Small Molecular Weight Fraction Research Articles

TLR ligands of ryegrass pollen microbial contaminants enhance Th1 and Th2 responses and decrease induction of Foxp3hi regulatory T cells

Microbial contamination of grass pollens could affect sensitization, subsequent allergic response, and efficacy of allergen-specific immunotherapy. We investigated whether bacterial immunomodulatory substances can direct PBMC responses of allergic and nonatopic subjects against ryegrass pollen (RGP) toward Th1, Th2, or regulatory T (Treg) cells. Aqueous extracts of RGP with high or low LPS were fractionated into large and small molecular weight (MW) components by diafiltration. CFSE-labeled PBMCs from allergic and nonatopic subjects were stimulated with RGP extracts (RGPEs) and analyzed for cytokine secretion and T-cell responses. High LPS RGPE increased IFN-γ(+) Th1 and IL-4(+) Th2 effector cell induction and consistently decreased CD4(+) Foxp3(hi) Treg-cell induction. IL-10-producing T-cell frequency was unaltered, but IL-10 secretion was increased by high LPS RGPE. RGPE-stimulation of TLR-transfected cell lines revealed that high LPS pollen also contained a TLR2-ligand, and both batches a TLR9-ligand. Beta-1,3-glucans were detected in large and small MW fractions and were also T-cell stimulatory. In conclusion, coexposure to allergen and proinflammatory microbial stimuli does not convert an established Th2- into a Th1-response. Instead, proinflammatory responses are exacerbated and Foxp3(hi) Treg-cell induction is decreased. These findings show that adjuvants for specific immunotherapy should enhance Treg cells rather than target immune deviation from Th2 to Th1.

Characteristics and role of groundwater dissolved organic matter on arsenic mobilization and poisoning in Bangladesh

The fluorescence and molecular weight characteristics of dissolved organic matter (DOM) in groundwater of Bangladesh were investigated to evaluate its multiple roles on arsenic (As) mobilization and poisoning. Fluorescence properties of DOM were measured in groundwater samples collected from two As contaminated areas of Bangladesh (Faridpur at the Ganges floodplain and Sonargaon at the Meghna floodplain) from different locations and depths. The three dimensional excitation–emission matrix (3DEEM) fluorescence spectra of groundwater samples showed two characteristic peaks around Ex/Em=335–365nm/435–480nm for fulvic-like peaks and peak at around Ex/Em=275–290nm/310–335nm for the protein-like materials. The similarity of fluorescence spectra of groundwater and surface water of both the study areas with high intensity of fluorescence and its strong correlation with DOC reflect the in situ generation of fluorescent DOM from sedimentary organic matter (SOM) and recent recharge of terrestrial labile organic carbon into shallow aquifer. High performance size-exclusion chromatography (HPSEC) analysis of DOM shows positive correlations between fluorescence intensities (FI) of small molecular fractions (0.65kDa) and As concentrations, with the signatures of protein-like peaks of DOM in groundwater. This result provides new evidence that small molecular weight fraction of DOM in groundwater of Bangladesh can play an important role on As mobilization and toxicity. In addition, high concentration of fluorescence materials in DOM of As contaminated groundwater of Bangladesh may pose a threat to public health.

Adsorption Characteristics of β-Ionone in Water on Granular Activated Carbon

The adsorption performance of β-ionone on four types of granular activated carbon (GAC) in water was investigated through batch experiments. The effect of initial β-ionone concentrations and natural organic matter (NOM) adsorbed on GAC, adsorption kinetic and isothermal models were also studied. The results showed that four types of GAC all had good adsorption performance for β-ionone, the equilibrium adsorption amount of the GAC employed was in the order of YK > GK > MZ-A > MZ-B. The adsorption amount increased with increasing initial concentrations. The presence of NOM could reduce adsorption of β-ionone to a certain extent, and small molecular weight (MW) fractions (particularly <1000 Da) exhibited a remarkably competitive effect on the adsorption of β-ionone. The experimental data showed good correlation with pseudo-first-order model. Furthermore, adsorption of β-ionone on GAC fitted Freundlich, Langmuir, and Tempkin isotherms in the range of experimental concentrations, but followed Freundlich isothermal model most appropriate. The thermodynamic parameters were calculated by the results of the experiment, which showed adsorption of β-ionone on GAC as being endothermic and spontaneous.

