Characterization of polymerized impurities in cefoxitin sodium for injection by two-dimensional chromatography coupled with time-of-flight mass spectrometry

Polymerized impurities in β-lactam antibiotics can induce allergic reactions, which seriously threaten the health of patients. In order to study the polymerized impurities in cefoxitin sodium for injection, a novel approach based on the use of two-dimensional liquid chromatography coupled with time-of-flight mass spectrometry (2D-LC-TOF MS) was applied. In the 1st dimension, high performance size exclusion chromatography (HPSEC) with a TSK-G2000SWxl column was employed. Column switching was applied for the desalination of the mobile phase used to separate polymerized impurities in the 1st dimension before they were transferred to the 2nd dimension which utilized reversed phase liquid chromatography (RP-LC) and TOF MS for further structural characterization. The structures of four polymerized impurities (which were all previously unknown) in cefoxitin sodium for injection were deduced based on the MS2 data. One novel polymerized impurity (PI-I), with 2H less than the molecular weight of two molecules of cefoxitin (Mr. 852.09), was found to be the most abundant (>50 %) in almost all the samples examined and could be regarded as the marker polymer of cefoxitin sodium for injection. This work also showed the great potential of the 2D-LC-TOF MS approach in structural characterization of unknown impurities separated with a mobile phase containing non-volatile phosphate in the 1st dimension.

Atomic force microscopy based conformation and immunological activity of Lentinan injections

The purpose of this study was to investigate the morphological characteristics of different brands of lentinan injections produced in China using atomic force microscopy (AFM) and their relationship to immunological activity. Based on AFM imaging, chain height could be used as characterizing the conformation of lentinan, and the heights of 95 % confidence interval for triple, double and single helix were 1.746 ± 0.039 nm, 1.564 ± 0.037 nm and 1.243 ± 0.031 nm, respectively, which were calculated using self-developed MATLAB protocol. AFM characters and their immunological activity of different lentinan injection were compared. In detail, two parameters, triple helix ratio 51.3 % and adhesion force 800 pN, of Jinling (JL) lentinan injection are much higher than samples of other four manufacturers. In addition, immunological activity of JL lentinan injection is also significantly higher than Yineng's. High performance size exclusion chromatography (HPSEC) profiles of different lentinans were also compared, and the data were in accordance with those from AFM. Molecular weight accumulation curves could be used for evaluation of quality consistence of different batches of lentinan from same manufacturer and/or different manufacturers. The results showed that quality consistence of lentinan from different manufactures is poor, which should be greatly improved.

Varying the hydrophobicity of humic matter by a phase-transfer-catalyzed O-alkylation reaction

An O-alkylation reaction catalyzed by tetrabutylammonium hydroxide (TBAH) as a phase-transfer agent was applied to a humic acid (HA) to modify its hydrophobic properties. The carboxyl and hydroxyl functional groups of HA acted as nucleophiles in substitution reactions (Sn²) with methyl iodide, pentyl bromide and benzyl bromide added in amounts equimolar to 20, 60 and 80% of HA total nucleophilic sites. The occurrence of O-alkylation was shown by DRIFT spectrometry, NMR spectroscopy, High Performance Size Exclusion Chromatography (HPSEC) and elemental analysis of reaction products. DRIFT spectra showed changes in C-H stretching and bending regions following the insertion of methyl and pentyl groups, while the incorporation of benzyl groups revealed the characteristics aromatic C-H stretching bands. Both liquid- and solid-state NMR spectra revealed characteristic signals for alkyl/aryl esters and ethers. HPSEC chromatograms of alkylated materials invariably displayed an increase in hydrodynamic volume in respect to the original HA, thereby suggesting that the enhanced hydrophobicity conveyed further associations among humic molecules. Analytical, HPSEC and spectroscopic results suggest that benzylation was the most effective reaction at all percentages of HA total nucleophilicity, followed, in the order, by pentylation and methylation, The benzylation reaction was used to improve reaction and work-up conditions and show that HA could be efficiently alkylated also with substantial reduction of TBAH amount, with no THF addition, increase of reaction time and of washing cycles to remove catalyst impurities. These findings indicate that the hydrophobicity of humic substances can be modulated through a mild O-alkylation reaction under a phase-transfer catalysis according to the extent of exposed HA nucleophilic sites. Such a structural modification of humic matter may have multiple chemical, environmental and biological applications.

