Search

Introduction. The aim of this study is to estimate the nutritional value of fish soup from cultured brook trout in terms of a healthy diet for human consumption.

This study represents new information on the nutritional value of soup prepared from cultured Rainbow trout (Oncorhyncus mykiss). The proximate contents of soup were represented by 87.56% moisture, 7.22% protein, 1.59% crude fat, 0.07% carbohydrate, 1.17% dietary fibre and 2.44% ash. The energy value was calculated as 48.0 kcal/100g. Amino acid values were in the range of 183.5-1128.5mg/100g while mineral contents were varied as 0.6µg/g-19.5mg/g. The value of polyunsaturated fatty acids (PUFA) was higher than saturated fatty acids (SFA). Total PUFA and eicosapentaenoic acid + docosahexaenoic acid (EPA+DHA) were observed as 37.2 and 7.2%, respectively. These values corresponded to the values of 673.3 and 123.2 mg/100g of the edible portion of the soup within the same respect. The results of this study demonstrated that a portion of trout soup would almost cover daily recommended n-3 PUFA intake, however, higher amounts are required for the necessary levels of EPA+DHA. The vitamin B12 content was well above the recommended levels. The values of α and β tocopherols were observed as 272.0 and 1131.0 µg/100g (wwb), respectively. This study indicates that trout soup has a good nutritional value for human consumption for a healthy diet.

Medicinal plants accumulate heavy metals from contaminated soil, and their consumption can cause poisoning. Our objective was to determine the levels of Pb, Cd, Zn, Cu, Fe, and Mn in four medicinal plant species (Achillea millefolium, Hypericum perforatum, Plantago lanceolata, and Urtica dioica) and their native soil, all sampled at a former smelter. The highest soil Cd, Pb, and Zn levels surpassed the maximum allowed limit 75-fold, 48-fold, and 14-fold, respectively. Their soil levels correlated with those in the plants, but this was not the case with Cu, Fe, and Mn. Heavy metal accumulation seems to depend on the plant species, yet even so, medicinal herbs should be cultivated and gathered only from controlled (uncontaminated) areas. Polluted areas should be monitored on a regular basis, while further research should investigate the connection between the heavy metal levels in the soil, their levels available for plants, and the levels extractable from plants.

New insights into the functioning, i.e. electrochemical behaviour and analytical performance, of in situ prepared antimony film electrodes (SbFEs) under square-wave anodic stripping (SW-ASV) and cyclic (CV) voltammetry conditions are presented by studying several key operational parameters using Pb(II), Cd(II) and Zn(II) as model analyte ions. Five different carbon- and metal-based substrate transducer electrodes revealed a clear advantage of the former ones while the concentration of the precursor Sb(III) ion exhibited a distinct influence on the ASV functioning of the SbFE. Among six acids examined as potential supporting electrolytes the HNO 3 was demonstrated to yield nearly identical results in conducting ASV experiments with SbFE as so far almost exclusively used HCl. This is extremely important as HNO 3 is commonly employed acidifying agent in trace metal analysis, especially in elemental mass spectrometry measurements. By carrying out a systematic CV and ASV investigation using a medium exchange protocol, we confirmed the formation of poorly soluble oxidized Sb species at the substrate electrode surface at the end of each stripping step, i.e. at the potentials beyond the anodic dissolution of the antimony film. Hence, the significance of the cleaning and initializing the surface of a substrate electrode after accomplishing a stripping step was thoroughly studied in order to find conditions for a complete removal of the adhered Sb-oxides and thus to assure a memory-free functioning of the in situ prepared SbFE. Finally, the practical analytical application of the proposed ASV method was successfully tested and evaluated by measuring the three metal analytes in ground (tap) and surface (river) water samples acidified with HNO 3 . Our results approved the appropriateness of the SbFE and the proposed method for measuring low μg L −1 levels of some toxic metals, particularly taking into account the possibility of on-field testing and the use of low cost instrumentation.

Medicinal plants accumulate heavy metals from contaminated soil, and their consumption can cause poisoning. Our objective was to determine the levels of Pb, Cd, Zn, Cu, Fe, and Mn in four medicinal plant species (Achillea millefolium, Hypericum perforatum, Plantago lanceolata, and Urtica dioica) and their native soil, all sampled at a former smelter. The highest soil Cd, Pb, and Zn levels surpassed the maximum allowed limit 75-fold, 48-fold, and 14-fold, respectively. Their soil levels correlated with those in the plants, but this was not the case with Cu, Fe, and Mn. Heavy metal accumulation seems to depend on the plant species, yet even so, medicinal herbs should be cultivated and gathered only from controlled (uncontaminated) areas. Polluted areas should be monitored on a regular basis, while further research should investigate the connection between the heavy metal levels in the soil, their levels available for plants, and the levels extractable from plants., Težke kovine iz onesnaženih tal se kopičijo v zdravilnih rastlinah, zaradi česar lahko njihovo uživanje privede do zastrupitev. Namen naše raziskave je bil ugotoviti vsebnosti svinca, kadmija, cinka, bakra, železa in mangana v vzorcih tal ter v vzorcih navadnega rmana (Achillea millefolium), šentjanževke (Hypericum perforatum), ozkolistnega trpotca (Plantago lanceolata) in velike koprive (Urtica dioica), nabranih na osmih lokacijah v Mežiški dolini. Koncentracije kadmija, svinca in cinka so kritično presegale mejne vrednosti. Vsebnost teh treh težkih kovin je značilno korelirala z njihovo vsebnostjo v proučevanih rastlinah, ki pa posamezne težke kovine kopičijo v različnem obsegu. Različen je bil tudi obseg njihove ekstrakcije v vročo vodo. Naša raziskava prispeva pomembne rezultate za nadaljnje proučevanje povezav med prehajanjem težkih kovin iz (onesnaženih) tal v rastline in rastlinske izvlečke. Poleg tega nakazuje tudi na izjemen pomen rednega spremljanja stanja tal, zlasti na področjih kritične onesnaženosti, saj je nabiranje zdravilnih rastlin v naravi v današnjem času izjemno priljubljeno.