Transformation characteristics of refractory pollutants in plugboard wastewater by an optimal electrocoagulation and electro-Fenton process

The treatment of the plugboard wastewater was performed by an optimal electrocoagulation and electro-Fenton. The organic components with suspended fractions accounting for 30% COD were preferably removed via electrocoagulation at initial 5min. In contrast, the removal efficiency was increased to 76% with the addition of H2O2. The electrogenerated Fe2+ reacts with H2O2 and leads to the generation of OH, which is responsible for the higher COD removal. However, overdosage H2O2 will consume OH generated in the electro-Fenton process and lead to the low COD removal. The COD removal efficiency decreased with the increased pH. The concentration of Fe2+ ions was dependent on the solution pH, H2O2 dosage and current density. The changes of organic characteristics in coagulation and oxidation process were differenced and evaluated using gel permeation chromatography, fluorescence excitation–emission scans and Fourier transform infrared spectroscopy. The fraction of the wastewater with aromatic structure and large molecular weight was decomposed into aliphatic structure and small molecular weight fraction in the electro-Fenton process.

TSQ (6-Methoxy-8-p-Toluenesulfonamido-Quinoline), a Common Fluorescent Sensor for Cellular Zinc, Images Zinc Proteins

Zn(2+) is a necessary cofactor for thousands of mammalian proteins. Research has suggested that transient fluxes of cellular Zn(2+) are also involved in processes such as apoptosis. Observations of Zn(2+) trafficking have been collected using Zn(2+) responsive fluorescent dyes. A commonly used Zn(2+) fluorophore is 6-methoxy-8-p-toluenesulfonamido-quinoline (TSQ). The chemical species responsible for TSQ's observed fluorescence in resting or activated cells have not been characterized. Parallel fluorescence microscopy and spectrofluorometry of LLC-PK(1) cells incubated with TSQ demonstrated punctate staining that concentrated around the nucleus and was characterized by an emission maximum near 470 nm. Addition of cell permeable Zn-pyrithione resulted in greatly increased, diffuse fluorescence that shifted the emission peak to 490 nm, indicative of the formation of Zn(TSQ)(2). TPEN (N,N,N'N'-tetrakis(-)[2-pyridylmethyl]-ethylenediamine), a cell permeant Zn(2+) chelator, largely quenched TSQ fluorescence returning the residual fluorescence to the 470 nm emission maximum. Gel filtration chromatography of cell supernatant from LLC-PK(1) cells treated with TSQ revealed that TSQ fluorescence (470 nm emission) eluted with the proteome fractions. Similarly, addition of TSQ to proteome prior to chromatography resulted in 470 nm fluorescence emission that was not observed in smaller molecular weight fractions. It is hypothesized that Zn-TSQ fluorescence, blue-shifted from the 490 nm emission maximum of Zn(TSQ)(2), results from ternary complex, TSQ-Zn-protein formation. As an example, Zn-carbonic anhydrase formed a ternary adduct with TSQ characterized by a fluorescence emission maximum of 470 nm and a dissociation constant of 1.55 × 10(-7) M. Quantification of TSQ-Zn-proteome fluorescence indicated that approximately 8% of cellular Zn(2+) was imaged by TSQ. These results were generalized to other cell types and model Zn-proteins.

