https://wowwiki.fandom.com/wiki/API_GetItemQualityColor
Try
/run local q;if MerchantFrame:IsVisible()then for i=1,300 do q=GetContainerItemLink(i/35,i%35)if (q and (q:sub(5,10)=="a335ee" or q:sub(5,10)=="0070dd")) then UseContainerItem(i/35,i%35)end;end;end