http://www.heinz.com/glutenfree/products.html
Heinz ketchup is gluten free. I don’t know what you are talking about with McDonald’s ketchup.
The things you don’t know eh ~ it’s packed by Heinz!
Here's the deal ~ McDonalds uses a lot of artificial and "natural" flavor enhancers. Those are listed as Natural Beef Flavor or Artificial Beef Flavor. The "artificial" item has wheat. The "beef" may have wheat.
Their site showing details on micro ingredients is not working this evening ~ but just a couple of weeks ago it was up and showing "stuff", so maybe it's down for adjustment. They warn you about that ~ there are NO guarantees that there are gluten free products at McDonald's ~ and there are NO guarantees that there are beef free products at McDonald's so beware.
I usually know within 1/2 hour if they've changed something previously gluten free into its poisonous counterpart!