STUDIA CHEMIA - Issue no.3 / 2017 - Table of contents

In Memoriam prof.dr. Simion Gocan

Keywords:

TLC is a powerful method used for separation of complex mixtures such as plant extracts. Employing different TLC techniques the separations can be improved. This paper presents a study of the Orthosiphon stamineus Benth extracts using isocratic reversed-phase thin layer chromatography (RP-TLC) and reversed-phase automated multiple development technique (RP-AMD). Methanol (SI) and a mixture of methanol– water–methyl acetate (SII) were used as extraction agents. Orthosiphon stamineus Benth. belongs to the Lamiaceae family. Its leaves contain rosmarinic acid, sinesetine and eupatorine as main compounds. After TLC separation the bioactive compounds from plant extracts were identified by comparison of the Rf values and in situ UV-Vis spectra with those of the standards and quantified using the calibration method. The rosmarinic acid was better extracted in the solvent mixture methanol–water–methyl acetate (10:10:80, v/v), while the sinesetine and eupatorine, which are more lipophilic, were better extracted in methanol. The study revealed the AMD technique superiority in comparison with the isocratic one.

Keywords: RP-TLC; RP-AMD; Orthosiphon stamineus Benth. extracts; rosmarinic acid; sinesetine; eupatorine.

Considering the international situation regarding the residues of pesticides in vegetables and fruits and the requirement for sensitive and reliable analytical methods that are able to ensure the compliance of marketed food commodities with the law on food safety, the aim of this paper was the identification and determination of some degradation products and metabolites of ten most often used pesticides. Two analytical approaches are proposed and used for the development of reliable screening, quantification and confirmation of pesticides metabolites in different vegetables. The proposed methods have different approaches than the other multi-residue methods for vegetables allowing the extensive investigation of previously undetectable or unknown pesticide metabolites in vegetables. These methods were tested on cherry tomato, cucumber, and chili pepper, some of the most widely consumed vegetables. The results suggests that spraying pesticides in high doses lead to high levels of pesticide residues in the case of some studied vegetables and the concentration of metabolites together concentration of parent pesticide must be taken into account in order to establish the MRL’s in vegetables and fruits.

Keywords: pesticides metabolites, GC-TOF-MS, LC-MS-QQQ, vegetables

A method for the identification of different classes of volatile organic compounds in the municipal landfill leachate using solid phase microextraction and comprehensive two dimensional gas chromatography coupled with mass spectrometry (SPME-GCxGC-qMS) is elaborated. The results showed that the proposed protocol is able to separate and identify in a single run different classes of volatile organic compounds responsible for the odor of leachate such as carbonyl compounds, aromatic compounds, terpenes, phenolic compounds and nitrogen and sulfur containing compounds. The use of solid phase microextraction not only eliminate the solvent from the samples processing step but also considerably reduces the time and the volume of the sample necessary for this step, being a viable green alternative for this type of analysis. The use of mass spectrometry gives the possibility to indentify many other compounds responsible for municipal landfill leachate odor, creating the premises for a better assessment of chemical composition of leachate. The developed protocol shows good performances in term of repeatability, linearity, limit of detection and limit of quantification being applicable for the real municipal landfill leachate analysis.

Keywords: Volatile organic compounds, municipal landfill leachate, solid phase microextraction, GCxGC-qMS

Efficiency of conventional solvent extraction (maceration and normal refluxing) and novel extraction techniques (ultrasound-assisted extraction-UAE and microwave-assisted extraction-MAE) were compared in order to obtain an enhanced content of total flavonoid, total phenolic compounds and rosmarinic acid from the Satureja hortensis L. (Summer savory) herb. Different mixtures of ethanol-water ratio were used for extraction of these compounds from dry plant material. High level of total flavonoid content was determined for a solvent system consisted of 40% respectively 50% ethanol (extraction systems ES6 and ES5) while the most efficient techniques were normal refluxing (R) and ultrasound-assisted extraction when sweep mode (UAE1) was selected. For the same solvent systems (ES6 and ES5), a high content of total phenolic compounds was determined when the normal refluxing (R) and microwave-assisted extraction (MAE1, with a duty coefficient of 40% and microwave action time1 min) were used for the extraction procedure. For the rosmarinic acid extraction, the maceration technique (M) combined with an ethanol-water system consisted of 60% ethanol (ES4) was found as the most efficient procedure.

