The second inquiry into a cobalt irregularity in a Queensland racehorse is set down for hearing on Wednesday.

Atherton trainer Glen Baker has been ordered to attend the inquiry at Racing Queensland's Deagon headquarters.

Baker's horse French Lesson won at Doomben on January 31.

The inquiry is the first in Queensland for a horse found to have an irregularity since the introduction of a national cobalt threshold at the beginning of this year.

Chief steward Allan Reardon said Baker had been notified the cobalt level in French Lesson had been confirmed at well above the threshold of 200 mcg per litre of urine.

Stewards last week adjourned an inquiry into high cobalt levels found in Vandalised following his Rockhampton Cup win in June, 2014.

Matt Tutt, counsel for Vandalised's trainer Jamie McConachy, asked for time to get a second opinion on how legal food supplements can impact cobalt levels in horses.

That inquiry is set to resume on May 20.

NSW trainer Darren Smith has been disqualified for 15 years after admitting to injecting horses with an unregistered product containing cobalt.