Water-insoluble Fraction Research Articles

Prediction of in vivo organic matter digestibility of beef cattle diets from degradation parameters estimated from in situ and in vitro incubations

AbstractThe objective of this meta-analysis study was to develop and validate equations estimated from in situ and in vitro methods to predict in vivo ruminal digestibility of organic matter (OM) of beef cattle diets. The database was composed of individual data of 23 diets from six experiments. Information collected from these studies was: in vivo digestibility and degradation parameters of OM calculated from in situ and in vitro incubations. The values of estimated times for the in situ and in vitro incubations to access in vivo digestibility of OM, and differences between degradation at 24, 48 and 72 h (in situ and in vitro) and in vivo digestibility were analysed in a model that included the fixed effects of forage neutral detergent fibre level. Thereafter, a multiple stepwise regression was carried out using OM digestibility as a dependent variable and degradation parameters (A = water-soluble fraction; B = potentially degradable water-insoluble fraction; and kd = degradation rate of fraction B) as independent variables. Equation validation was performed using data from a seventh experiment that have the same methods than previous studies. Stepwise regression results showed that the kd contributed significantly in most of the algorithms derived to predict in vivo digestibility. Validation analysis showed that equations developed from both in vitro and in situ incubations accurately estimated the in vivo digestibility of OM (P > 0.05). Our results suggest that equations developed to estimate OM digestibility showed both precision and accuracy; however, in situ method presented better results than in vitro.

Isolation and Characterization of Melanoidins from Dulce de Leche, A Confectionary Dairy Product.

Melanoidins, the brown-colored compounds formed through the Maillard reaction, are responsible for color development in dulce de leche (DL), a popular confectionary dairy product in the Río de la Plata region, particularly in Uruguay and Argentina. Color is a critical quality parameter that strongly influences consumer preference. This work aimed to develop a method to perform preliminary structural characterization of the chromophores produced by the Maillard reaction. Melanoidins are present in a water-insoluble fraction, linked to a protein backbone, conforming melanoproteins of high molecular weight. The insoluble melanoprotein fraction (10% total solids) was isolated, and the chromophores released by proteolysis and isolated by gel-permeation chromatography. The analysis of the products revealed that they present a high degree of molecular weight (MW) polydispersity, in a range of 300 to 2000 Da, where the compounds of higher molecular weight contributed the most to the color of the product. The isolated fractions were further analyzed by RP-HPLC using a diode array detector (DAD) detector. These results, together with H-NMR data, suggested that the chromophores isolated belonged to a relatively simple mixture of aromatic products with higher hydrophobic character relative to other products of the melanoprotein digestion.

Wheat-induced food allergy in childhood: ancient grains seem no way out

Wheat is a frequent elicitor of food allergy in childhood. Especially in popular media, the better digestibility and the lower allergenicity of ancient grains are repeatedly postulated. We addressed the question whether ancient wheat-related grains are less allergenic than modern wheat. Proteins from cultivars of spelt, einkorn, emmer and durum along with durum soft wheat flour, Tritordeum and bread wheat were separated by electrophoresis. Immunoblots were performed with a pool serum of six sera from wheat-sensitized children aged 1-11years (wheat-specific IgE 22 kUA/l). As controls, pool serum from five sera atopic patients aged 3-13years who had no sensitization to wheat (wheat-specific IgE 0.11 kUA/l) and six sera from non-atopics at the age of 3months to 5years (wheat-specific IgE 0.06 kUA/l) was used. Area under the curve (AUC) in Coomassie-stained gels and immunoblots was determined and related. Water/salt-soluble protein patterns were very similar among varieties. In einkorn cultivars, one protein band corresponding to an alpha-amylase/trypsin inhibitor (ATI) was absent. Water-insoluble protein fractions differed markedly among varieties and cultivars. IgE bound to a large number of proteins in all protein fractions both in wheat and in the wheat-related ancient grains. Patients with sensitization to wheat show a significant IgE binding against both modern and ancient grain varieties of the genus Triticum. Therefore, ancient grains do not appear to have a generally reduced risk for wheat allergy sufferers. However, few individuals only sensitized to ATI could benefit from the consumption of einkorn.

