The point is that blank lets you measure that level of "background" contamination, which you then use to correct the measurements made on actual samples.
Suppose you measure around 100 plastic particles per unit in your blank and 1000 in a sample of A. This suggests that A enriches (sheds, etc) microplastic particles. On the other hand, if you found (say) 101 particles/unit in a sample of B, you'd conclude B doesn't do that.
But in your example you still don't know if it was your testing process that shed 100 plastic particles or if your distilling process shed 100 plastic particles, meaning you don't actually know if B was or was not the source of the plastic particles. Was it your testing process that introduced those 100 particles, was it the distilling process that introduced them, 50/50, or something else?
B would be inconclusive against what you'd hope to be some kind of background, as its not significantly more but one couldn't conclude the source didn't shed that 100 because you don't actually know if in the blank the 100 particles of contamination was definitely your testing process or the source material genuinely having 100 particles of contamination.
I do agree though, in the A case one could pretty easily conclude whatever generated that sample is adding way more particles than an attempt at a baseline/background.
> B would be inconclusive against what you'd hope to be some kind of background
Correct. And this is why scientists use null hypothesis testing. You disprove things in science, not prove them. I think that's why you're confused. In the first situation you disproved that it comes from the background
I interpreted that sentence as more casual language. Maybe I'm wrong to assume that. But I didn't write it either.
Either way, the difference didn't matter to answer your question. Them getting that part wrong doesn't make the other part wrong nor hard to understand.
So why even bother mentioning the distilled water? And if you're testing an aqueous process don't you pretty much need some fluid to put through the process?
So then maybe don't give the first if you know its a flawed example? Its not that hard to grasp.
> You don't need some fluid
Entirely depends on your testing procedure, and not something always true. Like in the video you posted he pretty much needs to have some kind of fluid through the process. Otherwise, he'd be missing out on contamination in the process of artificial mastication, running through the filtration process, etc. Sure, examine a dry and plain filter as well to see what the filters look like and ensure they're not just completely covered in particles as well, but you're then missing out testing quite a lot of the rest of the process.
> So then maybe don't give the first if you know its a flawed example?
It's not a flawed example. As you can understand from the other poster talking about baselines.
> Its not that hard to grasp.
I agree!
> Like in the video you posted he pretty much needs to have some kind of fluid through the process.
And it looks like you're understanding too!
But if he used a different process he could have used it dry. There's a lot of ways to skin a cat. Different ways create different constraints.
So I'm confused here, did you just want to argue or did you actually want to understand? Because at this point it seems like you understand. And frankly, I don't want to argue
Sure seems like you do with all your passive aggressive takes of asserting I'm confused or can't read or can't understand things and that I lack understanding the most basic scientific concepts like null hypothesis testing.
My question was simply:
> But how do you know your source of distilled water isn't also contaminated?
You could have just replied with "you don't, and it doesn't always matter depending on the questions being asked and the processes being used" but instead you've drawn it out to this many comments.
Instead you chose to say "you read the rest of my comment" instead of actually answering my question and then talk down to me over and over.
Some of the other comments seemed to be acting like running a blank is a fool proof way to just make sure you get a clean answer, and my point was to show there are still limits to "just run a blank". And that's shown by the sibling thread here with the other poster thinking if your blank has 100 particles and your test sample having 101 that means the test process obviously introduced the particles, which is a flawed understanding of the results of the test. The results are inconclusive, it did not prove the sample contained no particles to start.
But how do you know your source of distilled water isn't also contaminated?