STUDIA CHEMIA - Issue no.3 / 2016 Tom 2 - Table of contents

Professor Cordos is part of a student generation that makes the most representative connection between the group of professors that founded the chemistry department in early 1920 and the generation that graduates in early 1960 and developed the chemistry department in both fundamental and engineering chemistry. This generation was the last to have the chance of lectures of great chemists of this country like Raluca Ripan in Inorganic Chemistry, Ioan Cadariu in Physical Chemistry or Ioan Tanasescu in organic Chemistry. Also, these generation had a very good background in physics with Professor Mercea and mathematic with Professor Chis.

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Arsenate was firstly prereduced to arsenite in 0.01 mol L-1 HCl (pH 2.00 ± 0.01) and 0.3% L-cysteine, than arsine was generated with 0.5% NaBH4 solution stabilized in 0.5% NaOH and introduced into a capacitively coupled plasma microtorch (10 W, 150 ml min-1 Ar) for measurement of As 228.812 nm emission with the Ocean Optics QE65 Pro spectrometer of low resolution. The optimization steps for arsine generation and plasma operation are presented. Under optimal operating conditions, linearity of calibration curve covers the range 0 – 100 µg L-1, while detection and quantification limits are 0.2 and 0.6 µg L-1 respectively. Thus, the proposed method is able for As quantification in drinking and groundwater at levels below maximum admitted concentration (10 µg L^-1). The method was validated by analyzing certified reference water samples containing 10 – 60 µg L-1 As with recovery of 99 ± 9%. (95% confidence level, n = 5 measurements). The analytical capability of the method was demonstrated in the analysis of test samples (drinking-, ground- and waste water) with As concentration in the range 0.6 – 80 µg L^-1 As with a precision of 1.2 – 10.8%. The completely miniaturized instrument including the capacitively coupled plasma microtorch has analytical potential to be used for monitoring the quality of water sources.

Keywords: arsenic, hydride generation, water, capacitively coupled plasma microtorch, optical emission spectrometry, miniaturized instrumentation

The calcium and magnesium content of liquid samples has been determined directly by flame atomic absorption (FAAS) and flame atomic emission (FAES) spectrometry using the methane-air (M-A) flame. We measured simultaneously the intensity of the 554 nm wavelength molecular bands emitted by excited CaOH molecules and the decrease of light intensity of a hollow cathode lamp (HCL) absorbed by ground state Mg atoms. The simultaneous multiwavelength measurements enhanced by a charge-coupled device (CCD) microspectrometer allowed fast background correction for each studied element. The instrumental and flame parameters were optimized; the best results were obtained using a lamp current of 1 mA, and an observation height of 5 mm, in case of a reducing flame. The calcium and magnesium content of bottled water samples and water standard certified reference material (CRM) have been determined with standard addition method. The recovery for CRM was 97.80% for Ca and 98.51% for Mg. Under optimal working conditions the detection limits (according to the 3s criterion) were 25 µg•L-1 for Ca and 5.4 µg•L-1 for Mg.

Keywords: methane-air flame, FAES, FAAS, CCD microspectrometer, Ca, Mg, simultaneous determination

Mercury is recognized as a highly toxic and widespread element in environment that can be transferred in the whole food chain. Thus the content of mercury in foodstuff become of great interest. The aim of this paper is to assess the analytical capability and validation of the method for quantitative determination of total mercury (Hg) in seafood using thermal desorption atomic absorption spectrometry (TD-AAS). TD-AAS is a simple technique which does not require sample digestion prior to analysis. The main figures of merit such are selectivity, linearity, limit of detection (LoD), limit of quantification (LoQ), working range, accuracy and precision were studied and discussed in relation with the requirements in the Commission Decision 2002/657/EC and Commission Regulations 2011/836/EU and 2007/333/EC. Measurement uncertainty was estimated using top-down approach and was compared with the maximum uncertainty value calculated as specified in the Commission Decision 2002/ 657/EC. LoD estimated using 3s criterion was found to be 3.0 µg kg-1, while LOQ 9.0 µg kg-1. The recovery (%), estimated by using the certified reference material BCR-463 Tuna Fish, was 95 ± 5.0 %, whereas recovery (%) estimated using spiked samples was 92 ± 5.6 %. Standard deviation of repeatability (sr) was 5.6% (n=10 parallel samples), while standard deviation of within-laboratory reproducibility (sR) was 9.8 % (n=10 parallel samples), which correspond to HorRat’s index for repeatability and reproducibility of 0.28 and 0.50, respectively. The estimated expanded relative uncertainty (k=2) was 15.6 %. The obtained figures of merit fulfil the requirements of the European legislation, and demonstrate that the laboratory can properly apply the method in order to achieve accurate results. The paper represents a model for the method validation in analytical laboratories in order to check the fit for purpose of analytical methods.

