LCMS:
Liquid Chromatography Mass Spectrometry (LC-MS) is a technique having the separation power of
HPLC and the detection power of mass spectrometry.
Liquid chromatography mass spectrometry is an analytical
chemistry technique that combines the physical separation capabilities of
Liquid chromatography (HPLC) with the mass analysis capabilities of as
spectrometry.
LC MS is powerful technique used for many applications which
has very high sensitivity and specificity.
It is application is oriented towards the specific detection
and potential identification of chemicals in the presence of the other mixture.
LC-MS Principle:
LC/MS is a hyphenated technique, combining the separation power of
HPLC, with the detection power of mass spectrometry.
Even with a very sophisticated
MS instrument, HPLC is still useful to remove the interferences from the sample
that would impact the ionization.
HPLC
system used for separation of components is connected to Mass spectrometer
which is the detector molecular weight from 30 – 3000 amu can be detected.
Requirement of LC-MS:
Individual HPLC analysis does
not give conclusive information about the structure of the analyte.
HPLC technique is coupled with
MS instrument we can deduce the molecular weight of each of the peaks. Coupled with
MS/MS we get information about daughter ions/fragments present in the compound
of interest.
Combine LC_MS technique gives
more structural information - aides in predicting the final structure of the molecule.
PARTS OF
LC-MS
1.
HPLC
Constitutes the LC part
2.
Mode of
injection the sample
a. Direct infusion
b. Flow injection analysis FIA
C. Column
3.
SOURCE FOR
THE PRODUCTION OF IONS
Ion spary
Heated nebulizer
Interface: Most important and critical. Ions are transferred
from LC to MS region
MS Analyzer: Quadruple consists of four rods
and acts as mass filter
Detector:
Channel electron multiplier (CEM) generates a current pulse for every ion that strikes the surface. Number of pulses detected at a given time reflects
abundance of the ion in the spectrum.
GPIB box: Communicates between the computer and the
main instrument
Software and Printer
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