Principles of Mass Spectrometry
Mass spectrometry (MS) is an analytical technique used
to identify and quantify the composition of a sample by
measuring the mass-to-charge ratio of ions. The
technique is widely used in various fields such as
chemistry, biology, medicine, and environmental
science.
Ionization
The first step in mass spectrometry is to convert the
sample molecules into ions. There are different
ionization techniques, such as:
1. Electrospray ionization (ESI): This method is
commonly used for large and polar molecules, such
as proteins and peptides. The sample is dissolved in
a solvent and sprayed through a narrow capillary
tube, creating a fine mist of charged droplets. The
solvent evaporates, leaving behind the charged
molecules.
2. Matrix-assisted laser desorption/ionization
(MALDI): This method is commonly used for large
and non-polar molecules, such as polymers and
biopolymers. The sample is mixed with a matrix
material and dried on a plate. The matrix absorbs
energy from a laser, causing it to explode and
ionize the sample.
Acceleration and Detection
After ionization, the ions are accelerated and focused
into a beam using an electric field. The beam is then
introduced into a mass analyzer, where the ions are
separated based on their mass-to-charge ratio. Finally,
the ions are detected and recorded using a detector.
There are different types of mass analyzers, such as:
1. Quadrupole mass analyzer: This type of analyzer
uses four parallel rods to create a quadrupolar
electric field. The ions follow a curved trajectory
Mass spectrometry (MS) is an analytical technique used
to identify and quantify the composition of a sample by
measuring the mass-to-charge ratio of ions. The
technique is widely used in various fields such as
chemistry, biology, medicine, and environmental
science.
Ionization
The first step in mass spectrometry is to convert the
sample molecules into ions. There are different
ionization techniques, such as:
1. Electrospray ionization (ESI): This method is
commonly used for large and polar molecules, such
as proteins and peptides. The sample is dissolved in
a solvent and sprayed through a narrow capillary
tube, creating a fine mist of charged droplets. The
solvent evaporates, leaving behind the charged
molecules.
2. Matrix-assisted laser desorption/ionization
(MALDI): This method is commonly used for large
and non-polar molecules, such as polymers and
biopolymers. The sample is mixed with a matrix
material and dried on a plate. The matrix absorbs
energy from a laser, causing it to explode and
ionize the sample.
Acceleration and Detection
After ionization, the ions are accelerated and focused
into a beam using an electric field. The beam is then
introduced into a mass analyzer, where the ions are
separated based on their mass-to-charge ratio. Finally,
the ions are detected and recorded using a detector.
There are different types of mass analyzers, such as:
1. Quadrupole mass analyzer: This type of analyzer
uses four parallel rods to create a quadrupolar
electric field. The ions follow a curved trajectory
