Faculty of Natural Sciences and Mathematics

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Pharmacokinetics of different selenium supplements in healthy individuals and patients with autoimmune thyroiditis after oral administration
(Society of Chemists and Technologists of Macedonia, 2025-06-24)
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Stafilov, Trajče
Selenium is essential for the function of key selenoproteins such as glutathione peroxidase, thiore-doxin reductase, and iodothyronine deiodinase, which have antioxidant properties and support thyroid hormone metabolism. Due to the low selenium content in European soils – particularly in the Southeast-ern regions, supplementation is often recommended, especially for conditions like Hashimoto's thyroidi-tis. However, careful consideration of selenium dosage and pharmacokinetics is crucial, as the margin be-tween essential and toxic levels is very narrow. The aim of this study was to investigate the pharmacoki-netics of selenium absorption and plasma concentration following oral administration of various selenium doses and chemical forms, both in the short and long term, in healthy individuals and patients with auto-immune thyroiditis. Selenium concentrations in blood plasma were measured using electrothermal atomic absorption spectrometry (ETAAS). The study found that L-selenomethionine is absorbed more efficiently than inorganic sodium selenite, with peak plasma concentrations reached and sustained within 6 – 8 hours. Selenium levels remained elevated 48 hours after ingestion compared to baseline. At a daily dose of 200 μg of selenium as L-selenomethionine, plasma selenium concentrations increased by approximate-ly 30 %, and by about 25 % at 100 μg/day, relative to the initial value. Long-term studies showed that plasma selenium concentrations rose significantly after the first month of supplementation, with a slower increase in subsequent months. After supplementation ended, selenium levels declined rapidly. Interest-ingly, no significant differences in selenium absorption or excretion were observed between patients with Hashimoto's thyroiditis and healthy controls.
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Multivariate extraction of dominant geochemical markers for deposition of 69 elements in the Bregalnica River basin, Republic of Macedonia (moss biomonitoring)
(2016-11)
Balabanova, Biljana
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Stafilov, Trajče
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Šajn, Robert
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Tănăselia, Claudiu
Atmospheric deposition was investigated using the terrestrial moss species Hypnum cupressiforme (Hedw.) and Homolothecium lutescens (Hedw.) in the Bregalnica River basin, Republic of Macedonia. Long-term emission occurs in this area due to the hydrothermal exploitation of Pb-Zn deposits (Sasa and Zletovo mines) and copper ore exploitation and floatation (Bučim mine). Determination of the chemical elements was conducted using atomic emission spectrometry with inductively coupled plasma (ICP-AES) and mass spectrometry with inductively coupled plasma (ICP-MS). A combination of multivariate techniques (PCA, FA and CA) was applied for data processing and identification of element association with lithogenic/anthropogenic origin. Seven dominant factors were extracted from the total of 69 analysed elements. Spatial distribution maps were constructed for the determination and localisation of smaller areas with higher contents of certain anthropogenic elements. In this way, the influences of selected human activities on local air pollution can be determined. The summarised data show quantification of the element distributions. This not only allows the determination of the distribution of hazardous elements but also presents complete characterisation of element deposition in the environs of mines.
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Determination of iron in drinking water after its flotation concentration by two new dithiocarbamate collectors
(2015)
Pavlovska, Gorica
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Stafilov, Trajče
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Čundeva, Katarina
Two new methods for the determination of iron by atomic absorption spectrometry (AAS) are proposed for drinking water. The determination was made after flotation concentration of Fe by using of two new flotation collectors: lead(II) heptyldithiocarbamate, Pb(HpDTC)2 and cobalt(III) heptyldithiocarbamate Co(HpDTC)3. All important parameters for the two proposed procedures were optimised (pH, mass of Pb, mass of Co, amount of HpDTC(-), type of surfactant, induction time, etc.). Flotation recovery (R) of Fe was very high (from 94.4 to 104.4%) for the two proposed procedures. The detection limit of the methods was 2.17 μg L(-1) for Pb(HpDTC)2 and 2.39 μg L(-1) for Co(HpDTC)3, respectively. The proposed methods have been applied for the analysis of five samples of drinking water. The acquired AAS results for Fe by both new methods were compared with those obtained by inductively coupled plasma-atomic emission spectrometry (AES-ICP). It is shown that they are in good agreement. The results are also confirmed by the method of standard additions.