Enhanced stability of Foot-and-Mouth Disease Vaccine Antigens with a novel formulation

The structural instability of inactivated foot-and-mouth disease virus antigen hinders the development of vaccine industry. The use of an inexpensive, biocompatible formulation to slow down the degradation of antigen would address the problem. Here, PBS was showed to be effective in stabilizing 146S and hence determined as basic solution buffer. Excipients such as Trehalose, Sucrose, Arginine, Cysteine, Calcium chloride, BSA and Ascorbic acid were found to protect 146S from massive structural breakdown. Using orthogonal test, we confirmed the novel formulation as a combination of 5% (w/v) trehalose, 5% (w/v) sucrose, 0.05 M arginine, 0.01 M cysteine, 0.01 M calcium chloride, 1% (W/V) BSA and 0.001 M ascorbic acid in PBS. The formulation increased vaccine stabilization, with retention rate of 14% after storage at 4 °C for 14 months. Particle size for vaccine was at approximately 220 nm and physicochemical detecting findings were rarely abnormal in morphology and emulsion type. In summary, these results revealed that the novel formulation is beneficial to make FMD vaccine more stable and effective, reducing the dependence on cold storage and delivery.

Analysis of the polymerized impurities in cefmetazole sodium based on novel separation principle by liquid chromatography tandem ion trap/time-of-flight mass spectrometry

To effectively control the polymerized impurities in cefmetazole sodium, novel high performance gel filtration chromatography (HPSEC) with TSK-gel G2000SWxl column and RP-HPLC method with C₁₈ column were used in replace of classical gel filtration chromatography with Sephadex G-10 gel. By studying the chromatographic behavior of polymerized impurities in both chromatographic systems with different chromatographic separation principles, the polymerized impurities in cefmetazole sodium were separated and detected effectively. The two-dimensional liquid chromatography tandem ion trap/time-of-flight mass spectrometry (2D LC-IT-TOF MS) was applied to characterize the structures of polymerized impurities eluted from HPSEC method, and liquid chromatography tandem ion trap/time-of-flight mass spectrometry was applied to characterize the structures of polymerized impurities and other unknown impurities eluted from RP-HPLC method. The structures of fourteen unknown impurities in cefmetazole sodium were deduced based on the MS ⁿ data, nine of which were polymerized impurities. The corresponding relationship between impurities in the HPSEC method and RP-HPLC method was established, and the specificity of the two methods was evaluated. The RP-HPLC method for analysis of the polymerized impurities has higher column efficiency and specificity than the HPSEC method. The RP-HPLC method is suitable for quality control of the polymerized impurities in cefmetazole sodium. The forming mechanisms of degradation impurities in cefmetazole sodium were also studied.

Study of the polymerized impurities in cefotaxime sodium and cefepime by applying various chromatographic modes coupled with ion trap/time-of-flight mass spectrometry

Polymerized impurities in β-lactam antibiotics can induce allergic reaction, which seriously threaten the health of patients. In order to study the polymerized impurities in cefotaxime sodium and cefepime, a HPSEC method with TSK-gel G2000SWxl column and a RP-HPLC method with C18 column were established to replace the classical gel filtration chromatography with Sephadex G-10 gel as stationary phase. Two-dimensional (2D) liquid chromatography was employed to further investigate the HPSEC and RP-HPLC method and ion trap/time-of-flight mass spectrometry was applied to characterize the structures of polymerized impurities eluted from the two methods. The structures of the polymerized impurities in cefotaxime sodium and cefepime were deduced based on the MSⁿ data, six of which were previously unknown. The corresponding relationship of impurities between the two methods was established, and the specificity of the two methods was compared. The results showed that the polymerized impurities in cefotaxime sodium and cefepime were co-eluted with other small molecular weight impurities with high polarity in HPSEC, leading to a poor specificity. The newly established RP-HPLC methods could effectively separate and detect polymerized impurities and were suitable for the quality control in daily analysis.

