Hi, Arlene. I gave some effort to an answer to this. It seems like it should be possible, but I'm not sure and have never done it. I fooled around trying and then made a swatch with one row of purl in a contrast color in a field of stockinette stitch of another color. I also made a sample of all one color with a row of purl in it. What I learned is that in one color the purl row has bumps rather like this "nununu"--some going up and some going down but of course all in one color, so that it looks like what we think of as one row of purl on a field of St st. But when I did the purl row in a contrast color the little "u" parts were purple and the the "n" parts were my background color. How to get both bumps in one color with needle and yarn is a puzzler. It may be possible. But maybe not for me.
Have you tried a Google search? Good luck.