Abstract: An easy-to-plug-in inlet is presented for various commercial mass spectrometers which enables ready and simple plugging into the mass detector thereby removing pollutants or a blockage of the entrance orifice by substances, restoring sensitivity and selectivity of the mass detection within minutes, and greatly reducing the time of standstill and of the costs. The easy-to-plug-in inlet can easily be adapted to the various mass spectrometers. In its simplest form the original entrance orifice of the mass spectrometer is enlarged and a tube is plugged in with a central bore of the very same diameter as the original orifice.