Dunkin Donuts' coffee Coolatta contains the following amounts of caffeine: 16 fl oz (16mg); 24 fl oz (23mg); 32 fl oz (35mg).
Dunkin Donuts recently reformulated their brewed coffee offerings to a much higher caffeinated version. Compare their new caffeine amounts with their old in the side table (courtesy of CaffeineInformer.com).
For more info, contact Dunkin Donuts or call their Consumer Care at 800-859-5339 (7AM - 7PM EST Monday - Friday).
You can also get in touch via their Twitter and Facebook channels.
Caffeine contents of some of the most popular beverages marketed today can be viewed here.