Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 22
Filtrar
1.
Food Microbiol ; 122: 104536, 2024 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-38839216

RESUMO

The aim of this study was to develop a novel and healthier fermented meat product by replacing pork fat with avocado pulp (AVP) during salami production. Experimental salamis were produced under laboratory conditions by substituting pork fat with AVP partially (10-AVP) and totally (20-AVP), while control salamis (CTR) remained AVP-free. The microbial composition of control and experimental salamis was assessed using a combined culture-dependent and -independent approach. Over a 20-days ripening period, lactic acid bacteria, coagulase-negative staphylococci, and yeasts dominated the microbial community, with approximate levels of 9.0, 7.0 and 6.0 log CFU/g, respectively. Illumina technology identified 26 taxonomic groups, with leuconostocs being the predominant group across all trials [constituting 31.26-59.12 % of relative abundance (RA)]. Gas Chromatography-Mass Spectrometry (GC-MS) analysis revealed changes in fatty acid composition and volatile organic compounds due to the substitution of pork fat with AVP. Specifically, monounsaturated fatty acids and terpene compounds increased, while saturated fatty acids and lipid oxidation products decreased. Although AVP influenced the sensory characteristics of the salamis, the highest overall satisfaction ratings were observed for the 10-AVP salamis. Consequently, substituting pork fat with AVP emerges as a viable strategy for producing healthier salamis and diversifying the meat product portfolio.


Assuntos
Fermentação , Produtos da Carne , Persea , Persea/microbiologia , Persea/química , Animais , Suínos , Produtos da Carne/microbiologia , Produtos da Carne/análise , Ácidos Graxos/análise , Ácidos Graxos/metabolismo , Humanos , Bactérias/classificação , Bactérias/isolamento & purificação , Bactérias/metabolismo , Bactérias/genética , Compostos Orgânicos Voláteis/análise , Compostos Orgânicos Voláteis/metabolismo , Frutas/microbiologia , Frutas/química , Microbiologia de Alimentos , Paladar , Lactobacillales/metabolismo , Lactobacillales/classificação , Lactobacillales/crescimento & desenvolvimento
2.
Molecules ; 28(9)2023 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-37175363

RESUMO

The raw cladode of Opuntia ficus indica (OFI) was evaluated as a sustainable biosorbent for the removal of heavy metals (Ni, Pb, Cu, and Cd) from aqueous solutions. The functional groups of OFI were identified by employing DRIFT-FTIR and CP-MAS-NMR techniques before and after contact with the ions in an aqueous media, showing a rearrangement of the biomass structure due to the complexation between the metal and the functional groups. The adsorption process was studied in both single- and multi-component systems under batch conditions at different pHs (4.0, 5.0, and 6.0), different metal concentrations, and different biomass amounts. The results show that the raw OFI had a removal capacity at room temperature of over 80% for all metals studied after only 30 min of contact time, indicating a rapid adsorption process. Biosorption kinetics were successfully fitted by the pseudo-second-order equation, while Freundlich correctly modelled the biosorption data at equilibrium. The results of this work highlight the potential use of the untreated cladode of OFI as an economical and environmentally friendly biosorbent for the removal of heavy metals from the contaminated aqueous solution.

3.
Molecules ; 28(2)2023 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-36677756

RESUMO

Edible insects have the potential to become one of the major future foods. In fact, they can be considered cheap, highly nutritious, and healthy food sources. International agencies, such as the Food and Agriculture Organization (FAO), have focused their attention on the consumption of edible insects, in particular, regarding their nutritional value and possible biological, toxicological, and allergenic risks, wishing the development of analytical methods to verify the authenticity, quality, and safety of insect-based products. Edible insects are rich in proteins, fats, fiber, vitamins, and minerals but also seem to contain large amounts of polyphenols able to have a key role in specific bioactivities. Therefore, this review is an overview of the potential of edible insects as a source of bioactive compounds, such as polyphenols, that can be a function of diet but also related to insect chemical defense. Currently, insect phenolic compounds have mostly been assayed for their antioxidant bioactivity; however, they also exert other activities, such as anti-inflammatory and anticancer activity, antityrosinase, antigenotoxic, and pancreatic lipase inhibitory activities.