Keywords: mercury, uncertainty estimation, validation, seafood, TD-AAS

Arsenic (As) is a toxic element which can occur in increased concentrations mainly in areas affected by mining and ore processing activities. To assess the As fractionation in soils from the Ogosta River floodplain, a seven-step sequential extraction procedure (SEP) followed by As determination using ultrasonic nebulization inductively coupled plasma optical emission spectrometry (USN-ICP-OES) was applied. The SEP fractionate between the ionically bound As; strongly adsorbed As; (3) As co-precipitated with acid volatile sulphide, carbonates, Mn oxides, very amorphous Fe oxyhydroxides; (4) As co-precipitated with amorphous Fe oxyhydroxides; (5) extraction in 0,2M NH4-oxalate buffer ascorbic acid; (6) As associated with crystalline Fe oxides; (7) orpiment and remaining recalcitrant As minerals. No significant differences were found between the pooled amount of As concentrations in each extraction step and the total As concentration measured using a XRF spectrometer (recoveries rate of 90 –110%). Total As concentration in soils varied widely, in the range of 36 - 72300 mg kg-1. The partitioning of As among the seven fractions in the six soil samples (%, medians and ranges) was: (1) 0.97 (0–4.8); (2) 12 (0–36); (3) 25 (12–44); (4) 8.7 (2.5–31); (5) 4.0 (0.2–25); (6) 34 (3.6–84); (7) 0.15 (0.02–1.1). However, significant differences on As distribution in contaminated and uncontaminated soils were observed, the fractions of mobile species, were found to be predominant in highly contaminated soils in contrast to the low-As soils, where As content were bound to the matrix.

Keywords: arsenic fractionation, floodplain soil, contamination, ICP-OES, sequential extraction procedure, Ogosta River

In this study, validation of a method for determination of free glycerol from biodiesel samples by using gas chromatography coupled with flame ionization detector (GC-FID) and the measurement uncertainty estimation was described. The derivatization reaction with N-methyl-N-trimethylsilyltrifluoroacetamide (MSTFA) was used to volatilize the glycerol prior to GC analysis. The 1,2,3-butanetriol was used as internal standard. Linearity, limit of detection, limit of quantification, precision and accuracy of the method were determined for the validation of the method. The limit of detection, estimated from chromatograms was 0.0006 % (w/w), while limit of quantification was 0.002 % (w/w). The recovery of free glycerol was determined by using certified reference material (CRMs) and was 102.4 ± 13.0 %. Also, the measurement uncertainty was estimated based on the bottom-up approach. The expanded uncertainty of the determination of free glycerol from biodiesel by GC-FID method was 16%

Keywords: free glycerol, validation, measurement uncertainty, GC-FID

The influence of aeration of soils polluted with heavy metals by using Thiobacillus-type microorganisms was studied using soil samples contaminated with heavy metals (Cu 4074 - 7550 mgkg-1, Zn 5870 - 9310 mgkg-1, Cd 36-50 mgkg-1, Pb 15000 - 42890 mgkg-1), from Romplumb, Baia Mare. The variation of the metal concentration extracted by bioleaching and aerated bioleaching was monitored for 16 weeks. The soil samples treated by bioleaching (Cu: 9 - 53%; Zn: 9 - 62%; Cd: 9 - 24%. Pb: 31 - 71%) have obtained a lower efficiency than the soil samples treated by aerated bioleaching (Cu: 34 - 70%; Zn: 36 - 76%; Cd: 17 - 38%. Pb: 44 - 78%), but there are percentage differences between the two processes (Cu: 17 - 27%; Zn: 14 - 27%; Cd: 8 - 14%, Pb: 7 - 13%).

Keywords: bioleaching, contaminated soils, heavy metals, in situ, microorganisms

Timely and effective warning sets the basis for building the prevention and awareness culture necessary for disaster risk reduction. The paper pursues to assess the awareness level of communities downstream some hydrotechnical facilities in NW Romania in terms of the risks these communities are exposed to and the availability of early warning systems. The research is based on the awareness on early warning systems of a community located downstream of some hydrotechnical facilities on the Somesul Cald River, NW Romania (Central-Eastern Europe), using the social investigation methodology, namely the questionnaire, applied to a group of 516 respondents from the risk-prone area, by the CATI (Computer Assisted Telephone Interviewing) method. The findings reveal the need to increase awareness of population and improve risk communication, as well as to conduct preparedness activities within the local community in order to build their resilience to disasters and improve the knowledge of population on the existing early warning systems.

