Abstract
Methods for detecting leakage from containment devices on FACS instruments are of interest in the flow cytometry and biosafety communities. Using a short-lived radionuclide, a method was developed to quantify such leakage. A Becton Dickinson FACS Aria™ cell sorter with an Aerosol Management System was run in normal and failure modes using a radioactive technetium-99m saline solution. The air outside of containment and the surfaces inside and outside were tested for radioactive contamination. An intrinsic high-resolution germanium gamma-ray detector and associated gamma-ray spectroscopy system were used to quantify the radioactivity in the starting solution and on air sampling filters. A liquid scintillation counter was used to quantify the radioactivity on wipe tests and on filter disks positioned inside and outside the instrument, and in collected liquid samples.
Radiation safety precautions were in place and no significant exposures to operators or statistically significant leakage outside of containment occurred. Based on the specific activity of the radioactive solution, the level of radioactive contamination detected provides an estimate of the volume of generated aerosol inside or outside containment. This technique can detect liquid volumes in the 1E-04 to 1E-05 microliter range. By assigning a theoretical number of infectious particles per milliliter to the sample, the number of infectious particles per filter disk, per wipe test, or per air sample may be determined.
This method cannot be implemented at institutions without proper licensure from the Nuclear Regulatory Commission/Agreement State and radiation safety expertise.