Assuntos
Insetos Comestíveis , Animais , Vitaminas/análise , Antioxidantes/farmacologia , Insetos/química , Polifenóis/farmacologia , Polifenóis/análise
4.
Ecotoxicol Environ Saf ; 182: 109435, 2019 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-31326728

RESUMO

Aliphatic hydrocarbon levels were determined by the GC/MS technique in fish livers of Engraulis encrasicolus (Ee) and Trachurus trachurus (Tt), collected from a particular area of the Mediterranean Sea, called GSA 10, which is located exactly in Tyrrhenian Sea between Campania coast and North Sicily coast. The aim was to evaluate their potential use as specific bioindicators towards this class of contaminants. Both Tt and Ee are considered to be pollution monitoring bioindicators, due to their dominance in marine communities and economic fishing interest. Ee showed a higher tendency to bioaccumulate TAHs, due to the lower quantity of fatty acids in liver tissues with respect to Tt. The area under study has been characterised a) chemically with the acquisition of temperature, oxygen and salinity profiles along the water column, and b) ecologically with the determination of amino acid contents in fish eyes, in order to gain information on the adaptation to environmental changes. Moreover, specific activities of two hydrolytic enzymes, such as alkaline phosphatase and peroxidase in fish epidermal mucus, together with lactate in blood plasma and cortisol levels, have been investigated for the first time, in order to obtain insights into the effects of hydrocarbons on animal welfare. A multiple co-inertia analysis was also applied to chemical and environmental parameters, in order to explore any possible correlation between different variables. The multivariate approach showed a clear spatial distribution between environmental and chemical variables in Ee, whilst there was an absence of a spatial trend in Tt. Moreover, the chemometric analysis showed a very high correlation between amino acid profiles and environmental variables for both species, confirming the possibility of being used as ecological welfare indices for short-term environmental variations.


Assuntos
Monitoramento Ambiental/métodos , Poluição da Água/estatística & dados numéricos , Animais , Biomarcadores Ambientais , Pesqueiros , Mar Mediterrâneo , Análise Multivariada , Alimentos Marinhos , Sicília
5.
Ecotoxicology ; 26(2): 250-260, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-28108889

RESUMO

In this study we analyzed Hg and Se concentrations in dolphin brain tissues of fifteen specimens of striped dolphin (Stenella coeruleoalba) and eight specimens of bottlenose dolphin (Tursiops truncatus) stranded in the Tyrrhenian and Adriatic Seas, in order to assess the toxicological risks associated with Hg exposure. High Hg concentrations were found in brain tissues of both analyzed specie (1.86-243 mg/kg dw for striped dolphin and 2.1-98.7 mg/kg dw for bottlenose dolphin), exceeding levels associated with marine mammals neurotoxicity. Althougth the results clearly suggest that the protective effects of Se against Hg toxicity occur in cetaceans' brain tissues, a molar excess of mercury with respect to selenium was found, particularly in adult specimens of Stenella coeruleoalba. On contrary, negligible neurotoxicological risks were found for Tursiops truncatus specimens, due to detoxification processes. Data obtained allowed to prove a more marked neurotoxicological risk for adult specimens of Stenella coeruleoalba in both Tyrrhenian and Adriatic Seas.


