> If you have access to distilled water that you have excellent reason to believe is free from what you're detecting

  > we don't have access to animal flesh guaranteed to be free of microplastics, do we?

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.

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

Just so you know, the tone of your comment is extremely off-putting.

I don't have the slightest idea why you're rudely telling me "don't make assumptions", especially if you don't have additional information to add. And the suggestion to "pursue a PhD in the domain" if I want answers is exceedingly obnoxious.

If you don't have helpful answers, you don't need to leave a comment. You don't need to say that you don't have answers but add a bunch of rude sentences while you do it. Better to just not reply at all.