rq info 72 visa waiver

Dear all
this is my itinerary:
QR 132 26MAR ROME-DOHA 1640 2310
QR 874 27MAR DOHA- GUANGZHOU 0255 1530
CZ3039 30MAR GUANGZHOU - SINGAPORE 1300 1650
QR 947 30MAR SINGAPORE - DOHA 2120 0015+1
QR 115 31MAR DOHA - ROME 0135 0655
I will stay at Guangzhou less than 72 hours but is not clear if is necessary to make a stop over more than 1 day in a third country (Singapore) or if is sufficient to make a transif of few hours to obtain the 72visa waiver.
Best regards
Cinzia