Halogens are a group of reactive elements, which are capable of making stable bonds with metals and nonmetals. Due to their properties, they play an important biochemical role in living organisms; some, such as F, Cl and I, are essential for humans, whereas others, such as Br, are non-essential and can cause key toxicological effects. This is probably the main reason why this group of elements has been extensively studied in food and biological materials, especially in recent years. The determination of halogens at trace levels requires suitable instrumentation, and plasma-based techniques, such as inductively coupled plasma optical emission spectrometry (ICP-OES) and especially inductively coupled plasma mass spectrometry (ICP-MS), are particularly well suited for this purpose. Although they are very versatile for performing multielemental determination, halogens present high ionization potentials and low wavelength emission lines, and they are prone to interferences due to matrix effects. Such drawbacks are difficult to overcome without changing instrumental features, such as mass or optical resolution. On the other hand, some interferences due to the presence of dissolved carbon in solution, enhancement or suppression of ionization, and related matrix effects can be minimized by applying an appropriate sample preparation step. In this sense, the present review covers the main sample preparation methods applied for halogen determination in food and biological materials by using ICP-OES and ICP-MS. Methods based on dilution, solubilization, extraction or those involving matrix decomposition (e.g., acid digestion and combustion) are discussed based on key applications selected in the last 20 years.

Currently, algae and algae products are extensively applied in the pharmaceutical, cosmetic and food industries. Algae are the main organisms that take up and store heavy metals. Therefore, the use of compounds derived from algae by the pharmaceutical industry should be closely monitored for possible contamination. The pollution generated by heavy metals released by industrial and domestic sources causes serious changes in the aquatic ecosystem, resulting in a loss of biological diversity and a magnification and bioaccumulation of toxic agents in the food chain. Since algae are at the bottom of the aquatic food chain, they are the most important vector for transfer of pollution to upper levels of the trophic chain in aquatic environments. Moreover, microalgae are also used for the bioremediation of wastewater, a process that does not produce secondary pollution, that enables efficient recycling of nutrients and that generates biomass useful for the production of bioactive compounds and biofuel

A new method based on synergism between MW and UV radiation was proposed for chocolate digestion using diluted HNO₃for subsequent determination of As, Cd, Ni and Pb by ICP-MS.