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Radiosterilization dosimetry of vitamins: an ESR study
J P Basly1, I Basly, M Bernard
1UPRES EA 1085 Biomolécules et cibles cellulaires tumorales, UFR de Pharmacie, Limoges, France. basly@unilim.fr
International Journal of Radiation Biology
|November 3, 1998
Summary
Electron spin resonance (ESR) can detect radiation sterilization in vitamins, offering a promising method for pharmaceutical quality control. This technique allows for dose estimation and can identify irradiated products for up to two years post-sterilization.
Area of Science:
- Pharmaceutical Science
- Analytical Chemistry
- Radiation Chemistry
Background:
- Ionizing radiation is an emerging sterilization method for pharmaceuticals.
- Accurate detection and dosimetry of radiosterilized products are critical for regulatory compliance.
- Traditional sterilization methods like heat and gas may degrade sensitive medicinal products.
Purpose of the Study:
- To evaluate electron spin resonance (ESR) spectrometry as a method for detecting and quantifying radiosterilization in pharmaceutical products.
- To establish mathematical models for ESR signal analysis concerning radiation dose and storage time.
- To determine the shelf-life for detecting radiation effects in model pharmaceutical compounds.
Main Methods:
- Six model vitamins (riboflavin, biotin, thiamine mononitrate, thiamine hydrochloride, folic acid, pyridoxine) were subjected to ionizing radiation.
- Electron spin resonance (ESR) spectrometry was used to measure free radical concentrations.
- Mathematical models, including exponential and bi-exponential functions, were developed to correlate ESR signals with radiation dose and storage time.
- Decay curves were analyzed to estimate the detection limit over time.
Main Results:
- Free radical yields ranged from 1.7 x 10^18 to 7.3 x 10^19 radicals mol⁻¹ (G values: 0.0003–0.025 mol J⁻¹).
- ESR spectrometry demonstrated a good correlation between peak-to-peak amplitude and radiation dose, enabling quantitative dosimetry.
- Irradiated vitamins showed detectable ESR signals for up to two years, with exceptions for folic acid and pyridoxine, suggesting potential degradation pathways.
Conclusions:
- ESR dosimetry is a viable and promising technique for detecting pharmaceutical radiosterilization.
- The method requires minimal sample preparation and is non-destructive.
- ESR offers a sensitive and efficient approach for post-sterilization quality control in the pharmaceutical industry.