The quantum mechanical effects in the double slit experiment was first demonstrated with photons, then also with electrons, then with atoms, then more recently with molecules having up to 114 atoms. http://www.livescience.com/19268-quantum-double-slit-experiment-largest-molecules.html
Without using Bose-Einstein condensates where we have quantum effects at the macro scale close to absolute zero temperature, how large can the mass of the particles being tested be theoretically before the quantum effect wave like interference patterns disappear and the results revert back to classical physics for the double slit experiment?
I know this is inversely proportional to level of quantum de-coherence which increases with temperature. This is for standard temperature.