Analysis of polymerized impurities in mezlocillin sodium and sulbenicillin sodium using two chromatographic separation mechanisms coupled to tandem mass spectrometry

To effectively control the polymerized impurities in mezlocillin sodium and sulbenicillin sodium, a HPSEC method with TSK-gel G2000SWxl column and a RP-HPLC method with C18 analytical column were established to replace the classical gel filtration chromatography with Sephadex G-10 gel as stationary phase. By studying the chromatographic behavior of polymerized impurities in both methods with different chromatographic separation mechanisms, the polymerized impurities in mezlocillin sodium and sulbenicillin sodium were separated and detected effectively. The column switching two-dimension liquid chromatography ion trap/time-of-flight mass spectrometry was applied to characterize the structures of polymerized impurities eluted from the HPSEC method and RP-HPLC method for both drugs. The structures of the polymerized impurities in mezlocillin sodium and sulbenicillin sodium were deduced based on the MSⁿ data. The results showed that the polymerized impurities detected by HPSEC method and RP-HPLC method were completely different. Therefore, two methods should be used meanwhile to control the polymerized impurities in mezlocillin sodium and sulbenicillin sodium.

Biodegradation and Structural Modification of Humic Acids in a Compost Induced by Fertilization with Steelmaking Slag under Coastal Seawater, as Detected by TMAH-py-GC/MS, EEM and HPSEC Analyses

The compost's humic acid (HA) content decreased when it was fertilized in coastal seawater with steelmaking slag, as confirmed. This study clarified the cause for this change by a detailed analysis of the structural changes in HAs based on the TMAH-py-GC/MS, HPSEC, and 3D-EEM spectra. An increase in the levels of pyrolysates of tannic acid with a low polymerization degree was attributed to the biodegradation of a high polymerized aromatic structure. Moreover, analyses of 3D-EEM, supported by HPSEC, indicated that approximately 20 kDa of the fluorescent matter was generated at the protein-like peaks (Ex/Em = 220/340 and 275/350 nm) in HAs derived from a mixture of compost with steelmaking slag. It would be caused due to the formation of HAs from the bacterial by-product by a catalytic reaction of the steelmaking slag. From these findings reported herein, we conclude that bio-degradation was a major reason for the decreased HA content, and the formation of HA from a part of the degradation products. This would be a reason for the structural modification of HA under the seawater condition.

Physicochemical and multi-scale structural alterations of pea starch induced by supercritical carbon dioxide + ethanol extraction

The objective of this study was to establish the impacts of supercritical fluid extraction (SFE) processing on the physicochemical properties of pea flour and the structure of isolated pea starch. A significant (p < 0.05) increase in protein content and reduction in several pasting and thermal parameters as measured by rapid visco-analyzer and differential scanning calorimeter were observed after SFE. Additionally, SFE increased starch digestibility as determined by an in vitro starch digestion assay. An increased amylopectin content and crystallinity along with the loss of double helix content was supported by size exclusion chromatography and FT-IR data, respectively. X-ray diffraction and scanning electron microscopy showed minimal alterations of starch, by SFE, in long-range crystalline and morphological structure of starch granules, respectively. The data demonstrated SFE influenced the physicochemical and structural characteristics of pea starch. These outcomes illustrated that SFE might be a green and novel technology for starch modification.

Digestibility of resistant starch type 3 is affected by crystal type, molecular weight and molecular weight distribution

Resistant starch type 3 (RS-3) holds great potential as a prebiotic by supporting gut microbiota following intestinal digestion. However the factors influencing the digestibility of RS-3 are largely unknown. This research aims to reveal how crystal type and molecular weight (distribution) of RS-3 influence its resistance. Narrow and polydisperse α-glucans of degree of polymerization (DP) 14-76, either obtained by enzymatic synthesis or debranching amylopectins from different sources, were crystallized in 12 different A- or B-type crystals and in vitro digested. Crystal type had the largest influence on resistance to digestion (A >>> B), followed by molecular weight (Mw) (high DP >> low DP) and Mw distribution (narrow disperse > polydisperse). B-type crystals escaping digestion changed in Mw and Mw distribution compared to that in the original B-type crystals, whereas A-type crystals were unchanged. This indicates that pancreatic α-amylase binds and acts differently to A- or B-type RS-3 crystals.

