Heavy metals are highly toxic to living organisms even in low concentrations owing to their cumulative effect. In this study the overall content of lead in herbal drugs was determined, as well as the content of lead which was released from tested drugs during the preparation of tea drinks. To determine the content of toxic lead, the highly sensitive microanalytical technique of the potentiometric stripping analysis (PSA) with oxygen as the oxidant was used. The lowest overall content of lead was detected for chamomile and ranged from 0.73 to 0.77 µg/g, while the greatest content of lead was determined in the samples of the frangula bark, and yielded approximately 3 µg/g. The lead content in the prepared tea drinks ranged from 0.26 to 1.23 µg/g and depended on the manner in which tea drink was prepared. All of the herbal drugs in this study contain a certain amount of the toxic metal lead, but at the same time, the contents were below the levels prescribed for this metal. The content of lead released from the herbal drug into the tea drink was three to five times lower than those of the overall content of this metal.

Although present in very small quantities, metals are important constituents of honey, having a significant impact on vital functions in the human body. Moreover, honey can be a good source of natural antioxidants, which have an important role in reducing the negative effects of certain human diseases. The content of the determined macroelements in the analyzed samples of domestic honey turned out to be of the following descending order: Na > K>Ca > Mg, and Ca > Na > Mg > K for the commercial types of honey. Generally, the detected content of macroelements was higher in domestic honey compared to commercial honeys, as well as in the case of the content of microelements. In some types of honey, the toxic elements Pb and Cd were detected, which is an indicator of environmental pollution. The results of total phenols content and antioxidant activities have shown that the sample of domestic floral honey from the area of Vlasina has the largest total phenols content and very high antioxidant activities, as well as manuka in the group of the commercial types of honey. The contents of the detected macro and microelements have shown lot of variations which confirms that the geographical origin of honey has a very important influence on its final mineral composition. The detected contents of Pb and Cd, were low, but due to the cumulative and toxic effects of these metals, it is necessary to constantly monitor the content of these pollutants in honey.

Antibiotics are among the most widely used classes of pharmaceuticals in modern medicine. Due to their frequent use, antibiotic residues have been detected in the environment, particularly in aquatic environments. In this study, HPLC method, with sample pretreatment was optimized and validated in order to analyze the presence of two commonly used antibiotics—cephalexin and tetracycline in water samples. Samples were collected from different sources, including wastewater, tap water, the Danube River and groundwater, in order to evaluate how the matrix affects the overall analysis. The main objective of this research was to develop an effective and reliable method for the detection of these antibiotic residues in water. A secondary aim was to establish the most effective sample preparation method. Samples were prepared using the dispersive solid-phase extraction (dSPE) technique with modified diatomaceous earth as the sorbent. The dSPE procedure was applied primarily for sample clean-up and reduction in matrix effects prior to HPLC-DAD analysis. The sorbents were characterized prior to use to investigate the influence of modification on their sorption properties.