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l-Proline is the only, out of 20 essential, amino acid that contains a cyclized substituted α-amino group (is formally an imino acid), which restricts its conformational shape. The synthesis of well-defined homo- and copolymers of l-proline has been plagued either by the low purity of the monomer or the inability of most initiating species to polymerize the corresponding N-carboxy anhydride (NCA) because they require a hydrogen on the 3-N position of the five-member ring of the NCA, which is missing. Herein, highly pure l-proline NCA was synthesized by using the Boc-protected, rather than the free amino acid. The protection of the amine group as well as the efficient purification method utilized resulted in the synthesis of highly pure l-proline NCA. The high purity of the monomer and the use of an amino initiator, which does not require the presence of the 3-N hydrogen, led for the first time to well-defined poly(l-proline) (PLP) homopolymers, poly(ethylene oxide)-b-poly(l-proline), and poly(l-proline)-b-poly(ethylene oxide)-b-poly(l-proline) hybrids, along with poly(γ-benzyl-l-glutamate)-b- poly(l-proline) and poly(Boc-l-lysine)-b-poly(l-proline) copolypeptides. The combined characterization (NMR, FTIR, and MS) that results for the l-proline NCA revealed its high purity. In addition, all synthesized polymers exhibit high molecular and compositional homogeneity. © 2011 American Chemical Society.

This article presents an analytical method based on solid-phase extraction (SPE) and gas chromatography coupled with mass spectrometry for the simultaneous determination of the most frequently used acidic pharmaceutical residues, ibuprofen, diclofenac, naproxen and ketoprofen (KFN), and phenolic endocrine disruptors, bisphenol (BPA), triclosan (TCS), nonylphenol, nonylphenol monoethoxylate and nonylphenol diethoxylate, in wastewater and sewage sludge samples. In the first phase of the study, each compound has been characterized individually and afterwards in mixture as a trimethylsilyl derivative in order to identify the characteristic ions (m/z ratio) constituting the mass spectrum and to choose the ions for quantification and confirmation. Subsequently, derivatization was evaluated by testing different variables such as the volume of the derivatization solvent bis(trimethylsilyl)trifluoroacetamide and the effect of each catalyst, pyridine and 1% trimethyl chlorosilane, in the derivatized solution. For the analysis of wastewater samples, two commercial SPE cartridges, C18 and Oasis HLB, were compared for their extraction efficiency of the target compounds. The key parameter of extraction procedure included the effect of pH (2.5, 5.3 and 7) of the loading solution. For solid samples, parameters such as the extracted biomass, the volume of the extraction organic solvent and the effect of matrix interferences in chromatographic analysis were evaluated. By using C18 cartridges as purification procedure and ultrasound sonication, satisfactory mean relative recoveries with BPA-d16 and meclofenamic acid as surrogates were obtained ranging from 91% to 117% for wastewater and 84% to 107% for sewage sludge samples. Nine-point calibration of the standard mixture was performed by linear regression analysis with a correlation coefficient0.99 for all the tested compounds. Limits of detection for the developed methods were established between 0.3 (KFN) and 14.8 (BPA) ng L(-1), and 15.0 (TCS) and 32.9 (BPA) ng g(-1) for wastewater and sewage sludge, respectively. Application to real samples of the wastewater treatment plant in Athens, the capital of Greece, demonstrated the presence of all tested compounds in most of the samples.

This paper presents the application of ion chromatography with electrolytic eluent generation and mobile phase suppression for the direct conductimetric detection of glyphosate and its degradation product aminomethylphosphonic acid (AMPA). The compounds were separated on a Dionex AS18 anion exchange column with a 12-40 mM KOH step gradient from 9 to 9.5 min. The effect of the suppressor current intensity on the electrostatic interaction of these amphoteric compounds with the suppressor cation exchange membranes was evaluated. A suppressor current gradient technique was proposed for the limitation of peak broadening and baseline noise, in order to improve method sensitivity and detectability. It was observed that residual sample carbonates co-eluted with AMPA when a large injection loop was installed for the low level determination of both compounds in natural waters. For this reason, glyphosate was isocratically eluted using 33 mM KOH in order to decrease analysis time within 10 min and a column clean up step using 100 mM KOH was used to ensure retention time reproducibility. The developed method was applied to the analysis of drinking and natural water and it was further successfully applied to orange samples with slight modifications. Instrumental LOD for glyphosate was 0.24 microg/L, while method LOD was 0.54 microg/L for spring waters and 0.01 mg/kg for oranges using a 1000 microL direct loop injection of the sample. Intra-day and inter-day precision (as %RSD) for water samples was 4.6% and 12% at a spiking level of 2 microg/L, and the recovery ranged from 64% to 88% depending on sample conductivity. For orange samples, the inter-day precision was 1.4% at a spiking level of 4.4 mg/kg, while overall recovery was 103%. The developed method is direct, fast, sensitive and relatively inexpensive, and could be used as an ideal fast screening tool for the monitoring of glyphosate residues in water and fruit samples.

