Marija Bralić
University of Split
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Featured researches published by Marija Bralić.
Talanta | 2001
Marija Bralić; Njegomir Radić; Slobodan Brinić; Eni Generalić
Fluoride-selective electrode with LaF(3)-membrane and stainless steel internal contact has been prepared. The electrode has been tested in F(-) concentration range 10(-2)-10(-6) M and the results compared with those of commercial electrode and electrode with laboratory renewed internal electrolytic contact. The properties of simple disjoining solid-state contact have been investigated by means of electrochemical impedance spectroscopy (EIS). The impedance spectra show two time constants, which suggest that, at lower frequencies, proceed some Faradic reaction which probably stabilizes the potential between LaF(3)-membrane and stainless steel disk.
Science of The Total Environment | 1995
Njegomir Radić; Marija Bralić
A potentiometric investigation of the rate and mechanism of the reaction between aluminium (III) ions and fluoride ions in buffered aqueous solution (pH values 2 and 5) is described. Potential-time curves recorded during the reaction, using fluoride-ion selective electrode, constitute the primary data in this study. The rate of aluminium fluoride complexation is calculated under different experimental conditions. In the solutions where the analytical ratios between fluoride and aluminium are > 6, the calculated average number of fluoride ligands bound by aluminium are in the range 1.8-3.7.
Analytical Letters | 2000
Marija Bralić; Eni Generalić; Silvestar Krka
ABSTRACT Design of the fluoride ion-selective electrode (FISE) as the tubular detector used in the flow injection analysis (FIA) has been described. Among other things, this design makes it possible to use various internal contacts. The effect of pH on peak height and detection limit in the pH range from 2.8 to 8.0 has been examined. The effect of flow rate and sample injection volume on peak height and range of linear response has also been examined. The flow rates range from 0.56 mL/min to 4.05 mL/min, while the injection volumes are 100 and 200 μL. The optimum conditions are carrier solution (0.1 M KNO3 buffer pH 4 and 10-6 M NaF), flow rate 1.54 mL/min and sample injection volume 100 μL. Applicability of the FISE as the tubular detector in determination of Fe(III)-ions and AI(III)-ions by flow infection analysis has been examined at pH values of 2.8 and 3.4.
Analytical Letters | 2013
Ante Prkić; Josipa Giljanović; Sandra Petričević; Mia Brkljača; Marija Bralić
The concentrations of Cd, Cr, Cu, Fe, K, Mg, Mn, Pb, and Zn in 14 different samples of mint leaves (Mentha piperitae folium) and tea bags purchased in local supermarkets and marketplaces in Split, Croatia were determined. Electrothermal atomic absorption spectrometry (ETAAS) was applied in this work. Mint tea samples purchased at marketplaces contained: Cd (0.021–0.357 mg kg−1), Cr (<0.01–52.3 mg kg−1), Cu (3.23–5.56 mg kg−1), Fe (47.7–208 mg kg−1), K (7.47–21.7 g kg−1), Mg (2.16–15.9 g kg−1), Mn (24.2–667 mg kg−1), Pb (1.31–1.49 mg kg−1), and Zn (2.33–19.5 mg kg−1). Those ones purchased at supermarkets contained: Cd (0.19–0.34 mg kg−1), Cr (7.3–99 mg kg−1), Cu (1.70–5.21 mg kg−1), Fe (0.16–1.42 g kg−1), K (0.23–60.8 g kg−1), Mg (0.13–16.3 mg kg−1), Mn (0.30–0.93 mg kg−1), Pb (<0.01–1.73 mg kg−1), and Zn (<0.01–24.9 mg kg−1). In order to get a better insight into the elemental patterns in mint leaves, a One-Way ANOVA program R was used for statistical data analysis. The One-way ANOVA was performed with the amount of each metal as the dependent variable and market as the independent variable. The PCA (principal component analysis) was applied to analyze the grouping of mint leaves on supermarket and marketplace samples.
Analyst | 1990
Njegomir Radić; Marija Bralić
A kinetic-potentiometric method is described for the determination of aluminium(III) based on monitoring its reaction with hydrofluoric acid using a fluoride ion-selective electrode at pH 2. At that pH the reaction Al3++ HF AlF2++ H+ is the predominant path for the initial consumption of aluminium in a complex with fluoride. The initial rate of the complex formation reaction was used to construct calibration graphs. There is a linear relationship between the initial rate of reaction and the amount of aluminium added. The method is rapid and can be used for the determination of aluminium down to 0.5 µmol with satisfactory precision (relative standard deviation < 6%).
