Originally Posted by
Loren Pechtel
It's not going to cause a false positive--if it didn't detect once it won't detect the next time.
It could pass other contamination, though.
Reusing a test strip, just like re-using hand and shoe swabs, can cause a false positive.
Let's say item one is swabbed with a swab and does not alarm. Then the same swab is used for swabbing a different item from another pax and it also does not alarm but when using the same swab for a third item from third pax, the combination of the residue from both the first and second swabs with the residue of the third item sets off the alarm. It's basic chemistry where A is good, B is good and C is good along with combining A & B but when you combine A, B AND C, you have a problem