Changes in the Soluble and Insoluble Compounds of Shelf-Stable Orange Juice in Relation to Non-Enzymatic Browning during Storage.

For the first time in literature, this study revealed the participation of polymeric components of orange juice cloud and pulp (such as proteins, arabinogalactan proteins, or protein-pectin complexes) during nonenzymatic browning. In a quest to better understand the nonenzymatic browning of shelf-stable orange juice during storage, the juice was fractionated into different fractions depending on the solubility in water/ethanol and the obtained fractions were characterized. The results showed that brown compounds that were formed during storage of orange juice were distributed over water insoluble (pulp), ethanol insoluble (cloud), and ethanol soluble (serum) fractions. In the ethanol insoluble fraction, the brown compounds are hypothesized to be associated with proteins, arabinogalactan proteins, and/or protein-pectin complexes of this fraction without significantly changing their molecular weight distributions, monosaccharide compositions, and protein contents. The changes in the ethanol soluble fraction including ascorbic acid degradation, acid-catalyzed hydrolysis of sucrose, and formation of furfural and 5-hydroxymethylfurfural were highly correlated to the browning development of the juice during storage.

An investigation on citrus peel as the lignocellulosic feedstock for optimal reducing sugar synthesis with an additional scope for the production of hydrolytic enzymes from the aqueous extract waste

Abstract In the current study, the use citrus peels as the lignocellulosic feedstock for the production of reducing sugars and hydrolytic enzymes was evaluated. Citrus peels were subjected to a two-step pre-treatment procedure to obtain two major fractions-the water soluble pectin rich fraction and the water insoluble solid fraction enriched with cellulose and hemicellulose. Three parameters (solid loading, acid concentration and time) that were found to be critically influencing the acid hydrolysis process were optimized by using Response surface methodology (RSM) - central composite design (CCD) for the improved synthesis of reducing sugars. A maximal total reducing sugar concentration of 13.34 g/L was predicted for the optimal processing conditions of solid loading = 3.87% w/w, acid concentration = 1% w/w and time = 48.4 min and at the processing temperature of 121 °C in a steam autoclave. Experimental validation studies carried out at these optimal conditions showed a slightly higher reducing sugar concentration of 13.65 ± 0.3 g/L than the predicted value. Further studies demonstrating the use of pectin-rich liquid fraction as the nutrient medium for hydrolytic enzymes production resulted in enzyme activities of 5.38 ± 0.2 IU/mL for pectinase and 1.17 ± 0.1 FPU (Filter Paper Units) for cellulase, without supplementation of any salts to the medium. These results suggest that the pre-treated citrus peels can serve as a potent feedstock for bioethanol production, while by-products resulting from pre-treatment can be employed to produce hydrolytic enzymes such as pectinases and cellulases as demonstrated through this work.

Non-Solvent Fractionation of Lignin Enhances Carbon Fiber Performance.

Even though lignin carbon fiber has been sought after for several decades, the poor mechanical performance remains to be a major barrier for commercial applications. The low mechanical performance is attributed to the heterogeneity of lignin polymer. Recent advances in fractionation technologies showed the great potential to reduce lignin heterogeneity, but current fractionation methods often depend on costly chemicals and materials such as enzymes, organic solvents, membranes, and dialysis tubes. Here, a new non-solvent strategy was developed to fractionate lignin by autohydrolysis. By using only water, lignin was efficiently fractionated into water-soluble and -insoluble fractions. The latter fraction had increased molecular weight and uniformity and resulted in more β-O-4 interunitary linkages as analyzed by size-exclusion chromatography and 2D heteronuclear single quantum coherence NMR spectroscopy, respectively. In particular, the water-insoluble fraction significantly enhanced the mechanical performances of the resultant carbon fibers. Mechanistic study by differential scanning calorimetry (DSC) revealed that the miscibility of lignin with guest polyacrylonitrile molecules was improved with the reduced lignin heterogeneity. Crystallite analyses by XRD and Raman spectroscopy revealed that the crystallite size and content of the pre-graphitic turbostratic carbon structure were increased. The fundamental understanding revealed how lignin fractionation could modify lignin chemical features to enhance the mechanical performance of resultant carbon fibers. The autohydrolysis fractionation thus represents a green, economic, and efficient methodology to process lignin waste and boost lignin carbon fiber quality, which could open new horizons for lignin valorization.