Keywords: Satureja hortensis L., flavonoids, phenolic compounds, rosmarinic acid, maceration, reflux extraction, ultrasound assisted extraction, microwave assisted extraction

Crataegus oxyacantha L., the hawthorn, is a well-known medicinal plant with cardiotonic effect. This paper presents a complex phytochemical screening of polyphenols profile, both qualitatively and quantitatively, in three different extracts obtained from fresh berries, flowers with leaves and young shoots. There were used spectral (UV-Vis) and chromatographic (TLC, HPLC) methods to evaluate the total flavonoids, total phenolic acids and qualitative polyphenols profile of the extracts. The antioxidant capacity was evaluated by DPPH, FRAP and NO radical inhibition methods, by UV-Vis spectrophotometry. The total flavonoid content expressed in rutoside ranges from 0.49 to 1.33 mg/ml, the total phenolic acids expressed in caffeic acid from 0.02 to 0.10 mg/ml, the most concentrated being the berries extract. In flowers with leaves extract can be identified and quantified a special flavonoid, the vitexine, 0.37 mg/ml. All three extracts present important antioxidant activity, both on ROS and RNS species. By FRAP method the berries extract was determined as most powerful, having also the best inhibition effect on NO radicals. The DPPH method indicates the special young shoots extract, used in gemmotherapy, as being the most powerful, with significant inhibiting effect on NO radicals. This indicates that the young shoots gemmotherapic extract is a good candidate for a powerful therapeutic tool.

Keywords: Crataegus oxyacantha extracts, spectral assays, TLC, HPLCDAD, antioxidant capacity

The Ranunculus species are mostly known for their toxic effect due to the anemonine and protoanemonine content. This paper studies the polyphenols and the antioxidant activity of four different spontaneous species from Ranunculus genus (Ranunculaceae family) harvested from Western Romania’s spontaneous flora. The polyphenols profile was established by TLC and UV-Vis spectrophotometric methods. The antioxidant capacity was evaluated by different in vitro methods: DPPH, TEAC, FRAP, CUPRAC and SNP. From the studied species were prepared two different extracts: hydroalcoholic extracts (HA) respectively glycerol-ethanol extracts (GE). The study indicates that the highest total flavonoid content is in R. ficaria herb HA extract (23 % mg/ml), while the total phenolic acids are the highest in R. bulbosus herb GE extract (14,88 % mg/ml). The most important antioxidant activity was observed at GE extracts obtained from herb of R. ficaria, R. sardous and R. bulbosus. With the less antioxidant effect are the R. sceleratus extracts.

Keywords: Ranunculus ficaria, Ranunculus bulbosus, Ranunculus sardous, Ranunculus sceleratus, antioxidant activity, total flavonoids and total phenolic acids content, rutoside

Based on advantages of available modern image processing techniques, thin-layer chromatography combined with image analysis becomes a promising alternative for the mycotoxins determinations in various foodstuffs. For this, the effect of digitizing channel selection and image processing parameters on aflatoxin B2 (AB2) and ochratoxin A (OTA) determination was evaluated and the obtained results were compared with those of classical photodensitometric analysis. The best exciting wavelength for OTA was found to be λexcitation=333nm while for AB2 λexcitation=365nm. Low detection and quantification limits were determined (LODOTA=0.310ng/spot; LOQOTA=0.616ng/spot, LODAB2=0.557ng/spot, LOQAB2=1.098ng/spot). For image processing, the parameter with the highest influence upon the regression calibration curve was brightness and the best digitizing channel was found to be the green one. First-order calibration curve with a good determination coefficient (R2>0.99) were obtained on the working range of 2.5-50ng/spot. Although image processing techniques do not provide higher LOD and LOQ values than classical photodensitometry, this method offers the advantage of simultaneous quantification of both mycotoxins.

