needs a specific computational program to process the spectrophotometric data, furnishes evidence the presence of some unexpected interference in the analysis and/or standards which are not representative of the analysed samples, from the square root of the sum of the squared differences at each point between the linear combination of the standards and the unknown spectra (RMS error).Finally, some aspects of the chemical, spectroscopic (UV, IR) and thermoanalytical (TG, DSC) behaviour of gamma-oryzanol and the values of the parameters which enable "computation" of its UV spectra are reported.

Enantiomeric enrichment of mandelic acid and phenylglycine racemics is achieved by using a liquid membrane containing cinchonidine as a chiral carrier (a = 1.5 and 0.9, respectively). Transport of the respective enantiomers through a liquid membrane was characterized by using mandelic acid as target analyte. To this end, the influence on this transport of different parameters was determined, for instance the amount of decanol added as modifier to the cinchonidine in dodecane solution (constituting the liquid membrane), the initial carrier:analyte ratio in the feed phase, the pH of the aqueous solutions (both feed and receiving), and the effect of varying the membrane solvent from dodecane-decanol to the more solvating chloroform. Additionally, and for the sake of comparison with the mandelic acid results, the transport of phenylglycine and phenylalanine was studied. The membrane showed a slight selectivity only for the phenylglycine transport, as phenylalanine was transported as a 50% racemic mixture under all the conditions examined. The observed results may perhaps be accounted for by hydrogen bonding interactions between carrier and analytes.

This work has focused on discriminating extra virgin olive oils from Sabina (Lazio, Italy) by olive fruit variety (cultivar). A set of oils from five of the most widespread cultivars (Carboncella, Frantoio, Leccino, Moraiolo, and Pendolino) in this geographical area was analyzed for chemical composition using only the Official Analytical Methods, recognized for the quality control and commercial classification of this product. The obtained data set was converted into a computer-compatible format, and principal component analysis (PCA) and a method based on the Fisher F ratio were used to reduce the number of variables without a significant loss of chemical information. Then, to differentiate these samples, two supervised chemometric procedures were applied to process the experimental data: linear discriminant analysis (LDA) and artificial neural network (ANN) using the back-propagation algorithm. It was found that both of these techniques were able to generalize and correctly predict all of the samples in the test set. However, these results were obtained using 10 variables for LDA and 6 (the major fatty acid percentages, determined by a single gas chromatogram) for ANN, which, in this case, appears to provide a better prediction ability and a simpler chemical analysis. Finally, it is pointed out that, to achieve the correct authentication of all samples, the selected training set must be representative of the whole data set.

The spectroscopic characteristics (IR and diffuse reflectance) and the thermal properties (TG, DTG and DSC) of the solid compounds obtained by the reaction of diclofenac (DH) with manganese(II), iron(II), cobalt(II), nickel(II), copper(II) and zinc(II) are reported and discussed. The complexes agreed with the empirical formula MeD 2 ·(H 2 O) x and the metal ions are co-ordinated through the carboxylate group of the ligand. The furnace atmosphere (N 2 or O 2 ) greatly influences the thermal decomposition trend of the complexes, less their thermal stability. On the contrary, the initial decomposition temperature depends on the co-ordinated metal ion, especially in the case of iron(II) and copper(II) compounds, which are much less stable than other complexes.

The reaction of iron(III) with chromium(III)–DTPA ‘chelating agent’ has been investigated, in aqueous solution, by measuring both hydrogen ion concentration and emf of the iron(III)/iron(II) couple. In acidic medium (pH

A calorimetric (DSC) method for the analysis of starches and food-related compounds, based on the determination of onset and peak temperature (To, Tp) and the apparent enthalpy change (ΔH) of the starch gelatinization process is described. To set up the best experimental conditions to apply, the parameters that could affect the calorimetric response, such as temperature range of thermal analysis, water/starch ratio in the mixture, heating rate, size and weight of sample, time-temperature condition, were investigated. The method was applied to characterise starches, semolina and alimentary pasta.

The reactions of diethylenetriaminepentaacetic acid (DTPA=H5L) or chromium(III)-DTPA, a ‘chelating agent’, with oxovanadium(IV) were investigated in aqueous solution by potentiometric methods. Homo- and hetero-binuclear species were evidenced as well as mixed complexes with hydrogen or hydroxide ions. The stability constants for these equilibria were calculated in 1.0 mol 1−1 NaClO4 solution at 20‡C. The mononuclear (VO)H3L·H2O and the heterobinuclear (VO)CrL·5H2O complexes were also obtained as solid compounds and were characterized by IR spectroscopy and thermoanalytical techniques (TG and DSC).

