STUDIA CHEMIA - Issue no.1 / 2022 - Table of contents

The aim of the study was the evaluation of greenness and whiteness profiles of UV/Vis photo-induced cold vapor generation (UV/Vis- PVG) capacitively coupled plasma microtorch optical emission spectrometry methods for Hg determination and speciation as CH3Hg+ and Hg2+. Sample preparation for CH3Hg+ determination in fish tissue consisted of an extraction in HBr–toluene–aqueous L-cysteine solution and UV-PVG in 0.6 mol L-1 HCOOH. Total Hg was determined in food samples following ultrasound assisted extraction in concentrated HCOOH and UV-PVG. Hg speciation was based on extraction in HCOOH and UV/Vis selective derivatization of total Hg/Hg2+. The greenness profile was assessed by National Environmental Methods Index, Analytical Eco-Scale, Green Analytical Procedure Index and Analytical Greenness Metric, while the whiteness profile was evaluated using the Red–Green–Blue (RGB) 12 algorithm. The methods, based on miniaturized instrumentation, were characterized by a higher greenness and whiteness compared to the traditional SnCl2 cold vapor generation inductively coupled plasma optical emission spectrometry, SnCl2 cold vapor generation atomic fluorescence spectrometry, and sometimes than that of thermal decomposition atomic absorption spectrometry. This study is a novelty because, to the best of our knowledge, is the first approach of this kind for Hg determination and speciation based on optical emission spectrometry using a fully miniaturized instrumentation.

Keywords: greenness and whiteness profile, mercury speciation, capacitively coupled plasma microtorch

Clopidogrel is a chiral compound, (+)-(S)-enantiomer has antiplatelet activity, while (-)-(R)-clopidogrel is considered an impurity of the active substance. The development of HPLC methods for optical purity analysis involves the use of expensive chiral columns and the methodologies could be different in the two well recognized compendia, European (Ph.Eur.) and United Stated (USP) Pharmacopoeias. The aim of this study was to optimise the chiral chromatographic assay of clopidogrel and its impurities from tablets taking into consideration the official pharmacopoeia provision by testing the influence of the variation of different chromatographic parameters on the relative retention times of clopidogrel and official impurities in order to achive the separation performance parameters described in USP43. HPLC-UV enantioseparation of clopidogrel was performed on a column with ovomucoid as a stationary phase chiral selector and phosphate – acetonitrile mixtures as mobile phase. The official relative retention of clopidogrel and its A and C impurities could not be achieved in this study, neither by applying a classical optimization methodology nor by using the experimental design methodology which raises the issue of reviewing the pharmacopoeia provisions. A comparative discussion between the two different approaches regarding chiral separation of clopidogrel in Ph.Eur. and USP is provided.

Keywords: clopidogrel, chiral separation, HPLC, ovomucoid, enantioseparation

The five agricultural soil preparation methods for the purpose of determining the pseudo-total content of 20 elements (Al, As, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Mg, Mn, Mo, Na, Ni, P, Pb, S, Si and Zn) in 4 soil samples taken from different plots of soils in the vicinity of Vranje (Southern Serbia) was applied in this paper. The following methods were used: digestion with aqua regia and hydrogen-peroxide with heating at temperature 190 0C, digestion with aqua regia and hydrogen-peroxide in combination with ultrasound with heating at temperature 95 0C, digestion with reverse aqua regia and hydrogenperoxide with heating at temperature 190 0C, and digestion with nitric acid and hydrogen-peroxide under reflux with heating at temperature 95 0C, and digestion with perchloric acid with heating at temperature 190 0C. The results were statistically processed using an ANOVA test. The results obtained by this study show that the amount of extracted elements from the soil is influenced by several different factors including the following: soil type, soil content and chemical form of the elements.

