I took some gold foils from a mix of gold plated pins, washed the foils real good, then done AR with the foils, I added to much nitric and now I have gold particles in suspension, usually I can evaporate it down and redo and all is good, but this time I evaporated it down and the solution was like syrup - I added HCL, then 1mil drops on nitric, I felt like there could not have been more than 4g of gold, but anyways I did a stannous test after each 1ml increment of nitric up to the final increment of 4 mil of nitric, the gold refused to go into solution, is it possible that the colloidal gold particles is covered with another metal that is preventing the nitric acid to do the job, I tried some sulfuric also in the solution in case of any Metastannic acid, either way, nothing is working and still have colloidal gold particles in solution, any one have some ideas or advice ?