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Bulletin of the Chemists and Technologists of Bosnia and Herzegovina
Issue 42
Publication date: June 2014 |
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Table of contents
Phenolic Compounds and Antioxidant Activity of Some Citruses Original Scientific Article
Fejzić Amina, Ćavar Sanja
Abstract:Citrus fruits (Rutaceae) are important source of phenolic compounds and their glycosides. These compounds are phenolic acids for bioactive responsible for the antioxidant and many other biological activities. In this paper five extracts from juice and peel of different types of citruses (tangerine, lemon, pink grapefruit, white grapefruit, and orange) were analyzed for total phenolic content and antioxidant activity. Total phenolic content was determined by spectrophotometric Folin-Ciocalteu method, and the values varied from 0.192 ± 0.015 mg GAE/mL for white grapefruit peel to 0747 ± 0098 mg GAE/mL for white grapefruit juice. Antioxidant activity of samples was tested using the total antioxidant method that implies reduction of molybdenum ions and it is expressed as IC50. The IC50 values were ranged from 6.00 ± 0.50 mg/mL for orange juice to 78.11 ± 6.70 mg/mL sample of lemon juice.
Bulletin of the Chemists and Technologists of Bosnia and Herzegovina 42, 1-4.
Determination of Total Phenolic Content and Antioxidant Activity of Ethanol Extracts from Aloe spp. Original Scientific Article
Vidic Danijela, Tarić Elvira, Alagić Jasmina, Maksimović Milka
Abstract: The ethanol extracts of leaf peel and gel of Aloe spp. were analyzed for their total phenolic and flavonoid profiles and screened for their antioxidant activity. The total phenolic content of the three different plant extracts and one commercial product of Aloe vera was determined by Folin-Ciocalteu method and flavonoid content was assessed by AlCl3 method. Peel extract had the highest total phenolic content (7.99 mg gallic acid equivalents (GAE)/g extract) and flavonoid content (9.17 mg quercetin equivalents (QE)/g extract). The lowest content of phenolic and flavonoid compounds was observed in Soxhlet extract of Aloe gel. The in vitro antioxidant activity determined by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid (ABTS) assays revealed that all extracts exhibited low antioxidant activity compared to quercetine and thymoquinone as standards. The best antioxidant activity had the peel extract what is in correlation with content of phenolic and flavonoid compounds.
Bulletin of the Chemists and Technologists of Bosnia and Herzegovina 42, 5-10.
Preconcentration of Metal Ions Using Silica Gel 60 F254 Original Scientific Article
Svraka Irnesa, Memić Mustafa, Sulejmanović Jasmina, Muhić-Šarac Tidža
Abstract: In this study, the use of a column packed with unmodified activated silica gel as sorbent for preconcentration of Cd, Co, Cr, Cu, Fe, Mn, Ni and Pb prior to their analysis by flame atomic absorption spectrometry (FAAS) was described. Factors affecting the preconcentration of analytes such as pH, sample flow rate and volume from pure multielement aqueous solutions of known concentration, were determined. The recovery values of prepared samples of known concentration of analytes were: 87.7% (Cd), 94.3% (Co), 95.7% (Cr), 91.2% (Cu), 105.2 % (Fe), 84.5 % (Mn), 96.6% (Ni) and 101.7% (Pb), under the optimum conditions (pH; 9, sample flow rate; 6mL/min, preconcentration factor; 10). The adsorption capacity of unmodified silica gel for Cd, Co, Cr, Cu, Fe, Mn, Ni and Pb was found to be 6.05, 11.54, 13.08, 10.70, 12.18, 12.38, 11.59 and 3.28 µmol /g of adsorbent, respectively. Detection limits of the method were 4.3, 35.0, 58.2, 18.5, 37.1, 10.3, 38.8 and 55.0 μg/L for Cd, Co, Cr, Cu, Fe, Mn, Ni and Pb, respectively.
Bulletin of the Chemists and Technologists of Bosnia and Herzegovina 42, 11-16.
