Snezana Nikolic-Mandic

Optimization of the QuEChERS extraction procedure for the determination of polycyclic aromatic hydrocarbons in soil by gas chromatography-mass spectrometry

Polycyclic aromatic hydrocarbons (PAHs) are listed as pollutants of great concern and the development of fast and reliable analytical procedures is a modern day challenge. The aim of this study was to optimize the QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) technique, in order to establish an efficient method for the extraction of 16 priority PAHs from soil, using various sorbent and solvent system combinations, followed by GC-MS analysis. The best results were obtained using acetonitrile/water as the extraction solvent and diatomaceous earth as the dispersive solid phase extraction sorbent. The proposed method is rapid, accurate, precise, as well as much cheaper and simpler than other methods used for the extraction of PAHs from soil. The optimized method was successfully applied on real soil samples from an urban area of Nis, Serbia. Analysis of real soil samples showed contamination of soil with mostly light PAHs, where acenaphthene was predominant. The content of total PAHs varied from 345.65 to 27 314.30 μg kg−1, with a mean of 3646.39 μg kg−1. Only three samples contained elevated amounts of PAHs according the Gazette of the Republic of Serbia.

Elemental Composition of Wild Edible Mushrooms from Serbia

The elemental composition of four wild edible mushroom species was determined by inductively coupled plasma optical emission spectrometry (ICP OES): scotch bonnet (Marasmius oreades), chanterelle (Cantarellus cibarius), porcini (Boletus edulis), and peppery milk-cap (Lactarius piperatus). Mushrooms are a potassium-rich food, which was confirmed in this study. M. oreades contained the highest concentration of almost all elements, except for cadmium, potassium, phosphorus, and lead. Lead and cadmium were present but at concentrations that are not hazardous to human health. A principal component analysis loading plot for elemental composition demonstrated that 95.51 percent of the total variance was present in the first two principal components. Cluster analysis separated the elements into three statistical significant clusters.

Chemometric approach to evaluate heavy metals' content in Daucus carota from different localities in Serbia

The aim of this study was to evaluate heavy metal content in carrots (Daucus carota) from the different localities in Serbia and assess by the cluster analysis (CA) and principal components analysis (PCA) the heavy metal contamination of carrots from these areas. Carrot was collected at 13 locations in five districts. Chemometric methods (CA and PCA) were applied to classify localities according to heavy metal content in carrots. CA separated localities into two statistical significant clusters. PCA permitted the reduction of 12 variables to four principal components explaining 79.94% of the total variance. The first most important principal component was strongly associated with the value of Cu, Sb, Pb and Tl. This study revealed that CA and PCA appear useful tools for differentiation of localities in different districts using the profile of heavy metal in carrot samples. [Projekat Ministarstva nauke Republike Srbije, br. 172051]

Determination of iodide and bromide by flow methods with amperometric detection

Determination of bromide and iodide in real samples (water, pharmaceutical preparations, and biological material) was performed using modified flow injection analyses (FIA) with amperometric detection on platinum electrode. As an additional confirmation of FIA experiments, cyclic voltammetry was employed. Iodide was determined by the kinetic method, its limit of detection was 1.0 nM, and the linearity was 0.1–100 μM. The limit of detection for bromide determination was 50.0 nM and the calibration was linear for 2.5–100 μM and 0.1–10 mM. The relative standard deviation for 1 μM of iodide was 3.03% and, for 5 μM of bromide, it was 1.23% (n = 6). Both methods enable 60 analyses per hour to be performed.