Through curves simulated (calculated) as previously reported, DSC/DTA/DTG peak shapes are discussed in terms of six parameters: height, position, left and right half width at half maximum, and also as left and right gaussian/lorentzian mixing ratio. By assigning several values to masses and heating rates (operational setting, OS), to transfer coefficients and thermal capacity (equipment features, EF), to Z, E, N (sample kinetic parameters, SK) and to Δ H , Δ c p (sample thermodynamic parameters, ST), peaks were simulated and the six parameters were calculated by a refinement procedure derived from X-ray photoelectron spectroscopy. The resulting peaks were hardly ever pure symmetric gaussian curves, as often assumed in so called “deconvolution” (peak sum resolution) procedures, where such an assumption may generate artifacts. A complete discussion of peak shapes versus OS, EF, SK and ST is reported. The extension of a previously described TG simulation procedure to DSC/DTA/DTG is also reported, together with a discussion of the already proposed method, for calculating true kinetic parameters, with respect to other approaches based on signal desmearing.

Four amorphous metal complexes with 1-(D-3-mercapto-2-methylpropionyl)-L-proline (L) with general formula Na2ML2·nH2O (M = Co, n = 14; M = Ni, n = 4; M = Zn, n = 4; M = Cd, n = 7) have been synthesized. LAXS (large angle X-ray scattering) provided information on the local order around the metal(II) ions. A 2:1 ratio between ligand and all examined metal ions was found. A tetrahedral configuration around zinc and cadmium ions has been found with two sulphur and two amidic oxygen atoms bonded to the metals. For nickel and cobalt complexes an octahedral configuration has been found with two water molecules bonded to the metal in axial position and two ligand molecules bonded via sulphur and amidic oxygen in equatorial position.

The determination of the moisture and ash contents in wheat mills was developed using multistep programmed thermogravimetric analysis. Preliminary research to determine the most suitable analytical conditions (carrier gas and flow rate, furnace temperature, isothermal time, type and weight of sample and size of particles) was also carried out. Commercial flours milled from soft and hard wheats with a wide range of fibre content were analysed using both the proposed method and the Italian official methods. The same results were obtained from all these methods. Nevertheless, the thermogravimetric method has some advantages: the analysis takes place on the same sample; it requires very small samples; and it is easy and rapid.

Kinetic data available from TG measurements are discussed with respect to thermal coefficients such as sample specific heat, reaction enthalpy, instrument heat-transfer coefficient and heat capacity. The dependence of the available kinetic parameters Z, E and N on these thermal coefficients is examined using a numerical model. A relationship is also derived for calculating the kinetic parameters from experimental TG curves whilst taking into account the perturbation induced by the above-cited thermal coefficients. The dehydration of calcium oxalate is used to evaluate experimentally the predictive power of the kinetic parameters obtained in this way, i.e. their ability to describe the sample behaviour under a wide range of operational conditions (different masses and heating rates), including isothermal reactions.

The complexes cis-Co[(AA)2(OCOR)2]NO3, where AA=1,10-phenanthroline or 2,2′-bipyridine and R=H, CH3, C2H5, or n-C3H7 were studied by TG, DTA and spectroscopic methods to obtain information concerning the decomposition mechanism. A comparison of the two series revealed that the first decomposition process involves breaking of Co-N bonds and elimination of the nitrogen ligand in both series; the phenanthroline complexes show a stability sequence, whereas all the bipyridine complexes start to decompose at the same temperature. The results were also compared with previous data on ethylenediamine complexes.

A flow microcalorimeter in the mixing mode has been employed to verify the possible application of calorimetric techniques in studying enzymatic reactions. In order to illustrate the optimum operative conditions, with special regard to chemical and instrumental factors affecting the reaction heat quantity, the urea enzymatic decomposition, which is a well studied reaction, was chosen.

The reactions between copper(II) or nickel(II) with thecis-pyridine-2-aldoxime complexes of the same metal ions have been investigated by spectrophotometric measurements. The homo and heterobinuclear chelates involved have been isolated as the chlorides and characterized by spectroscopic and thermoanalytical techniques. The first decomposition step is not dependent on the furnace atmosphere (N2 or O2) and is accompanied by a large exothermic effect (DSC curves in N2). TG curves show that binuclear complexes are generally slightly less stable than the respective mononuclear complexes but, in the case of [Cu(NiL2)Cl2(H2O)2], the complexation of copper(II) gives rise a drastic decrease of its thermal stability.

