A good point and thank you, though that's not what I'm actually trying to clean - I have a bad habit of walking away and forgetting the tests for a while and after years of use I have a number of tubes with colored residue from the test chemicals inside ... a very small pipe cleaner gets most of it but not the very end and it bugs me!! II' prolly gonna try something like a bit of sponge stuck on something but I just wondered if someone had found, I dunno, a baby's nose cleaning gidget or obscure cooking utensil #325 that just happened to be perfect for the jobbitseriously said:Running water, air dry.
Imagine there is, say, nitrate in your tap water, at (let’s go relatively high) 40 ppm. That nitrate could contaminate your next sample in that vial, but at literally 100ths of the concentration of what you’re measuring. So 20ppm in your next test might be 20.25ppm due to the contamination. Negligible and irrelevant, IMO.