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Bob,
If you are referring to the standard SMA, which is what I think you are
referring to, the tubing is after the point where the sample is being
recovered and has no effect on the viable count.
If you are using an SMA with the Remote Sampling Top, I agree with what
Jim
Agalloco said, sampling through a tube can reduce the recovery of viable
organisms. Whether you are using our remote SMA, like Ed White
suggested, or an STA unit with a remote sampling tube, like Gary Schmitt
suggested, both are still sampling the tube and both run the risk of loss
within the tube.
Sometimes it is necessary to utilize air samplers in this way but it is
important to keep the tubing length to a minimum.
Tobias originally asked about sampling at the beginning, middle and end of
a production run and he had concern about operators introducing viable
particulates while taking samples. Using a remote sampling tube will
remove the operator from the area but it also removes the "point of
recovery". As
Jim stated, accuracy can be compromised using this method.
To keep the recovery point in the critical area, we have tried to reduce
the possibility of the sampler itself being an added risk of contamination.
By making our SMA autoclavable, this should eliminate atleast one of the
concerns because you are intruducing a sterile sampler into your sterile
area.
Let me offer another suggestion to reduce possible operator
contamination.
We do have some companies that are concerned with sampling during
the entire production run and are equally concerned with operator
contamination from changing recovery media. To reduce the frequency of
operator interaction in the critical area, these companies are using a
modified version of the standard SMA that permits them to take 3 hour
(180 cfm) samples on one 100mm plate.
If your objective is to sample at all stages of the run while keeping
operator interaction to a minimum, then sampling this way can reduce
possible operator contamination. Accurate results are still maintained,
because the point of recovery remains at the point of sample.
If anyone would like more info on what is available, please let me know.
Jeff Churchvara (jeffc@pond.com)
Veltek Associates, Inc.
Exton, PA
610-363-6028
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>I wonder whether a lengthy sampling tube will provide any recovery of
>organisms from a Class 100 area. I have seen unpublished data that
>suggests that even a 15 foot [5 meter] tube reduced the count by over
>90%. Before using a sampling tube of this length, I strongly recommend
a
>validation study.
>
>Jim Agalloco JAgalloc0@aol.com
>Re: CLASS 100 MONITORING FREQUENCY
>