Surface Sampling of a Dry Aerosol Deposited Ricin

Sampling of small molecules from both porous and non-porous surfaces poses a significant challenge across biological agents. Particle sizes of toxins are smaller than living organisms and can be extremely toxic at low level concentrations. A small number of studies evaluating sampling efficiencies of commercial off the shelf (COTS) materials have been performed with toxins and proteins. However, they have been limited to non-ricin stimulants with drastically different physical properties than their native counterparts. We have identified a commercially available non-toxic recombinant ricin, complete with both A and B subunits present, which can be recognized by antibodies commonly used to assay native ricin. In evaluating recovery efficiency, we deposited the recombinant ricin by both liquid deposition, and as a dry aerosol. Our studies demonstrated a significant difference in recovery efficiencies from liquid deposited ricin, ranging between 30% and 70%, than from an aerosol generated deposition ranging from below detectable levels to 22%, depending on the contaminated surface and swab material being used. This study demonstrates the necessity for accurate dissemination techniques of sampling technologies for the consideration of use in an environment where suspected toxin contamination is being evaluated.