Quantitative speciation of insoluble chlorine in E-waste open burning soil: Implications of the presence of unidentified aromatic-Cl and insoluble chlorides

Open burning of electronic waste (E-waste) produces numerous organochlorine compounds (OCs). Although the presence of unidentified OCs has been suggested, the mass balance of identified and unidentified OCs in E-waste open burning soils (EOBSs) still remains unknown. In this study, the concentrations of Cl bonded with aromatic carbon (aromatic-Cl) and aliphatic carbon (aliphatic-Cl), and inorganic Cl in EOBSs were determined by focusing on chlorine (Cl) in water-insoluble fractions (insoluble Cl) and applying Cl K-edge X-ray absorption spectroscopy in conjunction with combustion ion chromatography. The concentrations of identified Cl (Cl in five individual OCs: polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, chlorinated polycyclic aromatic hydrocarbons and chlorinated benzenes) were calculated from the concentrations previously reported for the same samples. The proportions of identified Cl were less than 1% to aromatic-Cl, indicating the abundance of unidentified OCs. The concentrations of both aromatic-Cl and identified Cl were highest in the sample collected from the site in Vietnam (VN), where wires and cables were mainly burned, suggesting that unidentified aromatic-Cl were produced through pathways similar to those of identified OCs, and the pathway could be related to burning of wires and cables. Further, insoluble Cu (II) compound, Cu2(OH)3Cl were assumed to be present in EOBSs and the concentration was highest in VN, implying that insoluble inorganic chlorides could be related to the formation of aromatic-Cl and identified Cl.

Physicochemical Properties and Intestinal Health Promoting Water-Insoluble Fiber Enriched Fraction Prepared from Blanched Vegetable Soybean Pod Hulls.

Different methods can be used to change the fiber compositions of food, and they consequently affect the physicochemical properties and physiological activities. The present study compared the effects of a blanching treatment on the physicochemical properties of water-insoluble fiber enriched fraction (WIFF) from three varieties of vegetable soybean pod hulls (tea vegetable soybean pod hull, TVSPH; black vegetable soybean pod hull, BVSPH; 305 vegetable soybean pod hulls, 305VSPH) and evaluated their effects on intestinal health in hamsters. Blanching may increase the soluble dietary fiber (SDF) content of WIFF in the 305VSPH variety by solubilizing cell wall components and releasing water-soluble sugars. Thus, the WIFF in the 305VSPH variety after blanching may be composed of cellulose and pectic substances. The WIFF of the blanched 305VSPH (B-305VSPH) variety exhibited the highest physicochemical properties, such as a water-retention capacity (11.7 g/g), oil-holding capacity (9.34 g/g), swelling property (10.8 mL/g), solubility (12.2%), and cation-exchange capacity (221 meq/kg), of the three varieties examined. The supplementation of B-305VSPH WIFF in the diet resulted in significantly (p < 0.05) lower cecal and fecal ammonia; activities of fecal β-d-glucosidase, β-d-glucuronidase, mucinase, and urease; as well as higher cecal total short-chain fatty acids relative to other diets. In addition, microbial analysis suggested that fecal bifidobacteria growth was enhanced by the consumption of B-305VSPH WIFF. Therefore, B-305VSPH WIFF may be applicable as a potential functional ingredient in the food industry for the improvement of intestinal health.