Keywords: early warning systems, disaster risk reduction, community awareness, resilience, Romania

Any kind of perturbation or disruption in the usual activity of the critical infrastructures (CI) in the transport sector will have immediate impact on vital social functions, health, safety, security, environment and economy, but also on other infrastructures which are dependent on the systems previously mentioned. In the recent years events occurred during the road transportation of hazardous materials have caused important losses both to humans and the environment, therefore it is strongly recommended to study the possible outcomes of such events in the process of critical infrastructure management. The complexity of an urban environment might be challenging because different variables (like traffic congestion, vehicle routes, road condition, presence of people, specific weather conditions, etc.) are contributing decisively to the effects of a possible accident, but also on the authorities response capacity. This study is focused on showing which areas in Cluj-Napoca Municipality are more prone to be affected by possible outcomes of an accident which involves a propane cargo truck. Using specific software it is possible to generate a risk map which can be a good tool to improve the decision making process for authorities.

Keywords: critical infrastructure, hazmat transportation, modeling, risk, roads

Considering the increase of bottled mineral water consumption all over Europe, there is a growing interest related to its chemical composition and quality, especially for the elements that are not regularly monitored. This study reports the chemical composition of 21 bottled natural mineral waters available on the Romanian market. The studied mineral waters have low mineral contents (50-500 mg/l), except one, that was found to be rich in salts (>1500 mg/l). Generally, high bicarbonate contents (>600 mg/l) were found in the carbonated and partially degassed mineral waters, while the contents of sulfates and chlorides were low. The Piper diagram revealed that most of the waters are Ca-HCO3 type. Compared to the threshold limits, all samples comply with the legislated limits for natural mineral waters and the majority complies also with the requested standards for drinking water. The determined parameters were found to be in good agreement with those reported on the label.

Keywords: bottled natural mineral water, chemical composition, major and trace elements

Rare earth elements composition of Mocs meteorite was analyzed using two inductively coupled plasma mass spectrometry methods: a quadrupole and a single-detector sector-field high-resolution instrument. The obtained results are in good agreement with previous studies found in literature for both Mocs and chondritic materials analysis regarding REE composition. Allende meteorite reference material was used for calibration. Sample preparation for ICP-MS analysis was carried out following a custom protocol derived from the literature: the samples were finely ground, then treated in a multi-step procedure [1]. A mix of hydrofluoric acid, nitric acid and perchloric acid was used to digest the sample, which was finally dissolved in nitric acid and diluted accordingly, before being measured directly by ICP-MS instruments. Mocs samples were made available from Museum of Mineralogy, Babeș-Bolyai University Cluj-Napoca and Allende meteorite reference sample was provided by Smithsonian Institution (split 7, position 17) [2].

Keywords: HR-ICP-MS, ICP-QMS, meteorite, chondrite, Mocs, REE

The purpose of this study was to develop a quick procedure for the determination of α-phosphatidylcholine from soybean. The procedure is based on a simple solid-liquid extraction followed by a quick analytical method carried out with an LC-ESI-MS/MS system. A chromatographic column of 2×50 mm with a particle size of 2.5 µm was used. The LC-ESI-MS/MS method was developed in positive ionization mode. The analytical method was described in terms of: linearity, detection and quantification limits, accuracy and precision and matrix effect. The calibration curve was developed in the range of 5 to 200 ng/ml with a correlation coefficient r2 of 0.995 and detection limit of 0.5 ng/ml. The extraction method was tested for the recovery degree. The recovery obtained was 97.2±1.2%. The method was used to determine the content of α-phosphatidylcholine from five soybean varieties from Romanian market. No significant differences were obtained between the five varieties regarding the α-phosphatidylcholine content.