Camilleri J, Kralj P, Veber M, Sinagra E. Characterization and analyses of acid-extractable and leached trace elements in dental cements. International Endodontic Journal, 45, 737–743, 2012. Abstract Aims Determination of the elemental constitution and investigation of the total and leachable arsenic, chromium and lead in Portland cement, pure tricalcium silicate, Biodentine, Bioaggregate and mineral trioxide aggregate (MTA) Angelus. Methodology The chemical composition of Portland cement, MTA Angelus, tricalcium silicate cement, Biodentine and Bioaggregate was determined using X-ray fluorescence (XRF). Measurements of arsenic, lead and chromium were taken with inductively coupled plasma-mass spectrometry (ICP-MS), following acid digestion on the hydrated material and on leachates of cements soaked in Hank’s balanced salt solution (HBSS). Results All the cements investigated had a similar oxide composition with the main oxide being calcium and silicon oxide. Both the Portland cement and MTA Angelus had an additional aluminium oxide. The dental cements included a radiopacifying material. All the materials tested had higher acid-extractable arsenic content than the level set by ISO 9917-1 (2007) and an acceptable level of lead. Regardless these high levels of trace elements present in the materials, the leaching in HBSS was minimal for all the dental material tested in contrast to the high levels displayed by Portland cement. Conclusions Dental materials based on tricalcium silicate cement and MTA Angelus release minimal quantities of trace elements when in contact with simulated body fluids. The results of acid extraction could be affected by nonspecific matrix effects by the cement.

A sensitive hydrophilic interaction liquid chromatography/electrospray ionization mass spectrometry (HILIC/ESI-MS/MS) method was developed for determination of selected aliphatic (i.e. malonic, succinic, glutaric, adipic, pimelic, suberic, azelaic, maleic, fumaric, glycolic and pyruvic acid), alicyclic (i.e. cis-pinonic and pinic acid) and aromatic (i.e. trimesic, phthalic acid and its isomers) carboxylic acids. Analytes were separated on an amide column using a gradient elution with a 10 mM constant ionic strength mobile phase containing acetonitrile and aqueous ammonium acetate buffer (pH 5.0). The influence of the buffer type, pH, polar modifier and temperature on analyte retention under HILIC was studied. Static sonication-assisted solvent extraction was optimized for sample preparation prior to analysis. The recoveries obtained were higher than 90% for most analytes. The method was proven to be sensitive with limits of detection ranged from 0.03 to 16.0 μg/L in selected reaction monitoring mode (SRM). The repeatability and intermediate precision of the method, expressed as RSD (%) of the peak area ratio between analytes and their internal standards were generally lower than 5%. The method was successfully applied for determination of the studied acids in samples of ambient aerosol particles. A big advantage of the new method is also its ability to detect and separate the isobaric compounds of the selected carboxylic acids. Our results demonstrate that the method is specific and sensitive for the determination of a wider range of polar carboxylic acids at low concentrations in complex samples of aerosol particles.

The objective of this work was the development and validation of atomic absorption spectrometric (AAS) methods for the determination of residual active pharmaceutical ingredients (API) in rinse samples for cleaning validation. AAS as an indirect method for the determination of API in rinse samples can be applied when it is in the form of salt with metal ions or when the metal ion is a part of the API's structure. The electrothermal AAS methods (aqueous and ethanol medium) for the determination of magnesium in esomeprazole magnesium and the flame AAS method for the determination of lithium in lithium carbonate in rinse samples were developed. Various combinations of solvents were tested and a combination of 1% aqueous or ethanol solution of nitric acid for esomeprazole magnesium and 0.1% aqueous solution of nitric acid for lithium carbonate were found to be the most suitable. The atomization conditions in the graphite furnace and in the flame were carefully studied to avoid losses of analyte and to achieve suitable sensitivity. The cleaning verification methods were validated with respect to accuracy, precision, linearity, limit of detection, and quantification. In all the cases, the limits of detection were at the microgram level. The methods were successfully applied for the determination of esomeprazole magnesium and lithium carbonate in rinse samples from cleaning procedures.

The physical processes controlling the desorption of some elements (B, Cd, Co, Mn, Ni, and Sr) from soils in a continuous leaching system representing the human stomach are investigated here by fitting experimental leaching data to a mathematical particle diffusion model. Soil samples (50 mg) from Cornwall, UK, contained in a flow-through extraction chamber (ca. 6.5 mL) were intimately contacted with artificial gastric solution at various flow rates (0.42-1.42 mL min(-1)) for up to ca. 4 h, followed by analysis of the fractions collected with inductively coupled plasma mass spectrometry (ICP-MS). The leaching profiles of the various elements were fitted to a mathematical model incorporating two mass transfer processes (liquid film diffusion and apparent solid phase diffusion) to determine the effective external mass transfer coefficient (beta) and the apparent intraparticle soil diffusion coefficient (D(a)). A system of partial differential equations was solved numerically with a finite difference discretization of the computational domain allowing the rate limiting physical desorption process(es) for each element to be determined. The (thermodynamic) driving force of the leaching process is defined by the distribution coefficient (K(d0)) between soil and leachant. Although the K(d0) values investigated are very similar (ca. 6-15 L kg(-1)) for the elements studied with the exception of B (ca. 2.7 L kg(-1)), the leaching profiles are very different due to diffusion-limited processes. The elements may be classified as limited by beta (B, Sr, and Cd), by D(a) (Co, and Mn) or by beta and D(a) (Ni). This results in quantifiable parameters for the liability of elements in soil upon ingestion which may be implemented in future risk assessment protocols.