The Influence of Milk Type on the Proteolysis and Antioxidant Capacity of White-Brined Cheese Manufactured from High-Heat-Treated Milk Pretreated with Chymosin.

We investigated the effect of milk type on the proteolysis and total antioxidant capacity (TEAC) of white-brined cheeses prepared from high-heat-treated (90 °C, 10 min) cow’s and goat’s milk, pretreated with chymosin at a low temperature (4 °C). The cheeses produced showed improved antioxidant characteristics and a high content of denatured whey proteins. However, these characteristics depend on the type of milk and the ripening time. Ripened cow’s milk cheese had higher values of WSN/TN (water-soluble nitrogen per total nitrogen content) and TCA-SN/TN (nitrogen soluble in 12% trichloroacetic acid per total nitrogen), but similar PTA-SN/TN (nitrogen soluble in 5% phosphotungstic acid per total nitrogen) values were observed in ripened cheeses. The antioxidant potential of a WSF (water-soluble fraction) was higher in goat’s milk cheese, but higher TEAC (total antioxidant capacity) values of WINF (water-insoluble fraction) were observed in matured cow’s milk cheese. In vitro digestion slightly improved the radical scavenging capacity of WSF, whereas digested WINF had more than twice the capacity of their undigested counterparts. The cheeses prepared in this study could be a good source of antioxidant peptides. Further investigations of their in vitro and in vivo functionality need to be conducted.

Preparation of silver nanoparticles using different fractions of TEMPO-oxidized nanocellulose

The aim of this study was to examine efficacy of different fractions of TEMPO-oxidized cellulose nanocrystals (TOCNs) as a reducing and capping agent of silver nanoparticles (AgNPs). Silver nanoparticles were prepared by thermal treatment of AgNO3 in aqueous suspensions of TOCN fractions. Three different nanocomposite materials based on different fractions of TOCNs and reduced in situ by TOCN silver nanoparticles were obtained. It was demonstrated that three fractions of TOCNs, characterised by varying water-solubility, degree of oxidation and viscosity, bind silver nanoparticles differently. The capping of anionic TOCNs fractions on the surface of nanoparticles was confirmed by zeta potential measurements, and therefore good stability of AgTOCNs nanoparticles was shown. The size and dispersion of AgNPs seems to be affected mainly by the viscosity of a given TOCN fraction. Water-soluble TOCN fractions yielded spherical AgNPs, while water-insoluble fractions contributed to the formation of nanoparticles characterised by diverse morphologies. The application of TEMPO-oxidized cellulose fractions for greener synthesis of silver nanoparticles is discussed. A mechanism including a polylol process is proposed as a possible means of silver cation reduction. The morphology and structural features of the TOCN nanocellulose-silver nanoparticle composites were assessed with the use of spectroscopic and microscopic techniques.

Atmospheric particulate matter accumulation on trees: A comparison of boles, branches and leaves

A quantitative comparative analysis of PM accumulation on boles, branches and leaves is necessary to better understand the reduction of airborne PM by trees. This study compared the total water-insoluble particle accumulation mass per unit area, the distribution of water-insoluble particle size fractions, and the accumulation masses and compositions of water-soluble ions among different vegetative organs. The average accumulation capacity of water-insoluble particles was as follows: leaf epicuticular wax (11.1 ± 4.4 μg/cm 2 ), leaf surfaces (22.0 ± 3.2 μg/cm 2 ), terminal branch surfaces (101.6 ± 47.0 μg/cm 2 ), perennial branch surfaces (92.7 ± 20.0 μg/cm 2 ), and bark surfaces (1719.9 ± 684.7 μg/cm 2 ). Bole bark surfaces tended to accumulate the largest proportion of large particles, averaging 88 ± 4%. Branch surfaces and leaf epicuticular wax accumulated the largest proportions of fine particles, averaging 15 ± 5%. The total masses of water-soluble ions were 18 ± 10%, 33 ± 13% and 32 ± 6% of the total water-insoluble particles on boles, terminal branches and leaves, respectively. Leaf surfaces accumulated 2.2–6.0 times more SO2- 4 and NO 3 than did branch and bark surfaces. • PM accumulation differed significantly among vegetative organs. • Stem bark surfaces tended to accumulate large particles. • Branch surfaces and leaf epicuticular wax accumulated more fine particles. • Leaf surfaces accounted for greater proportion of water-soluble ions.