Keywords: aflatoxin B1, ochratoxin A, TLC; densitometry, image processing

Wine is a fermented beverage that could be affected by high concentrations of biogenic amines which alter organoleptic properties. In this work, new analytical approaches for determination of biogenic amines in wines were developed. For the first time, we studied the derivatization of BAs in wines with naphthalene- 2,3-dicarboxaldehyde (NDA) and with dabsyl chloride (DBS) and analysis of derivatized BAs by HPLC coupled to fluorescence (HPLC-NDA-FL) and thermal lens spectrometry (HPLC-DBS-TLS) detectors. The sensitivity of the two methods (LODs HPLC-NDA-FL in the range 27-73 μg/L; LODs HPLC-DBS-TLS in the range 3.4-11 μg/L) was higher than that of the official method for biogenic amines in wines, OIV-MA-AS315-18 (60-77 μg/L). For its best performances, the HPLC-DBS-TLS technique was applied to the analysis of putrescine, cadaverine, histamine and tyramine in two white wine samples. Additionally, exploiting the Berthelot reaction, the TLS fast screening of biogenic amines in wines, following the release of ammonia by transglutaminase, was also proposed. This approach allowed us to determine total biogenic amount content in concentrations below 0.1 mg/L, expressed as equivalents of histamine.

Keywords: biogenic amines, NDA, liquid chromatography, TLS, fluorescence, wine.

Six white wines from Blaj vineyard obtained from clone and new created varieties of grapes, have been studied. Their volatile compounds, free amino acids, free fatty acids, content in polyphenols and flavonoid, antioxidant and antityrosinasic activity were compared. The results showed few differences among the analyzed wines. The volatile extracts of wines gave very similar compounds. The major compounds were phenylethyl alcohol. All the white wines of Blaj contained a large amounts of proline in comparison with the other amino acids and important essential amino acids. The fatty acids were found in very small quantities. Antioxidant activity and total content in polyphenols of wines showed that Muscat Ottonel have a very high antioxidant potential comparable with some red wines. The content in flavonoids is small in all white wines. Antityrosinasic activity of studied wine proved to be high to Blasius and Muscat Ottonel wine. The GC-MS method proved to be an excelent method for wine characterization.

Keywords: essential amino acids, amino acids, fatty acids, antioxidant activity, GC/MS

The present work presents the optimization of differential pulse anodic stripping voltammetry with hanging mercury drop electrode for the determination of Zn, Cu, Cd and Pb in mushrooms. The optimized method was characterized in terms of limits of detection and quantification, accuracy and precision and applied for the analysis of 4 food supplements (Chaga and Shiitake powders; Reishi tablets and capsules containing a Mixture of mushroom extracts) and a fresh mushroom (King bolete (Boletus Edulis)). The concentrations of Zn and Cu as essential elements were discussed in relation with the recommended daily allowance, while Cd and Pb compared with maximum acceptable levels of toxic elements set in the European legislation. It has been found that fresh mushroom King bolete (100 g serving per day) represents a more significant source of Cu and Zn than food supplements, namely up to 24% and 10% from the recommended daily allowance. The concentration of Cd (0.09-0.69 μg g-1) and Pb (1.83-3.60 μg g-1) in the edible King bolete fungus and food supplements revealed no human health risk, since they were below 1.5 mg provisional tolerable monthly intake (Cd) and 72 mg/day (Pb) for 60 kg body weight.

Keywords: Differential pulse anodic stripping voltammetry, Zn, Cd, Pb, Cu, mushroom

Synthetic dyes are widely used in many fields, such as textile industry, plastics, cosmetics, paper industry and many others. Due to their toxicity, they should be removed from wastes before discharging in the environment. In order to determine the efficiency of the removal process, different methods are used to detect traces of dyes in wastewaters. The most used are spectrophotometry and FIA, however the expensive equipment and complicated testing process make these methods difficult to use. On the contrary, electrochemical sensors have multiple advantages such as short response time, low price and easiness to use. In this context, several electrochemical sensors based on new carbonaceous materials were developed and characterized. Carbon nanotubes, graphene and activated carbon from Abies nordmanniana cones together with Nafion were used to modify the surface of a glassy carbon electrode by drop casting. The resulting modified electrodes were tested by SWASV and amperometry for Malachite Green detection in aqueous solutions, having low detection limits in the order of μM