Keywords: soil, digestion methods, macro and microelements, inductively coupled plasma optical emission spectrometry, ANOVA

A supervised fuzzy method is described and efficiently applied for the first time in this study. The advantages of the new approach for the characterization and classification of various Roman potteries on the basis of their mineral composition has been explored. The new classification robust approach allows more relevant conclusions to be drawn, finding more specific groups and a better characterization of Roman potteries using their degrees of membership to each fuzzy partition and solving in this way some discrepancies. The efficiency of the supervised fuzzy method was also estimated by the values of quality performance features obtained applying different fuzzy quality criteria and highly illustrative graphs. The parameters of the prototype (class centre) illustrate much better than, for example, arithmetic mean the specific characteristics of each class, and the degrees of membership allow a rationale comparison of the similarity and differences of Roman pottery samples investigated.

Keywords: supervised fuzzy method, prototypes, fuzzy quality criteria, Roman pottery, spectrometry

A wealth of field facts, including the high human pressure on rivers, the eutrophication danger and the complexity of in-river phenomena (causing difficulties in water quality modelling) revealed the need to offer reliable tools for the pollutant transport modelling and for the understanding and estimation of the complex in-river pollutant behaviour. This paper presents an application of ADModel (a detailed advection dispersion pollutant transport model) for the case of River Swale (UK), in order to show why an improved representation (a) of the hydrodynamic river characteristics and (b) of the pollutant transformations; is very important for the advection-dispersion models, as it generates a major gain in the modelling skills (e.g. prediction improvement) and on the understanding of in-river phenomena. ADModel obtained good results during calibration against field measurements of concentration, showing that an improved version (using detailed representation of the river stretch and pollutant transformations) facilitates a better model performance and a wider applicability, including the identification of additional phenomena along the river stretch, of importance in ordinary situations and also during un-controlled pollution situations.

Keywords: ADModel, in-river pollutant transport model, river water quality, phosphorus prediction, rating equations

The synthesis of a new sorbent based on waste cotton cellulose and kinetics of adsorption of reactive textile dye from aqueous solution are the subject of the study in this manuscript. The sorbent is made of waste cotton fibbers collected from the textile plants for spinning yarn and weaving fabrics after being physically and chemically modified. Qualitative and quantitative characterization of the sorbent shows that carbon is dominant in the chemical composition. The sorbent used is a relatively finely divided material with heterogeneous porous particles, generally below 300 μm in size. Maximum adsorption capacity and the rate constant of the pseudo-second order generally depend on the amount of the cellulose-based sorbent, the initial dye concentration and the temperature. A new kinetic model based on the results of adsorption capacity and pseudo second order rate constant was defined. The low value of the activation energy means that the adsorption is mostly of a physical nature. Thermodynamic parameters, change of free Gibb's energy, change of enthalpy and change of entropy, as well as activation energy according to the standard equation confirm the adequacy of the new kinetic model of dye adsorption.

Keywords: adsorption, reactive dye, pseudo-second order, cellulose-based sorbent, new kinetic model, thermodynamic parameters

This work presents the development of new adsorbent materials to remove lead-210 (210Pb) from water. Adsorbents were constructed from the carboxylated carbon nanotubes modified with N,N'bis(salicylidene)1,3- diaminopropane (LH2) Schiff Base and N,N'bis(salicylidene)1,3-diaminopropane- Cu(II) (CuL) complexes. Scanning electron microscopy (SEM) was used to characterize the morphological features of the adsorbents. The effects of pH, contact time, temperature, and Schiff base concentration on lead(II) absorption were investigated in order to optimize the experimental conditions. The adsorption capacity of the adsorbents was determined using atomic absorption spectrometry. Both adsorbents had high adsorption capabilities, with about 98.0% in the first 30 minutes of contact time. The adsorption processes were also in good agreement with the Langmuir isotherm and pseudo-secondorder kinetic models. The adsorption of 210Pb from the tap water sample confirmed the applicability of the proposed adsorbents, and the results were satisfactory.