Quantitative Speciation of Insoluble Chlorine in Environmental Solid Samples

Since organically bound chlorine (organo-Cl) has been determined by different methods depending on samples and study fields, it has been difficult to compare organo-Cl in different environments. Here, we focused on Cl in water-insoluble fractions (insoluble Cl) and applied Cl K-edge X-ray absorption spectroscopy in conjunction with combustion ion chromatography. Quantitative speciation of insoluble Cl enabled us to compare the concentrations of Cl bonded with aromatic carbon (aromatic-Cl) and aliphatic carbon (aliphatic-Cl) as well as organo-Cl across different types of environmental solid samples (soils, particulate matter, dust, and ashes). The concentrations of organo-Cl in house dust and urban particulate matter exceeded those in forest soils, suggesting that house dust and urban particulate matter may be important pools of organochlorine compounds (OCs). Further, by studying representative samples with concentrations of some individual organochlorine compounds (OCs), we evaluated the mass balance of ...

The Effect of In Vitro Digestion on Antioxidant, ACE-Inhibitory and Antimicrobial Potentials of Traditional Serbian White-Brined Cheeses.

This study deals with the effect of in vitro digestion on the functional potential of traditional Serbian white-brined cheeses. The total antioxidant capacity, reducing power and iron (II) chelating properties as well as angiotensin-converting enyzme-inhibitory (ACE-inhibitory) and antimicrobial activities of traditional Serbian white-brined cheeses before and after in vitro digestion were assayed. The traditional cheeses had different antioxidant properties as well as different ACE-inhibitory activities. In vitro digestion improved the total antioxidant capacity (8.42–58.56 times) and the reducing power (by 17.90–99.30%) of investigated cheeses, whereas their chelating ability was slightly improved or unaffected after digestion. In vitro digestion reduced the ACE-inhibitory potential of water-soluble protein fractions, and digested water-insoluble fractions were the major source of ACE-inhibitory peptides. The digestates did not exhibit any antibacterial potential, whereas they showed moderate antifungal potential toward selected micromycetes. The best antifungal potential had Svrljig ovine cheese and Homolje cow cheese. The results of this study clearly point to a significant functionality of traditional white-brined cheeses.

Development of Bio-Based Films and 3D Objects from Apple Pomace.

Extensive quantities of apple pomace are generated annually but its disposal is still challenging. This study addresses this issue by introducing a new, environmentally-friendly approach for the production of sustainable biomaterials from apple pomace, containing 55.47% free sugars and a water insoluble fraction, containing 29.42 ± 0.44% hemicelluloses, 38.99 ± 0.42% cellulose, and 22.94 ± 0.12% lignin. Solution casting and compression molding were applied to form bio-based films and 3D objects (i.e., fiberboards), respectively. Using glycerol as plasticizer resulted in highly compact films with high tensile strength and low elongation (16.49 ± 2.54 MPa and 10.78 ± 3.19%, respectively). In contrast, naturally occurring sugars in the apple pomace showed stronger plasticizing effect in the films and resulted in a fluffier and connected structure with significantly higher elongation (37.39 ± 10.38% and 55.41 ± 5.38%, respectively). Benefiting from the self-binding capacity of polysaccharides, fiberboards were prepared by compression molding at 100 °C using glycerol or naturally occurring sugars, such as plasticizer. The obtained fiberboards exhibited tensile strength of 3.02–5.79 MPa and elongation of 0.93%–1.56%. Possible applications for apple pomace biomaterials are edible/disposable tableware or food packaging.

