NSAC Executive Director Keith Kizer confirmed the negative tests to MMAFrenzy.com on Monday afternoon.
The tested fighters were George Roop, Yoshiyuki Yoshida, Krzysztof Soszynski, Kyle Bradley, Brock Larson, Frankie Edgar, Chael Sonnen, Matt Hughes, Rashad Evans, and Lyoto Machida.
UFC 98 took place on Saturday, May 23, at the MGM Grand Garden Arena in Las Vegas and featured Machida scoring a second-round knockout of Evans in the pay-per-view headliner to capture the UFC light heavyweight title.
For complete UFC 98 results and news click here.
[Pictured: Lyoto Machida]