Heterogeneous catalysis is in recent focus of research for biodiesel production from vegetable oils because of advantages such as easy separation and reuse of catalysts, although homogeneous catalysis is most commonly used method. The aim of this study was preparation of γ-Al 2 O 3 supported by modified sol-gel procedure, synthesis of the KI/Al 2 O 3 catalyst and testing its activity in the transesterification of sunflower oil with methanol. Influences of different process parameters on conversion of sunflower oil to methyl esters were examined. The gained results implicate that the potassium iodide incorporation into/ /onto the structure of γ-Al 2 O 3 significantly influences textural and structural properties of the catalyst. Additionally, the catalyst basic strength is increased and all together those properties are positively affecting the activity of the catalyst in the reaction of transesterification of sunflower oil with methanol. The impregnation of alumina with potassium iodide resulted in the additional formation of basic catalytically active sites. The surface properties of the catalyst have an essential impact on its catalytic performance. Under relatively mild process conditions and relatively short reaction time, the usage of the KI/Al 2 O 3 catalyst resulted in very high conversion to fatty acids methyl esters (i.e., 99.99%).

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Three lichen secondary metabolites atranorin (1), evernic acid (2), and usnic acid (3), were evaluated for their in vitro clastogenic and antiproliferative effects on human lymphocytes using the cytochalasin-B blocked micronucleus (CBMN) assay at concentrations of 2 µg/mL, 4 µg/mL and 6 µg/mL of final culture solution. The frequency of micronucleus (MN) was scored in binucleated cells, and cytokinesis-block proliferation index (CBPI) was calculated. Among the tested compounds, 3 exhibited the most prominent effect decreasing the frequency of MN in the range of 42.5%-48.9%, that is about double of the positive control amifostin WR-2721 that reduces MN frequency for 22.0%. The effect of evernic acid was approximately equal to action of amifostin (23.2%-32.9%). Atranorin at concentrations of 2 µg/mL and 4 µg/mL decreasing the frequency of MN only for 11.1% and 1.8%, while in concentration of 6 µg/mL increases the frequency of MN for 9.6 %. The comparable CBPI values of the investigated compounds and control suggested that they did not show a statistically significant inhibitory effect on lymphocyte cell proliferation at applied concentrations.

A new, simple, rapid, sensitive and selective kinetic spectrophotometric method for Pd(II) traces determination was elaborated in this paper. It is based on the catalytic effect of palladium ions upon the oxidation of methylene blue B (MBB) by (NH 4) 2 S 2 O 8 (APS) in citric buffer (BUF) solution. At the working temperature of 25 °C and the wavelength of 662.4 nm, the optimal conditions for palladium determination were found. RSD value was found to be 2.6 to 4.9% for the investigated concentration range of Pd(II). Limit of detection (LD) was found to be 2.0 ng cm-3 Pd(II), and limit of quantification (LQ) is 6.9 ng cm-3 Pd(II). Only the presence of Pb 2+ , Hg 2+ and Sn 2+ in the reaction mixture interferes the determination of palladium by this method, while Au 3+ and Ag + have the catalytic effect upon the reaction rate. By this method, it is possible to determine the Pd(II) traces in the concentration range of 3.3×10-8 to 1.0×10-6 g cm-3. The method was confirmed by determination of Pd(II) traces in alloy PtRhG as well as in the powder of Pt. The obtained results were compared to those obtained by ICP-OES method and good agreement of results was found.

The objective of this paper was to develop and apply the kinetic-spectrophotometric method for the determination of the pesticide dicamba in infant baby foods available in Serbia. The method is based on the inhibition effect of dicamba on the oxidation of sulfanilic acid (SA) by hydrogen peroxide in universal buffer (pH = 9.66) in the presence of Co 2+ ion. The reaction was monitored spectrophotometrically at 368 nm. The HPLC method was used as a comparative method to verify the results of the kinetic method. Under the experimental conditions proposed, dicamba showed a linear dynamic range of 0.31 to 3.10 µg mL-1 , and from 3.10 to 31.00 µg mL-1 with standard deviation from 1.77 to 4.55 %. Limit of detection and a limit of quantification are 0.101 µg mL-1 and 0.306 µg mL-1 , respectively. The kinetic method was efficiently applied for dicamba determination in baby food samples after solid phase extraction. This method is highly sensitive, simple, easy to operate, and requires cheap reagents. It can be successfully used for routine analysis of dicamba in baby food.

The present paper describes two new, simple, rapid, selective and sensitive kinetic spectrophotometric methods for Co(II) and Sn(II) determination in solution at room temperature, based on their effect on phenyl fluorone (PF) oxidation by hydrogen peroxide in ammonia buffer. The new method was elaborated for nano amounts of Co(II) determination, based on its catalytic effect on the oxidation of PF by H 2 O 2 in the presence of citric acid (CA) as an activator. Also, the new method for micro amounts of Sn(II) determination was developed based on its inhibitory effect upon the same reaction. Comparison of the results showed that the activated catalytic reaction has better sensitivity than the inhibitory one. Methods were validated by the analysis of chemical substances and results were confirmed by examining the same samples by the AAS method.

A new, simple, rapid, sensitive and selective spectrophotometric kinetic method for Ag(I) traces determination at room temperature was elaborated in this paper. It is based on catalytic effect of silver ions upon the oxidation of methylene blue B (MBB) by K 2 S 2 O 8 (PPS) in citric buffer (BUF) solution. The method was confirmed by determination of Ag(I) in PbO. The obtained results were compared to those obtained by ICP-OES method and good agreement of results was found.The silver traces determination is present in analytical practice for a long time. At the first time silver was determined in the photographic materials and solutions for black and white films, silver-plating solutions and effluents. Recently, silver has also been analyzed in ayurvedic and other drugs and medicines, chemical substances, natural and waste water samples, electronics, flow-solders, white metals, ores, alloys, biological samples, etc. [1,3,4] The toxico-kinetics of silver is very complex: its ability to form organometalic compounds and chelate complexes with influence on the metabolic processes in living organisms is subject of investigations in biology and environmental studies.There are different methods for Ag(I) determination, like atomic absorption spectrometry (AAS) [1,2], capillary zone electrophoresis (CZE) [3], fluorimetric [4], high performance liquid chromatography (HPLC) [5], kinetic [16][17][18][19], flow injection analysis (FIA) [20], spectrophotometric [21-28], photometric, etc. Silver was also determined using PVC-membrane electrodes based on 18-crown-6 and dibenzo-18-crown-6 ethers [29].Kinetic methods for Ag(I) determination with spectrophotometric detection, are mainly based on catalytic effect of silver ions upon the reaction rate of oxidation of different reductors by K 2 S 2 O 8 or (NH 4 ) 2 S 2 O 8 [6][7][8][9][10][11][12][13][14][15]. So, silver was determined as a catalyst of Kongo red oxidation in the presence of 1,10-phenantroline as an activator [6], and oxidation of BAPDAB in the presence of 2,2-dipyridyl as an activator [7], oxidation of

A rapid, simple, sensitive and selective new spectrophotometric kinetic method for Ni(II) traces determination at room temperature was elaborated in this paper. It is based on the catalytic effect of nickel ions upon the oxidation of alizarine (AL) by hydrogen peroxide in borate buffer (BUF) solution. The method was confirmed by determination of Ni(II) traces in fresh water samples. The obtained results were compared to those obtained by ICP-OES method and good agreement of the results was found.