Silicon (Si) is one of the most important elements on the Earth, and an essential element for all living organisms. In the last two decades, the benefits of silicon in plants, animals and humans have been proven. The content of this element in the human body is from 6 to 7 grams, almost twice as much as iron, which confirms its biological significance. The level of Si in the body decreases significantly with age, and a need for its supplementation arises. The mean daily requirement for the element is 20-40 mg, and a diet does not fully provide this amount. Many plant-based supplements with a low content and low bioavailability of the element as well as preparations in the form of aqueous solutions with a high Si concentration, up to 2%, are supplied commercially. The target of the research was to determine the content of silicon in the bioavailable form of orthosilicic acid (H2SiO4) in dietary supplements, seawater, tap water, carbonated water and still water, tested with the colorimetric method. The silicon content in bottled waters was determined to be in the range of concentrations of 1 to 20 mg dm-3, while in tap water, seawater and plant preparations it ranged from 0.2 to 1700 mg dm-3. Commercially available preparations with a high concentration of Si (0.1-2 %) are characterized by a varied level of bioavailability of H2SiO4, not exceeding 20%. The colorimetric method for the determination of orthosilicic acid is well-known, but requires strict conditions to the complex to be formed. The kinetics of the steps during the reaction of complex formation, and the influence of the ambient pH on possible complications were investigated.    

24.3.2019