Mass spectrometry is an analytical technique used to identify unknown compounds, quantify known materials, and elucidate molecular structures. It works by generating ions from a sample, separating them based on mass-to-charge ratio, and detecting the relative abundance of each ion. A mass spectrometer contains several main components: a vacuum system to reduce collisions between ions and gas molecules; an ion source to convert the sample into ions; an analyzer that separates ions by mass; and a detector that records ion abundances. Common analyzers include magnetic and quadrupole devices, while detectors frequently employ electron multipliers or Faraday cups. Mass spectrometry has a variety of applications including proteomics, space exploration, medical diagnosis, and isotopic analysis.

1. Mass Spectrometry Instrumentation
Introduction and basic principle
Mass spectrometry is a powerful analytical technique that is used to identify unknown
compounds, to quantify known materials and to elucidate the structure and chemical
properties of molecules. A mass spectrometer generates multiple ions from the sample by
the bombardment of a beam of energetic electrons, it then separates them according to
their specific mass-to-charge ratio (m/z), and then records the relative abundance of each
ion.
Main components of instrument
.
Vacuum system
 BS Chemistry
 Bushra (02), Anam (20)
 Msc Chemistry
 Aleesha (4), Rabia (14), Sundas (18), Amna (23).
Presented By:
• Introduce sample into ion source
• Covert substance into ions
• Separation of ion according to mass
• Detection of ions
Sample inlet system
• All the types sample analyzes (liquid, solid, gas).
• Small amount of sample introduce.
• Samples are introduce by direct probes inlets (for solid
and thermally unstable sample), chromatographic inlets
(for mixtures) and batch inlet system for liquid and
gaseous sample that volatile.
• Sample must be in the vapour phase prior to ionization.
• Pressure inside the mass spectrometer kept low. Chromatographic inletsProbes inlets
Key steps of process
• Electron impact ionization is the most common type of ionization in which beam of electrons
passes by heated filament through the gas-phase sample.
• An electron that collides with a neutral analyte molecule can knock off another electron, resulting
in a positively charged ion.
• The ionization potential is the electron energy that will produce a molecular ion.
• Most mass spectrometers use electrons with an energy of 70 electron volts (eV) for EI.
• The energy used to produce these ions is controllable which is practically an advantage
Ionization chamber:
Ionization Acceleration Deflection Detection
Sample
inlet
Ion
source
Analyzer Detector
Detectors/ion collectors:
For the detection of mass spectrometry different detectors are used;
 Electron multiplier
 Faraday cups
 Ion-to-photon
 Microchannel plate
• The most common detector for mass spectrometry is Faraday cup.
• Faraday cup is metal cup designed to catch particles in vacuum.
• Resulting current is used to determine no of ions or electrons hitting the cup.
Applications of mass spectroscopy :
• Used for characterization and sequencing of proteins(Proteomics).
• Used in space to measure composition of plasmas.
• Used as respired gas monitor for patients.
• Preparative mass spectroscopy(m/z).
• Used for the determination of isotopic abundance(IR-MS).
• Used to locate individual atom (Atom probe).
Analyzer:
• In mass spectrometer, different types of analyzers are used but the most common is magnetic analyzer.
• The analyzer is evacuated (about 10-7 torr) curved metallic tube placed between the poles of electromagnet
with magnetic field perpendicular to it.
• The magnetic field causes the ionic beam to issume curved path.
• Here ions are separated on the basis of m/z value.
• The ions with higher m/z values follow the path of larger radius.
• The ions with low m/z values follow the path of smaller radius.
.
All mass spectrometers need a vaccum to allow ions to reach the detector without colliding with
other gaseous molecules or atoms. If such collision did occur, the instrument would suffer from
reduced resolution and sensitivity. 102 to 105 Pa ( 10-4 to 10-7)
Sample
Presented to Ma’am Ayesha