Partitioning of metals between operational fractions in the sediment record from Lake Peipsi

A sequential extraction procedure was used to study the partitioning of metals (Ca, Mn, Fe, Cu, Zn and Cd) between operationally defined fractions in the interval covering the last 150 years of the sediment record from Lake Peipsi, Estonia. The results indicated decreased total and bioavailable Cu and Zn levels from the 1980s to the present, and increased Cd. The variability in Mn and Fe concentrations was possibly induced by changes in redox conditions at the bottom of the lake. The dissolved organic fraction of the sediment core was characterised by high-performance size-exclusion chromatography and spectroscopy. The dissolved organic matter pool was comprised mainly of humic substances and of a very small high molecular weight fraction. This study revealed increasing trends for general sediment characteristics (organic matter, dissolved organic carbon and absorbance ratio) since the 1960s, together with some molecular characteristics (peak areas of humic and high molecular weight fractions). Statistical cluster analysis revealed that metal concentration data in combination with some chromatographic and spectrometric parameters can be used to reveal periods with similar characteristics in Lake Peipsi sediments.

Understanding the behaviour of molecular weight fractions of natural organic matter to improve water treatment processes

Water utilities have experienced increasing pressure to minimise the formation of disinfection by-products (DBPs), as reflected in the increasingly stringent regulations and guidelines for the concentrations of DBPs in drinking water. Understanding the disinfection characteristics and molecular weight (MW) distribution of natural organic matter (NOM) will assist in the optimisation of drinking water treatment processes to minimise the formation of DBPs. This study investigated the disinfection behaviour of MW fractions of NOM isolated from a Western Australian source water. The NOM was fractionated and separated using preparative size exclusion chromatography (SEC) and the fractions were chlorinated in the presence of bromide ion. The larger MW fractions of NOM were found to produce the highest concentrations of DBPs (trihalomethanes, haloacetic acids, haloacetonitriles, haloketones, and haloaldehydes), with the low MW fractions still producing significant amounts of these DBPs. The results also showed a trend of an increasing proportion of brominated DBPs with decreasing MW and aromatic character. Considering that the smaller MW fractions of NOM produce significant amounts of DBPs, with a higher relative contribution from brominated DBPs, water treatment processes need to be optimised for either bromide removal or the removal of aliphatic, small MW fractions of NOM, in order to meet DBP guidelines and regulations.

Neutrophil chemotactic factor in supernatant from pulmonary fibroblasts stimulated with cytokines

Fibroblasts are important for maintenance of the structural frame network for most tissues, and they also play an important role in the inflammatory process via production of various mediators. In this study, we demonstrated that pulmonary fibroblasts may participate in pulmonary inflammation by production of neutrophil chemotactic factor (NCF). Pulmonary fibroblasts were stimulated with various cytokines (IGF-1, PDGF, IL-1 alpha, IL-1 beta, IL-2, IL-6, TNF, IFNr). Fibroblasts stimulated with either TNF, IL-1 alpha or IL-beta but not IGF, PDGF, IL-2 or IL-6 demonstrated a kinetic and dose-dependent increase in NCF activity. The NCF activity of crude supernatant was heat-stable and was not changed by anti-C5 antibody treatment or ether extraction. Characterization of the NCF activity by gel-filtration using high pressure liquid chromatography showed two active fractions, one with MW greater than 100 kD and the other with MW less than 10 kD. NCF activity in the small molecular weight fraction was demonstrated by inhibition of chemotaxis by addition of anti-IL-8 antibody. These data suggest that cytokine-treated fibroblast-derived NCF may be important in the pathogenesis and expression of a variety of pulmonary disease processes associated with neutrophil accumulation and activation.