A strategy was newly developed to rapidly screen seventeen sulfonamides and five tetracyclines in a single run from fish tissues using ultra-high performance liquid chromatography (UHPLC) coupled with comprehensive mass spectrometric approaches, including precursor-ion scan and data dependent scan. The product ions for precursor-ion scanning were selected by studying the MS/MS fragmentation of the analytes. All sulfonamides share the same diagnostic product ion at m/z 156 in positive MS/MS scan, while for tetracycline antibiotics the diagnostic product ion was proved to be at m/z 153.8. Further characterization of each compound was performed using a data dependent scan. Separation was performed on a Zorbax Eclipse Plus C18 column with a gradient elution using acetonitrile - 0.1% formic acid mobile phase at a flow rate of 0.1 mL min(-1). This approach has proven to be a powerful, highly selective, and sensitive tool for rapid screening and detection of non-targeted components in fish tissue and requires a minimum sample preparation such as one generic extraction step with MeOH:ACN 50:50 (v/v) acidified with 0.05% formic acid. The method has also been applied successfully to porcine and poultry meat. The validation of such a screening method was performed for the first time according to Commission Decision 2002/657/EC and satisfactory method performance characteristics were achieved.

The occurrence of three endocrine disrupting compounds, 4-n-nonylphenol, triclosan and bisphenol A, was investigated in different bivalves originating from the Aegean Sea (Greece). The bioconcentration potential of these compounds was studied using the Mediterranean mussel (Mytilus galloprovincialis). Tissue samples were extracted by sonication. Analysis was performed by gas chromatography-mass spectrometry. According to the field survey results, the average concentrations of 4-n-nonylphenol, triclosan and bisphenol A, were 158, 461 and 404 ng g(-1) (dry weight), respectively. During 28 days of exposure at 300 ng L(-1), the tissue concentrations of compounds were constantly increased. Steady state was not observed up to the end of the experiment. Kinetic bioconcentration factors varied from 1.7 (4-n-nonylphenol and triclosan) to 4.5 L g(-1) (bisphenol A). Following exposure, mussels were relocated to clean water for 28 days. This experiment revealed that depuration rates for all of the target compounds were lower than uptake rates. The biological half-lives of each compound ranged between 12 days (triclosan) and 26 days (bisphenol A).

We present a framework for designing optimal allocation strategies for large stock portfolios using dynamic factor models and multivariate volatility parametrisations. We attempt to elaborate on the fundamental structure of the Fama and French (FF) factor model with a special focus on the time variation in risk and correlation between stocks returns and systematic factors. For this reason, variants of the multivariate GARCH models are employed to capture the dynamics in means, variances and covariances of the FF factors structure. Based on these models, we derive optimal capital allocation strategies in the framework of Markowitz’s mean-variance portfolio theory. We outline and compare the out-of-sample performance of these mean-variance allocations with those obtained using simpler techniques, such as sample historical and Exponentially Weighted Moving Average (EWMA) estimates.

The presence of organotin (OT) compounds was investigated in coastal areas (10 stations), wastewater treatment systems (six stations), rivers (19 stations) and lakes (12 stations) throughout Greece, in three sampling campaigns organized between October 1998 and September 1999. A screening method for the determination of toluene extractable organotins (TEOTs) by Electrothermal Atomic Absorption Spectrometry (ETAAS) was used during the first two sampling campaigns. TEOTs (sum of tributyltin, TBT, dibutyltin, DBT and triphenyltin, TPhT) were detected in most seawater and wastewater samples at concentrations up to 19.4 and 89.9 ng l−1, respectively, while they were detected occasionally in surface water. During the third sampling campaign, OT compounds were extracted in selected stations using direct derivatization with NaBEt4 in acidic medium and analysed by Gas Chromatography–Mass Spectrometry (GC–MS). In seawater, the levels of TBT, DBT and monobutyltin (MBT) were varied between < 2 and 70, 159 and 19 ng l−1, respectively and tend to decrease with increasing distance from the coastline. TPhT was not detected in any of the samples. Significant concentrations of OT species were detected in influent wastewater, up to 384, 76.2 and 67.8 ng l−1 for TBT, DBT and MBT, respectively. OTs were mainly associated with the suspended solids and were totally removed during wastewater treatment.