Keywords: Multiwalled carbon nanotube, 210Pb removal, Schiff base, radioisotopes

The main environmental problems of pulp and paper production are water consumption, pollutant fillings of effluents (biogenic and refractory organic compounds, suspended solids, colloids, toxic inorganic compounds). This industry is obliged to sminimize its impacts on the aquatic environment and at the same time, due to huge water consumption, must adopt strategies for sustainable use of water resources, in the context of ensuring European requirements for integrated pollution prevention and control and implementation of the Framework Directive of water. The original experimental research refers to the improvement of the efficiency of conventional physicochemical treatment of residual effluents from the pulp and paper industry by using new prehydrolysed coagulationflocculating agents. This stage is preliminary to the advanced effluent treatment stage, for its recirculation in the technological process. Correlating these structures with the efficiencies obtained in coagulation, it is noted that the low coagulant doses of PAC-1 and PAC-2 compared to SA, are due to the existence of more active polymeric species of 7 13 Al or 18 30 Al , with higher load and molecular weight than in the case of aluminium monomeric species formed in the use of aluminium sulphate. There are high efficiencies for removing turbidity between 98-99% as well as organic loading of about 70% for the three coagulants studied (SA, PAC-1, PAC-2), but for the same efficiencies the doses of SA were double or even triple those required for PAC-1 and PAC-2.

Keywords: pollutants, water treatment, flocculation coagulation

The present study introduces a new approach for the quantitative structure-activity relationship (QSAR) issue, which can be called a statistically intensive or condensed QSAR model. This idea was successfully applied to the published data of 32 biologically active molecules derived from 4-(1-aryl-2-oxo- 1,2-dihydro-indol-3-ylideneamino)-N-substituted benzene sulfonamides for mixed bacteria and specific bacteria like B.subtilis, E.coli, and S.aureus. The suggested four statistically intensive QSAR (SIQSAR) models possess only two descriptors with excellent statistical parameters, as their values of the square regression coefficient (r2) and cross-validation (q2) are lying within the range of 0.967−0.997 and 0.961−0.996, respectively. A zero-one correction term (ZO) reflects the effect of substituents, which was proposed as a second descriptor for two sets of biologically active compounds. In general, the results showed that the biological activity is depended majorly on the topographical properties, and predominated by the field-effect in contrast to an electronic one. The interesting feature of SIQSAR models is their closeness to mathematical methods such as simultaneous linear equation method by eliminating the common inaccuracy and unrealistic statistical treatments. The obtained SIQSAR models were employed for predicting new and efficient biologically active molecules derived from isatin.

Keywords: QSAR, computational chemistry, isatin derivatives, biological activity, DFT

Late blight (LB) caused by the Phytophthora infestans is a devastating tomato disease, distributed worldwide. Tomato wild species could be a potential source of resistance, however, there are little data about their biochemical response to LB infection. Therefore the aim of the study was to evaluate total phenolic and total flavonoid content and antioxidative activity in the leaves of wild (Solanum pimpinellifolium) and cultivated genotype (Bizon) depending on disease severity. S. pimpinellifolium compared to Bizon was less susceptible and had five times lower disease severity index (11% and 55% respectively). Additionally, during the disease progression wild genotype showed a much slower decrease of total biochemical parameters compared to the cultivated one. Parameters such as total phenolic content (TP), DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging test and ABTS (2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid)) radical scavenging activity in the symptomless leaves and the leaves infection 10-25% remained the same in S. pimpinellifolium. The susceptible genotype Bizon had about 40% of leaves with the disease severity 25-50%, and a rapid decrease of all biochemical parameters. A strong negative correlation was observed between late blight infection and biochemical parameters in Bizon, while in S. pimpinellifolium late blight infection negatively correlated only with TP, TF (total flavonoid content) and total antioxidant activity (TAA).

Keywords: biochemical response, late blight, S. pimpinelifolium

Endotoxemia, known as the presence of Gram (-) bacterial endotoxin in the circulation, is associated with high mortality. Here, it was aimed to investigate the effects of lactoferrin on inflammation and iron homeostasis and cytokine production in lipopolysaccharide (LPS)-induced experimental endotoxemia in rats. Tumor necrosis factor (TNF-α) and interferon gamma (IFN-γ) levels, which are important cytokines, and iron and hepcidin levels, which play a role in iron homeostasis, DNA damage marker 8-hydroxy- 2'-deoxyguanosine levels were evaluated in endotoxemia model. Enzymelinked Immunosorbent Assay (ELISA) method is a technique based on antigenantibody complex and using enzymes as marking. Serum TNF-α, IFN-γ and hepcidin levels and the liver 8-OHdG levels were measured by ELISA methods, serum iron levels were determined using iron assay kit. The results indicated that increased serum TNF, hepcidin and iron levels decreased at 1st, 3rd and 6th hours after LPS injection with lactoferrin supplementation, and increased IFN-γ level at 3rd and 6th hours returned to normal range. 8-OHdG increased immediately after LPS injection and this damage returned to normal within 6 hours by lactoferrin. The findings of the study revealed that lactoferrin might be beneficial in the prognosis and treatment of endotoxemia.