Interpretation of Results Obtained from Analyses of Some Raw Materials from Cement Production, from Ribnica and Grabovica Deposits Original Scientific Article
Avdić Nurudin, Delić Said, Merdić Nevzet
Abstract: Basic raw materials used for portland cement clinker production are calcium, silicon, aluminium and iron oxides. In avaliable raw materials, these components are rarely found in ratio needed for clinker production. Consequently, it is important to prepare appropriate raw mixture from materials with high limestone (calcium carbonate) contents and materials with suitable contents of oxides, but with low fraction of limestone. To achieve this, it is essential to perform reliable qualitative and quantitative characterization of raw materials. In this paper, results obtained from analyses of samples used for cement production (marlstone from Ribnica and Greben quarries and marl from Greben) are presented. Chemical composition of analyzed samples is satisfactory, according to EN 197-1 standard.
Bulletin of the Chemists and Technologists of Bosnia and Herzegovina 42, 17-20.
Fundamental Thermal Concepts Understanding: The First-Year Chemistry Student Questionnaire Results Original Scientific Article
Hadžibegović Zalkida, Sulejmanović Suada
Abstract: The main aim of this study is to show the research results of learning outcomes on thermal physics that have gained a group of first-year chemistry students in the fall semester of the academic 2013-2014 year. In this paper is described the use of a questionnaire to explore chemistry freshmen capacity to which they achieve their understanding of thermal physics concepts they learn within the chemistry and physics courses during the first study year. A used questionnaire contains 20 questions including a question on which the 94 study participants had the task to give their explanations related to a selected question. Research results show that knowledge about thermal equilibrium, the first law of thermodynamics and other relations among physical quantities students did not acquire in a way to present their scientific literacy developed enough at university learning outcomes level. Students need some additional instructions to find their pathways from pre-instructional alternative concepts to learn the scientific concepts through new working sessions enriched with experiments and demonstrations by instructors, teaching assistants as well as a group of students actively involved in learning on thermal physics subject matter.
Bulletin of the Chemists and Technologists of Bosnia and Herzegovina 42, 21-30.
DTF Study and Biological Activity of Some Methylxanthines Original Scientific Article
Salihović Mirsada, Huseinović Šukrija, Špirtović-Halilović Selma, Osmanović Amar, Dedić Alema, Ašimović Zilha, Završnik Davorka
Abstract: Using quantum chemical methods (density functional theory level), biologically active methylxanthines were investigated. All calculations were performed at B3LYP/6-31G* level of theory. The electronic chemical potential, highest occupied molecular orbital (HOMO)/lowest unoccupied molecular orbital (LUMO) gap, dipole moment, vibration frequencies, electrophilicity, chemical hardness and logP were calculated. Obtained results correspond well with some of the pharmacological properties. Calculated properties could be useful for quantitative structure-activity relationship (QSAR) analysis which will be performed in the future.
Bulletin of the Chemists and Technologists of Bosnia and Herzegovina 42, 31-36.
Phenolic Compounds and Antioxidant Activity of Cocoa and Chocolate Products Original Scientific Article
Ibrić Amerisa, Ćavar Sanja
Abstract: Cocoa is the fruit of the tree Theobroma cacao L., growing in tropical regions of Africa and South America. Prefermented and fried cocoa serves as a basic raw material for the preparation of chocolate food products. Cocoa is extremely rich in antioxidants, which are responsible for the overall health of the humans. These antioxidants include polyphenols and catechins. This paper presents the investigation of total phenolic contents and antioxidant activity of extracts obtained from cocoa powder and different types of chocolate. The total content of phenolic compounds was determined by spectrophotometric Folin-Ciocalteu method and it varied from 0.046 ± 0.013 to 0.376 ± 0.022 mg GAE/g. The antioxidant activity of the extracts was tested using total antioxidant capacity method. The IC50 value was in the range of 1.968 ± 0.076 mg/ml to 42.200 ± 1.737 mg/ml. Cocoa powder and chocolate with a high content of cocoa contain relatively high amount of total phenolics, as well as high antioxidant capacity.
Bulletin of the Chemists and Technologists of Bosnia and Herzegovina 42, 37-40.
