Link to where it says they were randomly purchased?
Or do you mean anonymously purchased?
The only thing I recall seeing in print from the source is:
"
The liquids and flavorings tested are extremely popular..."
https://www.indiegogo.com/projects/...is-evaluating-potentially-harmful-ingredients
This, at least to me, says to me that the particular samples were not random -- but in fact, intentional, based on popularity..
What that popularity means, who knows.. Are popular juices more popular than others, perhaps at least in part
because their consumers prefer the taste of diacetyl? One could argue that there's a flaw in the study right there, depending on how its worded...
I've also heard or read, and I wish I could recall the source, that the samples were actually purchased based on what the doc & his team
suspected that they contained diacetyl (targeting custard-flavored juices, in particular?).. Again, doesn't sound exactly random (or un-flawed) to me..
But, who knows the veracity of that claim, to begin with...