Assuntos
Golfinho Nariz-de-Garrafa/metabolismo , Mercúrio/metabolismo , Selênio/metabolismo , Stenella/metabolismo , Poluentes Químicos da Água/metabolismo , Animais , Encéfalo/metabolismo , Itália
6.
Rapid Commun Mass Spectrom ; 30(1): 230-8, 2016 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-26661990

RESUMO

RATIONALE: Self-assembling processes of surfactants in the gas phase constitute a developing research field of interest since they allow information to be gained on the peculiar structural organization of these aggregates, on their ability to incorporate from small molecules up to proteins and on their possible use as carriers of drugs in the gas phase or as cleaning agents and exotic reaction media. METHODS: The mass spectra of charged aggregates of the chiral surfactant (1R,2S)-dodecyl(2-hydroxy-1-methyl-2-phenylethyl)dimethylammonium bromide (DMEB) in the gas phase have been recorded using a Synapt G2-Si mass spectrometer in the positive and negative ion mode. For comparison purposes, the mass spectra of sodium bis(2-ethylhexyl)sulfosuccinate and sodium octane sulfonate aggregates have also been recorded under the same experimental conditions. The collisional cross sections of positively and negatively charged DMEB aggregates were obtained through an appropriate calibration of the measured drift times. RESULTS: For all the surfactants investigated, it has been found that there is a lowest and a highest limit of the aggregation number at each charge state: no aggregates are found outside this range. Moreover, the occurrence at each aggregation number and extra charge of a unique value of drift time points toward aggregates whose conformations do not show discernible shape change in the experiment time scale. The analysis of the collisional cross sections emphasizes that the DMEB aggregates are nearly spherical clusters somewhat affected by the charge state and constituted by interlaced polar and apolar domains. CONCLUSIONS: The analysis of all the experimental findings indicates that in the gas phase DMEB forms supramolecular aggregates characterized by an internal organization whose stability is triggered by the charge state. The comparison of the behavior of DMEB aggregates with that of sodium bis(2-ethylhexyl)sulfosuccinate and sodium octane sulfonate aggregates allows us to highlight the effects on the aggregate organization in gas phase due to nature of the head group and alkyl chain steric hindrance.

7.
Anal Bioanal Chem ; 405(2-3): 881-93, 2013 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-22941067

RESUMO

A study on the interactions between CH(3)Hg(+) and some S, N and O donor ligands (2-mercaptopropanoic acid (thiolactic acid (H(2)TLA)), 3-mercaptopropanoic acid (H(2)MPA), 2-mercaptosuccinic acid (thiomalic acid (H(3)TMA)), D,L-penicillamine (H(2)PSH), L-cysteine (H(2)CYS), glutathione (H(3)GSH), N,N'-bis(3-aminopropyl)-1-4-diaminobutane (spermine (SPER)), 1,2,3,4,5,6-benzenehexacarboxylic acid (mellitic acid (H(6)MLT)) and ethylenediaminetetraacetic acid (H(4)EDTA)) is reported. The speciation models in aqueous solution and the possible structures of the complexes formed are discussed on the basis of potentiometric, calorimetric, UV spectrophotometric and electrospray mass spectrometric results. For the CH(3)Hg(+)-S donor ligand systems, the formation of ML(1-z) and MLH(2-z) complex species is observed, together with a diprotonated MLH(2)(3-z) species for CYS(2-), PSH(2-) and GSH(3-) and the mixed hydrolytic one ML(OH)(-z) for TLA(2-) and MPA(2-). The dependence of the stability on ionic strength and on temperature is also analysed. In the other CH(3)Hg(+)-L systems (L = MLT(6-), SPER and EDTA(4-)), ML(1-z), MLH(2-z) and MLH(2)(3-z) complex species are formed, together with the MLH(3)(4-z) species for SPER, the mixed hydrolytic ML(OH)(-z) one for SPER and EDTA, and the M(2)L(2-z) for EDTA only. On the basis of the speciation models proposed, the sequestering ability of the ligands towards methylmercury(II) cation is evaluated. All S donor ligands show a good sequestering power (at 10(-11) mol L(-1) level, in the pH range 4 to 8) following the trend MPA(2-) < PSH(2-) < GSH(3-) < TLA(2-) < CYS(2-) < TMA(3-), while significantly lower is the sequestering ability of MLT, SPER and EDTA (at 10(-3)-10(-5) mol L(-1) level, in the pH range 4 to 8).