A standardized, innovative method to characterize the structure of aquatic protein hydrolysates

The performances of protein hydrolysates highly depend on their peptide composition (amount, size and diversity), which itself closely depends on raw material origin and the hydrolysis parameters of the manufacturing process. The current analyses that characterize protein hydrolysates provide information on the level of hydrolysis (degree of hydrolysis, DH). However, they need additional describers to better characterize peptide profiles and product standardization. To reach this objective, we developed a fast and standardized method to characterize the abundance and the diversity of low-molecular-weight peptides in protein hydrolysates. This method innovatively combines classical HPSEC and nLC-ESI-MS analytical tools to characterize any kind of hydrolysate, whether solid or liquid, in terms of peptide level and diversity, and then merge peptides into 2D diagrams to visualize comparisons between protein hydrolysates. The targeted applications of this new tool for characterizing complex protein hydrolysates are (i) verifying the standardization of the produced products across batches, and (ii) analyzing and understanding the consequences of the modifications of the hydrolysis process on the molecular profiles of the generated peptides. The sample standardization described in this study is therefore an essential prerequisite for the functional characterization of hydrolysates in vitro.

Investigation of the fouling behaviors correlating to water characteristics during the ultrafiltration with ozone treatment

This study investigated the fouling behavior and mechanism of ozone treatment correlating to water characteristics for micro-polluted water during ultrafiltration (UF). The results indicated that pre-ozonation efficiently mitigated membrane fouling of natural organic matter (NOM). The higher ozone doses were, the more the performance transmembrane pressures (TMPs) decreased. Ozone mainly converted macro molecule organics into low molecule organics. Macro molecular biopolymers (BP) can be removed up to 35.5% with an ozone treatment of 9 mg/L, while low molecular weight building blocks of acids and humics (BB) and neutrals (LMWN) increased 7.25% and 14.62%, respectively, with an ozone treatment of 9 mg/L. Analysis of fluorescence excitation emission matrices (EEMs) coupled with parallel factor analysis (PARAFAC) indicated that ozone mainly removed soluble microbial organics and fulvic-like and humic-like organics but not tyrosine organics. Hydrophobic organics (HPO) were reduced with an increase of ozone doses, especially macro molecular BP and humic substances (HS), and the neutral hydrophilic fraction (N-HPI) was enhanced. Ozone treatment helped to reduce the interception of BP and HS in HPO and improved the interception of BP and HS in N-HPI, as well as BB and LMWN, in both fractions. Principal component analysis suggested that BP, as well as UV₂₅₄, had high correlations with a membrane fouling index, which can be used as the fouling indicator during ozone treatment.

HPLC with charged aerosol detector (CAD) as a quality control platform for analysis of carbohydrate polymers

Objective

QC analysis of carbohydrates has been historically cumbersome due to lengthy and laborious derivatization techniques and the requirement of complimentary instrumentation. HILIC-CAD has emerged as an effective platform for direct monosaccharide composition analysis of complex carbohydrates without derivatization. Although, several neutral sugars have been separated and detected using HILIC-CAD, there has not been any report on acidic and amino sugar analysis using this method. In this study, we developed a gradient method for simultaneous analysis of acidic, amino and select neutral monosaccharides. As an application of the HILIC-CAD method, we performed composition analysis of commercially purchased hyaluronic acid products. Additionally, since CAD is suitable for SEC experiments, we tested the homogeneity of hyaluronic acids using a SEC-CAD method.

Results

We separated common uronic acids (GlcA, GalA, LIdoA and Neu5Ac), amino sugars (GlcN, GalN and GlcNAc) and select neutral sugars (LRha, LFuc, Man and Gal) using a gradient HILIC-CAD method. The optimized gradient method demonstrated good linearity (R² > 0.99), precision (RSD < 8%), LOD (< 85 ng/mL) and LOQ (< 280 ng/mL). HILIC-CAD analysis of commercially purchased hyaluronic acid products indicated that samples were composed of GlcNAc and GlcA. Additionally, SEC-CAD chromatograms indicated the heterogeneous nature of the samples.

