alt Hacker NewsHere'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.
Replies
> 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?
> 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.