The applicability of nitric acid, palladium nitrate and a mixture of palladium and magnesium nitrate as matrix modifiers was estimated for the accurate and reproducible determination of cadmium (Cd), lead (Pb) and arsenic (As) in sediments of the Sava River by electrothermal atomic absorption spectrometry, ETAAS. Decomposition of the samples was done in a closed vessel microwave-assisted digestion system using nitric, hydrochloric and hydrofluoric acids, followed by the addition of boric acid to convert the fluorides into soluble complexes. The parameters for the determination of Cd, Pb and As in sediments were optimized for each individual element and for each matrix modifier. In addition, two sediment reference materials were also analyzed. In determination of Cd and Pb, nitric acid was found to be the most appropriate matrix modifier. The accurate and reliable determination of Cd and Pb in sediments was possible also in the presence of boric acid. The use of a mixture of palladium and magnesium nitrate efficiently compensated for matrix effects and enabled the accurate and reliable determination of As in the sediments. Quantification of Cd and As was performed by calibration using acid matched standard solutions, while the standard addition method was applied for the quantification of Pb. The repeatability of the analytical procedure for the determination of Cd, Pb and As in sediments was ?5 % for Cd, ?4 % for Pb and ?2 % for As. The LOD values of the analytical procedure were found to be 0.05 mg/kg for Cd and 0.25 mg/kg for Pb and As, while the LOQ values were 0.16 mg/kg for Cd and 0.83 mg/kg for Pb and As. Finally, Cd, Pb and As were successfully determined in sediments of the Sava River in Slovenia.

A sequential extraction procedure (three-step), proposed by the Standards, Measurements and Testing Programme (formerly BCR) of the European Union, was applied to street dust and spiked soil samples for the determination of PGEs. Analyses were carried out using inductively coupled plasma-mass spectrometry (ICP-MS). The results indicate that up to 5% from Pt, 70% from Pd and 14% from Rh are in mobile forms in street dust. The results for the soil samples spiked with crushed catalytic converter are significantly lower indicating that PGEs are oxidised more efficiently in natural conditions. Additionally Pt and Pd bound to humic acids were investigated.

Currently for compound detection the most difficult are sampling steps and sample preparation for analysis of highly volatile compounds (VOC) and their derivatives, such as ethylene, propylene, acetaldehyde and acetone. For this purpose single- and multibed sorbent tubes were prepared, filled with the following materials: Tenax TA, Carbotrap, Carbopack C, Carbosieve SIII, Carboxen 569. The linear relationship between the mass of analysed compounds and decreased recovery from carbon molecular sieve was determined. The highest desorption recovery (∼100%) for C2–C5 hydrocarbons from multibed sorption traps contained Tenax TA/Carbotrap/Carbosieve SIII. Sorbent traps were also used to determine selected VOC (acetone, acetaldehyde, 2-butanone, benzene, toluene, m,p-xylene) in gas phase of tobacco smoke from single 1R5F reference cigarette. Quantitative analysis of selected compounds was done by standard addition method with r 2 = 0.9931 for 2-butanone and 0.9773 for acetaldehyde. The best combination of sorbent...

The uncertainty was estimated for the determination of jasmonic acid (JA) content in Lemna minor L. plant extracts using a reverse-phase liquid chromatography with fluorescence detection. JA was extracted from plant material, followed by solid-phase extraction procedures, derivatisation and quantification. In the estimation of uncertainty, the sampling, sample processing and chromatographic determination that may significantly influence the uncertainty of analytical data were considered. The results show that the method recovery and sample homogeneity are the two main contributors to uncertainty. The method has a relative expanded uncertainty (coverage factor k = 2) of about 17% at the JA content of approximately 100 ng/g.

A quadrupole inductively coupled plasma mass spectrometer was evaluated for use in the detection of phosphorus. The influences of nitric acid and methanol (simulating the composition of a sample solution after nitric acid digestion) on phosphorus determination were studied using two different measuring methods at different plasma conditions: detection of phosphorus ions at m/z 31 and detection of phosphorus oxide ions at m/z 47. The existence of polyatomic interferences at m/z 31 and 47 was explored. Nitric acid and methanol are shown to be the sources of polyatomic ions and therefore cause poorer detection limits. Better detection limits were achieved in such matrices when phosphorus was detected as 31P+. The presence of methanol improves the system sensitivity towards phosphorus sevenfold ; however, this positive effect is hindered by the high background signal due to carbon-based polyatomic ions. For samples with an organic matrix an appropriate mineralization procedure should be applied (high excess of nitric acid and high temperature) to quantitatively oxidize organic compounds to carbon dioxide, which is easily removed from the sample, in order to achieve correct results.

Diclofenac sodium (2-[(2,6-dichlorophenyl)amino]benzeneacetic acid monosodium salt) was investigated as a low-solubility drug and Naklofen® retard prolonged release tablets, containing 100 mg of diclofenac sodium as a prolonged release lipophilic matrix system using factorial design approach. First, the solubility characteristics of diclofenac sodium in aqueous media with various ionic strengths, ionic compositions and pH in the range of 1–8 were determined. The obtained results showed that the solubility of diclofenac sodium depends mainly on pH of the aqueous medium and less on the composition and ionic strength of the medium. Next, the estimation of the effects of six different factors (type of the dissolution apparatus, rotation speeds of the stirring elements, pH, ionic strengths of dissolution medium, the applied salt, and the producer of the on-line connected dissolution apparatus and UV spectrophotometer) on the release of diclofenac sodium, using the two-level six-factorial design was investigated. It was found that rotation speeds of the stirring elements, pH, and ionic strengths of the dissolution medium have a significant impact on the drug release and should be further followed in future drug release analyses. The advantages of the factorial design approach are obvious in this work. It is a very economic way of obtaining the maximum amount of information in a short period of time, especially in the case of prolonged release formulations where each experiment requires at least 24 h.