Electronic supplementary material

The online version of this article (10.1186/s13104-019-4296-y) contains supplementary material, which is available to authorized users.

Identification of textile wastewater in water bodies by fluorescence excitation emission matrix-parallel factor analysis and high-performance size exclusion chromatography

Identifying the causes of water body pollution is critical because of the serious water contamination in developing countries. The textile industry is a major contributor to severe water pollution due to its high discharge of wastewater with high concentrations of organic and inorganic pollutants. In this study, fluorescence excitation emission matrix-parallel factor (EEM-PARAFAC) analysis was applied to characterize textile industry wastewater and trace its presence in water bodies. The EEM spectra of textile wastewater samples collected from 12 wastewater treatment plants (WWTPs) revealed two characteristic peaks: Peak T1 (tryptophan-like region) and Peak B (tyrosine-like region). Two protein-like components (C1 and C2) were identified in the textile wastewater by PARAFAC analysis. The components identified from different textile WWTPs were considered identical (similarity >0.95). C1 and C2 were not sensitive to changes in pH, ionic strength, or low humic acid concentration (TOC < 4 mg/L). Therefore, C1 combined with C2 was proposed as a source-specific indicator of textile wastewater, which was further demonstrated by conducting high-performance size exclusion chromatography analysis. These results suggested that EEM-PARAFAC analysis is a reliable means of identifying textile wastewater pollution in water bodies and may also enable the identification of other industrial wastewater.

Humic substances in Fluvisols of the Lower Vistula floodplain, North Poland

The present study describes properties of humic substances of the Fluvisols (the Lower Vistula, Poland). Fluvisols under agricultural management (arable soil and grassland) were sampled from the surface horizon 50, 200, 600, and 900 m from the Vistula River. The content of carbon in the fractions of humic acids (C_HAs), fulvic acids (C_FAs), and humins (C_HUMIN) as well as the content of dissolved organic carbon (DOC) were assayed. The organic matter of the soils that were sampled 200 m from the river demonstrated a lowest share of the humic acids (HAs) and fulvic acids (FAs). The percentage share of the hydrophilic fractions (HIL) in the HAs and, as a result the value of the HIL/ΣHOB ratio, increased with the distance from the riverbed. The HAs of the soils located further from the riverbed had a higher degree of humification compared to the HAs of the soils that were sampled 50 and 200 m away. Based on the research results, it was determined that the properties of HAs can be used to evaluate the effect of flood events, their location, and scope on the transformation of the organic matter in fluvial sediments.

Natural organic matter undergoes different molecular sieving by adsorption on activated carbon and carbon nanotubes

We have comprehensively compared the molecular sieving of natural organic matter (NOM) by adsorption on activated carbon (AC) and multi-walled carbon nanotubes (CNT) using different types of NOM. All water samples were characterized using UV-visible and fluorescence spectroscopies as well as high-performance size-exclusion chromatography (HPSEC) before and after adsorption. Adsorption isotherm results fitted well with Freundlich model (R² = 0.95-0.99) and the model parameters indicated higher adsorption of NOM on CNT than AC. Fluorescence index (FI) and freshness index (BIX) showed preferential adsorption of microbial derived and fresh NOM on AC, whereas, terrestrial derived and decomposed NOM were preferentially adsorbed on CNT. Further, HPSEC revealed that AC adsorbed NOM fractions with small molecular weight (MW) (<0.4 kDa) faster than the fractions with higher MW. In contrast, CNT adsorbed NOM fractions characterized by high MW (>1 kDa) while the smallest fraction (<0.4 kDa) was not adsorbed, possibly due to its hydrophilic character. Our results also demonstrated a good correlation between FI and average MW of NOM (R² > 0.93). These findings illustrate the influence of the adsorbent's type and characteristics (i.e., porosity and pore size distribution) on the preferential adsorption of different NOM fractions.