The purpose of this research was to study the fate and toxicity of triclosan (TCS) in activated sludge systems and to investigate the role of biodegradation and sorption on its removal. Two continuous-flow activated sludge systems were used; one system was used as a control, while the other received TCS concentrations equal to 0.5 and 2 mg l −1 . At the end of the experiment, 1 mg l −1 TCS was added in the control system to investigate TCS behaviour and effects on non-acclimatized biomass. For all concentrations tested, more than 90% of the added TCS was removed during the activated sludge process. Determination of TCS in the dissolved and particulate phase and calculation of its mass flux revealed that TCS was mainly biodegraded. Activated sludge ability to biodegrade TCS depended on biomass acclimatization and resulted in a mean biodegradation of 97%. Experiments with batch and continuous-flow systems revealed that TCS is rapidly sorbed on the suspended solids and afterwards, direct biodegradation of sorbed TCS is performed. Regarding TCS effects on activated sludge process, addition of 0.5 mg l −1 TCS on non-acclimatized biomass initially deteriorated ammonia removal and nitrification capacity. After acclimatization of biomass, nitrification was fully recovered and further increase of TCS to 2 mg l −1 did not affect the performance of activated sludge system. The effect of TCS on organic substrate removal was minor for concentrations up to 2 mg l −1 , indicating that heterotrophic microorganisms are less sensitive to TCS than nitrifiers.

A microwave-assisted extraction (MAE) method for the determination of Irgarol 1051 (2-methylthio-4-tert-butylamino-6-cyclopropylamino-s-triazine) and its main degradation product M1 (2-methylthio-4-tert-butylamino-s-triazine) in marine sediments by gas chromatography-mass spectrometry (GC-MS) was developed. The key parameters of MAE procedure, including the amount of the sediment, the volume of the extraction solvent, the duration and the temperature of the extraction procedure were optimized. The extraction procedure was followed by solid-phase extraction (SPE) on reverse phase C18 cartridges. The isolation of the target compounds from the matrix was found to be efficient when 3 g of marine sediment were extracted with 30 ml of water for 10 min at 115 degrees C. Final determination was accomplished by GC-MS. Quantification was performed with matrix-matched calibration using atrazine-d5 as internal standard. Mean recoveries higher than 85.4% were obtained for both compounds at three fortification levels with relative standard deviations (R.S.D.)or = 14%. The limits of detection (LOD) of the developed method were 0.9 and 1.7 ng g(-1) dry weight for M1 and Irgarol 1051, respectively.

The biodegradation behavior of four organotin (OT) compounds, namely tributyltin (TBT), dibutyltin (DBT), monobutyltin (MBT) and triphenyltin (TPhT), was studied in lab-scale activated sludge batch reactors. The activated sludge was spiked with the OT compounds at a level of 100 microg l(-1) as Sn. Determination of the OT compounds by GC-FPD after ethylation in the dissolved and particulate phase revealed that 24 h after the start of the experiments, almost the total of OT compounds has been removed from the dissolved phase and is associated with the suspended solids. Calculation of mass balance in batch reactors showed that OT compounds biodegradation was performed via a sequential dealkylation process. Removals due to biodegradation were differentiated according to the parent compound. In experiments with non-acclimatized biomass, a percentage of 27.1, 8.3, 73.8 and 51.3 was still present as TBT, DBT, MBT and TPhT, respectively, at the end of the experiment (18th day). Half-lives (t1/2) of 10.2 and 5.1 days were calculated for TBT and DBT, respectively, whereas apparent t1/2 values could not be determined for MBT and TPhT (t1/2>18 days). The capacity of activated sludge to biodegrade OT compounds in the absence of supplemental substrate indicated that these compounds can be metabolized as single sources of carbon and energy in activated sludge systems. Excluding TBT, the presence of low concentrations of supplemental substrate did not affect the biodegradation potential of activated sludge. The acclimatization of biomass on OT compounds enhanced significantly biodegradation, resulting in significant decreases of half-lives of OT compounds. As a result in the presence of acclimatized biomass, half-lives of 1.4, 3.6, 9.8 and 5.0 days were calculated for TBT, DBT, MBT and TPhT, respectively.