Assuntos
Quelantes/química , Poluentes Ambientais/química , Recuperação e Remediação Ambiental , Cinética , Compostos de Metilmercúrio , Estrutura Molecular
8.
Artigo em Inglês | MEDLINE | ID: mdl-36182080

RESUMO

The aim of this work is to study the immune responses of the polychaete Sabella spallanzanii after exposure to copper sulphate, an immunomodulating agent in marine organisms, and the multiple stresses caused by Escherichia coli infection, to validate the species as a model organism in marine-coastal biomonitoring programmes. Polychaetes were housed in laboratory and divided into five experimental groups: 1. Control (no microinjected), 2. filtered seawater + TBS injection (control of point 3), 3. filtered seawater + E. coli injection (control of point 4), 4. CuSO4 + TBS injection (control of point 5), and 5. CuSO4 + E. coli injection. The immune variables, esterase and alkaline phosphatase activity, cytotoxicity and detoxifying/antioxidant enzymes such as glutathione peroxidase were evaluated in total body extracts of the animals. Moreover, toll-like receptor, allograft inflammatory factor-1, lysozyme and haemagglutinating activity were investigated to highlight possible interactions. Indeed, the results of this work demonstrate the immunomodulating effect of copper sulphate on S. spallanzanii total body extracts related to oxidative stress and inflammatory markers.


Assuntos
Sulfato de Cobre , Poliquetos , Animais , Sulfato de Cobre/toxicidade , Escherichia coli , Água do Mar , Estresse Oxidativo
9.
Foods ; 12(6)2023 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-36981119

RESUMO

BACKGROUND: Fish oil is one of the most common lipidic substances that is consumed as a dietary supplement. The high omega-3 fatty acid content in fish oil is responsible for its numerous health benefits. Fish species such as mackerel, herring, tuna, and salmon are particularly rich in these lipids, which contain two essential omega-3 fatty acids, known as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). OBJECTIVES: Due to the scarcity of information in the literature, this study aimed to conduct a qualitative and quantitative characterization of triglycerides (TAGs) in crude tuna fish oil using HPLC/HRMS. Fatty acid (FA) determination was also performed using GC/MS. The tuna fish oils analyzed were produced using a green, low-temperature process from the remnants of fish production, avoiding the use of any extraction solvents. RESULTS: The analyses led to the tentative identification and semi-quantitation of 81 TAGs. In silico saponification and comparison with fatty acid methyl ester results helped to confirm the identified TAGs and their quantities. The study found that the produced oil is rich in EPA, DHA, and erucic acid, while the negligible isomerization of fatty acids to trans-derivatives was observed.

10.
Antioxidants (Basel) ; 12(6)2023 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-37372023

RESUMO

In the present work, oregano essential oils (OEOs) were applied to process the fresh ovine cheese "Tuma" obtained by pressed cheese technology. Cheese making trials were performed under industrial conditions using ewe's pasteurized milk and two strains of Lactococcus lactis (NT1 and NT4) as fermenting agents. Two experimental cheese products (ECP) were obtained through the addition of 100 (ECP100) and 200 (ECP200) µL/L of OEO to milk, while the control cheese product (CCP) was OEO-free. Both Lc. lactis strains showed in vitro and in vivo ability to grow in the presence of OEOs and to dominate over indigenous milk lactic acid bacteria (LAB) resistant to pasteurization. In the presence of OEOs, the most abundant compound found in cheese was carvacrol, constituting more than 65% of the volatile fraction in both experimental products. The addition of OEOs did not influence ash, fat, or protein content, but it increased by 43% the antioxidant capacity of the experimental cheeses. ECP100 cheeses showed the best appreciation scores by the sensory panel. In order to investigate the ability OEOs to be used as a natural preservative, a test of artificial contamination was carried out, and the results showed a significant reduction of the main dairy pathogens in OEO-added cheeses.

