OXYGEN-18

MAIN AREAS OF APPLICATION OF THE ISOTOPE OXYGEN-18

Constantly growing interest in the stable isotopes of oxygen is explained by its huge role in plant and animal life, in development of isotopic analysis methods, in transition of pure research techniques in biochemistry into the practice of clinical medicine. Use of the compounds, “labeled” Oxygen-18 isotope, allows identifying causes of many diseases of the nervous and cardiovascular systems, to diagnose lung diseases and determine the effectiveness of pharmaceuticals in the study and treatment of brain diseases.

THE MOST COMMON APPLICATIONS OF STABLE ISOTOPE OXYGEN-18 INCLUDE:

• Oxygen-18 is used as precursor for medical radioisotope Fluorine-18 [18F] production which finds its utilization in PET (positron emission tomography).

This is one of the most typical applications of Oxygen-18. Rapidly developing in recent years, positron emission tomography (PET) is a modern method of medical clinical diagnosis and biochemical research. Oxygen-18 in the water or gaseous form serves as a source for short-lived positron-emitting isotope fluorine-18, which allows tracking the processes of cerebral blood flow, glucose metabolism in the central nervous and cardiovascular systems, evaluating the impact of drugs on neuroreceptors. 18F is also used in brain imaging. Several hundred PET centers which provide invaluable assistance to tens of millions of people every year function now in various countries.

• Use of Flourine-18 as the tracer during the medical and biological researches.

This kind of utilization of the product has been found its implementation because of the necessity to study life processes of the brain according to the analysis of metabolic products of biogenic acids in the blood, urine, cerebrospinal fluid under the supervision and treatment of patients with schizophrenia, manic depression, Parkinson’s disease, or the study of oxygen exchange in the lung alveoli in the diagnosis of pulmonary diseases. In these cases, Oxygen-18 can be introduced into the body by simple inhalation of molecular oxygen. It should be noted that such use of the isotope Oxygen-18 has become possible due to the rapid development of methods of isotopic analysis.

• Use of Oxygen-18 for the same purpose in the formulation of large-scale environmental studies.

Through the development of various methods of isotopic analysis has been achieved the possibility of the effective use of stable isotope-labeled compounds in many environmental programs. Moreover, experts note that the use of stable isotopes of oxygen contributes significantly to the overall environmental program. For example, the utilization of sulfur dioxide, marked isotope oxygen-18 makes it possible to identify the source of acid pollution after clouds moved for hundreds of kilometers.

• Use of Oxygen-18 to create therapeutic cancer drugs.

This direction is currently exploratory in nature. Positive results of studies in this area could lead to a sharp increase in demand for the isotope Oxygen-18.

Thus, increased production of Oxygen-18 is the essential condition for successful accomplishment of launched programs and for gaining achievements and improvements in health and environmental programs, and basic sciences. This is very important not only for individual countries and regions but also for humanity as a whole.

BRIEF DESCRIPTION OF PRODUCTION PROCESS

Oxygen is the most abundant element on Earth. The atmosphere contains 23% by weight of free oxygen. The hydrosphere and lithosphere contain 86% and 47% accordingly by weight of bound oxygen.

Oxygen is a mixture of three stable isotopes: Oxygen-16 (99.76% at.), Oxygen-17 (0.04% at.) and Oxygen-18 (0.20% at.).

The difference of mass numbers of isotopes affects their basic properties to a small extent, and therefore oxygen isotope composition of various natural compounds is approximately equal. The content of Oxygen-18 in the air, fresh water and ocean water is 0.204% at., 0.198% at. and 0.200% at. respectively. The content of Oxygen-18 in various minerals varies by no more than 0.008% at. Therefore, as a raw material for the production air or natural water should be used.

To enrich the material with Oxygen-18 in production quantities rectification of liquid oxygen, nitrogen oxyde, water or chemical isotope exchange can be applied. Based on economic considerations and technical feasibility of each method in the present conditions of Russia rectification of water has been chosen as a base method. Moreover, it is the most convenient to store, transport and use Oxygen-18 in the form of water enriched with this isotope.

Rectification method is well studied and widely used for purification of substances in the chemical industry and for the separation of substances with different boiling points.

Natural water can be regarded as a mixture of low-boiling component H216O with a boiling point at normal pressure of 100 oC and high-boiling component H216O with boiling point 100,15 oC. Separation H216O and H218O occurs in distillation columns. Each column consists of a cube-evaporator, the actual columns filled nozzle, condenser and the upper reservoir.

In the cube takes place a continuous evaporation of water coming from the column. Steam rising up the column interacts with the water flowing in the form of film on the nozzle – mass transfer occurs. In this case, steam is depleted, and the flowing water is enriched with high boiling component H218O.

At the top of the column steam enters into the condenser, cooled by water from a water recycling system. In the condenser takes place a continuous condensation of depleted Oxygen-18 water vapor. Gravity condensate enters the upper reservoir and mixed with water located there. Then this water is fed to the power of the column. The consumption of water corresponds to the mass flow of steam.

Thus, during operation process of the column Oxygen-18 transfers from the upper reservoir to the cube: water in cube enriches with Oxygen-18 and water in the upper reservoir is depleted of this isotope.

CJSC “Global Scientific Technology” together with “Center of Molecular Research” Ltd. carry out manufacture of Oxygen-18, based on a specially elaborated project. Implementation of the project has been carried out at a site in Sosnovy Bor city near St. Petersburg.

¹⁸O enriched normalized water (H₂¹⁸O)

ADDITIONAL INFORMATION:

• The total radioactivity of the present water specimen are no more than the natural background (10-15 mkr/h).

• Package size: 50 gram in the borosilicate US standard glass vials with rubber-stoppers and aluminum crimp seals. The vials special sterilized prior to filling.

• Guarantee validity period is two calendar years from the shipment day.