I have some pathological wax blocks that I would like to study on protein modification, does anyone know that pathological wax blocks can be used as samples for mass spectrometry ,and which technology do I need to use
Yes, the use of formalin-fixed, paraffin embedded tissue for MS is standard practice. It is advisable to keep fixation time as short as possible, if you can influence that. Perfusion fixing is, of course, ideal. With archival samples you have to take what you can get. For recent reviews, check for example doi:10.1002/pmic.201300311, doi:10.2144/000114414 or for nucleic acids doi:10.3390/toxics6020030.