The effect of soluble microbial products on membrane fouling in a fixed carrier biological system

The fixed carrier biological system (FCBS) has been developed for treatment of wastewater with an intent to achieve high simultaneous removal of carbon and nitrogen in a single through-put process. It is believed that a longer sludge retention time (SRT), high dissolved oxygen (DO), low suspended solids and good contact with the bio-balls in an FCBS possibly enable less production of extracellular polymeric substances (EPS) and soluble microbial products (SMP). The present study relates the role of SMP in membrane fouling and the characteristics of SMP in two different biological processes, a fixed carrier biological system (FCBS) with 300 d SRT and an activated sludge process (ASP) with 15 d SRT. Unfiltered effluent was directly taken from both reactors and filtered effluent was also produced to eliminate the role of suspended solids, and both were subjected to the membrane module for fouling studies. Results of this study indicated that suspended solids and bound EPS unexpectedly played a negligible role in membrane fouling and the fouling was actually controlled by SMP. The results also showed that the FCBS achieved an approximately 25–30% higher permeate flux than that of the ASP because of the presence of higher SMP (71%), total carbohydrate (60%) and total protein (77.5%) in the ASP as compared to the FCBS. Studies on gel filtration chromatography (GFC) revealed that smaller molecular weight fractions (<1 kDa and 1–10 kDa) from both the FCBS and the ASP might be responsible for most of the membrane fouling. Further, the findings with l -tyrosine and glucose as the model foulants for protein and carbohydrate respectively showed that protein ( l -tyrosine) caused more severe permeate flux decline than carbohydrate (glucose). The conclusions suggest that the use of an FCBS could hamper membrane fouling by producing less SMP.

Modification of cellulose acetate with oligomeric polycaprolactone by reactive processing: Efficiency, compatibility, and properties

AbstractOligomeric polycaprolactone (oPCL) was used for the modification of cellulose acetate by reactive processing in an internal mixer at 180°C, 50 rpm, 60 min reaction time, and 45 wt % caprolactone (CL) content. The product of the reaction was characterized by several analytical techniques and its mechanical properties were determined by dynamic mechanical thermal analysis and tensile testing. The synthesized oPCL contained small and large molecular weight components. The small molecular weight fraction plasticized cellulose acetate externally and helped fusion. Although composition and structure did not differ considerably from each other when CL monomer or polycaprolactone oligomer was used for modification, the grafting of a few long chains had considerable effect on some properties of the product. The large molecular weight chains attached to CA increased the viscosity of the melt considerably and resulted in larger deformability. oPCL homopolymer is not miscible with cellulose acetate and migrates to the surface of the polymer. Exuded polycaprolactone oligomers crystallize on the surface but can be removed very easily. More intense conditions may favor the grafting of long chains leading to polymers with advantageous properties. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Synaptic effects of low molecular weight components from Chilean Black Widow spider venom

α-Latrotoxin is the principal component of the venom from the euroasiatic Black Widow spider and has been studied for its pharmacological use as a synaptic modulator. Interestingly, smaller molecular weight fractions have been found to be associated with this toxin, but their cellular actions have not been studied in detail. The venom from the Chilean Black Widow spider ( Latrodectus mactans) does not produce α-latrotoxin, however it does contain several small polypeptides. We have recently demonstrated cellular effects of these peptides at the synaptic level using whole-cell patch clamp techniques. Purified venom from the glands of L. mactans was studied in 12 DIV rat hippocampal neuronal cultures. Venom at a concentration of 10 nM was able to decrease neuronal conductance thereby increasing membrane resistance. This effect on the passive properties of the neurons induced a change in action potential kinetics simulating the action of classic potassium channel blockers. These changes produced an increase in spontaneous synaptic activity in rat hippocampal cultures in the presence of the venom in a concentration- and time-dependent manner. These results indicate that venom from Chilean spider L. mactans is capable of increasing cell membrane resistance, prolonging the action potential and generating an increase in synaptic activity demonstrating an interesting pharmacological effect of these low molecular weight fragments.

