It seemed the Dutch side were set to make it a perfect six points after two rounds of games in Group L when defender Jeffrey Gouweleeuw netted the opening goal in the 81st minute.
Yet in the fourth minute added on, Greek visitors PAOK secured a 1-1 draw when Salpingidis tucked home.
Both teams had won their openers, with AZ beating Maccabi Haifa and PAOK overcoming Shakhter Karagandy, and until the breakthrough they appeared evenly matched at the AFAS Stadion.
AZ were coming into the fixture on the back of victory over PSV Eindhoven in the Eredivisie, while PAOK drew with Crete side OFI.
Alexandros Tziolis, Martinez Lucas and Stelios Kitsiou all showed purpose and rained shots on the AZ goal in the opening quarter, with a 20-yard strike from Nemanja Gudelj that Sanz Jacobo had to palm away the best the Dutch outfit managed early on.
AZ's United States international forward Aron Johansson then sent a shot the wrong side of the left post, before team-mate Esteban Alvarado kept it tight and goalless with a terrific save, using his feet to keep out Miroslav Stoch's classy 18-yard attempt.
Chances continued to flow at each end, and in the 51st minute Martinez Lucas' powerful header from a cross by Konstantinos Katsouranis shook the AZ crossbar.
Johansson also headed against the bar for PAOK, in the 71st minute, yet the opening goal, which looked to be a clinching goal, went the hosts' way.
Johann Berg Gudmundsson saw his goal-bound effort turned aside for a corner by Jacobo, and when the visiting defence failed to clear their lines a cross from Willy Overtoom picked out Gouweleeuw to bury a right-footed finish from six yards.
AZ seemed sure to hang on, only for their resistance to be broken when a cross delivered from the left by Stefanos Athanasiadis reached Salpingidis, and the Greece international striker made no mistake at the far post.