Particles and droplets containing liquid water represent very important media for chemical reactions. The presented investigation was focused on the formation of acidic product (sulfate) during SO2 oxidation in the presence of manganese under haze conditions, i.e. at relative humidity below 100%. Since the reaction kinetics of the transformation of atmospheric trace gases depend on the concentration and composition of the aqueous phase, the influence of these parameters was studied. Synthetic deposits of varying composition containing mainly NaCl and NaNO3 were exposed to SO2/air gas mixture at concentrations typical for heavily polluted atmosphere. Experiments were carried out in a specially designed reaction chamber under controlled conditions. Formation of sulfate was negligible below the deliquescent point on both matrices in the presence and absence of Mn(II). However, above this threshold relative humidity, the production of SO42− was observed only in the presence of Mn(II). The reaction rate increases exponentially with relative humidity. A considerable increase was noticed at relative humidity above 85%, where the amount of condensed water becomes substantial. For example, the reaction rate at SO2 concentration of 3 ppmv on MnCl2/NaCl deposits at T=10°C increased from 3.2 to 16.6 mg SO42−/(gsalt h), if the RH is increased from 80% to 90%. Our results also showed that the process of SO2 conversion on deposits is self-limited due to a decrease of pH of condensed water.

Using Plackett-Burman experimental design the parameters of different ways of sampling (design and materials of the sampling mold, conditions of solidification of samples) that influence on the homogeneity of copper-titanium-zinc alloy samples in the production of titanium zinc were determined. Based on these results, the homogeneity of samples taken with two different sampling molds was investigated with GD-OES technique regarding alloyed elements (Cu and Ti) and impurities (Fe, Pb, Cd, Sn, Al) and was evaluated with analysis of variance (ANOVA). For Cu, Ti and Fe an overall (combined) uncertainty for different sampling approaches were estimated and compared to the expanded uncertainty evaluated without including the uncertainty due to sampling.

Certain types of samples contain chloride in concentrations that are too high to accurately determine other anions by ion chromatography without any pretreatment. One of the most widely used approaches for such samples is matrix elimination using disposable cartridges containing a cation-exchange resin in the Ag+ form. The efficiency and characteristics of the commercially available cartridge for Cl− removal were tested by the on-line connection of the cartridge effluent to an inductively coupled plasma mass spectrometer. Displacement efficiency of Ag+ ions and loading capacity of the cartridges were studied at different flow-rates. Significant amounts of silver were detected in the effluent, which were attributed to colloidal AgCl as well as dissolved Ag+ ions. Because silver ions can cause irreversible damage to the analytical column, an Ag cartridge followed by an on line filter (pore size 0.22 μm) and cartridge in the H3O+ form were proposed for improvement of this sample pretreatment technique for chloride removal.

Summary Various aqueous wood preservative solutions containing Cu(II) in the form of copper(II) sulphate or copper(II) octanoate, ethanolamine and in one case octanoic acid were investigated by spectrophotometry, polarography and Electron Paramagnetic Resonance (EPR) spectroscopy. Results have shown the same coordination environment around Cu(II) in all solutions with ethanolamine. Computer simulation of the EPR spectra also revealed that the coordination in the first coordination sphere of copper is the same at low concentration of ethanolamine. At 20% ethanolamine concentration, a mixture of two complexes (one with two nitrogens and the other with three) could be detected. The active compound in the investigated ethanolamine containing solutions is the same when previously synthesised copper(II) octanoate was used, or when copper(II) sulphate and octanoic acid were utilized instead. Fungicidal and leaching experiments with the treated wood resulted in the same conclusion: it is not necessary to use pre-synthesised copper(II) octanoate for the preparation of waterborne copper/ethanolamine wood preservatives. Preservative preparation time and costs can be reduced by simply dissolving copper(II) sulphate and octanoic acid in aqueous ethanolamine solutions.

The optimization of glow discharge lamp control parameters (voltage, current) for the determination of Cu by glow discharge optical emission spectrometry (GD-OES) at 327.3 nm in copper–titanium–zinc alloy was performed using Simplex optimization. This approach substantially reduces the required number of experiments. The efficiency of the optimization procedure was tested using samples at two concentration ranges of copper. While at the lower concentration range (0.001–0.200%) the optimal parameters were 15 mA for the current and 1400 V for the voltage; at a higher range (0.50–2.00%) they were 50 mA and 700 V for current and voltage, respectively. At selected experimental conditions the method was validated for both concentration ranges and the results were compared with those obtained by the ICP-AES technique.

Volatile organic compounds (VOCs) of anthropogenic and biogenic origin play an important role in different photochemical processes in the atmosphere. In order to evaluate the lifetime of individual VOCs in the atmosphere and their impact on the photochemical processes, a detailed knowledge about their abundance in the atmosphere as well as kinetic parameters for the reactions with reactive species are required. Coding capabilities of different structural descriptors for the prediction of reactive rate constants of VOCs with ozone were studied. A diverse data set of 117 compounds with known reaction rate constants was taken from the literature. A 6-parameter MLR model was selected based on prediction capabilities of the model. The final prediction ability of the model was evaluated by 10-fold cross-validation procedure. The average root-mean squared error value for the prediction of log k O 3 was 0.99.