11.
Front Chem ; 10: 944021, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35991603

RESUMO

The production of red wine plays a key role in the local and international economies of several nations. During the winemaking process, to clarify the final product, before bottling, and to remove undesired substances (proteins, phenols, and tannins), fining agents are commonly added to wines. These substances have different origins (animal and vegetable proteins or mineral compounds), and they show a potential risk for the health of allergic subjects. For these reasons, the residues of fining agents, constituted by exogenous proteins based on gluten, egg, and milk proteins, should not be present in the final product and their trace residues should be quantified with accuracy. In the last decade, several analytical approaches have been developed for their quantitative determination using different sample treatment protocols and analytical techniques. These methods are based on liquid chromatography coupled with mass spectrometry or enzyme-linked immunosorbent assays (ELISAs). Recently, biosensors have been proposed as a potential alternative to immunoassay approaches, allowing rapid, cheap, and simple multi-residue detection. This short review aimed to report the most recent and relevant findings in the field.

12.
Front Chem ; 10: 971792, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36212056

RESUMO

Even though petroleum-based plastics are advantageous in complying with the performance requirements in many applications, these are related, throughout their life cycle, to several environmental problems, including greenhouse gas emissions and persistence in marine and terrestrial environments. Therefore, the preservation of natural resources and climate change is considered worldwide, the main reason for which is necessary to reduce consumption and dependence on fossil-based materials. Biopolymers (PLA, PHAs, etc.) are examples of plastics whose use is grown exponentially over the years because of the improvements of their physical and mechanical properties using additives of various nature and depending on the scope of application. This review aims to discuss various ways of biopolymer degradation, to evaluate if they represent a new Frontier in eco-sustainability or rather a re-proposal of old problems. Related to this topic, we also have focussed our attention on the different methods for the quantitative analysis of bioplastics, or their degradation by-products, comparing and evaluating the advantages and disadvantages of each technique.

13.
Interdiscip Sci ; 9(3): 392-405, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28478537

RESUMO

Surfactants are an interesting class of compounds characterized by the segregation of polar and apolar domains in the same molecule. This peculiarity makes possible a whole series of microscopic and macroscopic effects. Among their features, their ability to segregate particles (fluids or entire domains) and to reduce the surface/interfacial tension is the utmost important. The interest in the chemistry of surfactants never weakened; instead, waves of increasing interest have occurred every time a new field of application of these molecules has been discovered. All these special characteristics depend largely on the ability of surfactants to self-assemble and constitute supramolecular structures where their chemical properties are amplified. The possibility to obtain structural and energy information and, above all, the possibility of forecast the self-organizing mechanisms of surfactants have had a significant boost via computational chemistry. The molecular dynamics models, initially coarse-grained and subsequently (with the increasing computer power) using more accurate models, allowed, over the years, to better understand different aspects of the processes of dispersion, self-assembly, segregation of surfactant. Moreover, several other aspects have been investigated as the effect of the counterions of many ionic surfactants in defining the final supramolecular structures, the mobility of side chains, and the capacity of some surfactant to envelope entire proteins. This review constitutes a perspective/prospective view of these results. On the other hand, some comparison of in silico results with experimental information recently acquired through innovative analytical techniques such as ion mobility mass spectrometry which have been introduced.


Assuntos
Simulação por Computador , Lipossomos/química , Micelas , Tensoativos/química , Gases/química , Água/química
14.
Biophys Chem ; 122(3): 221-31, 2006 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-16690202