Co-ingestion of whole almonds and almond oil with carbohydrate suppresses postprandial glycaemia in mice in an insulin-dependent and insulin-independent manner.

Co-ingestion of almonds with carbohydrate prevents excessive increase in plasma glucose level (PGL), but information about the functional fraction is limited. Identifying the functional fraction is necessary to use almonds more efficiently in terms of controlling postprandial glycaemia after a high-carbohydrate meal. In the present study, we evaluated the effects of almond skin, oil, water-soluble fraction and water-insoluble fraction on both postprandial glycaemia and insulinaemia. The effect of almond skin was tested by comparing the effect of whole almonds with the effect of skinless almonds. Male ICR mice were administered dextrin and 4g/kg body weight test samples. After the administration, 2-h postprandial changes in glycaemia and insulinaemia were measured. Oil was the only fraction being able to blunt postprandial glycaemia. Interestingly, when co-ingesting with dextrin, almond oil did not change the insulin level compared with the control but whole almonds or skinless almonds triggered a 4-fold increase in insulin level. The co-ingestion of whole almonds or skinless almonds similarly suppressed the PGL at 15 and 30min (P<0·05), which means almond skin has no effect on postprandial glycaemia. Neither soluble nor insoluble fractions lead to any significant changes in postprandial glycaemia and insulinaemia. In conclusion, oil is the main functional component accounting for the glycaemia-lowering effect without altering insulin level.

Two-stage alkali-oxygen pretreatment capable of improving biomass saccharification for bioethanol production and enabling lignin valorization via adsorbents for heavy metal ions under the biorefinery concept

Converting lignin into value-added products in current lignocellulosic biorefineries has been challenging, which in turn restricts the commercialization of many lignocellulosic biorefineries. In this work, a two-stage alkali-oxygen assisted liquid hot water pretreatment (AlkOx) was proposed as the first step of biorefinery. This alkali-oxygen pretreatment facilitated biomass fractionation by solubilizing majority of lignin in water-soluble fraction, while remaining most of cellulose and hemicellulose in water-insoluble fraction. As a result, biomass saccharification was significantly improved by selective removal and oxidative modification of lignin through alkali-oxygen pretreatment. Moreover, lignin residues from both pretreatment hydrolysate and enzymatic hydrolysate were shown to be favorable adsorbents for Pb(II) ions, with adsorption capacity of 263.16 and 90.91 mg/g, respectively. Results demonstrated that this integrated process could not only improve biomass saccharification but also enable lignin valorization, which encouraged the holistic utilization of lignin residues as part of an integrated biorefinery.

Cytotoxicity comparison between fine particles emitted from the combustion of municipal solid waste and biomass.

Fine particles (PM2.5) emitted from municipal solid waste incineration (MSWI) contain high amounts of toxic compounds and pose a serious threat to environment and human health. In this study, entire particles as well as extracted water-soluble and -insoluble fractions of PM2.5 collected from MSWI and biomass incineration (BMI) were subjected to physiochemical characterization and cytotoxic tests in A549 and BEAS-2B cells. MSWI PM2.5 had higher contents of heavy metals (including Pb, Zn, and Cu) and dioxins (PCDD/Fs) than did BMI PM2.5. The metals were enriched in the water-insoluble fraction, as measured by inductively coupled plasma-atomic emission spectrometry. BMI PM2.5 had a higher content of endotoxin, which was also enriched in the water-insoluble fraction. MSWI PM2.5 caused more serious cell injuries, as indicated by the lower viability, higher ROS generation, and DNA damage, whereas BMI PM2.5 presented higher pro-inflammatory potential, as indicated by increased mRNA levels of interleukin 6. Normal human BEAS-2B cells were more sensitive than A549 cells in all these tests. Toxic effects caused by MSWI and BMI PM2.5 were mostly attributable to their water-insoluble fractions. Our results indicate different chemical and biological compositions in MSWI and BMI PM2.5 probably dominate in different toxic endpoints in vitro.