The pollution of the surface waters of Greece from the priority compounds of 76/464/EEC Directive was evaluated. The occurrence of 92 toxic compounds, 64 of which belong to priority compounds of List II, candidates for List I, of 76/464/EEC Directive, was studied in surface waters and wastewater through the developed network of 62 sampling stations, which covers the whole Greek territory. The analytical determination was performed by Purge and Trap-Gas chromatography-Mass spectrometry for volatile and semivolatile organic compounds (VOCs), Gas Chromatography-Electron Capture Detection for organochlorine insecticides, Gas Chromatography-Nitrogen Phosphorous Detection for organophosphorous insecticides, High Performance Liquid Chromatography-Photodiode Array Detection for herbicides, and Electrothermal Atomic Absorption Spectrophotometry and Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) for metals and the toluene extractable organotin compounds. The concentrations of VOCs and insecticides detected in the surface waters of Greece were very low, whereas the concentrations of herbicides and metals ranged generally at moderate levels. VOCs were detected almost exclusively in the rivers and very rarely in the lakes, while the frequency of occurrence of insecticides, herbicides and metals was similar for rivers and lakes. Water quality objectives (WQO) and emission limit values (ELV) have been laid down in national legal framework for a number of compounds detected in the samples, in order to safeguard the quality of surface waters from any future deterioration. Keywords: Pollution, Surface waters, Greece

The inhibition effect of arsenite, As(III), arsenate, As(V), inorganic mercury, Hg(II) and methylmercury, MeHg, on the respiration rate of activated heterotrophic sludge microorganisms was evaluated. As(III) and MeHg were much more toxic to activated sludge than As(V) and Hg(II) respectively. The effect of various experimental parameters on the toxicity, such as sludge age, concentration of suspended solids and exposure time, was investigated. An increase of sludge age or the concentration of suspended solids reduces the observed inhibition. Longer exposure seems to dramatically increase the inhibition of As(III), MeHg and Hg(II) during the first hours of exposure, while the later inhibition increases at a slower rate. On the contrary, in the presence of As(V), 24 hours after exposure, the respiration rate was similar to that of the control biomass.

The purpose of this research was to compare trivalent chromium (Cr(III)) and hexavalent chromium (Cr(VI)) removal by activated sludge and to investigate whether Cr(VI) reduction and/or Cr(III) oxidation occurs in a wastewater treatment system. Chromium removal by sludge harvested from sequencing batch reactors, determined by a series of batch experiments, generally followed a Freundlich isotherm model. Almost 90% of Cr(III) was adsorbed on the suspended solids while the rest was precipitated at pH 7.0. On the contrary, removal of Cr(VI) was minor and did not exceed 15% in all experiments under the same conditions. Increase of sludge age reduces Cr(III) removal, possibly because of Cr(III) sorption on slime polymers. Moreover, the decrease of suspended solids concentration and the acclimatization of biomass to Cr(VI) reduced the removal efficiency of Cr(III). Batch experiments showed that Cr(III) cannot be oxidized to Cr(VI) by activated sludge. On the contrary, Cr(VI) reduction is possible and is affected mainly by the initial concentration of organic substrate, which acts as electron donor for Cr(VI) reduction. Initial organic substrate concentration equal to or higher than 1000 mgl(-1) chemical oxygen demand permitted the nearly complete reduction of 5 mgl(-1) Cr(VI) in a 24-h batch experiment. Moreover, higher Cr(VI) reduction rates were obtained with higher Cr(VI) initial concentrations, expressed in mg Cr(VI) g(-1) VSS, while decrease of suspended solids concentration enhanced the specific Cr(VI) reduction rate.

