6 ms·

Here's a very naïve example to help illustrate how you can do a "blank" (a control). Say you're testing a sample of water in a test tube. Repeat all steps in e

Here's a very naïve example to help illustrate how you can do a "blank" (a control). Say you're testing a sample of water in a test tube. Repeat all steps in exactly the same way, but use distilled water. You can even do all the steps and use no water! (Including having an empty container and pouring nothing from the empty container into the test tube). By doing things like this you create samples that allow you to look for contamination. How do you know that the thing you're testing has microplastics? (Or whatever) because it has more than the blanks/controls. That's it. Congrats, you've isolated a variable in your experiment. Btw, this is pretty common practice. In fact! Here's a video of someone doing exactly that "nothing" control looking for microplastics. Those steps are done at 10:20. https://youtube.com/watch?v=oDDQjEpuFfQ https://youtube.com/watch?v=oDDQjEpuFfQ

vel0city 7mo ago
> Repeat all steps in exactly the same way, but use distilled water. But how do you know your source of distilled water isn't also contaminated?
- godelski 7mo ago
  You continue reading the comment and use the other version of a blank
  - vel0city 7mo ago
    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?
    - godelski 7mo ago
      I gave the second example to try to avoid this type of response. It's not that hard to grasp. You don't need some fluid
      - vel0city 7mo ago
        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.
        godelski 7mo ago
        > 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
        vel0city 7mo ago
        > 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.
- mattkrause 7mo ago
  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.
  - deleted 7mo ago
    [deleted]
  - vel0city 7mo ago
    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.
    - godelski 7mo ago
      > 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
      - vel0city 7mo ago
        I don't think I'm the one confused, as I'm not saying things like: > On the other hand, if you found (say) 101 particles/unit in a sample of B, you'd conclude B doesn't do that I'm fully aware of null hypothesis testing.
deleted 7mo ago
[deleted]
crazygringo 7mo ago
> Repeat all steps in exactly the same way, but use distilled water. You can even do all the steps and use no water! This is where I get lost. Maybe I don't understand what a blank is. If you have access to distilled water that you have excellent reason to believe is free from what you're detecting, then great. But my point is we don't have access to animal flesh guaranteed to be free of microplastics, do we? Because they're everywhere in the environment. And if you use no water at all, it seems like you're missing the entire vector of contamination from acquiring and transporting the water. E.g. if the water container is producing contamination, then your blank of no water isn't revealing the source of contamination! The blank isn't helping at all. I don't have any issue with the concept of a blank sample when they're feasible. My issue is, I don't see how you can produce a blank sample of animal tissue without microplastics specifically because microplastics are everywhere in nature, and I don't see how a slide with zero animal tissue at all is a useful blank.
- BlarfMcFlarf 7mo ago
  It doesn’t have to be an identical material, just one that has similar properties in attracting and holding contaminants.
  - crazygringo 7mo ago
    So if you're studying slices of e.g. brain to look for microplastic particles, what would be a material with similar properties, that you would then go through the same steps of preserving, preparing, slicing, mounting, etc.? I'm genuinely curious. Are there standard widely used stand-in materials for animal flesh, for plant materials, etc.?
- godelski 7mo ago
  > If you have access to distilled water that you have excellent reason to believe is free from what you're detecting Don't make assumptions. > we don't have access to animal flesh guaranteed to be free of microplastics, do we? Don't make assumptions. These two assumptions could potentially be at odds. > And if you use no water at all, it seems like you're missing the entire vector of contamination from acquiring and transporting the water. Don't use water? Use another liquid that doesn't interact the same way. I gave examples, they are clearly non-exhaustive. I don't have an answer for you for the exact process but I'm also not a scientist working on these experiments. But the people who are doing the experiments are. They know the answers to these questions. A lot of it is going to be detailed in the papers but some won't be because it's more common knowledge among the niche, but you'd likely learn it if you pursued a PhD in the domain

vel0city 7mo ago

> Repeat all steps in exactly the same way, but use distilled water. But how do you know your source of distilled water isn't also contaminated?

godelski 7mo ago
You continue reading the comment and use the other version of a blank
- vel0city 7mo ago
  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?
  - godelski 7mo ago
    I gave the second example to try to avoid this type of response. It's not that hard to grasp. You don't need some fluid
    - vel0city 7mo ago
      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.
      - godelski 7mo ago
        > 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
        vel0city 7mo ago
        > 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.
mattkrause 7mo ago
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.
- deleted 7mo ago
  [deleted]
- vel0city 7mo ago
  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.
  - godelski 7mo ago
    > 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
    - vel0city 7mo ago
      I don't think I'm the one confused, as I'm not saying things like: > On the other hand, if you found (say) 101 particles/unit in a sample of B, you'd conclude B doesn't do that I'm fully aware of null hypothesis testing.

deleted 7mo ago

[deleted]

crazygringo 7mo ago

> Repeat all steps in exactly the same way, but use distilled water. You can even do all the steps and use no water! This is where I get lost. Maybe I don't understand what a blank is. If you have access to distilled water that you have excellent reason to believe is free from what you're detecting, then great. But my point is we don't have access to animal flesh guaranteed to be free of microplastics, do we? Because they're everywhere in the environment. And if you use no water at all, it seems like you're missing the entire vector of contamination from acquiring and transporting the water. E.g. if the water container is producing contamination, then your blank of no water isn't revealing the source of contamination! The blank isn't helping at all. I don't have any issue with the concept of a blank sample when they're feasible. My issue is, I don't see how you can produce a blank sample of animal tissue without microplastics specifically because microplastics are everywhere in nature, and I don't see how a slide with zero animal tissue at all is a useful blank.

BlarfMcFlarf 7mo ago
It doesn’t have to be an identical material, just one that has similar properties in attracting and holding contaminants.
- crazygringo 7mo ago
  So if you're studying slices of e.g. brain to look for microplastic particles, what would be a material with similar properties, that you would then go through the same steps of preserving, preparing, slicing, mounting, etc.? I'm genuinely curious. Are there standard widely used stand-in materials for animal flesh, for plant materials, etc.?
godelski 7mo ago
> If you have access to distilled water that you have excellent reason to believe is free from what you're detecting Don't make assumptions. > we don't have access to animal flesh guaranteed to be free of microplastics, do we? Don't make assumptions. These two assumptions could potentially be at odds. > And if you use no water at all, it seems like you're missing the entire vector of contamination from acquiring and transporting the water. Don't use water? Use another liquid that doesn't interact the same way. I gave examples, they are clearly non-exhaustive. I don't have an answer for you for the exact process but I'm also not a scientist working on these experiments. But the people who are doing the experiments are. They know the answers to these questions. A lot of it is going to be detailed in the papers but some won't be because it's more common knowledge among the niche, but you'd likely learn it if you pursued a PhD in the domain