Aerosol performance testing

The two critical attributes characterizing the performance of DPIs are the imiformity of the delivered dose and the aerodynamie assessment of partiele size distribution. To determine the imiformity of the delivered dose, an apparatus capable of quantitatively retaining the dose leaving the deviee is used. For aerodynamic particle size assessment, a multistage liquid impinger or easeade impaetor is used. All aerosol performance testing must be condueted under defined temperature and humidity conditions. 

Verification of the microbial retention efficiency of the membrane filters may be undertaken using either Hquid or aerosol challenge tests. A Hquid challenge test is more stringent. Furthermore, this test can provide retention information for process conditions such as extreme moisture after sterilization or air entrained with water drops. A Hquid challenge is performed using a protocol similar to that described for Hquid filtration. 

Aftergenerating the aerosol, the test subject shall be instructed to perform the exercises in section LA. 14. of this appendix. 

A correlation study was performed to prove that the manufacturing integrity test for LYOGUARD trays could accurately detect small flaws and to verify that the leak test could predict the results of the aerosol challenge test. 

The steel fiber filter and the Venturi scrubber were tested under similar conditions (Dickinson et al., 1990 McCormack et al., 1990). The decontamination factors for manganese and cesiiun with the steel fiber filter were on the order of 10 for particle iodide, a retention on the same order of magnitude was measured, whereas the decontamination factor for total iodine was only on the order of 10 , probably due to a partial decomposition of Csl or to an incomplete consumption of HI during the generation of the Csl aerosol. The tests performed with the Venturi scrubber showed aerosol decontamination factors of more than 10 here also, the iodine decontamination factor was lower by a factor of about 10. More than 99% of the retained matter remained in the scrubber solution, less than 1% in the steel fiber filter, which is installed downstream. In contrast with the solid-state filters, in the Venturi scrubber no problems resulted from the aerosol load of the retention system. 

Denmark 1.5 days after the explosion. Air samples collected at Roskilde, Denmark on April 27-28, contained a mean air concentration of 241Am of 5.2 pBq/m3 (0.14 fCi/m3). In May 1986, the mean concentration was 11 pBq/m3 (0.30 fCi/m3) (Aarkrog 1988). Whereas debris from nuclear weapons testing is injected into the stratosphere, debris from Chernobyl was injected into the troposphere. As the mean residence time in the troposphere is 20-40 days, it would appear that the fallout would have decreased to very low levels by the end of 1986. However, from the levels of other radioactive elements, this was not the case. Sequential extraction studies were performed on aerosols collected in Lithuania after dust storms in September 1992 carried radioactive aerosols to the region from contaminated areas of the Ukraine and Belarus. The fraction distribution of241 Am in the aerosol samples was approximately (fraction, percent) organically-bound, 18% oxide-bound, 10% acid-soluble, 36% and residual, 32% (Lujaniene et al. 1999). Very little americium was found in the more readily extractable exchangeable and water soluble and specifically adsorbed fractions. 

The Britter and McQuaid10 model was developed by performing a dimensional analysis and correlating existing data on dense cloud dispersion. The model is best suited for instantaneous or continuous ground-level releases of dense gases. The release is assumed to occur at ambient temperature and without aerosol or liquid droplet formation. Atmospheric stability was found to have little effect on the results and is not a part of the model. Most of the data came from dispersion tests in remote rural areas on mostly flat terrain. Thus the results are not applicable to areas where terrain effects are significant. 

Liquid instillation and nebulised aerosols are the most common methods for pulmonary administration to experimental animals [22, 54, 109, 134], The use of pressurised metered dose inhaler (pMDIs) and dry powder inhaler (DPIs) in preclinical studies is limited by the need for formulation development, which often cannot be performed in early drug discovery due to short supply of test materials. A number of alternative techniques for intra-tracheal administration of coarse sprays and powder formulations have been described [9, 15, 21, 36, 71, 80, 99, 138],... 

Existing data on characteristics of particles from various types of sources are inadequate for general use, though they have been used in specific studies with some success. Most of the source tests have been made for purposes other than receptor modeling and complete chemical and microscopical analyses have not been performed. Source operating parameters which might affect the aerosol properties of emissions have not been identified nor measured in ambient sampling and no provision is made for likely transformations of the source material when it comes into equilibrium under ambient conditions. 

Introduce DOP aerosol upstream of the filter through a test port and search for leaks downstream with an aerosol photometer. Filter testing shall be performed after operational air velocities have been verified and adjusted where necessary. 

HEPA filter integrity testing is performed at 6-month intervals on level I and level II HEPA filters. HEPA filter testing includes Measuring (Machines, Eilters, Diffusers) Inlet and Outlet Air Velocity or Volume and Integrity Test of HEPA Filters Using Aerosol and Photometer. Refer to (provide reference to attachment no.). 

Figures 2 through 4 are graphical representations of the tests performed on the filter/sorbent sampling trains to test for sorbent capacity or breakthrough, and to best determine aerosol/vapor partitioning.

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