Keywords: lecithin, α-phosphatidylcholine, soybean, solid-liquid extraction, detection limits, accuracy

Celery is recently the subject of various studies due to its role in human nutrition and for medicine purposes. One of the most speculated ideas is that celery contains high quantities of androsterone which makes it suitable for infertility treatments. Due to this trend, the purpose of this study was to develop an analytical method suitable to confirm and measure the quantity of androsterone from celery root. A LC-MS/MS method was developed using a Turbo V source in positive ionization mode. Analytical parameters such as: linearity, detection and quantification limits, accuracy and precision and matrix effect were evaluated. The calibration curve was developed in the range of 100 to 400 ng/ml with a correlation coefficient r2 of 0.9968 and detection limit of 10 ng/ml. The extraction method was tested for the recovery degree. The recovery obtained was 92.1±2.2%. The method was used to determine the content of androsterone from three celery varieties from Romanian market.

Keywords: androsterone, celery, solid-liquid extraction, detection limits, accuracy

Preservation of old entomology items, although very important, is very difficult due to the contamination which they were subjected. In order to test the items contamination level with the classical sampling method, one must be very careful because they are very easily to break and can develop mold spores due to the moistening. The subject of this study is to recreate in the laboratory the stages of preserving the entomology samples by using petroleum products and naphthalene. Then the samples are subjected to two types of sampling, the classical sampling and a new sampling using a special pump for air sampling. After a month in which the items were kept in controlled environment, the sampling procedure was performed and the sample were analyzed. The results showed differences in the results obtained by two sampling techniques. The classical method proved to be more efficient but the items which were studied presents several defects.

Keywords: sampling procedure, museum, entomology items, naphthalene, total petroleum hydrocarbons

Stir bar sorptive extraction (SBSE)-thermal desorption (TD) procedure combined with gas chromatography electron capture detection (GC–ECD) was applied to the determination of 20 organochlorine pesticides (OCPs) in six white Romanian grape varieties. Analyses were performed using stir bars coated with 1.0 mm polydimethylsiloxane. The method provided satisfactory analytical performance to monitor OCPs in grape matrices at the trace level. By using the standard addition methodology, good linearity (r2>0.99) was found for all cases, depending on the particular OCP and also good sensitivity was achieved for all the investigated OCPs in agreements with the European Union regulations for the maximum residue limits (MRLs) of pesticides in agricultural vegetables. The method has multiple advantages, such as: simplicity, almost solventless and requires low sample amount, in comparison with conventional methods of sample preparation to analyse pesticides in vegetable matrices. The obtained results showed that OCPs were detected in all the investigated grape samples, with total contents varied between 0.32 µg/kg and 3.48 µg/kg, the concentrations were much lower than their specific MRLs.

Keywords: organochlorine pesticides, stir bar sorptive extraction, GC-ECD, grapes

The transfer of active substances of pharmaceutical forms is influenced by several factors, among which the nature of the excipients used in compression. The objective of this study was to investigate the influence of cellulose and its derivatives (hydroxypropylcellulose, hydroxylpropylmethylcellulose, carboxymethylcellulose) on the release profile of magnesium from marketed tablets (T1-T4). In vitro release experiments were carried out using a dissolution apparatus, in ultrapure water and simulated intestinal fluid (pH=6.8). In selected formulations, the amount of magnesium released was determined using inductively coupled plasma optical emission spectrometry (ICP-OES). The magnesium dissolution profiles demonstrated complete dissolution for T1, even just after 5 min. Magnesium release rate decreased with the increase in cellulose and/or its derivatives proportion: T1T3T2T4. An agitation speed of 50 rpm showed a more satisfactory magnesium release profile than 100 rpm.

Keywords: magnesium release, in vitro, pH, matrix tablet

High concentrations of nitrogen compounds in drinking water may cause negative health effects. The aim of the present study was to assess the content of nitrogen compounds namely, nitrates, nitrites and ammonium in drinking waters from Medias region (Medias, Copsa Mica towns and Tarnava village) and to investigate the health risk associated with the consumption of drinking water contaminated with these compounds. The health risk was calculated using chronic daily intake, hazard quotient and total hazard quotient. High concentrations of nitrite, nitrate and ammonium were found, at least one of the nitrogen compounds exceeding the maximum allowable concentrations (0.5 mg/L NO2-, 0.5 mg/L NH4 , 50 mg/L NO3-) in about half of the analysed samples. Generally, the chronic daily intake values were lower for nitrite and ammonium than for nitrate. The hazard quotients for nitrate were higher than the critical unity value, indicating that the consumption of contaminated waters from Tarnava village and Medias town may cause potential non-carcinogenic risk. Moreover, for the same samples, the total hazard quotients were higher than the critical unity value, suggesting that potential adverse health effects may appear after the consumption of drinking water.