Keywords: Malachite Green; electrochemical detection; activated carbon; carbon nanotubes; reduced graphene oxide; modified electrodes

In order to preserve and restore the door that separate the Naos and Pronaos belonging to the wooden church of Petrindu, Salaj County, the scientific expertise (with FTIR, XRF spectroscopy and restoring) of the wooden stage and of the painting materials (ground, pigments) was performed. FTIR spectroscopy offers information about the wooden stage whereas XRF and FTIR spectroscopic methods were employed for structural painting materials characterization. These structural data can be correlated with the artistic, theological and historical analysis of this religious patrimony object. After obtaining information about wooden stage and the painting materials, the door was restored.

Keywords: wooden church, painting materials, XRF and FTIR spectroscopy

This paper focuses on the obtaining of carboxylate precursors through the redox reaction of cobalt nitrate and ethylene glycol, in different stoechiometric ratios, as well as the decomposition of precursors into cobalt oxides. The influence of the NO3−:C2H6O2 stoichiometric ratio on the formation of the precursors is studied through thermal analysis, FTIR spectroscopy and acido-basic analysis (conductometric/potentiometric titrimetry). Phase analysis by XRD and FTIR of the powders obtained at the decomposition of the precursors at 400°C has evidenced the formation of CoO for a high NO3- :C2H6O2 synthesis ratio and of Co3O4 for a low NO3−:C2H6O2 ratio. The Scherrer equation and scanning electron microscopy (SEM) were used to determine the dimensions of the nanoparticles obtained.

Keywords: carboxylate precursors, cobalt oxide, acido-basic titration

In the context of the large and increasing interest for an efficient and ecological recycling of the Waste Electrical and Electronic Equipments (WEEEs), we decide to evaluate the feasibility of an electrochemical recycling process for waste printed circuit boards (WPCBs) based on bromine-bromide leaching system. For this preliminary study, a perforated rotating drum chemical reactor (RDCR), interconnected with a divided electrochemical reactor (DER) in a closed hydraulic loop, was successfully used to dismantle consecutively three computer motherboards (CMB) after a minimal mechanical pre-treatment. Essentially, the base metals were leached at the RDCR level and the bromine-bromide system was regenerated at the DER level, simultaneously with the partial electrodeposition of dissolved metals. Even if the operating parameters were not optimized, each CMB was completely dismantled in around 18 h, with cathodic and anodic mean current efficiencies of 43.6% and 58.4%, respectively. Notably, grace to the proposed process, the remaining undissolved parts (fiberglass reinforced epoxy boards, electronic components, plastics, etc.) preserve their original shape and structure, allowing an easier consequent separation-classification and a more efficient and profitable recycling.

Keywords: Waste printed circuit boards, metals recovery, electrochemical recycling, bromine-bromide leaching system, environmentally friendly process

The effect of coupled substitution of Zr4+/Ga3+ for In3+ in In2O3 upon the structural, electrical and optical properties has been studied. The In2-2xGaxZrxO3 solid solution with bixbyite structure has been synthesized for 0 ≤ x < 0.15. A decrease in resistivity for the composition x = 0.025 (ρRT = 5.5x10-3 Ω.cm) by approximately one order of magnitude if compared to In2O3 (ρRT = 2.2x10-2 Ω.cm) was obtained. The maximum percent reflectance around 500 nm is lowered by 15% with respect to pure In2O3. These novel oxides show their potential as transparent conductors

Keywords: transparent conducting oxides, solid state reaction, electrical conductivity, optical properties

Dimensionality of a relatively big data set (95 compounds) observed for toxicity (mutagenicity) was explored in order to compute QSAR models. Distinct molecular descriptors were used. Dimensionality of data, using PCA, correlation plots and clustering, was evaluated. Analyzing data dimensionality allowed model optimization. Docking studies and PCA were used in order to expand data dimensionality. Pearson correlation coefficient (r2) values, obtained for both perceptive and predictive models, were satisfactory.