Inhibition of respiration rate of activated sludge heterotrophic microorganisms was determined for tributyltin (TBT), dibutyltin (DBT), monobutyltin (MBT), and triphenyltin (TPhT). TBT, DBT, and TPhT exhibit similar acute toxicity to activated sludge, while MBT is less toxic. The effect of various experimental parameters, such as sludge age, concentrations of suspended solids, and exposure time, on toxicity was investigated. An increase in sludge age or in the concentration of suspended solids reduces the observed inibition. Longer exposure seems to increase the inhibition of TBT, DBT, and TPhT during the first hours of exposure, while later the inhibition remains constant. In the case of MBT, 24 h after exposure, the respiration rate was similar to that of the control biomass.

The development of a method for the simultaneous determination of eight artificial sweeteners, namely aspartame (ASP), alitame (ALI), neotame (NEO), acesulfame (ACS), saccharin (SAC), cyclamate (CYC), sucralose (SCL) and neohesperidin dihydrochalcone (NHDC), under hydrophilic interaction liquid chromatography (HILIC) conditions is presented herein. The ionization of all the compounds was achieved by negative electrospray. Two silica-based columns, a fully porous (XBridge HILIC) and a fused-core one (Kinetex HILIC), were compared. For HILIC optimization, the effect of the following parameters was studied: the mobile phase, column temperature, pH and ionic strength of the ammonium formate buffer. The optimized mobile phase was 5 mM ammonium formate buffer pH 3.5–methanol–acetonitrile (15/10/75 v/v), with a flow rate of 100 μL min−1 at 50 °C. The asymmetry factor of the peaks was lower on the Kinetex HILIC column than that on the XBridge HILIC. The predominant retention mechanism of all the analytes on silica columns seems to be partition to the aqueous layer. The method was validated in tap water and wastewater samples using Kinetex HILIC. Three deuterated internal standards were used, one for each category of sweeteners (dipeptides, sulfamates and sugars). The instrumental limits of detection ranged from 0.24 (SAC) to 4.4 (SCL) μg L−1. The recoveries in influent samples ranged from 39% (CYC) to 97% (NEO), while recoveries were better for the other two matrices. Inter-day precision (%RSD, n = 6) ranged from 4.2% (SAC) to 20% (ALI) in influent samples. The method was applied to influents and effluents from the wastewater treatment plant of Athens for seven consecutive days and high levels of sucralose and sulfamates were found.

The primary aim of this review is to extensively demonstrate the available analytical methodologies for the environmental determination of all eight popular artificial sweeteners: sucralose, acesulfame, saccharin, cyclamate, alitame, aspartame, neotame, and neohesperidin dihydrochalcone. Liquid chromatography-mass spectrometry methods play a key role in their sensitive and reliable determination in environmental matrices. In addition, all peer reviewed literature concerning their environmental impact (distribution and ecotoxicology) is presented. Moreover, the role of sucralose, acesulfame, saccharin and cyclamate as pollution markers is also demonstrated. Future prospects in terms of method developments on artificial sweeteners in environmental samples are suggested and discussed.

We present a framework for designing optimal allocation strategies for large stock portfolios using dynamic factor models and multivariate volatility parametrisations. We attempt to elaborate on the fundamental structure of the Fama and French (FF) factor model with a special focus on the time variation in risk and correlation between stocks returns and systematic factors. For this reason, variants of the multivariate GARCH models are employed to capture the dynamics in means, variances and covariances of the FF factors structure. Based on these models, we derive optimal capital allocation strategies in the framework of Markowitz's mean-variance portfolio theory. We outline and compare the out-of-sample performance of these mean-variance allocations with those obtained using simpler techniques, such as sample historical and exponentially weighted moving average (EWMA) estimates.

The mechanism of platinum atomization in electrothermal graphite atomizers was investigated in aqueous solutions and in serum samples. The methods of Rojas-Olivares and Yan et al., representing a chemical approach to the investigation of atomization mechanisms, as well as the physical approach developed by L’vov, were used. The activation energies for 1–8 ng of Pt in aqueous solution, calculated with use of the first two methods, increased with the increase of Pt mass, ranging from Ea = 245 ± 13 kJ mol−1 to Ea = 387 ± 11 kJ mol−1. The change of ratio Tapp/E from 6 to 4 with increasing Pt masses suggests that the atomization mechanism of Pt is progressively changing from an adsorption to an evaporation process. In serum samples, for all the Pt masses examined, one mechanism is observed. The calculated activation energy had a mean value of Ea = 203 ± 8 kJ mol−1 and is ascribed to an atomization mechanism via thermal desorption of Pt atoms from the carbon residue produced by the pyrolysis of the organic matrix. Confirmation of the above conclusions is provided by the physical method of L’vov, as the ratio Tapp/E was approximately 8 in the presence of serum matrix. All the methods used gave consistent conclusions rendering them more reliable.