The effect of methanol, acetone and acetonitrile on the sensitivity, selectivity and the detection limits (LODs) of the determination of chromium species by ion chromatography was investigated. A collinear dual-beam thermal lens spectrometer was used for the direct detection of chromium complexes [pre-column derivatized Cr(III)–pyridine-2,6-dicarboxylic acid, and post-column derivatized Cr(VI)–1,5-diphenylcarbazide] following the ion chromatographic separation on a Dionex HPIC-CS5A solvent compatible column. Different amounts of organic solvents were added directly to the eluent (up to 30%) and to the post-column reagent (up to 60%) to improve the thermooptical properties of the solvents. Consequently, the sensitivity of the technique was increased by a factor of 2–3 and LODs of 0.1 and 10 μg dm −3 were achieved for Cr(VI) and Cr(III), respectively, when the eluent reaching the detector contained 30% of acetonitrile. The addition of organic solvents also resulted in significant changes in retention times, which improved the Cr(III)/Cr(VI) separation.

A slightly modified three-step sequential extraction procedure proposed by the Community Bureau of Reference (BCR) for analysis of sediments was successfully applied to soil samples. Contaminated soil samples from the lead and zinc mining area in the Mezica valley (Slovenia) and natural soils from a non-industrial area were analysed. The total concentrations of Cd, Pb and Zn and their concentrations in fractions after extraction were determined by flame or electrothermal atomic absorption spectrometry (FAAS, ETAAS). Total metal concentrations in natural soils ranged from 0.3 to 2.6 mg kg-1 for Cd, from 20 to 45 mg kg-1 for Pb and from 70 to 140 mg kg-1 for Zn, while these concentrations ranged from 0.5 to 35 mg kg-1 for Cd, from 200 to 10000 mg kg-1 for Pb and from 140 to 1500 mg kg-1 for Zn in soils from contaminated areas. The results of the partitioning study applying the slightly modified BCR three-step extraction procedure indicate that Cd, Pb and Zn in natural soils prevails mostly in sparingly soluble fractions. Cd in natural soils is bound mainly to Fe and Mn oxides and hydroxides, Pb to organic matter, sulphides and silicates, while Zn is predominantly bound to silicates. In contaminated soils, Cd, Pb and Zn are distributed between the easily and sparingly soluble fractions. Due to the high total Cd, Pb and Zn concentrations in contaminated soil close to the smelter, ! and their high proportions in the easily soluble fraction (80% of Cd, 50% of Pb and 70% of Zn), the soil around smelters represents an environmental hazard.

A procedure was developed for the preconcentration and determination of aluminium and copper in dialysis concentrates at the ng cm–3 level. The preconcentration was achieved on microcolumns filled with Chelex-100 resin adjusted to a pH of 4.0. Five repetitive cycles of the sample through the column ensured a sufficient contact time for quantitative retention of aluminium and copper ions. The retained ions were eluted with HNO3 (0.5 mol dm–3). Aluminium and copper were determined in the eluate by Zeeman ETAAS using the standard addition technique. The procedure was performed under clean room conditions (class 10,000), The reliability of the results was evaluated by recovery tests, using dialysis concentrates spiked with aluminium and copper. The recoveries obtained ranged from 86 to 106% for aluminium and from 92 to 97% for copper. Using the recommended procedure, the LOD of aluminium and copper in dialysis concentrates (preconcentration factor 2) was found to be 0.5 ng cm–3 and 0.2 ng cm–3, respectively.

Hydride generation AAS was applied for the determination of total selenium in soil. The influence of various anions and cations present in the sample solution on the generation of selenium hydride was investigated. Special attention was paid to the wet oxidation procedure for the sample dissolution. The proposed procedure involves microwave sample preparation by using a mixture of H2O2/HNO3/H2SO4. The accuracy of the procedure was checked by the analysis of the standard reference material Buffalo River Sediment (SRM-2704, NIST). Satisfactory agreement of the results obtained with the values reported was achieved. The detection limit of the procedure was 25 ng Se/g of soil. The relative standard deviation of the measurements varied from 5.5% for SRM-2704 up to 10% for the real soil samples.

Unspecific fragmentation of organic substances in the ion source of MS detector hinders identification of organic substances in gas chromatographic separation. In such instances theoretical prediction of the retention indices could be a useful tool. A new method for theoretical prediction of gas chromatographic retention indices is described. Artificial neural networks were trained in counterpropagation mode to predict retention data. Extensive data sets of simple organic compounds with known retention indices taken from the literature were serving for training and test sets. The structure of molecules was described with a 12-dimensional vector the components of which were topological and chemical parameters. Various geometries of artificial neural networks were tested and different divisions into training and testing sets tried. The ANN with the configuration of 15 × 15 neurons has been chosen for routine work. The average RMS value was 36.6 retention time units.

Copper(II) derivatives of penicillins (benzypenicillin, phenoxymethylenepenicillin, ampicillin, amoxycillin and carbenicillin) have been prepared. Copper(II) ions promote hydrolysis of penicillins (L) to corresponding penicilloic acids (L∗) owing to β-lactam group. Coordination compounds isolated under equilibrium conditions showed stoichiometries of the type CuL∗, CuL∗2, and CuL∗3. Two compounds with molar metal to ligand ratio 1:1 and 1:3 are aqueous soluble and interactions at molar ratio 1:2 result in precipitate formation. The solubility of the precipitates undergoes no changes in a broad pH region. It takes place only in highly acidic or alkaline media. The infrared spectra suggest that penicillins behave as monoanionic bidentate ligands coordinating the Cu(II) ion through the carboxylic group.