Investigation of Possibility for Reducing AISI 303 Stainless Steel Pitting Corrosion by Microalloying with Boron or Zirconium Original Scientific Article
Bikić Farzet, Mujagić Derviš
Abstract: AISI303 has the highest machinability comparing with all other austenitic stainless steel grades. The good machinabilityis result of sulphur presence in the steel composition. Sulphur improves machinability but at the same time causes a decrease in the corrosion resistance.The aim of the research was to examine the possibility of reducing the effect of sulfur content on the corrosion behavior of AISI 303 by microalloying with boron or zirconium. The intention is to keep high machinabilityof this steel grade but make it corrosion resistant. The results show that after microalloying with boron or zirconium the intensity of pitting corrosion of AISI 303 stainless steel can be significantly reduced. The results show that the effect of reducing the intensity of pitting corrosion of AISI 303 stainless steel microalloyed with boron or zirconium is higher at lower concentrations of chlorides. This is confirmed trough comparing the intensity of pitting corrosion of the 303 stainless steel samplesmicroalloyed with boron or zirconium with the samples of 304 stainless steel. The intensity of pitting corrosion 303 stainless steel microalloyed with boron or zirconium is closer to the intensity of pitting corrosion of 304 stainless steel in 1.5% NaCl solution than in a 3% NaCl solution. Results also clearly indicate that the increase of NaCl concentration leads to an increase of pitting corrosion in all tested samples.
Bulletin of the Chemists and Technologists of Bosnia and Herzegovina 42, 41-46.
Quantification of Some Phenolic Acids in The Leaves of Melissa officinalis L. from Turkey and Bosnia Original scientific article
Ibragić Saida, Salihović Mirsada, Tahirović Ismet, Toromanović Jasmin
Abstract: Melissa officinalis L. (lemon balm) contains many potentially biologically active compounds, including the caffeic acid (CA), chlorogenic acid (CGA), rosmarinic acid (RA), succinic acid, ursolic acid and thymol. In this study, using the HPLC-ED system, determinations of gallic acid (GA), CGA, RA and CA were performed in hot water extracts of lemon balm. Analyses of GA, CGA, CA and RA were performed in supernatants of lemon balm leaf extracts. The standard solutions of GA, CGA, CA and RA were prepared by dissolving pure substances in the mobile phase. The lemon balm leaves (fresh weight) from Bosnia contained 0.38 mg/g GA, 0.25 mg/g CGA, 0.14 mg/g CA and 5.10 mg/g RA. The lemon balm leaves from Turkey had a higher CA content (0.71 mg/g), while the GA, CGA and RA content was lower (0.22 mg/g, 0.23 mg/g and 0.24 mg/g, respectively). Having many beneficial properties due to the phenolic compounds, lemon should be used as a supplement to a balanced diet.
Bulletin of the Chemists and Technologists of Bosnia and Herzegovina 42, 47-50.
Total Phenolic Content and Antioxidant Capacitiy in Infusions of Various Herbal Teas Original Scientific Article
Tahirović Ismet, Kožljak Mirnesa, Toromanović Jasmin, Čopra-Janićijević Amira, Klepo Lejla, Topčagić Anela, Demirović Hana
Abstract: Among numerousorganic compounds, herbal teas contain various phenolic compounds that may affect the physiological and antioxidant activity of the tea. The aim of this work was to evaluate total phenolic content (TPC) and antioxidant capacity (AC) against peroxide free radicals in the infusions of various herbal teas.
TPC was determined using the spectrophotometric method with Folin-Ciocalteu's reagent, where Me(VI) ions are reduced with phenolics from tea samples to blue-coloured Me(V)-oxides with absorption maximum at 743 nm. Gallic acid, was used as a standard.
AC against peroxyl free radicals, was determined by using the manual spectrofluorimetric method with fluorescein. Trolox (T), which is a hydrosoluble synthetic analogue of natural vitamin E, was used as a standard. TPC varied from 488.8 mg GAE/100 mL (for bearberry tea) to 13.7 mg GAE/100 mL (for sage). Obtained values for AC were in a range 4076.3 mmol TE/100 mL (for bearberry tea) to 251.4 mmol TE/100 mL (for tea against gastritis).
Bulletin of the Chemists and Technologists of Bosnia and Herzegovina 42, 51-55.