Phase Model Interpretation of the Structural Properties of Two Molecular Soy Protein Fractions

The structural properties of mixtures of two molecular soy fractions, 11S (glycinin) and 2S, were investigated in the presence of glucono-delta-lactone (GDL) during an isothermal run at 25 degrees C for 1500 min. Analytical methodology included small-deformation dynamic oscillation, visual observations, scanning electron microscopy, and blending-law modeling. The aim of the work was to identify the state of phase separation and the pattern of solvent distribution between the two constituent polymers. It was found that the high molecular weight distribution of 11S supported rapid kinetics of structure formation, with this continuous matrix being concentrated and, hence, further reinforced in the presence of small additions of 2S. Blending-law modeling suggested that 2S was able to retain disproportionate volumes of solvent within its phase. A consequence of such property was that high additions of 2S leading to equal concentrations of the two molecular fractions in the blend resulted in a catastrophic drop in the values of the overall network strength. This behavior is rather unexpected for the structural properties of a phase-separated system, and it has been rationalized on the basis of the high water-holding capacity of the small molecular weight fraction. 2S entraps in its phase the polymeric segments of glycinin, which are then unable to become structural knots of a cohesive three-dimensional morphology observed in single 11S preparations.

Decolorization of molasses wastewater by Lactobacillus plantarum No. PV71-1861

Lactobacillus plantarum No. PV71-1861, isolated from pickle samples in Thailand, showed the high potential for use in decolorization of molasses wastewater under both anaerobic and facultative (static) conditions. The strain showed the highest melanoidin pigment (MP) decolorization yield of 68.12% with MP solution (color intensity corresponding to an optical density of 3.5 units at 475 nm) containing 2% glucose, 0.4% yeast extract, 0.1% KH 2PO 4, 0.05% MgSO 4 · 7H 2O and initial pH of 6 under static condition at 30 °C within 7 days. But, it showed low growth and MP decolorization yields under aerobic conditions. Gel filtration chromatograms of the MP solutions showed that the small molecular weight fraction of MP solution was decolorized by the strain when the large molecular weight fraction still remained in the effluent. For application, the strain could apply to treat anaerobic treated-molasses wastewater (T-MWW) with high removal efficiency. The highest MP removal efficiencies and growth yield of 76.6% and 2.6 mg/mL, respectively, were observed with the T-MWW within 7 days of culture, and the effluent pH of the system was decreased to lower than 4.0 after 2–3 days operation.

Control of residual organic matter to reduce bacterial regrowth potential for wastewater reuse

Several problems have been reported about accumulated microorganisms in reclaimed water distribution systems. This paper presents the results of residual organic matter (OM) removal and apparent bacterial regrowth potential of treated wastewater obtained from laboratory-scale experiments using advanced biological treatments: two immobilization processes in series and a membrane bioreactor (MBR) process. Furthermore, a nanofiltration (NF) membrane process was applied to effluents of both advanced biological treatments. The immobilization process removed large molecular weight (MW) fractions >5,000 since immobilized microorganisms had sufficiently acclimated. The NF membrane was more effective in rejecting large MW fractions in the effluents of the immobilization and the MBR treatments. But it was difficult to reject small MW fractions <1,000 by NF. Neutral hydrophilic fraction of DOC was reduced by both advanced biological processes, and it can be thought that the microorganisms in the advanced processes could decompose and grow on some part of the neutral hydrophilic fraction. Quantity of attached microorganisms in the second immobilization reactor was significantly reduced compared to that in the first immobilization reactor. This suggests that apparent bacterial regrowth potential is controlled by the accumulation of effective microorganisms in the first reactor.