An electrothermal atomic absorption spectrometric procedure for the determination of nickel in active pharmaceutical ingredients was developed. Since the recoveries of nickel by the direct dissolution of samples in diluted nitric acid were low and caused errors in the determination of Ni in pharmaceutical samples, different approaches for sample pre-treatment were examined. It was found that the microwave digestion was the most suitable way for sample preparation. Various combinations of digestion agents and different microwave conditions were tested. The combination of nitric acid and hydrogen peroxide was found to be the most appropriate. The validity of the method was evaluated by recovery studies of spiked samples and by the comparison of the results obtained by inductively coupled plasma mass spectrometry (ICP-MS). The recovery ranged from 87.5 to 104.0% and a good agreement was achieved between both methods. The detection limit and the limit of quantification were 0.6 and 2.1 µg g-1 respectively. The precision of the method was confirmed by the determination of Ni in the spiked samples and was below 4%, expressed in terms of a relative standard deviation. The method was applied to the determination of nickel in production samples of active pharmaceutical ingredients and intermediates.

Experimental MS response factors were measured for 36 different saturated and unsaturated volatile organic compounds (VOC) containing carbon, hydrogen and halogen atoms. Chemical structure was encoded using various molecular descriptors. A quantitative structure-property relationship model was established using the multiple linear regression models. The cross-validation ability of the created model was estimated by leave-one-out cross-validation procedure. Error in the cross-validation of response factors was calculated by cross-validation procedure and was 15%, which is sufficient for the determination of VOCs in the air. The proposed procedure can be used for simultaneous qualitative and quantitative determination of volatile organic compounds in the atmosphere.

Described herein is a procedure for calculating the relevant concentrations of sulfur dioxide in a MgO−SO2−H2O system and the construction of an equilibrium diagram showing the relationships between total SO2, combined SO2, true free SO2, and pH. The procedure used the Rudzinski method for determining the pH of complex aqueous solutions and the modified Debye−Huckel expression for calculating activity coefficients. The calculated concentrations matched closely those obtained from Hagefeldt's diagram and measured concentrations from an actual industrial magnesium based pulping process. The equilibrium diagram was used for the graphical representation of the mass balances of the industrial absorption process.

This study was conceived to evaluate the global scientific output of secondary organic aerosol (SOA) research over the past 20 years and to assess the characteristics of the research patterns, tendencies, and methods in the papers. Data were based on the online version of Science Citation Index Expanded from 1992 to 2011. Publications referring to SOAs were assessed by distribution of the number of publications and times cited, source categories, source journals, author keywords, KeyWords Plus, and the most cited publications in these years. By synthetic analysis of author keywords, KeyWords Plus, titles, and abstracts, it was concluded that modeling is currently and will at least over the next decade continue to be the predominant research method to validate state-of-the-art knowledge of SOAs, and that the foci of SOA research will be the key precursors terpenes and isoprene, the mechanisms of oxidation and gas-phase reactions, and emission inventories.

A continuous flow hydride generation (HG) technique was applied for the determination of Se and As in highly mineralized mineral waters. The atomization was performed either conventionally in a heated silica tube or in the graphite furnace after collection and thermal decomposition of the hydrides. In most cases the determination of As in real samples was not subject to serious problems. Significant matrix effects were found only for mineral waters with higher Mg, Na and sulfate concentrations. With the conventional flow through HG technique reasonably good linearity (r= 0.998) and satisfactory precision [relative standard deviation (RSD)

In the presence of ampicillin copper(II) ions form different coordination compounds. Their formation and the properties of particular species were examined by means of UV, Vis and IR spectrometry. The dynamics of complex formation was studied. Firstly, an unstable blue-violet coordination compound with an absorption maximum at 590 nm was formed, later being transformed into a more stable compound. Hydrolysis of the β-lactam group is promoted by copper(II) and/or hydroxide ions and as a result the ampicillin ligand (L) is transformed into ampicilloic acid (L∗). Consequently, the coordination compounds [CuL]+, CuL2, [CuL3]− are changed to [CuL∗]+, CuL2∗ and [CuL3∗]−, respectively.

The interactions in the copper(II) ion-ampicillin system were studied by the use of electrochemical and spectroscopic methods under equilibrium conditions. In the system, two aqueous soluble coordination compounds with molar compositions of 1:1 and 1:3 and a precipitate with molar ratio 1:2 were formed. Copper(II) ions promoted the hydrolysis of the β-lactam group of ampicillin, therefore the ampicillin ligand in the compounds was transformed into ampicilloic acid as a result of hydrolysis. The soluble compounds are relatively stable, log K st being 5.0 and 14.5, respectively. The solubility of the precipitate was constant over a broad pH range (4–10) and the solubility product constant K sp of the compound was evaluated as 2.7 × 10 −11 under equilibrium conditions.

Volatile organic compounds (VOCs) play an important role in the chemistry of the atmosphere and in biogeochemistry. They contribute to the oxidative capacity of the atmosphere, particle and air pollutants, as well as to the production of greenhouse gasses (for instance ozone). Among analytical techniques for their determination in the atmosphere gas chromatography coupled with mass spectrometry (GC–MS) offers several advantages. However, for an accurate quantification calibration with standard substances is necessary. A quantitative structure–property relationship (QSPR) model for the prediction of MS response factors was developed on basis of our experimental measurements for the quantification of ozone precursors present in the atmosphere. A linear correlation between chemical structures and response factors was established by using a 7-parameter MLR model. The average error in the prediction of response factors was calculated by cross-validation procedure and was below 20%, which is sufficient for the determination of VOCs in the air. The proposed procedure is time consuming so it is more suited for the quantification of tentatively identified organic compounds during the reprocessing of MS chromatograms in cases when the original sample is no longer available.