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Multi-element atmospheric deposition in Macedonia studied by the moss biomonitoring technique
(Springer Science and Business Media LLC, 2015-10)
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Frontasyeva, Marina V
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Stafilov, Trajče
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Šajn, Robert
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Ostrovnaya, Tatyana M
Moss biomonitoring technique using moss species Homolothecium lutescens (Hedw.) Robins and Hypnum cupressiforme (Hedw.) was applied to air pollution studies in the Republic of Macedonia. The study was performed in the framework of the International Cooperative Programme on Effects of Air Pollution on Natural Vegetation and Crops under the auspices of the United Nations Economic Commission for Europe (UNECE) Convention on Long-Range Transboundary Air Pollution (LRTAP). The presence of 47 elements was determined by instrumental epithermal neutron activation analysis, atomic absorption spectrometry and atomic emission spectrometry with inductively coupled plasma. Normality of the datasets of elements was investigated, and Box-Cox transformation was used in order to achieve normal distributions of the data. Different pollution sources were identified and characterized using principal component analysis (PCA). Distribution maps were prepared to point out the regions most affected by pollution and to relate this to the known sources of contamination. The cities of Veles, Skopje, Tetovo, Radoviš and Kavadarci were determined to experience particular environmental stress. Moreover, three reactivated lead-zinc mines were also shown to contribute to a high content of lead and zinc in the eastern part of the country. However, a comparison with the previous moss survey conducted in 2005 showed a decreasing trend of pollution elements that are usually associated with emission from industrial activities.
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Bioavailability and bioaccumulation characterization of essential and heavy metals contents in R. acetosa, S. oleracea and U. dioica from copper polluted and referent areas
(Springer Science and Business Media LLC, 2015)
Balabanova, Biljana
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Stafilov, Trajče
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Bačeva, Katerina
Bioavailability of metals occurring in soil is the basic source of its accumulation in vegetables and herbs. The impact of soil pollution (due to urban and mining areas) on the food chain presents a challenge for many investigations. Availability of metals in a potentially polluted soil and their possible transfer and bioaccumulation in sorrel (Rumex acetosa), spinach (Spinacia oleracea) and common nettle (Urtica dioica), were examined.
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Biomonitoring of air pollution with mercury in Croatia by using moss species and CV-AAS
(Springer Science and Business Media LLC, 2014-07)
Spirić, Zdravko
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Vučković, Ivana
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Stafilov, Trajče
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Kušan, Vladimir
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Bačeva, Katerina
Moss samples from four dominant species (Hypnum cupressiforme, Pleurozium schreberi, Homalothecium sericeum and Brachythecium rutabulum) were collected during the summer and autumn of 2010 from 121 sampling sites evenly distributed over the territory of Croatia. Samples were totally digested by using microwave digestion system, whilst mercury was analysed by using cold vapour atomic absorption spectrometry (CV-AAS). Descriptive statistics were done from analyses of mercury in all moss samples. The content of mercury ranged from 0.010 to 0.145 mg kg(-1) with a median value of 0.043 mg kg(-1). Hg distribution map shows the sites of the country with higher levels of this element. High contents of Hg were found in moss samples collected from the regions of Podravina and Istria as a result of anthropogenic pollution. Comparison of median values and ranges with those found in moss samples in 2006 shows slight reduction of mercury air pollution. When compared to the results obtained from recent studies conducted in Slovenia, Macedonia and especially in Norway-which serves as a reference considering the fact that it is a pristine area-mercury air pollution in Croatia is insignificant.