Treatment of molasses wastewater by acetogenic bacteria BP103 in sequencing batch reactor (SBR) system

Acetogenic bacteria BP103 cells could be used as the absorbent for melanoidin pigment (MP) and molasses wastewater (MWW). The maximum MP adsorption yield of this strain observed from the dead (autoclaved) cell. It was two times higher than that with resting cells. However, the MP adsorption yield of the strain was 50–60% decreased by acclimatization with the media containing MP. The deteriorated cells (MP-adsorbed cells) could be recovered by washing with 0.1% SDS, 0.1% Tween 80 and 0.1 mol/L NaOH solutions. Among them, 0.1 mol/L NaOH solution was most suitable according to highest elution ability and no-effect to the MP adsorption capacity (The adsorption yield of deteriorated cell was reduced only 10% after washing three times with 0.1 mol/L NaOH solution). In SBR system, the strain showed very low MP removal yield with both molasses wastewater (MWW) from the anaerobic pond (An-MWW) and stillage from an alcohol factory (U-MWW). However, the MP removal yield was increased by supplementation with carbon sources (glucose). Also, the MP removal efficiency was increased with the increase of supplemented-glucose concentration. The highest COD, BOD 5, TKN and MP removal efficiencies of the SBR system with 10 times-diluted An-MWW solution containing 30 g/L glucose under HRT of seven days were 65.2 ± 2.5%, 82.8 ± 3.4%, 32.1 ± 0.8% and 50.2 ± 3.7%, respectively. The large molecular weight fraction of MP in both U-MWW and An-MWW solutions were rapidly removed by acetogenic bacteria BP103, while the small molecular weight fractions of MP still remained in the effluent.

Toxicity assessment of the extract of compost as a final product from Bio-Toilet

Bio-Toilet is the name of a dry closet or composting toilet using sawdust as an artificial soil matrix for bioconversion of human excrement into compost. Since feces and urine contain several chemicals such as pharmaceutical residues and endocrine disruptors and they may still remain in compost after biological reaction in the Bio-Toilet, it is required to examine the possibility of soil and/or groundwater pollution by applying compost to a soil system in farmland. In this study, toxicity of Bio-Toilet compost was evaluated by measuring the viability of human neuroblast (NB-1). The bio-assay was applied to the water extract of compost from the Bio-Toilets which are in practical use in Japan. The assay results showed that (1) the extract of feces showed no toxicity, and the extracts of unused sawdust had no or low level toxicity and (2) the extracts of composts had heavier toxicity than unused sawdust. These results implied that some chemicals that have toxicity were generated by biological reactions or accumulated in toilet system. The bioassay results with fractionated organic matter by its molecular weight showed that the small molecular weight fraction had stronger toxicity than other fractions. The effect of inorganic matter on toxicity was examined by comparing the dose-response relationship of the extracts of compost with positive control with 1M of sodium chloride solution. The comparison showed that sodium concentration in the extract was too low to develop the toxicity and the effect of inorganic matter could be neglected in this study.

Fractional Distributions of Trace Metals in Surface Water of Lake Biwa as Studied by Ultrafiltration and ICP-MS

Abstract The distributions of 33 trace metals in the total dissolved fraction (TDF), small molecular weight fraction (SMWF; &amp;lt;10000 Da), and large molecular weight fraction (LMWF; &amp;gt;10000 Da) of surface water from two sampling stations (No. 1 and No. 2) in Lake Biwa (Japan) were investigated. In the experiment, the concentrations of trace metals in TDF and SMWF were determined by inductively coupled plasma mass spectrometry (ICP-MS) using a laboratory-made chelating resin-packed minicolumn for the preconcentration of trace metals. The concentrations of trace metals in LMWF were calculated by subtracting those in SMWF from those in TDF. The comparison between the distributions of trace metals in each fraction collected from the sampling stations No. 1 and No. 2 was made, and the enrichment factors of trace metals in LMWF were estimated. As a result, it was found that soluble biogenic large molecule–metal complexes and hydrogenic particulates were predominantly distributed in LMWF of surface water from Lake Biwa. Furthermore, positive anomalies of Ce and Gd were observed in the shale-normalized rare earth element (REE) distribution patterns.

