Separating gold, platinum and palladium

I've dissolved all 3 metals together in aqua regia due to them being mixed together as $\ce{Pt}$ black, $\ce{Pd}$ black and gold. I isolated the gold with no problem using sodium metabisulfate, but I am struggling to separate the $\ce{Pt}$ and $\ce{Pd}$. Any suggestions? I have tried sodium chlorate for palladium isolation and ammonium chloride for platinum isolation, none had worked for some reason. Any tips would be amazing.