The priority substances of List I, 76/464/EEC Directive, some of which belong to the new Water Framework Directive 2000/60/EC, have been monitored in the surface waters of Greece through the developed network of 53 sampling stations. The analytical methods used for the determination of these substances included Purge and Trap-Gas chromatography-Mass spectrometry for volatile and semivolatile organic compounds, Gas Chromatography-Electron Capture Detection for organochlorine insecticides, High Performance Liquid Chromatography for pentachlorophenol and Atomic Absorption Spectrometry for metals. The results have shown the presence of several priority substances in Greek surface waters, in most cases at concentrations well below the regulatory limits. However, non-compliance was observed for a limited number of compounds. The monitoring network and the analytical determinations have to be expanded to more water bodies and more priority substances, in order to safeguard the quality of Greek surface waters.

Chemical modifiers (isomorphous metals and other compounds such as NH4SCN and ascorbic acid) for the determination of vanadium are described. Ascorbic acid (100 µg) eliminated the interferences from NaCl, CaCl2 and FeCl3 salts. The mass of the metallic modifiers and the maximum permissible pyrolysis temperature (tpyr) have been carefully optimized. Magnesium nitrate (20 µg), rhodium (2 µg) and platinum (2.5 µg) increased tpyr from 1100 °C, without modifiers, to 1500, 1700 and 1600 °C, respectively. The characteristic mass without modifiers was 21.2 pg, whereas in the presence of 20 µg of Mg(NO3)2, 1 µg of Rh and 1 µg of Pt, the characteristic mass was 20.5 pg, 14.7 pg and 14.4 pg, respectively, measuring the peak absorbance with a moderately used graphite tube (around 100 atomization cycles). The LOD was generally 0.5 µg l–1 without chemical modifier and the same with 1 µg of Pt. The efficiency of the above metals as chemical modifiers was tested in the analysis of oil standards diluted with isobutyl methyl ketone (IBMK). It was found that 1 µg of Pt increased the tpyr from 1000 °C to 1400 °C and decreased the characteristic mass from 27.5 to 15.3 pg, measuring the peak absorbance with a new graphite tube. Magnesium nitrate was inadequate for this type of sample. The ageing of the graphite tube surface affected the vanadium determination. A slow drift in sensitivity appeared with increasing atomization cycles. This was controlled with periodic recalibration using integrated absorbance measurements.

The determination of Cr in the presence of various isomorphous metals has been studied. The atomic absorption signal for Cr was increased and stabilized by the presence of 20 µg of Mg(NO3)2, 1 µg Rh and 1 µg Pt. Magnesium, Rh and Pt gave comparable characteristic masses of 3.2, 3.0 and 2.8 pg, respectively, when integrated absorbance was measured. The limits of detection were 0.18, 0.14 and 0.091 µg 1–1, respectively. The efficiency of these modifiers was tested with the direct determination of Cr in rain-water and serum samples. Quantification was performed with aqueous standards in the case of the rain-water samples, and with matrix-matched standards in the case of the serum samples. Recovery tests and a serum reference material were used to check the accuracy of the proposed methods. Accurate results and good agreement with the certified serum values were found in the presence of platinum as a modifier. Chemical modifiers were not necessary for the determination of Cr in rain water.

The use of various isomorphous metals as chemical modifiers on the determination of gold has been investigated. The temperature programmes and the masses of modifiers were carefully optimized. Noble metals, copper, nickel, and rhenium increased the atomic absorption signal of gold and raised the maximum pyrolysis temperature from 700 to 1000 °C. In the presence of 20 µg of ascorbic acid this temperature was 1000 °C, whereas in combination with 1 µg of Pd it increased to 1150 °C. On the basis of platform atomization and integrated absorbance measurements, the best sensitivity for aqueous solutions was obtained with the mixed modifiers rhodium–rhenium (m0= 7.3 pg), ascorbic acid–palladium (m0= 7.1 pg) or ascorbic acid–rhodium (m0= 6.8 pg), whereas the characteristic mass in the absence of modifiers was 12.2 pg. The limit of detection was 0.23 µg l–1 in the absence of modifier, whereas it was 0.12 µg l–1 in the presence of the mixed modifier rhodium–rhenium. In the absence of chemical modifiers, a fractional order of release was observed for gold, whereas in the presence of modifiers an approximately first-order release was observed. The determination of gold in biological fluids was interference-free and complete recovery was obtained when stabilized temperature platform furnace conditions were fulfilled. Constant signals, without double peaks and shoulders, were obtained only in the presence of modifiers. It was found that gold solutions stored in the autosampler cups during measurements of the samples were stable only in the presence of 0.5 g l–1 NH4SCN or 1.0 g l–1 ascorbic acid.