Keywords: topological descriptor, QSAR, data dimensionality, mutagenity, principal component analysis (PCA), Ames test.

Polycyclic aromatic hydrocarbons (PAHs) make part of the persistent organic pollutants (POPs) class. The most harmful PAHs are generated during the incomplete combustion of organic material. European legislation has recommended the use of bioindicators to estimate the impact of PAHs on the ecosystem. The aim of this work was to investigate the occurrence of atmospheric PAHs in 14 urban areas in Romania, using moss as bioindicator. The pollution emission sources, applying diagnostic ratios, were also evaluated. The PAHs were analyzed by gas chromatographymass spectrometry (GS-MS). This study showed the presence of PAHs in moss samples in concentrations which are dependent on the sampling zone, ranging from 2.7 to 394 ng g-¹. The cities with the highest amounts of total PAHs were found within the Carpathian arch, while the cities situated in the western part of the country had the lowest amounts. The FLA/(FLA+PYR) and FL/(FL+PYR) ratios indicate both the diesel emission source, fossil fuels combustion source and wood or coal combustion source which may come either from traffic, industrial activities, centralized heating systems, or from other type of industry.

Keywords: Polycyclic aromatic hydrocarbons, urban atmosphere, bioindicators, moss, GC-MS

Dental erosion is a frequent complication of patients with gastro-esophageal reflux disease. Loss of superficial enamel can be observed by a color change towards yellow and increased translucency of the teeth. The aim of our study was to analyze salivary parameters and dental erosion status in patients with gastro-esophageal reflux disease, and to evaluate optical properties (color parameters variation) and microstructural modifications (using atomic force microscopy) of eroded compared to healthy dental structures. The association of dental erosion and gastro-esophageal reflux disease was significant. Variations of ΔE are higher than general average variations of ΔL in these patients.

Keywords: gastro-esophageal reflux disease, dental erosion, color parameters variation, atomic force microscopy

The aim of the study is to evaluate the suitability of a local strain of the microalga Scenedesmus opoliensis in remediation of water pollution with different amounts of chromium(VI), and also to identify new biochemical and physiological markers for a more reliable indication of sustainability and efficiency of bioextraction and phytoaccumulation processes. Quantitative analysis of photosynthetic pigments reveals that the chlorophylls to carotenoids ratio is a sensitive marker of chromium toxicity and of algal metal tolerance on which the remediative capacity relies. From among the chlorophyll fluorescence parameters, the Fv/Fm ratio, related to potential quantum yield of photochemical reactions, indicates that alkaline pH of the medium (8.65-9.15) favors algal vitality as compared to acidic conditions with pH values around 5. The highest extraction rate (91%) is achieved upon exposure of algae for one week to lower chromium concentrations (5 μM) in alkaline water environment, and a longer exposure time does not increase bioaccumulation. These results may directly contribute to optimization of remediation technology for chromium-polluted water, providing new markers and a new algal strain to be introduced in wastewater treatment.

Keywords: bioaccumulation, chromium, microalgae, photosynthetic pigments

The aim of the study is to compare biochemical and physiological reactions of two related species of green microalgae (Scenedesmus acuminatus and Scenedesmus opoliensis), both considered suitable for bioindication and remediation of aquatic environments polluted with herbicides. Monoalgal axenic cultures were treated for 10 days under controlled conditions with different concentrations (from 0.1 μM to 100 μM) of glufosinate (a nonselective contact herbicide that inhibits glutamine synthase activity, thus disturbing photorespiration, inhibiting photosynthetic carbon assimilation, and generating ammonium excess in plant cells). S. opoliensis was found to be a better indicator of adverse effects of glufosinate than S. acuminatus. Changes in the ground chlorophyll fluorescence (reflecting light energy harvesting capacity), in cell division rate and in chlorophyll-a content may be early, costeffective and sensitive markers of herbicide impact on microalgal communities inhabiting polluted water. Our results bring new data concerning the need of selection among related test organisms based on differentiated tolerance, as well as concerning biochemical parameters suitable for evaluation of water pollution impact when organic xenobiotics accumulate in aquatic environments. Thus, the presented results may be applied in optimizing bioindication of water quality using microalgae, and in treatment of wastewater polluted due to agricultural practices.