Palmyra palm (Borassus aethiopum Mart.) fruits: novel raw materials for the pectin industry

BACKGROUND

Preventing post-harvest waste of Palmyra palm (Borassus aethiopum Mart.) fruits is possible by recovery of pectin as a value-added ingredient. Extraction conditions on yield and functionality of Palmyra palm pectin was determined at different temperatures and pH values with 30 min extraction time.

RESULTS

Palmyra palm fruits contain more than 650 g kg^-1 galacturonic acid and produce soft gels with sucrose in acidic media despite a high degree of acetylation (∼5%). Mechanical deformation of pectin gel was similar when extracted at pH 2.5 and 70 °C or under natural pH at room temperature or 70 °C. Pectins isolated at pH 7 exhibited comparable gel softness (G'/G″) with commercial pectin. Palm pectins also showed emulsifying activity greater than 50%, attributed to high protein content of 8 g 100 g^-1 . For pectins extracted at pH near 5.2-5.5, molar mass ranged from 3.00 to 3.38 × 10⁵ g mol^-1 ; intrinsic viscosity ranged from 218 to 297 mL g^-1 ; arabinose was the main neutral sugar; ζ-potential ranged from -23 to -25 mV.

CONCLUSION

Palm fruit offers an inexpensive raw material to extract pectin in environmentally friendly and economical way and yield a pectin with unique gelling, viscosifying and emulsifying properties. © 2016 Society of Chemical Industry.

Understanding the Effects of Roasting on Antioxidant Components of Coffee Brews by Coupling On-line ABTS Assay to High Performance Size Exclusion Chromatography

INTRODUCTION

Coffee is a widely consumed beverage containing antioxidant active compounds. During roasting the phytochemical composition of the coffee bean changes dramatically and highly polymeric substances are produced. Besides chlorogenic acids that are already present in green coffee beans, melanoidins show antioxidant capacity as well.

OBJECTIVE

To employ post-column derivatisation by coupling high performance size exclusion chromatography (HPSEC) to an antioxidant assay to investigate the effect of roasting on the properties of antioxidant active compounds in coffee brews.

METHODOLOGY

We have investigated the antioxidant capacity of Coffea arabica (Arabica) and C. canephora (Robusta) beans that were roasted over the full spectrum of roast conditions (four roasting speeds to three roast degrees) by comparing the results from HPSEC coupled on-line to the ABTS assay with those from two batch assays, Folin Ciocalteu (FC) and oxygen radical absorbance capacity (ORAC) assay.

RESULTS

The antioxidant capacity showed a general decrease towards slower and darker roasted coffee for all three assays, indicative of heat degradation of active compounds. Hence, low molecular weight (LMW) compounds such as chlorogenic acids (CGAs) decreased progressively already from relatively mild roasting conditions. In contrast, high molecular weight (HMW) compounds (e.g. melanoidins) increased from light to dark roast degrees with lowering magnitude towards slower roasting profiles.

CONCLUSION

By coupling HPSEC on-line to the ABTS assay we were able to separately quantify the contribution of HMW and LMW compounds to the total antioxidant capacity, increasing our understanding of the roast process. © 2016 The Authors. Phytochemical Analysis Published by John Wiley & Sons Ltd.

Pectin from Opuntia ficus indica: Optimization of microwave-assisted extraction and preliminary characterization

Optimization of microwave-assisted extraction (MAE) of water-soluble pectin (WSP) from Opuntia ficus indica cladodes was performed using Response Surface Methodology. The effect of extraction time (X₁), microwave power (X₂), pH (X₃) and solid-to-liquid ratio (X₄) on the extraction yield was examined. The optimum conditions of MAE were as follows: X₁=2.15min; X₂=517W; X₃=2.26 and X₄=2g/30.6mL. The maximum obtained yield of pectin extraction was 12.57%. Total carbohydrate content of WSP is about 95.5% including 34.4% of Galacturonic acid. Pectin-related proteins represent only the 0.66% of WSP mass. HPSEC and light scattering analyses reveal that WSP is mostly constituted of high molecular pectin and FTIR measurements show that the microwave treatment does not alter the chemical structure of WSP, in which Galacturonic acid content and yield are 34.4% and 4.33%, respectively. Overall, application of MAE can give rise to high quality pectin.