Talanta | 2004
Marija Bralić; Slobodan Brinić; Eni Generalić; Ladislav Vrsalović
Continuous-flow (CF) and flow-injection (FI) analysis using the fluoride ion-selective electrode (FISE) as detector have been investigated. The measurements were performed in a home-made cell under appropriate flow conditions (2.86 or 3.45mlmin(-1), 0.2ml samples, 10(-6)M sodium fluoride). The calibration graph was obtained by plotting the signal height versus concentration of iron in the range of Fe(III) concentration from 10(-5) to 10(-1)M in acetate buffer (pH 2.8 or 3.4). In all described procedures, the range of linear response extends to the Fe(III) concentration from 1x10(-3) to 1x10(-1)M, with detection limit 9x10(-5)M. The effect of double-line, two-line flow manifold and CF was investigated and discussed.
Journal of Electroanalytical Chemistry | 1988
Njegomir Radić; D. Prugo; Marija Bralić
Abstract Potentiometric titrations of aluminium with fluoride in a background of acetate buffer (pH 5) in different organic solvent + water mixtures were carried out in order to study the effect of the organic solvent (namely: ethanol, methanol, n-propanol, tert-butanol and p -dioxane) on the titration curve and the analytical data. On the basis of potentiometric titration experiments the overall conditional formation constants of AlF i (3−i)+ complexes have been calculated. The calculated constants increase with increas- ing vol.% of organic solvent for all mixtures tested. Among the solvents tested, p -dioxane yielded a greater potential break than the other solvents and the measurements in mixtures with this solvent and ethanol also showed the best precision. In p -dioxane-rich media a concentration of aluminium in the cell solution of 10 −5 mol dm −3 was established as the detection limit for the potentiometric titration experiment. At a low concentration of aluminium, the stoichiometric ratio between aluminium and fluoride is constant for a narrow range of aluminium concentrations and can be determined by experiment only. The formation of aluminium hexafluoride complex in organic solvent + water mixtures may be accepted for the titration of higher concentrations of aluminium ( > 10 −5 mol dm −3 ).
Analytical Letters | 2014
Maša Buljac; Danijela Bogner; Marija Bralić; Nenad Periš; Marijo Buzuk; Slobodan Brinić; Nives Vladislavić
The distributions of cadmium and lead in marine sediments, surrounding soil, stones, and atmospheric particulate matter were determined at different locations in Split, Croatia. The determination of cadmium and lead was performed by flame atomic absorption spectrometry whereas atmospheric particulate matter samples were analyzed by inductively coupled plasma–optical emission spectrometry. Cadmium concentrations in the stones and soil were between 0.2 to 0.6 µg g−1 and 0.2 to 0.9 µg g−1. The concentration in the atmospheric particulate matter were <0.2 µg m−2 d−1(detection limit) to 1.4 µg m−2 d−1. Lead concentrations in marine sediments, stones, soil, and atmospheric particulate matter ranged from 31.2 to 144.4 µg g−1, 9.3 to 29.4 µg g−1, 11.3 to 66.1 µg g−1, and 0.5 to 241.4 µg m−2 d−1, respectively. The relationship between determined parameters was established using principal component analysis and the results are in agreement with the assumption that anthropogenic sources play important roles for lead and cadmium distribution.
Monatshefte Fur Chemie | 2016
Marijo Buzuk; Slobodan Brinić; Nives Vladislavić; Marija Bralić; Maša Buljac; Ivana Škugor Rončević
A novel approach for investigation of a mechanism and rate of “self-oxidation” of cysteine in the presence of Cu2+ is presented. Continuous monitoring was performed using simple, low-cost, and widely available commercial ion-selective electrode for Cu2+. Presented procedure provides a complete real-time picture of overall oxidation process and has revealed a sequentially organized process, with the domination of certain reactions in each stage. A plausible mechanism, in the light of the previously reported explanation, has been proposed to account for the experimental results together with an adequate scheme of the overall process. The dependence of both the pH (measurements were performed at pH 5, 7, 8) and the concentration of the initially present Cu2+ is presented and discussed. Additionally, information into the process was collected by experiments performed in oxygen-free atmosphere and changes in the mechanism of oxidation, at weakly alkaline pH values, were observed. Information presented in this study can be utilized in advanced biochemical monitoring systems, when considering the importance of the position of cysteine and cysteine containing peptides in metabolic processes.Graphical abstract
Mikrochimica Acta | 1995
Njegomir Radić; Marija Bralić
The potential response of a symmetrical configuration in which the LaF3-membrance is placed between two solutions is discussed. The electrode body provides contact with the inner surface of the fluoride membrane, with a solution containing Fe(CN)63−-Fe(CN)64− redox couple and a Pt wire as internal reference electrode. The electrode was examined in terms of potentialconcentration curves and potential-time response and shown to behave similarly to the commencal Orion fluoride electrode. The advantage of the proposed redox reference system is that the electrode has minimal drift immediately after assembly.