Summarization: In this paper we investigate the application of a methodology based on fuzzy-sets theory to the selection of an optimal portfolio of Greek government bonds. Investors' goals for the different bond market scenarios are formulated in fuzzy qualitative terms, while a model of fuzzy mathematical programming is used for the specification of the portfolio that optimally meets the given goals. The reliability of the results obtained with this methodology is checked with the aid of simulation. Παρουσιάστηκε στο: Fuzzy Economic Review

Summarization: This paper discusses applications of nature-inspired techniques in optimisation problems encountered in portfolio selection and applied econometrics. By means of an empirical study, we show how particle swarm intelligence can be effectively used in the estimation of a GARCH and an EGARCH model, two popular econometric parametrisations for the volatility of financial prices. We discuss several issues emerging from the application of nature-inspired techniques in financial optimisation. Presented on

The distribution coefficient ( K d ) and the organic carbon distribution coefficient ( K OC ) were determined for four Perfluorinated Compounds (PFCs) to three different types of sludge taken from a conventional Sewage Treatment Plant (STP). Batch experiments were performed in six different environmental relevant concentrations (200 ng L −1 to 5 μg L −1 ) containing 1 g L −1 sludge. K d values ranged from 330 to 6015, 329 to 174 32 and 162 to 11 770 L kg −1 for primary, secondary and digested sludge, respectively. The effects of solution’s pH, ionic strength and cation types on PFCs sorption were also evaluated. Sorption capacities of PFCs significantly decreased with increased pH values from 6 to 8. Furthermore, the divalent cation (Ca 2+ ) enhanced PFCs sorption to a higher degree in comparison with the monovalent cation (Na + ) at the same ionic strength. The obtained K d values were applied to estimate the sorbed fractions of each PFC in different stages of a typical STP and to calculate their removal through treated wastewater and sludge. In primary settling tank, the predicted sorbed fractions ranged from 3% for Perfluorooctanoic Acid (PFOA) to 55% for Perfluoroundecanoic acid (PFUdA), while in activated sludge tank and anaerobic digester sorption was more than 50% for all target compounds. Almost 86% of initial PFOA load is expected to be detected in treated wastewater; while Perfluorodecanoic acid (PFDA), PFUdA and Perfluorooctanesulfonate (PFOS) can be significantly removed (>49%) via sorption to primary and excess secondary sludge. In anaerobic digester, the major part (>76%) of target PFCs is expected to be sorbed to sludge, while almost 3% of initial PFOA load will be detected in sludge leachates.

Pesticides have been used in large amounts around the world for decades and are responsible for environmental pollution and various adverse effects on human health. Analysis of untreated wastewater can deliver useful information on pesticides’ use in a particular area and allow the assessment of human exposure to certain substances. A wide-scope screening method, based on liquid chromatography coupled to quadrupole-time-of-flight mass spectrometry, was applied, using both target and suspect screening methodologies. Daily composite influent wastewater samples were collected for seven or eight consecutive days in Athens between 2014 and 2020 and analyzed for 756 pesticides, their environmental transformation products and their human metabolites. Forty pesticides were quantified at mean concentrations up to 4.9 µg/L (tralkoxydim). The most abundant class was fungicides followed by herbicides, insect repellents, insecticides and plant growth regulators. In addition, pesticide transformation products and/or metabolites were detected with high frequency, indicating that research should be focused on them. Human exposure was evaluated using the wastewater-based epidemiology (WBE) approach and 3-ethyl-carbamoyl benzoic acid and cis-1,2,3,6-tetrahydrophthalimide were proposed as potential WBE biomarkers. Wastewater analysis revealed the presence of unapproved pesticides and indicated that there is an urgent need to include more transformation products in target databases.