The best idea is to digest a carefully weighed amount of dried Pd/C by refluxing it in aqua regia, filtering off any remaining carbon, and then precipitate the soluble Pd2+ quantitatively.
In the following prep, they precipitate with dimethylglyoxime: http://www.cpachem.com/en/Clas/Pd-grav.htm (http://www.cpachem.com/en/Clas/Pd-grav.htm)
Maybe you could precipitate palladium black (free Pd metal) instead: https://www.thevespiary.org/rhodium/Rhodium/chemistry/pd-catalyst.faq.html (https://www.thevespiary.org/rhodium/Rhodium/chemistry/pd-catalyst.faq.html)
The precipitate is then dried in vacuo and weighed carefully (if you prepare palladium black, you need to dry it in an inert atmosphere, as the compound is pyrophoric in air).
the Pd is in the form of the finely divided metal itself. like Pt, a black powder of the element is formed by reduction. it will work great in all reactions calling for Pd powder,supported Pd or Pd sponge, as long as it hasnt been contaminated by S cpds. it is hard to beelieve it was "discarded" the value is, um, a bit higher than most scrap metals. this would be like throwing away 250000. to find out how much you have, boil in HCl and evap soln, calc Pd from wt of the PdCl2.
today is my turn in the barrel