Abstract
Research on new products made of naturally occurring substances that possess regenerative and recuperative characteristics of benefit to humanity occurs continuously. In light of this, birch sap is receiving more and more attention. The aim of this work was an assessment of concentration changes of selected elements in birch sap depending on the day of collection. Herein, we utilized a ContrAA 700 high-resolution atomic absorption spectrometer with continuous light source (HR-CS-AAS) and we applied electro-thermal and flame techniques. Our results indicate that the concentration of the marked elements is variable and is connected with the date of collection. For most of elements, a downward trend can be observed. Only the amount of iron increased with time