RESUMO

The interaction of natural (alginic and fulvic acids) and synthetic (polyacrylic acid 2.0 kDa) polyelectrolytes with some protonated polyamines [diamines: ethylendiamine, 1,4-diaminobutane (or putrescine), 1,5-diaminopentane (or cadaverine); triamines: N-(3-aminopropyl)-1,4-diaminobutane (or spermidine), diethylenetriamine; tetramine: N,N'-bis(3-aminopropyl)-1,4-diaminobutane (or spermine); pentamine: tetraethylene-pentamine; hexamine: pentaethylenehexamine] was studied at T=25 degrees C by potentiometry and calorimetry. Measurements were performed without supporting electrolyte, in order to avoid interference, and results were reported at I=0 mol L(-)(1). For all the systems, the formation of (am)L(2)H(i) species was found (am=amine; L=polyelectrolyte; i=1...4, depending on the amine considered). The stability of polyanion-polyammonium cation complexes is always significant, and for high-charged polycations, we observe a stability comparable to that of strong metal complexes. For example, by considering the formation reaction (am)H(i)+2L=(am)L(2)H(i) we found log K(i)=6.0, 6.5 and 10.8 for i=1, 2 and 3, respectively, in the system alginate-spermidine. Low and positive formation DeltaH(degrees) values indicate that the main contribution to the stability is entropic in nature. The sequestering ability of polyelectrolytes toward amines was modelled by a sigmoid Boltzman type equation. Some empirical relationships between stability, charges and DeltaG(degrees) and TDeltaS(degrees) are reported. Mean values per salt bridge of formation thermodynamic parameters (DeltaX(degrees) (n)) are DeltaG(degrees) (n)=-5.8+/-0.4, DeltaH degrees (n)=0.7+/-0.5 and TDeltaS(degrees) (n)=6.5+/-0.5 kJmol(-)(1) for all the systems studied in this work.


Assuntos
Alginatos/química , Benzopiranos/química , Aminas Biogênicas/química , Ácidos Carboxílicos/química , Eletrólitos/química , Ácido Glucurônico/química , Ácidos Hexurônicos/química , Matemática , Modelos Químicos , Poliaminas/química , Polieletrólitos , Polímeros/química , Prótons , Compostos de Amônio Quaternário/química , Termodinâmica
15.
Environ Toxicol Chem ; 35(12): 3062-3070, 2016 12.
Artigo em Inglês | MEDLINE | ID: mdl-27187528

RESUMO

Trace metal concentrations were measured in different tissues of Sabella spallanzanii, Styela plicata, and Mytilus galloprovincialis collected in the Termini Imerese Harbor (Sicily, Italy) to evaluate the potential use of these species as bioindicators. Higher bioaccumulation factors (BAFs) were calculated in the tube of S. spallanzanii, except for As, which had a higher BAF in the branchial crown of the same species. Regarding the other species analyzed, higher BAFs were found in the digestive gland of M. galloprovincialis. An exception was Pb, which was significantly more concentrated in the branchial basket and tunic of S. plicata. The BAFs calculated in the present study show that all the species analyzed accumulate a certain amount of metals as a consequence of filter feeding mechanisms, and thus it was possible to assess the suitability of S. plicata, S. spallanzanii, and M. galloprovincialis as indicators of water quality. In particular, the tube of S. spallanzanii is an important compartment in terms of metal retention and is more suitable for the evaluation of contamination from trace elements. Environ Toxicol Chem 2016;35:3062-3070. © 2016 SETAC.


Assuntos
Cordados/metabolismo , Mytilus/metabolismo , Poliquetos/metabolismo , Oligoelementos/metabolismo , Poluentes Químicos da Água/metabolismo , Animais , Monitoramento Ambiental , Distribuição Tecidual , Oligoelementos/análise , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/química
16.
Ann Chim ; 92(5-6): 551-62, 2002.
Artigo em Inglês | MEDLINE | ID: mdl-12125460

RESUMO

The binding capacity of 5-sulfosalicylic acid (ssa) towards cationic macro-components of natural waters has been investigated in different ionic media (NaCl, MgCl2 and CaCl2 aqueous solutions) and in the ionic strength range 0 < or = I < or = 1 mol dm-3. In order to contribute to the speciation of this multi-sites ligand, measurements have been carried out also in a synthetic seawater (SSWE) containing the major components of seawater (Na+, K+, Ca2+, Mg2+, Cl- and SO4(2-)). Measurements have been performed by potentiometry ([H+]-glass electrode), at t = 25 degrees C. A critical analysis on the experimental and literature data is also given.