Keywords: lactoferrin, endotoxin, cytokine, 8-hydroxy-2'-deoxyguanosine, iron transport

Two experimental giomers (G1 and G2) were obtained and then evaluated for water sorption- by weighing the specimens before and after water immersion, for conversion degree (DC)- by Fourier Transform Infrared Spectrometry, for radiopacity- by using the intraoral sensor system Ez Sensor 1.5 Vatech E-Woo (Korea), in relation to their microstructural characteristics assessed by Scanning Electron Microscopy (SEM). They were compared to a commercial giomer: Beautifil II. Both experimental and commercial giomers were also tested by subcutaneous and intramuscular implantation tests, to establish and compare their biological behavior. Intensity of the inflammatory reaction, tissue repair status and the presence of the capsule were the main criteria assessed. After 7 days, the mean values of DC were: 65.8% (Beautifil II), 62.2% (G2) and 60.5 (G1). DC increased after the initial polymerization. Giomers showed mean values of water sorption, below 40 μg/mm3. A certain swelling of the polymer matrix without dislocations of particles could be seen on SEM images. The mean values of radiopacity were between 2.15-2.99 [mmAl]. Giomers were slight to moderate irritants for soft tissues, with no significant difference between the samples. Promising results make G1 and G2 possible alternative to Beautifil II, that can be further improved.

Keywords: giomer, conversion, water sorption, radiopacity, SEM, biocompatibility

All investigated extracts of red mulberry (Morus rubra L.) contain a high content of total phenols. The highest content of total phenols was shown by red mulberry in the ethanolic extract (50%). Certain extracts of the fruit of red mulberry (aqueous, ethanolic 50%, acetonic 50% and acetonic) contain very small quantities of anthocyanins. Four phenolic acids were identified in the extracts of red mulberry: chlorogenic, neochlorogenic, cryptochlorogenic acid and caffeic acid, and four flavonoids using HPLC analysis: quercetin-3-O-rutinoside, quercetin-3-O-glucoside, quercetin-3-Orhamnoside, and kaempferol-3-O-rutinoside. Cyanidin-3-O-glucoside was identified in the methanolic extract of red mulberry. The content of heavy metals (Fe, Cu, Mn, Cd, Ni, Zn and Pb) was determined using atomic absorption spectroscopy in fruits and the extracts of red mulberry. Mulberry fruit has been shown the highest content of Fe and low content of toxic metals. The content of metals is the highest in the majority of cases in the extracts of acetone and acetone 50%. The methanolic extract of red mulberry shows the antimicrobial properties against all investigated bacteria except Staphylococcus aureus. Obtained results show that fresh fruits of red mulberry and its extracts can be used in nutrition and the preparation of pharmaceutical formulations.

Keywords: Morus rubra L., heavy metals, antimicrobial activity

Different types of chitosan were used to prepare membranes with enhanced antibacterial properties, via the solvent casting method. Nisin, an antimicrobial peptide, already use in food preservation, was incorporated in chitosan membranes to enhance the bactericidal effect, to obtain a starting material intended for use as wound dressings. The physico-chemical properties of the membranes were monitored and the results showed a good swelling capacity and water vapor transmission rate of the membranes. Optical characterization data showed that chitosan-based membranes could provide ultraviolet light protection while in vitro biodegradability assay demonstrated good stability of the films under enzymatic degradation. Nisin improved significantly the antibacterial effect of the membranes, while the nisin-chitosan membrane-forming solutions had a bactericidal effect against both Grampositive and Gram-negative bacteria.

