Sorry, it seems the link didn't appear. Here it is again.
http://edis.ifas.ufl.edu/pp259rry

Here is a link that might be useful: TPLD

hers has most likely a nutrient problem and the purple leaf tomatoes are in florida. you are in zone 6 so i dont think you are close enough to miami.

TPLD is rare, a commercial grower problem, and currently only documented in Dade and a couple of surrounding counties in Florida according to what little literature there is on it. Are you in So. Florida?

It's cause is currently unknown but the best guess is viral so contagion odds are slim to none. Research seems to be focusing on a soil problem trigger. TPLD takes leaves and plants down quickly, P deficiency does not. How old is this plant?

Whatever the problem with here plant - 1000x more likely to just be phosphorus deficiency - it needs help. She should consult her local county AG extension office.

Dave

Thank you all. Its only one plant so she is not as worried as I am. I gave it a shot of tomato tone to see if that helps. I saw that it was a Miami area issue but got nervous because of the "big box store" connection.
Thanks again.
Karen

Purpling can occur with some viral disorders. Usually bronzing is seen with it (that is why in the UF page it mentions no bronzing is seen).

I wonder if TPLD is a response to higher light or UV levels due to changes in the atmosphere. With the "atv" plants, whose foliage will be purple in the right conditions, the purpling from increased anthocyanin acts as a "sun block" from high light levels. Same with Aft fruits. And that seems odd since dark colors attract more heat. Also these atv and Aft types will be green in shaded areas. But this makes me wonder if the TPLD is such a response. I don't know - just pondering out loud.