It’s worth pointing out that it is extremely difficult to contact users on Twitter without an existing relationship. If your account isn’t followed by a user, the best you can do is @ mention him. I worked with a research team that reached out to some Twitter users to participate in a study. The response rate: 0%.
Twitter’s Developer Policies for Researchers, Archivists, and Librarians
Justin Littman

It’s more complicated but not impossible. For example, Meredith Clark does research that puts her in direct contact with Twitter users. There are others.