Assuntos
Salicilatos/química , Água do Mar/química , Purificação da Água/métodos , Benzenossulfonatos , Cloreto de Cálcio/química , Humanos , Eletrodos Seletivos de Íons , Cloreto de Magnésio/química , Cloreto de Sódio/química
17.
J Colloid Interface Sci ; 434: 77-88, 2014 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-25170600

RESUMO

Systematic kinetic and equilibrium studies on the lead ions removal ability by Ca-alginate gel beads have been performed by varying several internal parameters, namely, number of gel beads, nature and composition of the ionic medium and pH, which allowed us to model a wastewater in order to closely reproduce the composition of a real sample. Moreover, the effects brought about the different ionic species present in the reacting medium have been evaluated. Differential Pulse Anodic Stripping Voltammetry (DP-ASV), has been systematically used to perform kinetic and equilibrium measurements over continuous time in a wide range of concentration. Kinetic and equilibrium data have been quantitatively analyzed by means of robust approach both for the non-linear regression and the subsequent residuals analysis in order to significantly improve the results in terms of precision and accuracy. Alginate gel beads have been characterized by SEM and an investigation on their swelling behavior has also been made. Removal efficiency of the calcium-alginate gel beads has been calculated and results obtained have showed a relevant dependence on ionic strength, composition of ionic media, pH of solution and number of gel beads. The number of gel beads takes part as key crucial components, i.e., the higher the number of beads the greater the amount of Pb(II) species removed from the sample, the lower the time needed to reach the maximum removal efficiency of 90%.

18.
Talanta ; 68(4): 1102-12, 2006 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-18970438

RESUMO

Protonation constants of carbonate were determined in tetramethylammonium chloride (Me(4)NCl(aq) 0.1Me(4)NCl>NaCl. An ion pair formation model designed to take into account the different protonation behaviours of carbonate in different supporting electrolytes was also evaluated.

19.
Anal Bioanal Chem ; 383(4): 587-96, 2005 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-16184367

RESUMO

Acid-base behaviour of a commercial sodium alginate extracted from brown seaweed (Macrocystis pyrifera) has been investigated at different ionic strengths (0.1

Assuntos
Alginatos/química , Biopolímeros/química , Metais/química , Prótons , Ácido Glucurônico/química , Ácidos Hexurônicos/química , Estrutura Molecular , Phaeophyceae
20.
Anal Bioanal Chem ; 375(7): 956-67, 2003 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-12707767

RESUMO

The binding ability of diethylene triamine pentaacetate (dtpa(5-)) and triethylene tetraamine hexaacetate (ttha(6-)) ligands towards major components, H(+), Na(+), Mg(2+) and Ca(2+), of natural waters was studied in both single and mixed ionic media at different ionic strengths and at T=25 degrees C. Some measurements, performed in Mg(2+)-Ca(2+) mixtures, allowed us to find the formation of new mixed species MgCa(dtpa), MgCa(ttha) and MgCaH(ttha), here reported for the first time. All the complexes formed in the various systems were characterized in terms of both stoichiometry and stability, and an attempt was made to find general rules for the stability of mixed metal complexes in comparison with that of simple species. To obtain quantitative information on the complexing ability of dtpa and ttha in seawater, measurements have been carried out in artificial seawater ionic medium (Na(+), K(+), Ca(2+), Mg(2+), Cl(-) and SO(4)(2-)). Calculations, performed by considering the salt mixture as single salt BA, allowed us to find some quite stable B(i)H(j)L species. Under the natural seawater conditions [S(salinity)=35], we found for the most important species logbeta( B(dtpa))=9.64 and. Literature data comparison is also reported.


Assuntos
Quelantes/química , Ácido Edético/análogos & derivados , Ácido Edético/química , Ácido Pentético/química , Água do Mar/química , Cloretos/química , Íons/química , Ligantes , Metais/química , Compostos Organometálicos/química , Sulfatos/química
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA