Refrigirator Off for months, and I want to sell it?

I moved flats and moved my refrigerator with me. It has been turned off for ten months now! It used to work very efficiently but now I wonder if having turned it off for so long affects the cooling gas, as some friends suggested. It it neatly wrapped with bubble wrap and I want to sell it and advertise that it is working properly but wondering if this gas may have leaked/evaporated/etc.?