After the 50-year-old Hall of Famer finished her round and was told of the disqualification, Inkster passed quickly by autograph seekers and reporters without comment. She quickly left in a course shuttle.
It was heartbreaking for Inkster, who shot a 67 and was 8 under after the first two rounds. She was in a group just three strokes behind leader Ai Miyazato.
Inkster, who had a 30 minute wait on No. 10's tee, apparently used a "doughnut" weight on her 9-iron to stay loose.
LPGA Director of Tournament Competitions Sue Witters said a viewer noticed the device from the television broadcast of the event and contacted tournament officials.
Inkster was already on the 17th hole of the course at Pumpkin Ridge when officials determined she had indeed used the device. She was told when she came off the course after the final hole, Witters said.
Witters said Inkster was surprised and unaware she had broken the rule.
"The rules staff here made the decision on the rule and we took it one step further and called the USGA," Witters said. "We would have loved to have some wiggle room on that. But it's pretty cut and dried.
"Being the professional she is, there wasn't much to say once the decision was read."
Inkster issued a brief statement.
"I had a 30-minute wait and I needed to loosen up," she said. "It had no effect on my game whatsoever, but it is what it is. I'm very disappointed."
