GC-MS can find all of the compounds mixed together in a sample object. The operator dissolves the sample in a liquid. The operator then injects the liquid into a stream of gas. (Helium, Hydrogen or Nitrogen gas are used most often.) The gas flows through a tube with a special coating. Because each compound in the sample sticks to the coating in a different way, each compound comes out of the tube at a different time. So the coating is used to separate each compound that was mixed together in the sample. As each compound comes out at the end of the tube, it is ionized and gets an electric charge. Most compounds break apart when they are ionized. The different pieces fly under a magnet which separates the pieces based on their weight and charge. A computer then measures all of the pieces of each compound. By comparing the measurements against a computer library of known compounds, the computer makes a list of the names of all of the compounds in the sample. The computer can also tell how much of each compound was in the sample.