Keywords: bioindication, chlorophylls, glufosinate, herbicide, water pollution

A new validated capillary zone electrophoresis method was developed for the quantification of three aromatase inhibitors - anastrozole, letrozole and exemestane. After preliminary analysis a sodium tetraborate background electrolyte containing carboxymethyl β-cyclodextrine was selected for the simultaneous determination of the three aromatase inhibitors. 100 mM sodium tetraborate containing 5 mM carboxymethyl β- cyclodextrine as buffer addtive, 25 kV applied voltage, 20 mbar/2 s injection pressure and 25°C temperature were selected as optimum parameters for the determination. Analysis was performed in approximately 10 minutes. Validation parameters, including linearity, precision, detection and quantification limits were determined. Our results prove the applicability of capillary zone electrophoresis for the simultaneous determination of the three aromatase inhibitors from pharmaceutical products. The applicability of the optimized method was also tested for biological samples, proving its reliability for the determination of letrozole without any special treatment of the analyzed spiked urine sample and presenting potential for other biological matrices.

Keywords: aromatase inhibitors, anastrozole, letrozole, exemestan, capillary zone electrophoresis, cyclodextrines

Our energy requirements increased significant in the last decades. For this reason the potential utilization of renewable energy sources come into view. Biogas is a kind of renewable energy sources. Purification of raw biogas is essential prior to use. Mainly the hydrogen sulfide content of gas is very harmful. It can cause corrosion in compressors and engines. Furthermore sulfur dioxide and sulfur trioxide are formed from hydrogen sulfide due to combustion, which similarly corrosive present of water and toxic like hydrogen sulfide. We examined the hydrogen sulfide absorption from biogas model gas mixtures (CO2, H2S, N2) based on alkali competitive chemisorption technology.

Keywords: biogas, chemisorption, sodium hydroxide, hydrogen sulphide, carbon dioxide

Significant part of the energy need of the world is covered by utilization of natural gas. Due to the hydrogen sulphide content of raw gas the natural gas industry has to tackle some serious problems, for example corrosion-, environmental-, economic- and safety engineering problems. Our aim is to develop the selective hydrogen sulfide absorption by using alkali solutions. Experiments were performed in a specially designed atomizing reactor by using potassium- and sodium hydroxide absorbents. During the tests the following parameters have changed: contact time, pressure, volumetric flow rate of gas and liquid, concentration and material quality of absorbents. Three different model gas mixtures were used for measurements; they consist of nitrogen, carbon dioxide and hydrogen sulfide.

Keywords: selectivity, absorption, hydrogen sulfide, carbon dioxide, sodium hydroxide, potassium hydroxide, atomization

In the present study, the changes of the concentration of air pollutants were examined, based on air pollution, meteorological and climatologic data gathered over an interval of two years (2012-2013) by the regional measuring station located in the basin, as well as the sources of the air pollutants were studied with the help of factor analysis. Biomass burning, traffic and photochemistry were characteristic regarding the source of air pollutants. This was also confirmed by the correlations between pollutants. Furthermore, the increasingly busy car traffic in the cold season and the atmospheric stability characteristic for it are also important observations with regard to the sources of air pollutants.

Keywords: air pollution, factor analysis, air quality, atmospheric stability, environment and human originated ozone sources

This study describes the cloning of the gene encoding a novel phenylalanine ammonia-lyase from Kangiella koreensis (KkPAL) into pET19b expression vector. Optimization of protein expression and purification conditions yielded 15 mg pure soluble protein from one liter of E. coli culture. Enzymatic activity measurements of the ammonia elimination reaction from different natural aromatic amino acids proved the protein to be a phenylalanine ammonia-lyase. The isolated protein showed remarkably high, 81.7 °C melting temperature, making it especially suitable for biocatalytic applications.

Keywords: phenylalanine ammonia-lyase, Kangiella koreensis, protein expression, optimization