Water-18O

DescriptionOnly 0.2% of the oxygen-18O isotope exists in atmospheric oxygen. The Water-18O is manufactured by enriching the oxygen-18O over 98 atom% and is used to produce the [18F]FDG *1 PET diagnostic reagent for cancer. Water enriched in the oxygen-18 isotope (Water-18O) is widely used in medicine, agrochemistry and biochemistry. Oxygen-18 was first enriched to 99.5% in 1943 using thermal diffusion. To date, the use of electrolysis, chemical isotope exchange, gas diffusion, and rectification of oxygen, nitric oxide, and water has been described to enrich water with oxygen-18. Among them, the method of rectification of water, first demonstrated in 1944, is successfully used now in industry.

UsesWater-18O, 97 atom % 18O is used in DNA stable isotope probing (SIP) to investigate microbial growth and death in environmental samples.

UsesWater-18O is an isotopically modified water, which is appropriate for PET applications.It can also be used:In paleoclimatology, hydrology, and plant ecology to determine soil stable oxygen isotope analysis of plant cellulose using δ18O.To determine the diffusion of moisture into crystals using secondary ion mass spectrometry (SIMS).

PreparationWater-18O (H₂¹⁸O), also known as ¹⁸O water, has the chemical registry number (CAS RN=14314-42-2) and a molecular weight of 18.02 g/mol. As early as 1943, Clusius and Dickel enriched 99.5% of oxygen-18 using a thermal dispersion method. The main methods for enriching deuterated water include: thermal dispersion, electrolysis, chemical conversion reaction, thermal diffusion, and water distillation. Currently, deuterated water is mainly produced through a redox reaction of H₂ and O₂ in the presence of a noble metal catalyst. O₂ is produced by electrolyzing double-standardized water (D₂O), while D₂O is obtained by distillation of natural water. Patents eNloo342955e and CN101618857B disclose a method for obtaining heavy oxygen water from natural water through distillation, electrolysis, and catalytic reaction. Its main feature is the use of platinum wire mesh or precious metal catalysts such as catalysts.