YouTube Transcript:
Mass Spectrometry explained – how it works

Mass spectrometry AKA Mass Spec is an
analytical technique that measures mass
to charge ratio in this video you will
learn how this method works and why it
is such a powerful tool in research
before we jump right into it I would
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lot scientists apply Mass spectrometry
if they opt to measure the m mass of
different molecules within a sample Mass
back helps to quantify molecules of
interest and identify them based on
their Mass quite often the technique is
used for protein analysis which makes
Mass back an important tool in the field
of proteomics but how does it work well
as for many laboratory techniques there
are different devices to accomplish Mass
back with which work all a bit
differently so be aware that some steps
shown in this video might deviate a bit
depending on the mass spectrometer and
analyzer used let's have a look at a
simplified Mass spectrometer consisting
of an iron Source an analyzer and a
detector before inserted into the mass
analyzer complex samples are often
separated for example by liquid
chromatography the first two steps in
Mass spectrometry are called desorption
and ionization and they usually occur
simultaneously this refers to the
process of transferring molecules into
the gas phase during which singly or
multiply charged ions are generated a
common method is called electrospray
ionization short ESI the sample is
passed through a capillary with an
applied electric field electrostatic
repulsion of ions and other physical
effects causes a fine aerosol that
eventually evaporates resulting in
charged gas phase ions after ionization
the ions pass through tiny slits in the
mass spectrometer and are accelerated in
a focused iron beam using an electric
field there are various analyzers in
Mass spectrometry all of which aim to
determine the mass to charge ratio of
ions one commonly used analyzer type is
the time of flight analyzer the
principle is straightforward the ions
are accelerated in an electric field
with a known voltage and ions with the
same charge gain the same kinetic energy
consquently lighter ions travel faster
through the fly tube than heavier ions
with the same
charge and more highly charged ions
travel faster compared to singly charged
ions with the same mass the time of
flight through the tube to the detector
is then measured since the the distance
is known the mass to charge ratio can be
determined the ions are also Quantified
and the mass spe result will be featured
as a chart looking like this which is
referred to as a Mass Spectrum the mass
to charge ratio is displayed on the
xaxis and the relative intensity is
shown on the Y AIS the most abundant ion
for example will be the one with the
highest peak the relative intensity is
set to 100% for that ion in this example
the iron Peaks at 24 MZ and some lower
Peaks are found with an isotopic mass of
25 and 26 MZ playing detective while
taking a look at the periodic table one
would discover that this looks pretty
much like magnesium with an atomic mass
of
24.3 U and indeed it is the smaller
Peaks are some heavier isotopes of the
element m spectrometry is usually used
for more complex molecules such as
protein samples databases help to
identify the molecules of
interest during mass spectrometry a
sample of interest is first transferred
to the gas phase and ionized which means
charge is added to the sample these
charged ions are then accelerated which
helps to separate them inside the
analyzer according to their Mass to
charge ratio a common way to accomplish
that is by measuring time it takes for
the irons to hit the detector the result
will be shown as a Mass Spectrum which
in combination with databases is used to
identify the sample of interest you want
to know how to interprete or analyze
your mass back results take a look at
this clip here if you need a break from
studying check out this video where I
explain whether and maybe even how we
could bring back dinosaurs or other
extinct species if this video could
introduce you a bit to mass spectrometry
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