The thermal behaviour of [Co(en)n(phen)m]Cl3 complexes has been studied using thermogravimetry (TG), differential thermogravimetry (DTG) and differential thermal analysis (DTA) in air, nitrogen and oxygen atmospheres. The effect of the stoichiometry of the complexes and that of the gas atmosphere in the furnace chamber on the thermal decomposition reaction is evidenced and discussed. The following thermal stability order has been found [Co(en)3]Cl3 ≌ [Co(en)2(phen)]Cl3 > [Co(en)(phen)2]Cl3 ⪢ [Co(phen)3]Cl3

The thermal properties of some complexes of copper(II) with pyridine-2-aldoxime (HPAO), where the ligand appears either as the ion (PAO−) or as a neutral molecule, were determined in vacuo and in dynamic nitrogen and oxygen gas atmospheres. The study was carried out by thermoanalytical (TG, DTG. DTA), spectroscopic and spectrometric (UV-visible, IR, diffuse reflectance, mass) techniques.

samples. The thermal stabilities are discussed in terms of the strengths of the bonds in the solids [1] and steric hindrance; the thermal decompositions are described with the aid of hypothesized intermediates and IR spectra. Reaction steps axe identified and the thermal stability sequence is discussed: the cis compounds are less stable than the corresponding trans compounds, due to the lower reticulation effect; the sequence of the cis compounds is the reverse of the sequence of carboxylate ion basicity, while the sequence displalyed by the trans compounds can be interpreted in terms Of solid lattice stabilization. In systematic investigations of the thermal behaviour of solid metal complexes containing carboxylato groups in the coordination shell [2-6], compounds of gefleral formula cis- or trans-[Coen2(RCOO)2]NO 3 were prepared, characterized an.d examined by TG and DTA. These compounds contain cobalt(Ill); R = H, CH3, C2H s or C3H 7 corresponds to formate, acetate, n-propionate or n-butyrate, and en represents ethylenediamine. The presence ofen allows the possibility of examining the behaviour of the cis and trans isomers, while the increasing length of R affects steric hindrance and/or solid reticulation. Whereas dicarboxylato bis-ethylenediamine cobalt(Ill) complexes are generally prepared as perchlorates, in the present work they" were made as nitrates. The reason for this is the general behaviour of perchlorate during heating: sputtering phenomena are frequent, introducing unacceptable noise in the recorded signals

Pyrazine-2,3-dicarboxylic and pyridine-2,3-dicarboxylic acids act as chelating agents to copper(II), and give complexes whose solubility varies with respect to the solvent. The characterization of the solid compounds was carried out by IR and thermogravimetry (TG), while the thermodynamic values of the soluble complexes were determined by spectrophotometry and microcalorimetry. The effect of the solvents is discussed on the basis of their properties (DN, DEC).

Copper(II) complexes of 3- and 4-pyridinealdoxime have been prepared and analyzed by spectroscopic (ir and diffuse reflectance) and thermoanalytical (TG, DTG and DTA) techniques. For both these systems, only species with metal: organic ligand: chloride ratio of 1∶2∶2 were found, and the organic ligand appears as a neutral molecule. The spectral data suggest a polymeric structure where the copper(II) ions are in a distorted octahedral environment.

The complexes between cobalt(III) and aminoacids such as glutamine, asparagine, glutamic acid, aspartic acid and proline were studied.

The resolution of a mixture containing some α-aminoa-cids, theirβ-isomers and dipeptides is realized on column by the ligand-exchange (LE) chromatography. The support used is a chelating exchanger bounded with a copper(II)- or a nichel(II)-ammonia complex.

Two series of [Co(III)(AA)2(OCOR)2]NO3 complexes (where AA = 1.10-phennanthroline or 2,2′-bipyri-dine and R = H.CH3, C2H5 or C3H7) were prepared by the reaction of [Co(III)(AA)2Co3]No3 with the appropriate carboxylic acid in aqueousn solution at 50–60°C. A convenient high-yield route to [Co(phen)2Co3]No3 is proposed. The complexes were characterized spectroscopic and by chromatographic(TLC) techniques. A linear relationship is found between the number of carbon atoms in the carboxylic ligand and the chromatographic RM values of the two homologgous series of complexes.

Complexation of copper(II) with two different pyridinols in three solvents has been studied by visible spectrophotometry and flow-microcalorimetry. The influence of the solvent on tautomeric equilibrium of the ligand, on distribution, on stability and on formation enthalpies of the main complex species is discussed.

The complexes formed between iron(II) and some aromatic anions (benzoate and 4-aminoderivate, salicylate and 4-aminoderivate, thiosalicylate) have been investigated in dimethylsulphoxide (DMSO). The complexation ratios and the stability constants of the species have been determined at 25 °C and compared, when possible, with the data obtained in ethanol. The results allow us to discuss the effect of the solvent properties and of the substituent position on the aromatic ring.

The complexes formed between iron(II) and some aromatic anions (benzoate and 4-aminoderivate, salicylate and 4-aminoderivate, thiosalicylate) have been investigated in dimethylsulphoxide (DMSO). The complexation ratios and the stability constants of the species have been determined at 25 °C and compared, when possible, with the data obtained in ethanol. The results allow us to discuss the effect of the solvent properties and of the substituent position on the aromatic ring.