Keywords: chitosan, membrane, nisin, antimicrobial peptide, biodegradable polymer

One of the challenges of smart and thin silica layers preparation on metallic substrates consists in the simultaneous network formation and introduction of corrosion inhibitors in it. Taking into account that both steps are affected by the temperature, it is really important to evaluate first its effect on the silica network formation. In this context, this paper aims the presentation of findings regarding the optimal heat treatment parameters in the preparation of thin silica (SiO2) coatings on zinc. These silica layers were prepared by sol-gel method (dip-coating technique) and were tested as protective films against zinc (Zn) corrosion. After optimization of several parameters such as the drying temperature, drying duration, the corrosion resistance of the coatings was evaluated mainly by means of electrochemical methods (electrochemical impedance spectroscopy and potentiodynamic polarization). The electrochemical evaluation corroborated with morphostructural characterization led to the conclusion that the SiO2 coatings have better protection properties when dried at 150°C for 1h.

Keywords: zinc; sol-gel; silica coating; electrochemical impedance spectroscopy; potentiodynamic polarization curves

The paper reports the AMS (accelerator mass spectrometry) radiocarbon investigation results of two superlative elms from Romana, the very large field elm of Calafat, with a wood volume of 85 m3, and the wych elm of Sadova. Two wood samples were extracted from each elm and were analysed by AMS radiocarbon. The oldest dated sample from the elm of Calafat had a radiocarbon date of 350 ± 19 BP, which corresponds to a calibrated age of 415 ± 25 years, while the oldest sample from the elm of Sadova had a radiocarbon date of 188 ± 24 BP, corresponding to a calibrated age of 260 ± 25 years. These values indicate high ages for the two elms, namely 430 ± 25 years or the elm of Calafat and 400 ± 25 years for the elm of Sadova.

Keywords: AMS radiocarbon dating, Ulmus minor, Ulmus glabra, dendrochronology, age determination, Romania

Recycling Li-ion batteries (LIBs) is a globally discussed issue in relation with waste management and environmental protection. This review reports the recent research and industrial progresses in LIBs recycling. After a brief introduction concerning the importance of LIBs recycling, and their structure and applications, the main aspects dedicated to LIBs recycling (pre-treatment, pyrometallurgical and hydrometallurgical processes) are presented. Greater attention has been paid to the hydrometallurgical processes due to their complexity but also because they can lead to the production of valuable products without a high ecological impact (compared to pyrometallurgical ones). Given that today, worldwide, only about 5% of spent LIBs are recycled, the data presented in our review can inspire the design and implementation of competitive technologies that fit into a sustainable circular economy that preserves the primary resources and ensures the environmental protection.

Keywords: Li-ion batteries recycling, pre-treatment, pyrometallurgy, hydrometallurgy, environmental protection

Due to its optical, chemical and electronic properties, graphene oxide (GO), among others subtypes of graphene-based materials, has been broadly studied over the past decade. Thanks to its contact-based antimicrobial activity GO represents a good candidate for the construction of materials with antimicrobial properties. Thus, GO’s capability to interact with microbes delivers a prospect to improve textiles designed for usage as personal protective equipment. This paper presents the results concerning the obtain of the GO-impregnated SFM-1 polypropylene membrane, its morpho-structure and antimicrobial activity and adherence on two gram-negative bacteria (E. coli, S. thyphimurium), a gram-positive bacterium (S. aureus) and a yeast (C. albicans). The investigations on the GO-impregnated polypropylene membrane, through Raman spectroscopy, Scanning and Transmission electron microscopy (SEM, TEM), Energy Dispersive X-Ray Analysis (EDX), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR) suggested the successful polypropylene impregnation with GO. The antibacterial tests have shown that all but one of the microorganisms (S. typhimurium) displayed to be susceptible to the antimicrobial activity of the GO material. Bacterial adhesion was also checked to simulate their affinity for the polypropylene surface immediately after impregnation, in this case the best results were observed on the S. aureus strains.

Keywords: graphene materials; polymer; composite; bacterial adherence, antimicrobial activity