A double isotope method for characterizing hygroscopic selenious acid aerosols used in inhalation exposures

Methods of generating and characterizing selenious acid aerosols for use in deposition and toxicity studies are described. Selenious acid aerosols were nebulized and heat treated at varied temperatures. Because selenious acid is hygroscopic, a solution containing 3H2O and 75Se was nebulized to determine the water content in selenium aerosols after generation. The stable aerosol was a hydrate of selenious acid, H2SeO3 X 1/2 H2O, at New Mexico ambient relative humidity (ca. 20%). The mass median aerodynamic diameter of the collected droplets was 0.6 micron with a geometric standard deviation of 1.3.