The sources part of an APA reference list are only those that are traceable, and can be used by others. Because a personal interview does not constitute recoverable data, it should not be included in an APA reference list. Instead a personal interview should be referenced as a parenthetical citation. For example: (J. Smith, personal communication, May 17, 2008).
If you would like to include a personal interview as part of your APA reference list, then include the interviewee, the date of the interview, and the type of interview. See the fictional examples below:
Personal interview by phone
Soriano, A. (2008, April 5). Telephone interview.
Personal interview by email
Soriano, A. (2008, April 5). Email interview.
Personal interview in person
Soriano, A. (2008, April 5). Personal interview.
Personal interview overheard and conducted by a third party
Soriano, A. (2008, April 5). Personal interview with K. Walter & J. Smith.