How a Mass Spectrometer Works

How a mass spectrometer works

Mass spectrometer works on the technique of mass spectrometry in which basic composition of an element or molecule could be calculated. In order to understand the basic working principle of a mass spectrometer we need to understand the process an element of molecule undergoes when it is fired into a mass spectrometer to the time it is recorded into the detector. When a molecule is loaded onto a Mass Spectrometer instrument, the molecule under goes the process listed below:

As the gas molecules are placed inside the mass spectrometer, the elements first enters the ionization chamber in which the molecule is converted into positive ions as the mass spectrometer only deals with positive ions and by the help of the metal plates, the positive ions are passed further into the instrument by a metal placed known as the ion repeller plate.

The positive ions leave the ionization chamber having a high charge and therefore by the help of metal plates, all positive ions are accelerated to have same amount of kinetic energy. And, be accelerated into a single beam onto the magnetic field.

After the ions are accelerated by the metal plates, the ions are subjected to a magnetic field placed at angle inside the mass spectrometer instrument. The amount of deflection mainly determines the element as it is being recorded as the deflection occurs on the phenomena of the mass/charge ratio. According to mass/charge ratio, the ion with a higher charge and a lesser mass are deflected more rather than ions with a lower charge and a higher mass.

After the ions are deflected by the magnetic field, the ions passing through the slit are recorded into the detector while other ions hit the walls and get neutralized by reacting with electrons and these ions can be removed from the instrument by the help of a vacuum pump. Even though only one flow of ions is being detected while other ions are hitting the metal surface. Therefore, in order to detect the other ions in the element the magnetic field should increase to deflect the remaining ions in the element into the detector.

Moreover, the ions detected at the recorder give us a chart relating the amount of relative abundance with the mass/charge ratio from which we analyze the composition of the molecule or element being fired into the mass spectrometer.