Matrix effects with fused-silica aperture thermospray (FSApT) sample introduction for ICP-AES are found to be higher than those for pneumatic sample introduction. The effects are comparable to those reported for sample introduction to ICP-AES using ultrasonic nebulization with desolvation. The matrix effects for >mg/mL levels of Ca are found to be influenced by the thermospray operating temperature. By the use of higher thermospray temperatures, matrix effects due to transport losses are reduced to low levels, presumably by reduction of primary aerosol particle sizes. Background increases due to higher Ca input with the thermospray system result in small changes in background noise that do not appear to have a large effect on limits of detection (LODs). Matrix effects occurring within the plasma appear to be the primary source of interferences. Ca interferences can also be reduced or eliminated by appropriate adjustment of the aerosol carrier gas flow rate. For simultaneous multielement analysis, a compromise flow rate must be chosen. With the use of such compromise conditions, LODs for a wide range of elements were increased in the presence of Ca, but were on average within a factor of 1.7 of those obtained in the absence of Ca. LODs obtained for analytes in the presence of 1000–3000 μg/mL Ca for FSApT/ICP-AES were all below United States Environmental Protection Agency (EPA) required limits for Toxicity Characteristic Leaching Procedure (TCLP) samples derived from concrete stabilized hazardous waste, while pneumatic sample introduction provided inadequate detection for half the key elements tested.

A thermospray nebulizer using a fused silica capillary with a short length of small internal diameter tubing laser-fused at the exit end is described as a means to provide high performance thermospray at low liquid pump pressures with moderately high liquid flow rates (1–2 ml min ), while also providing high chemical robustness and low background contamination. The smaller exit diameter provides higher sensitivity than an identical capillary without the aperture. For the elements reported, both sensitivity and limits-of-detection were enhanced by factors between 15 and 19 with a 50 μm fused silica aperture system, compared to conventional pneumatic sample introduction. The system is also able to operate with high dissolved solids levels without problems of capillary clogging. The fused silica system provides high chemical stability and low background contamination for metals. Reduction of the exit diameter of the capillary using this approach also provides smaller primary aerosols which reduce transport losses and matrix interferences due to high dissolved solids with desolvation systems.

Thermospray aerosols are generated by forcing a liquid sample through a capillary tube that is heated to partially vaporize the solvent, resulting in a blast of vapor that converts the remaining liquid to droplets. The droplet size character of thermospray aerosols can be electrically varied by changing the temperature and degree of solvent vaporization of the liquid stream. The primary droplets produced by thermospray under optimal conditions are smaller on average then those produced by pneumatic nebulizers, particularly of the types used for inductively coupled plasmas (ICPs). Solvent vaporization is enhanced for smaller particles and higher temperatures, with both aspects leading to faster size reduction due to solvent evaporation than would occur with pneumatic sample introduction at room temperature. As smaller droplets are more efficiently transported through sample introduction systems, the use of thermospray aerosol generation provides higher analyte transport, higher sensitivity, and lo...

Determination of trace element concentrations in atmospheric aerosols is important because of their toxic effects on human health. Additionally, they are now widely used in source apportionment studies. There is a number of methods for sample preparation of ambient particulate matter. One of the most widely used is microwave-assisted digestion of filter-based samples. Since the water-soluble fraction is bioavaliable, the aim of our study was to determine the concentration of selected trace elements (V, Cr, Mn, Ni, Cu, Zn, As, Cd, Sb, Tl, and Pb) in this fraction and compare it to the amounts obtained by two different microwave digestion procedures - one using a mixture of H2O2 and HNO3 and the other using a mixture of HF, HCl, and HNO3. The recoveries of the digestion procedures used were tested on certified reference material (NIST SRM 1648 Urban Particulate Matter). The procedures were applied to filters containing PM10 particles collected at an urban background location in Ljubljana, Slovenia. Among the elements analysed, V, Zn, As, and Cd displayed the highest concentration within the water-soluble fraction, with Cr, Ni, Tl and Pb displaying the lowest concentrations. The comparison between the two applied digestion procedures showed that Cr, Ni, Sb and Tl were strongly bound to the sample matrix.

Determination of trace element concentrations in atmospheric aerosols is important because of their toxic effects on human health. Additionally, they are now widely used in source apportionment studies. There is a number of methods for sample preparation of ambient particulate matter. One of the most widely used is microwave-assisted digestion of filter-based samples. Since the water-soluble fraction is bioavaliable, the aim of our study was to determine the concentration of selected trace elements (V, Cr, Mn, Ni, Cu, Zn, As, Cd, Sb, Tl, and Pb) in this fraction and compare it to the amounts obtained by two different microwave digestion procedures – one using a mixture of H2O2 and HNO3 and the other using a mixture of HF, HCl, and HNO3. The recoveries of the digestion procedures used were tested on certified reference material (NIST SRM 1648 Urban Particulate Matter). The procedures were applied to filters containing PM10 particles collected at an urban background location in Ljubljana, Slovenia. Among the elements analysed, V, Zn, As, and Cd displayed the highest concentration within the water-soluble fraction, with Cr, Ni, Tl and Pb displaying the lowest concentrations. The comparison between the two applied digestion procedures showed that Cr, Ni, Sb and Tl were strongly bound to the sample matrix., Določevanje elementov v sledovih v atmosferskih delcih je pomembno zaradi njihovega toksičnega vpliva na človekovo zdravje. V zadnjem času se koncentracije teh elementov tudi zelo pogosto uporabljajo v študijah povezanih s porazdelitvijo po virih. Za določevanje elementov v sledovih se uporabljajo različne priprave vzorcev. Najpogostejši je razklop filtrov s pomočjo mikrovalovne peči. Ker je vodotopen delež tudi biološko dostopen, je bil namen naše študije določitev te frakcije posameznih elementov (V, Cr, Mn, Ni, Cu, Zn, As, Cd, Sb, Tl and Pb) in primerjava s koncentracijami po dveh različnih razklopih – prvi z mešanico H2O2 in HNO3 ter drugi z mešanico HF, HCl in HNO3. Izkoristke uporabljenih razklopov smo preverili s standardnim referenčnim materialom (NIST SRM 1648 Urban Particulate Matter). Preverjena postopka smo uporabili na filtrih, ki so vsebovali delce PM10, vzorčevane v Ljubljani, Slovenija. Med analiziranimi elementi so bili izrazito dobro topni v vodi V, Zn, As in Cd, najmanj pa Cr, Ni, Tl, in Pb. Primerjava med obema uporabljenima razklopoma je pokazala, da so Cr, Ni, Sb in Tl v delce izredno stabilno vezani.

