Grammar, Usage / Correct Usage of "Rolls" in a sentence [3]

Hi, I'm preparing a statement of purpose for graduate school.

I'm trying to explain my work experience at a research lab. Here's how I put it:

"I was put on rolls at the materials mixing lab, composition analysis division and testing lab of Dupont, where..."

I mean to say that I was asked to work on those 3 labs before I was permanently deployed to a specific lab.

How should I put it? Is the usage correct? Clear?