TEMPO-mediated oxidation on galactomannan: Gal/Man ratio and chain flexibility dependence

Guar (GG) and locust bean (LBG) galactomannans (GMs) oxidation at C-6 was performed with catalyst TEMPO, in which the reaction progress was monitored by consume of NaOH solution. The products were characterized by spectroscopic analysis, infrared, and (1)H-nuclear magnetic resonance, confirming the presence of aldehydes groups as intermediate of reaction to carboxylic acid. From high performance anion exchange chromatography with pulsed amperometric detection Man/Gal molar ratio was determined and demonstrated a preference to oxidize Man during the reaction on both GMs, following a first order kinetics of oxidation. The comparative macromolecular behavior of native and oxidized GMs was obtained through the analysis by high performance size exclusion chromatography, and the persistence length (Lp) was 6nm and 4nm to native LBG and GG, respectively. A more accessible OH-6 at mannose residue in LBG could be related with a two times faster reaction than GG. The selective oxidation with catalyst TEMPO proved to be efficient to increase the flexibility of the GMs during oxidation. Short reaction time and β-elimination process were mainly observed to LBG, probably due to a more favorable oxidation access to the polysaccharide main chain.

Characterisation of dissolved organic matter in stormwater using high-performance size exclusion chromatography

Understanding the complexity of dissolved organic matter (DOM) in stormwater has drawn a lot of interest, since DOM from stormwater causes not only environmental impacts, but also worsens downstream aquatic quality associated with water supply and treatability. This study introduced and employed high-performance size exclusion chromatography (HPSEC) coupled with an ultraviolet-visible (UV-vis) diode array detector to assess changes in stormwater-associated DOM characteristics. Stormwater DOM was also analysed in relation to storm event characteristics, water quality and spectroscopic analysis. Statistical tools were used to determine the correlations within DOM and water quality measurements. Results showed that dissolved organic carbon (DOC) and UV absorbance at 254 nm (UV254) as conventional DOM parameters were found to be correlated well to the changes in stormwater quality during each of the three storm events studied. Both detector wavelengths (210 and 254 nm) and their ratio (A210/A254) were found to provide additional information on the physiochemical properties of stormwater-associated DOM. This study indicated that A210/A254 is an important parameter which could be used to estimate the DOM proportions of functional groups and conjugated carbon species. This study provided also an understanding of stormwater quality constituents through assessing variability and sensitivity for various parameters, and the additional information of rainfall characteristics on runoff quality data for a better understanding of parameter correlations and influences.

Extracellular polymeric substances (EPS) and surface properties of activated sludges: effect of organic carbon sources

The study aims to clarify how the type of organic substrate in a wastewater affects the production and composition of extracellular polymeric substances (EPS) and hydrophobicity and surface charge of activated sludges. For this purpose, three activated sludge reactors were operated in parallel with feeds composed of the organics (i) peptone, glucose, and acetate and (ii) peptone and (iii) glucose. EPS extracted from sludges were fractionated into very loosely bound, loosely bound, and tightly bound fractions and analyzed for protein and polysaccharide. Also, molecular weight distribution of proteins was determined by using high-pressure size exclusion chromatography (HPSEC). Regardless of the type of organic substrate, in each sludge, tightly bound EPS (TB-EPS) prevailed. The type of organic substrate affected the relative proportion of protein and polysaccharide and had an impact on hydrophobicity and surface charge. The sludge fed with peptone was distinctly more hydrophobic and had a lower negative surface charge than others. HPSEC fingerprints revealed that the variety and size of proteins were dependent on the type of feed. HPSEC also pointed to a shift of high molecular weight (MW) proteins from TB-EPS to others. In addition, results of a parallel study examining the inhibitory effect of Ag(+) on three sludges were interpreted along with feed composition, EPS, and surface measurements. The response of each sludge to toxic Ag(+) ion seemed to change with the type of feed.

