Sample Prep Part 6

Slide 16 shows InnovaPrep’s new ACD-200 “Bobcat” aerosol collector.  The ACD stands for Aerosol collector, Dry.  The 200 is because it operates at 200 liters per minute aerosol collection rate.  The Bobcat aerosol collector could also be called an air sampler.  Dry filter air collectors are nothing new.  The problem with them has always been how to harvest the collected particles in a quick, efficient and useful way. 
 
We figured out that if we could extract particles from hollow fiber filters using wet foam elution, we could extract particles from flat filters too.  This discovery led us to develop of a hand-held wet foam elution cartridge that is made to fit directly onto the filter holder.  Just collect the sample, transport it dry, and extract it with the hand held extractor into a sample cup.  The resulting sample is about 6-7 milliliters of final volume (watch the video). If that is too big, it can be rapidly concentrated down using one of the concentrators (HSC-40 or integratable HCI-40) or even a centrifuge…  But then, wouldn’t you rather use a 21st century solution to solve a 21st century need?
 
The first tests we did were done using aerosolized polystyrene microspheres, also known as PSMs or beads.  We started out with 1-micron beads to simulate aerosolized spores.  The sampling efficiency was about 100%, and so was the extraction efficiency.  This is a big improvement in the extraction efficiency, and opens up the idea of using a dry filter collection system for bioaerosols.  One thing to remember, however, is that dry collection can be hard on viability.  Later on, we did some testing aerosolizing vegetative organisms and saw a drop in viability.  Of course, if you are doing a rapid identification method like PCR, effects on viability aren’t as important.
 
So, if the next thing you are going to do with the samples is concentrate them, you would be curious about the test results for the concentrators.  The testing program has gotten to be very large; so we call it “The Matrix”.  We settled on a middle-of-the road initial sample volume of 20 milliliters and a final concentration volume of 250 microliters.  You can see in slide 19 that in this range, the concentration takes a matter of minutes for each sample, allowing us to generate a lot of data quickly for comparison purposes.