Cod Residual Protein Prevented Blood Pressure Increase in Zucker fa/fa Rats, Possibly by Inhibiting Activities of Angiotensin-Converting Enzyme and Renin.

Hypertension is the leading risk factor for cardiovascular disease, and prevention of high blood pressure through diet and lifestyle should be a preferred approach. High intake of fish is associated with lower blood pressure, possibly mediated through the proteins since peptides with angiotensin-converting enzyme (ACE) inhibiting capacities have been identified in fish skin, backbone, and fillet. The effects of cod meals made from residual materials and fillet on blood pressure were investigated in obese Zucker fa/fa rats which spontaneously develop high blood pressure. Rats were fed diets containing water-soluble (stickwater) or water-insoluble (presscake) fractions of protein-rich meals from cod residual materials (head, gut, backbone with muscle residuals, skin, trimmings) or fillet. Rats were fed diets containing 25% of total protein from cod meal and 75% of protein from casein, or casein as the sole protein source (control group) for four weeks. Results show that a diet containing residual presscake meal with high gut content prevented blood pressure increase, and this cod residual meal also showed the strongest in vitro inhibitions of ACE and renin activities. In conclusion, a diet containing water-insoluble proteins (presscake meal) with high gut content prevented increase in blood pressure in obese Zucker fa/fa rats.

Study of anticorrosive coatings based on high and low molecular weight polyphenols extracted from the Pine radiata bark

In this work, two primers with organic corrosion inhibitors were extracted from Pinus radiata bark, from the waste generated by the timber and paper industries. The process resulted in a water-soluble fraction (WSF) and water-insoluble fraction (WIF). The additives were incorporated in a two-component (2 K) primer based on epoxy-polyamide resin with a ratio formulation of λ = 0.85 (PVC = 34.79). Spectroscopy techniques, such as electron paramagnetic resonance (EPR), high-performance liquid chromatography (HPLC), Raman spectroscopy, and electrochemical impedance spectroscopy (EIS) were used for both the extract and coating characterizations. Coating performances were obtained in the order of 109 Ω. cm2 for the impedance, and the systems were simulated using a circuit (R1(Q1(R2(Q2(R3(R4C))))). The formation of tannin-Fe complexes was demonstrated using RAMAN spectroscopy.

Partitioning of the water soluble versus insoluble fraction of trace elements in the city of Santiago, Chile

The total elemental composition and the water-soluble fraction of PM 10 from three different urban areas in Santiago, Chile, from downtown to the suburbs, were investigated. PM 10 samples collected during the month of May (mid-autumn in the Southern Hemisphere) in 2006, 2008, 2009, and 2010 were analyzed for major and trace metals, and the partitioning between the insoluble and soluble fractions was determined for most of them. PM 10 average concentrations ranged from 71 µg m –3 (Cerrillos) to 128 µg m –3 (La Pintana), which are within the seasonal ranges observed in Santiago. Twenty five major and trace elements (Fe, Al, Ca, K, Mg, P, Pb, S, Ti, Mn, Cu, Zn, Ba, Zr, Cr, As, Sn, Sb, Ni, V, Li, Co, Cd, La, and Rb) were determined in the present study. Ba, Sb, Cd, As, and Zn, with proportions in the soluble fraction varying from 50% to 98%, were the most soluble elements. On the contrary, the less soluble trace elements were Ti, Sn, Pb, and Cr. Most of the high-solubility trace metals are strongly linked to non-exhaust traffic emissions, as well as to certain industrial sources. Our results evidence the significant amount of soluble trace elements in Santiago’s urban atmosphere classified as toxic and/or carcinogenic, thus suggesting a non-negligible health impact.