In vitro dissolution of uranyl acetate using different methods
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In vitro dissolution of uranyl acetate using different methods Maisha M. Murry • Stephen P. LaMont Samuel E. Glover • Henry B. Spitz
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Received: 17 August 2012 / Published online: 15 September 2012 Ó Akade´miai Kiado´, Budapest, Hungary 2012
Abstract The dissolution rate of a material in the lung is an important parameter in evaluating the risk to humans following accidental inhalation of a substance and is also a parameter that may be useful in characterizing particles for nuclear forensics analysis. Conventional methods of measuring dissolution rates in vitro involve exposing the material or particles to a solvent, such as water, saline, or solutions that simulate lung fluid, and measuring the fraction of material that dissolves with time. A new device for measuring dissolution rates for small samples, especially individual particles, was evaluated that incorporates a regenerated cellulose dialysis membrane fixed to the bottom of a small, 2 mL plastic cup that fits into the top of a 50 mL plastic centrifuge tube. The cup is easily transferred among a series of tubes containing solvent to measure rate of dissolution. The dialysis membrane has a diffusion rating of 20 kDa molecular weight cut off which greatly exceeds the size of the dissolved uranium molecule. The performance of the dialysis cup device was evaluated by measuring the dissolution rate of uranyl acetate in distilled water, phosphate buffered saline (PBS), and simulated lung fluid (SLF). These results were compared to the dissolution M. M. Murry (&) S. E. Glover H. B. Spitz Nuclear & Radiological Engineering, University of Cincinnati, 598 Rhodes Hall, Cincinnati, OH 45221-0072, USA e-mail: [email protected] S. E. Glover e-mail: [email protected] H. B. Spitz e-mail: [email protected] S. P. LaMont Los Alamos National Laboratory, P.O. Box 1663/MS B224, Los Alamos, NM 87545, USA e-mail: [email protected]
rate measured using the traditional filter sandwich method in which a sample is sealed between two hydrophilic membranes. Although the majority of uranyl acetate dissolved in SLF within 30 min using the filter sandwich method, most of the uranyl acetate was undissolved in PBS and SLF using the dialysis membrane device. Reactions between the dissolved uranyl acetate, solvent, and the dialysis membrane likely caused the membrane to swell, shrinking the pore size, and thus reducing the transport of dissolved uranium across the membrane. Use of the dialysis cup device for evaluating dissolution rates for uranium-bearing materials in solvents containing a high concentration of salts is therefore not recommended. Keywords Dissolution rate Uranyl acetate Dialysis Simulated lung fluid
Introduction Traditional methods for estimating the lung dissolution rate of radioactive contamination collected on a filter involve sealing the filter between two hydrophilic membranes, immersing the assembly in the desired solvent, and measuring the fraction of contaminant that dissolves with time [1–3]. The ‘‘filter sandwich’’ method is impractical for nuclear fo
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