word choice - Do we use "which" or "that" when referring to the preceding main clause as a whole?

Sorry, I don't think I can use all the grammatical terms right, so I'll illustrate:

Peptide
adsorption curves may cross [...] results in the inversion of peptide
elution order.

I've found a lot about "which" and "that" in this question, and it says that generally those are interchangeable, but I haven't seen this particular use case mentioned there. (After writing this it occurred to me that the linked question discusses "which" and "that" as conjunctions, whereas this question is about them as relative pronouns. I got this from this answer. Correct me if I'm wrong) The only thing that might be applicable is the "rule of thumb" that

"Commas, which cut out the fat, go with which, never with that."

On this basis, "which" should be the only correct option, because that gap needs a comma. Is that so?

Answer

Which is the correct relative pronoun you should use in your sentence, because you have a main clause ("Peptide adsorption curves may cross"), followed by a non defining, or non restrictive, relative clause that gives additional information or, as per your example, the consequence of what has been mentioned before.

I had never heard of the so called "rule of thumb", but I like it and I'll try to pass it on to others in order to try and sort out this kind of difficulty.