Keywords: drinking water source, nitrite, nitrate, ammonium, chronic daily intake, hazard quotient, total hazard quotient

Drinking water represents a direct source for the toxic and persistent metals entrance in the organisms. Their bioaccumulation makes them harmful for living organisms, including humans. Assessing the quality of the drinking water sources represents a significant prevention and protection measure. Quality assessment methods such as heavy metal pollution index, degree of contamination and heavy metal evaluation index are applied worldwide. The aim of current study was to evaluate the metal contamination of drinking water sources from Medias town using the pollution and quality assessment indices. The concentrations of As, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn were assessed in 21 drinking water sources (19 well waters and 2 public springs). Results indicate Mn and Cd concentrations exceeding the threshold limits of the drinking water quality guidelines, only in summer season, in three samples. In the spring season the regulatory limits were not exceeded. The quality assessment indices show low contamination degree, all values being lower than the critical ones. Positive correlations were observed between pollution indices, As, Cd, Mn, Zn, Ni and Cu concentrations.

Keywords: drinking water sources, contamination index (Cd), heavy metal evaluation index (HEI), heavy metal pollution index (HPI)

Microbial fuel cells are based on the ability of microorganisms to produce energy through biomass degradation. This study presents the construction, electrical characterization and possible applications of a type of MFC with microorganisms from soil. Although the obtained power density is low compared to other authors (1W/m3, respectively 500mA/m2), the proposed construction is very simple, without moving parts, chemical substances or external electrical energy consumption. Possible applications of this type of MFC are presented: sodium acetate aqueous solution sensor and electrical energy source in isolated areas.

Keywords: microbial fuel cell, soil microorganisms, power density, miniaturised MFC

A novel class of counting polynomials, called Cluj polynomials was proposed on the ground of Cluj matrices. The polynomial coefficients are calculated from the above matrices or by means of orthogonal edge-cuts. In this paper Cluj polynomial in bipartite hypercube hypertubes is presented. Definitions and relations with other polynomials and topological indices are derived.

Keywords: Cluj polynomial, vertex-Padmakar-Ivan index, Wiener index

The current study aimed to evaluate the mass transfer parameters for the dissolution of spherical urea particles in fixed bed with downward flow of water. The impact of several operating parameters (particle size, height of the bed, liquid flow rate) on the key mass transfer parameters was investigated in isothermal conditions and atmospheric pressure. It was found that the mass transfer coefficient and urea dissolution degree increases by flow rate increase and decreases with the increase of particle size and bed height. The experimental values of the mass transfer coefficients were in good agreement with the ones found in the literature and the ones predicted by the Cussler equation.

Keywords: urea dissolution, mass transfer coefficient, dissolution degree, packed bed, downward flow

A diet rich in antioxidants is a heath choice most people make when it comes to options in fighting free radicals, that are formed natural in the body, but that cause damage to DNA and are connected to aging. The study was done in order the evaluate fruit teas that are a sources of antioxidants that can be easily introduce in the diet and are found all year along. 20 tea samples were analyzed to evaluate the antioxidant capacity and total polyphenols content. For the antioxidant capacity a photochemiluminescence methods was used and the Photochem instrument from AnalytikJena and for the total polyphenols content the Folin-Ciocalteu method was used. The average results where compared to the results obtained from black tea. The antioxidant capacity values obtained where from 0,53 to 2,27 mg/l Ascorbic Acid equivalents. The total polyphenols content was between 54 to 96 mg/l Gallic Acid equivalents. A positive correlation of 0.9664 was obtained between the antioxidant capacity and the total polyphenols content. A negative correlation of -0.962031201 was obtained between the antioxidant capacity and the number of the ingredients found in the tea samples.

Keywords: antioxidants, tea, polyphenols, Gallic acid, Ascorbic acid, antioxidant capacity

Adulteration of alcoholic drinks is often common, due to the products high prices and large commercialization. Using Mass Spectrometry and a Multi-Variate Statistical Package soft with PCA analysis application, whiskey from different sources was identified and compared in order to create a successfully method for identification possible adulterants. For PCA analysis the m/z abundance values (obtained from fingerprints mass spectra) were used. The results showed that the complex spectrum is a good chemical fingerprint of whiskey sample, indicating its origin and type and facilitate a good differentiation of different samples. By classification the models obtained for all whiskey samples, a method for adulterants detection was created.

Keywords: whiskey, GC-MS, PCA analysis, spectrum fingerprint