I think your going to be looking a long time as there is no platinum in caps. only palladium and silver for PM's. http://www.goldnscrap.com/index.php?option=com_content&view=article&id=62:re covering-palladium-and-silver-from-monolithic-ceramic-capacitors&catid=38thers&Itemid=50
http://www.goldnscrap.com/index.php?option=com_content&view=article&id=69:re covering-palladium-and-silver-from-ceramic-monolithic-capacitor-part-2&catid=38thers&Itemid=50