APA citation of a published interview
According to the APA guidance on handling interviews, if it is an interview not done by you found in a standard source (book chapter, in your case) then you follow the normal formatting for that source (book chapter if you are summarizing the whole interview; book as a whole if you are taking quotes from the interview with matching citation in-text that denotes speaker of quote).  

With regards to the book chapter formatting in this case involving multiple people (interviewer, interviewee, etc.), the APA style blog has all the details on how to capture all of the different authors in the case of a book chapter.  Most of these details apply to the idea of multiple "authors" in the book.  Interviewees wouldn't be classified as authors (i.e., they aren't listed in the front matter of the book as authors), so you don't need to worry about that in this case.

For your specific case, I would do the reference as the whole book, not individual chapters, and not listing the authors as editors as they are credited as writing the whole book in its front matter, and not listing the names of the interviewees in the reference itself (as explained in the APA guidance links):


  Dolphijn, R., &amp; Tuin, I. van der. (2012). New materialism: Interviews &amp; cartographies (1st ed.). Ann Arbor, MI: Open Humanities Press.


Then, I would do the in-text citations in a manner that highlights the speaker of the quotes and the location in the book:


  As stated by Rosi Braidotti, "[insert quote from interview here]" (Dolphijn &amp; Tuin, 2012, Chapter 1, p. [insert single page number of quote]).


When you are quoting the authors of the book, not the interviewee, the in-text citation should just be:


  "[insert quote from authors here]" (Dolphijn &amp; Tuin, 2012, p. [insert single page number of quote]).


In this manner, you keep your reference style consistent with the standard APA book reference style and you clarify the speaker of each quote using the in-text citation, which is the recommended APA method.  You don't want to cite the whole chapter in either case because the result would not specify the specific page where the quote was found.  You would only cite the whole chapter if you were summarizing the chapter's insights as a whole.