Trainer Sam Kavanagh will front a NSW stewards inquiry over positive results to caffeine and cobalt returned by Gosford Cup winner Midsummer Sun.

Samples taken from the gelding after his Gosford Cup win on January 9 showed the presence of caffeine and a higher than allowed level of cobalt.

Midsummer Sun subsequently died after suffering a catastrophic leg injury in a barrier trial.

Newcastle trainer Darren Smith has been found guilty of more than 40 charges relating to cobalt administered before the 200mcg threshold was introduced in NSW in January.

Chief steward Ray Murrihy said investigations into the Kavanagh samples were continuing and certain products had been taken away from his Rosehill stable for further analysis.

He said the inquiry would not be held until after those results were known.

Smith will find out his fate at a penalty hearing on Friday week.

Victorian trainers Peter Moody, Mark Kavanagh, Danny O'Brien and the Lee and Shannon Hope partnership are also under investigation for high cobalt levels found in horses from their stables.

Two as yet unnamed Queensland trainers have also had horses return illegal levels of cobalt.

The substance alters a horse's blood pattern and can be toxic in high doses.