Diet Coke Plus Caffeine Report
Harv asked about caffeine in the new Diet Coke Plus. My initial reaction was, "Don't know", but thinking about it more, perhaps the label can give us some clues. The first clue is the list of ingredients - Caffeine is after Acesulfame Potassium (an artificial sweetener) and before Zinc Gluconate. This should be enough to do a back-of-the-envelope calculation of the the upper and lower levels of Caffeine, since ingredients are supposed to be listed by descending amount.
The lower bound is easy - the second clue on the label is that there is 15% of the daily recommended value (RV) of Zinc in one 12 oz bottle. A quick Google search found the RV for Zinc to be 8-11 mg. Picking 10 mg, 15% of that is 1.5 mg. Using the mole ratio of Zinc Gluconate to Zinc (455.685/65.39), the amount of Zinc Gluconate in the 12 oz bottle is about 10.5 mg.
The upper bound is a bit more tricky, but at this site, discussing safe levels of Acesulfame Potassium consumption, it states that there's 900 mg of Acesulfame Potassium in roughly two gallons of beverage. This works out to be about 42 mg in a 12 oz bottle (12 oz/256 oz (two gallons) x 900 mg).
So the amount of Caffeine is between 10 and 42 mg. Looking at a table of Caffeine content, this looks like it should be in the ballpark - Diet Coke has about 46 mg, Coke Classic has 34 mg.
So Diet Coke Plus probably has a similar amount of Caffeine that 'normal' Diet Coke has.