Radiation-Induced Transformations of 2-Fluoroethanol in Aqueous Solutions
- PDF / 550,599 Bytes
- 7 Pages / 612 x 792 pts (letter) Page_size
- 96 Downloads / 187 Views
ATION CHEMISTRY
Radiation-Induced Transformations of 2-Fluoroethanol in Aqueous Solutions S. D. Brinkevicha, *, O. V. Tuhaia, A. A. Sladkovaa, and O. I. Shadyroa aBelarusian
State University, Minsk, 220030 Belarus *e-mail: [email protected]
Received May 16, 2020; revised May 16, 2020; accepted July 6, 2020
Abstract—Steady-state radiolysis has been used to study the radiation-induced transformations of 2-fluoroethanol in dilute aqueous solutions as a model system for examining the autoradiolytic dehalogenation of the radiopharmaceutical drug 2-[18F]fluorodeoxyglucose ([18F]FDG). A derivatization–gas chromatography procedure for determining the fluoride anion in the presence of organofluorine compounds has been developed. It has been established that •OH and H• induced the dehalogenation of 2-fluoroethanol in − aqueous solutions. Unlike bromo- and chlorohydrins, 2-fluoroethanol does not interact with eaq according to the dissociative attachment mechanism. It has been shown that О2 halved the radiation-chemical yield of fluoride due to the oxidation of hydroxyl-containing carbon-centered radicals of 2-fluoroethanol. The constant of unimolecular dehalogenation of the 2-fluoroethanol radical is 3.9 × 106 s−1, as calculated using the method of competing reactions. Keywords: steady-state radiolysis, dehalogenation, fluoride, 2-fluoroethanol, FDG DOI: 10.1134/S001814392006003X
INTRODUCTION Radiolysis of organofluorine compounds in aqueous solutions still has remained a poorly studied area of high-energy chemistry, although radiation-induced processes involving this group of substances are of great practical importance. Thus, the electron-beam irradiation of polyfluorinated compounds (for example, perfluorooctanoic acid) in solutions and in complex dispersed systems (soil) is considered as an industrial technology for the treatment of these persistent organic pollutants [1]. The radiation-induced transformation of labeled compounds under the influence of their own radiation—autoradiolysis—is a serious problem for the manufacturers of radiopharmaceuticals labeled with the fluorine-18 isotope [2]. In most cases, this process is accompanied by the elimination of the [18F]fluoride anion, which is accumulated in the bone tissue and hence is of high radiobiological hazard. For 2-[18F]fluoro-2-deoxy-D-glucose ([18F]FDG), which is the most widespread radiopharmaceutical for the diagnosis of cancer, cardiac, and neurological diseases by positron emission tomography (PET) [3], the accumulation of radiolytic fluoride is a key factor limiting the shelf life of the finished dosage form [4]. At high initial volumetric activities of [18F]FDG, which provide the lowest production cost [5], the drug
becomes unsuitable for diagnostic use as early as 1 h after synthesis [6]. The studies of autoradiolysis [4, 6–8] and the tests of stabilizers [6, 8] are actively underway in order to improve the quality of the radiopharmaceutical drug and increase its shelf life. However, the identification of nonradioactive products of the decomposition o
Data Loading...