Soy soluble polysaccharide stabilization at oil–water interfaces

Soybean soluble polysaccharide (SSPS) is obtained from the by-product of the production of soy protein. SSPS has been employed as a functional ingredient in numerous food applications. When used to prepare oil-in-water emulsions, SSPS forms thick, stable interfaces in a wide pH range, in both acidic and neutral conditions. SSPS forms stable interfacial layers at relatively low biopolymer concentrations (about 4% (w/w) in 20% (w/w) oil-in-water emulsions), and although rich in galacturonic acid, its functionality does not seem to be affected by varying concentration of cations. This work describes the emulsifying properties of SSPS and its stability under various environmental conditions and the principles that regulate the stabilization behavior of this polysaccharide. SSPS contains a high molecular weight polysaccharide fraction with interfacial properties and a small molecular weight fraction. A polypeptide fraction, with an estimated molecular mass of 50 kDa, is covalently linked to the SSPS backbone chains and acts as an anchor to the oil–water interface. The carbohydrate moieties of the SSPS stabilize the emulsion droplets via steric interactions, forming a thick (ranging between 15 and 30 nm, depending on the SSPS type), hydrated layer on the surface of the oil droplet.

Screening for Angiotensin 1-Converting Enzyme Inhibitory Activity of Ecklonia cava

Seven brown algal species (Ecklonia cava, Ishige okamurae, Sargassum fulvellum, Sargassum horneri, Sargassum coreanum, Sargassum thunbergii and Scytosiphon lomentaria) were hydrolyzed using five proteases (Protamex, Kojizyme, Neutrase, Flavourzyme and Alcalase) and screened for angiotensin 1-converting enzyme (ACE) inhibitory activities. Most algal species examined showed good ACE inhibitory activities after the enzymatic hydrolysis. However, E. cava was the most potent ACE inhibitor of the seven species. Flavourzyme digest of E. cava exhibited an IC_(50) of around 0.3 ㎍/mL for ACE; captopril has an IC_(50) of ~0.05 ㎍/mL. The Flavourzyme digest was separated to three fractions by an ultrafiltration membrane (5, 10, 30 kDa MWCO) system according to the molecular weights. The active components were mainly concentrated in ＞30 kD fraction which are composed of the highest protein content (27%) and phenolic content (261 mg/100 mL) compared to the other two smaller molecular weight fractions. Therefore, the active compounds appear to be relatively high molecular weight complex molecules associated with protein (glycoprotein) and polyphenols. Therefore, E. cave is a potential source of antihypertensive compound.

Distribution of elements binding to molecules with different molecular weights in aqueous extract of Antarctic krill by size-exclusion chromatography coupled with inductively coupled plasma mass spectrometry

The distribution of silver, arsenic, cadmium, cobalt, chromium, copper, iron, manganese, nickel, lead, selenium and zinc binding to species with different molecular weight in aqueous extract of krill was studied by on-line size-exclusion chromatography (SEC)/inductively coupled plasma mass spectrometry (ICP-MS). The extract was fractionated in three fractions with different molecular weight (MW) ranges (>20,000 relative molecular mass (rel. mol. mass), 2000–20,000 rel. mol. mass and <2000 rel. mol. mass), which were further analyzed by SEC with columns having different optimum fractionation ranges in order to obtain more detailed information about the MW distribution of the elements. Various distribution profiles for the target elements among different MW ranges were observed. The results obtained indicated that manganese, zinc, silver, cadmium and lead species were mostly distributed in the higher MW range (>20,000 rel. mol. mass). In the case of chromium, iron, cobalt, arsenic and selenium, most of them bind to species with lower MW (<2000 rel. mol. mass). Only copper and nickel species was predominantly present in middle MW range (2000–20,000 rel. mol. mass). Further speciation of arsenic compounds in the small MW fraction was carried out with anion exchange chromatography (AEC) coupled with ICP-MS. The results showed that the dominant arsenic species in this fraction is As(III) (63% of extractable arsenic), while As(V) (13%) and two unknown arsenic species (19% and 5%, respectively) are present in lower amounts.