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Study of nitrogen pollution in Croatia by moss biomonitoring and Kjeldahl method
(2014)
Špirić, Zdravko
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Stafilov, Trajče
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Vučković, Ivana
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Glad, Marin
During the summer and autumn of 2006 moss samples were collected from 98 sampling sites evenly distributed all over the territory of Croatia. Moss sampling was repeated in 2010 when additional sampling sites were added and a total of 121 samples were collected. Kjeldahl method was used to determine the nitrogen content in the samples. Descriptive statistics and distribution maps were prepared. Data obtained from these two surveys were compared, and additional comparison was done with data obtained from similar studies in neighbouring countries and Finland as a clean area. The median value of N content in the samples collected in 2006 is 1.60% and varies from 0.79% to 3.16%. The content of N in samples collected in 2010 ranges between 0.71% and 2.93% with the median value of 1.49%. High contents of N (2.32% - 3.17%) were found in the regions of Slavonia, Podravina, Posavina and cities Zagreb and Sisak as a result of agricultural activities, industry and traffic.
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Study of the influence of maceration time and oenological practices on the aroma profile of Vranec wines
(2014-12-15)
Petropulos, Violeta Ivanova
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Bogeva, Elena
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Stafilov, Trajče
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Siegmund, Barbara
Vranec is one of the most important red grape varieties in Republic of Macedonia, grown in all vineyards, mostly in the Tikveš wine region. In this study, Vranec wines produced with different maceration times (4, 7, 14 and 30 days) in presence of enzyme and oak chips during fermentation were studied in order to determine the influence of vinification conditions on the aroma profile. The volatile compounds were determined using headspace solid phase microextraction (HS-SPME) with a PDMS/Carboxen/DVB fibre, coupled with gas chromatography-mass spectrometry (GC-MS). In total 63 aroma compounds were detected revealing a complex aroma profile of Vranec wines composed of esters, alcohols, fatty acids, aldehydes, ketones and sulphur compounds. The content of aroma compounds was related mostly to maceration time, observing increased relative amount of alcohols, esters and fatty acids from the fourth to seventh day of maceration and the presence of oak chips during the fermentation enhanced their formation. The Student-Newman-Keuls test has been applied to ascertain possible significant differences between the studied wines, and principal component analysis has been employed, showing separation and grouping of the wines according to maceration time and oak chips treatment.
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The study on air pollution with nickel and vanadium in Croatia by using moss biomonitoring and ICP-AES
(2013-10)
Vučković, Ivana
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Špirić, Zdravko
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Stafilov, Trajče
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Kušan, Vladimir
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Bačeva, Katerina
Moss samples were collected from 121 sampling sites all over Croatia during the summer and autumn of 2010. They were totally digested by using microwave digestion system and analysed by using atomic emission spectrometry with inductively coupled plasma (ICP-AES). Descriptive statistics and maps of distribution were made. The data obtained in this study were compared with those from the study in 2006 and additionally with the data obtained in the similar studies in neighbouring countries and Norway as pristine area. The median value of nickel is 3.16 mg kg(-1) and the content varies from 1.04 to 14.66 mg kg(-1). The content of vanadium ranges between 0.23 and 37.26 mg kg(-1) with the median value of 2.55 mg kg(-1). High contents of these elements are found in the vicinity of Rijeka, Zagreb and Sisak as a result of their emission from oil refinery, thermal power plant and industrial processes.
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Moss biomonitoring of air pollution with chromium in Croatia
(Informa UK Limited, 2013)
Vučković, Ivana
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Spirić, Zdravko
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Stafilov, Trajče
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Kušan, Vladimir
The purpose of this study was to determine the atmospheric deposition of chromium in Croatia by using moss biomonitoring technique and atomic emission spectrometry with inductively coupled plasma (ICP-AES). Moss samples (Hylocomium splendens, Hypnum cupressiforme, Brachythecium rutabulum and Homalothecium Sericeum) were collected from 121 sampling sites evenly distributed over the country, during the summer and autumn of 2010. Collected samples were air dried, then cleaned and digested by using microwave digestion system. The median value obtained in this study (1.94 mg kg⁻¹) compared with the median value of previous investigation performed in 2006 (2.75 mg kg⁻¹) shows that the content of chromium decreased. Higher contents of chromium were found in moss samples collected in the regions of Central Croatia, in/near the cities of Zagreb, Sisak and Kutina, which, in the most of the cases, are result of anthropogenic activities. In Costal Croatia, higher values have a natural origin due to the significantly higher content of Cr in soil from this region. The results were compared with those from similar studies in neighboring and other Balkan countries. It was established that the content of chromium in Croatia is lower than in the most of these countries.

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