Improved evaporative light scattering detection for carbohydrate analysis

Optimization and validation of evaporative light scattering detector (ELSD), aided by response surface methodology (RSM), has been developed for the liquid chromatography analysis of a wide molecular weight (MW) range of carbohydrates, including polysaccharides and oligosaccharides. Optimal experimental parameters for the ELSD detection were: 88.8°C evaporator temperature, 77.9°C nebulizer temperature and 1.1 standard litres per minute nitrogen flow rate. Optimal ELSD detection, used together with high performance size exclusion chromatography (HPSEC) of carbohydrates, gave a linear range from 250 to 1000 mg L(-1) (R(2)>0.998), with limits of detection and quantitation of 4.83-11.67 and 16.11-38.91 mg L(-1), respectively. Relative standard deviation was lower than 1.8% for intra-day and inter-day repeatability for apple pectin, inulin, verbascose, stachyose and raffinose. Recovery ranged from 103.7% to 118.3% for fructo-oligosaccharides, α-galacto-oligosaccharides and disaccharides. Optimized and validated ELSD detection is proposed for the analysis of high- to low-MW carbohydrates with high sensitivity, precision and accuracy.

Effect of Pre-Harvest Sprouting on Physicochemical Properties of Starch in Wheat

Pre-harvest sprouting (PHS) in wheat (Triticum aestivum L.) occurs when physiologically mature kernels begin germinating in the spike. The objective of this study was to provide fundamental information on physicochemical changes of starch due to PHS in Hard Red Spring (HRS) and Hard White Spring (HWS) wheat. The mean values of α-amylase activity of non-sprouted and sprouted wheat samples were 0.12 CU/g and 2.00 CU/g, respectively. Sprouted samples exhibited very low peak and final viscosities compared to non-sprouted wheat samples. Scanning electron microscopy (SEM) images showed that starch granules in sprouted samples were partially hydrolyzed. Based on High Performance Size Exclusion Chromatography (HPSEC) profiles, the starch from sprouted samples had relatively lower molecular weight than that of non-sprouted samples. Overall, high α-amylase activity caused changes to the physicochemical properties of the PHS damaged wheat.

Thermal and chemical evaluation of naturally auto-oxidised virgin olive oils: a correlation study

BACKGROUND

The nature of the relationship between differential scanning calorimetry thermal properties and the oxidation and hydrolysis compounds formed during a real auto-oxidation process in virgin olive oils has not been evaluated so far, as these samples are difficult to find. In this work, 21 samples of virgin olive oil, stored under ideal conditions since their years of production (production range 1991-2005) to develop the natural auto-oxidation process, were analysed in order to evaluate this relationship.

RESULTS

Oils stored the longest time showed the highest hydrolytic degradation while the others exhibited higher contents of oxidised fatty acids and triacylglycerols, instead. Thermal properties of transitions were differently influenced by degradation compounds with the onset of both the cooling and heating profiles particularly influenced by diacylglycerols and oxidised lipids. Chemical data and thermal properties were correlated by using principal component analysis. Twenty-three variables were selected for the analysis with the first component fully segregating samples into two groups according to the year of storage and the level of hydrolysis and/or oxidation, on the basis of selected thermal properties obtained by cooling and heating transitions.

CONCLUSIONS

These preliminary findings showed that differential scanning calorimetry could be considered an useful tool to evaluate lipid degradation in virgin olive oils, indicating its value as a support to chemical techniques.

Characterization of polysaccharides from Ganoderma spp. using saccharide mapping

Polysaccharides from Ganoderma spp. and their adulterants were firstly investigated and compared using saccharide mapping, enzymatic (endo-1,3-β-D-glucanase and pectinase) digestion followed by polysaccharide analysis using carbohydrate gel electrophoresis analysis. The results showed that both 1,3-β-D-glucosidic and 1,4-α-D-galactosiduronic linkages were existed in Lingzhi (Ganoderma lucidum and Ganoderma sinense), and the similarity of polysaccharides from G. lucidum and G. sinense was high, which may contribute to rational use of Lingzhi. Different species of Ganoderma and their adulterants can be differentiated based on the saccharide mapping, which is helpful to well understand the structural characters of polysaccharides from different species of Ganoderma and to improve the quality control of polysaccharides in Lingzhi.