A new method is described for the determination of endogenous jasmonic acid (JA) in Lemna minor plant extracts using liquid chromatography (LC) with fluorescence detection. Plant tissues were extracted and derivatised using 9-anthryldiazomethane (ADAM reagent) prepared in situ. Accuracy and precision were improved by using the internal standard dihydrojasmonic acid (dh-JA) for the correction of JA losses during sample preparation steps. Liquid chromatography-mass spectrometry (LC/MS) analysis of ADAM derivatives of JA and dh-JA confirmed that a single molecule of JA and dh-JA was coupled with one molecule of reagent. Derivatives of JA and dh-JA were separated with gradient elution on a C18 reversed-phase column using acetonitrile/water as a mobile phase and detected by a fluorescence detector at excitation and emission wavelengths of 254 and 412 nm, respectively. The detection limits of JA and dh-JA were 2.9 ng mL(-1) and 3.7 ng mL(-1) per 50-microL injection. The method is reproducible and selective and yields single peaks for each compound regardless of isomer. The specificity and accuracy of the proposed LC/FD method was confirmed by liquid chromatography-TurboIon Spray tandem mass spectrometric (LC/MS/MS) analysis of free JA in Lemna minor samples under multiple reaction monitoring conditions.

The purpose of this work was the development of a method for the determination of Se compounds in leaves of plants. Water-soluble Se compounds were extracted from samples by water. Enzymatic hydrolysis with the non-specific enzyme protease XIV was used for the release of Se compounds bound to proteins. Separation of Se species was made by ion exchange chromatography, using an anion exchange column for Se(IV), Se(VI) and selenomethionine (SeMet), and a cation exchange column for selenomethylselenocysteine (SeMeSeCys) and selenocystine (SeCys(2)). Columns were connected "on line" to a hydride generation atomic fluorescence spectrometer (HG-AFS) using a UV lamp between the separation and detection system. The repeatability of the results obtained by the developed method was under 15% (R.S.D.) for all Se species; the detection limit was 2-10 ng Se/g of supernatant. The accuracy was checked by comparison with some literature data for reference materials since there were no suitable certified reference materials available. The method was used for the determination of Se compounds in chicory (Cichorium intybus L.) leaves from plants which were cultivated aeroponically with elevated concentrations of Na(2)SeO(4) for different periods. Se accumulated efficiently in chicory leaves; up to 480 microg/g after 41 days of exposure, mostly (64%) as Se(VI), i.e. in the form of Se added. Beside inorganic Se, in the extracts from enzyme hydrolysis we also found SeMet (4.2-8.4%) and SeMeSeCys (

A well-balanced incubation saline is necessary for permeability experiments with the rat jejunal tissue in the diffusion chambers. At the same time the investigated substance must be chemically stable and sufficiently soluble in this incubation saline. To investigate whether the absence of some ions in incubation salines influences the tissue viability and integrity or the diffusional characteristics of the epithelial membrane the electrical parameters were monitored and the permeability of fluorescein and acyclovir was evaluated during the experiments in side-by-side diffusion chambers. Our results show that the tissue integrity and viability are seriously impaired when Ca2+ and Mg2+-free conditions are applied on both sides of the diffusion chambers, but not when only mucosal or only serosal side is Ca2+ and Mg2+-free. Bicarbonate-free incubation salines can also alter the measured apparent permeability coefficients even though the tissue viability and integrity do not change. This change in the apparent permeability is most likely due to a change in the pH of the mucosal surface and can be prevented if the buffer capacity of the incubation saline is increased.

Chromium, cadmium and lead were determined in different fractions of the winemaking process such as in grape, pressed pomace, must deposit, deposit of lees, must and wine. Grape, pressed pomace, must deposit and deposit of lees were digested by a high-pressure microwave-assisted digestion system with a mixture of nitric acid and hydrogen peroxide, while for must and wine no special treatment was required. The temperature programs of the graphite furnace were optimised and different matrix modifiers were applied: Mg(NO3)2, NaVO3 for Cr and NH4H2PO4, Pd(NO3)2 for Pb and Cd determinations. Mg(NO3)2 and NaVO3 thermally stabilized Cr and enabled the increase of pyrolysis temperatures up to 1500 degrees C. NH4H2PO4 and Pd(NO3)2 are suitable modifiers for Pb and allowed pyrolysis temperatures up to 800 degrees C in grape, pressed pomace and wine samples, 1100 degrees C in must samples and 1200 degrees C in deposit of lees. The non-specific background absorption of NH4H2PO4 was 1.5-2 orders of magnitude higher than that of the Pd(NO3)2.

Considerable uncertainties are associated with the experimental estimates of emission rates of different volatile organic compound (VOC) species from the biosphere to the atmosphere. Some of this uncertainty derives from the sampling and analytical procedures used in emission rate measurements. A calibration system was developed in order to evaluate possible errors in the measurements of biogenic emission rates using a branch enclosure system. Two types of calibration procedures were tested, a standard additions technique and an internal standard procedure. Both techniques were used to evaluate possible losses while sampling isoprene and monoterpenes, which are the most abundant VOCs of biogenic origin. The losses to Teflon lines and the empty sampling system were tested and losses to the branch enclosure system installed on two VOC emitting plant species were evaluated. A considerable loss of isoprene (approximately 18% of inflow concentration 65 ng l(-1)) to the empty enclosure system and to the system installed on the plant was measured, but no losses of monoterpenes were observed.