AA 2921 then QF 7552 at O'Hare
Buffalo → Chicago → Los Angeles
Timetable, Chicago time
19:00AA 2921 from Buffalo at the gate
18:50QF 7552 to Los Angeles leaves the gate
23 h 50 apart on the timetable, overnight
QF 7552 leaves 23 h 50 after AA 2921 arrives on the timetable: more than half a day, so not a connection we count.