Mixin Classes in Odoo 17 How to Extend Models Using Mixin Classes
Hplc
1.
2. Contents
• What is chromatography?
• HPLC ( high performance
liquid chromatography)
• Separation Modes of
HPLC
• Isoelectric Vs Gradient
Elusion
• The Stationary Phase
• The mobile phase
• Selecting a Stationary
and mobile phase
• The HPLC System
• Main components of a
HPLC system
• Operating Procedure for
HPLC
• Temperature control in
HPLC
• Retention time
• Application of HPLC
• References
4. What is Chromatography?
• Chromatography is a technique which separates
components in a mixture due to the differing
time taken for each component to travel through
a stationary phase when carried through it by a
mobile phase.
• The stationary phase is fixed in place either in a
column (a hollow tube made up of a suitable
material, e.g. glass) or on a planar surface and
the mobile phase moves over or through the
stationary phase carrying with it the sample of
interest.
5. How Separation is Achieved?
• Figure shows how the separation is achieved. Mixture of component A
and component B is introduced to the mobile phase. A and B are travelling
at the same rate as the rate of flow of the mobile phase.
• At time t1 they encounter the stationary phase. A has a slightly greater
affinity for the stationary phase than B. This means that relative to B, A
spends more time on the stationary phase and travels at a slower rate
than B.
• At time t2 A and B are beginning to separate.
• At time t3 they are fully separated.
• At time t4 there is further separation of A and B.
7. High Performance Liquid
Chromatography (HPLC)
• HPLC( high performance liquid chromatography) is a separation
technique that involves:
• Injection of a small volume of liquid sample into a tube packed
with tiny particles, called the stationary phase where individual
components of the sample are moved down the packed tube
(column) with a liquid (mobile phase) forced through the
column by high pressure developed by a pump.
8. • These components are separated from one another by the
column packing that involves various chemical and/ or
physical interactions between their molecules and the
packing particles.
• These separated components are detected at the exit of this
tube(column) by a flow-through device (detector) that
measures their amount. An output from this detector is called
a liquid chromatogram.
• In principle, LC and HPLC work in the same way except the
speed, efficiency , sensitivity and ease of operation of HPLC is
vastly superior. HPLC is also known as high pressure liquid
chromatography or high priced liquid chromatography.
9. Representation of High Performance Liquid
Chromatography
Injector
Detector
Column
Solvents
Mixer
Pumps
Waste
Separation in based upon differential migration
between the stationary and mobile phases.
Stationary Phase - the phase which
remains fixed in the column, e.g. C18, Silica
Mobile Phase - carries the sample through
the stationary phase as it moves through the
column.
26. Separation Modes of HPLC
• Key Point to Remember:
• The correct selection of the column packing and the mobile
phase are the most important factors in successful HPLC.
• There are four major separation modes that are used to
separate most compounds:
1. Partition or Reversed-phase chromatography
2. Adsorption or Normal-phase chromatography
3. Ion exchange chromatography
4. Size exclusion chromatography
.Let's briefly look at each mode
27. Partition or Reversed-phase
Chromatography
• In partition or reversed-phase chromatography the stationary
phase is non-polar organic species (e.g. C18, C8, etc)
covalently bonded to the packing and the mobile phase is
water (buffer) + water-miscible organic solvent (e.g.
methanol, acetonitrile).
• In a mixture of components to be separated those analytes
which are relatively less polar will be retained by the non-
polar stationary phase longer than those analytes which are
relatively more polar. Therefore the most polar component
will elute first. The attractive forces which exist are mainly
non-specific hydrophobic interactions. The exact nature of
these interactions is still under discussion.
28. • Partition or Reversed-phase Chromatography is the most widely
used type of HPLC in pharmaceutical analysis. Over 90% of
chromatographers use this mode.
• The technique can be used for:
o non-polar molecule
o polar molecule
o Ionizable molecules
o and ionic molecules.
• For samples containing a wide range of compounds, gradient
elution is used:
o One begins with a predominantly water-based mobile phase and
then adds organic solvent as a function of time.
o The organic solvent increases the solvent strength and elutes
compounds that are very strongly retained on the RPC packing.
29. Adsorption or Normal-phase
Chromatography
• In adsorption or normal phase chromatography the
stationary phase is polar (e.g. silica gel, cyanopropyl-
bonded, amino-bonded, etc.) and the mobile phase is
non-polar (e.g. hexane, iso- octane, methylene
chloride, ethyl acetate).
• In a mixture of components to be separated those
analytes which are relatively more polar will be
retained by the polar stationary phase longer than
those analytes which are relatively less polar. Therefore
the least polar component will elute first. The
attractive forces which exist are mostly dipole-dipole
and hydrogen bonding (polar) interactions.
30. • Adsorption or Normal phase chormatography is used
by about 10% of the liquid chromatographers.
• The technique is useful for:
o water-sensitive compounds
o geometric isomers
o cis-trans isomers
o class separations
o and chiral compounds.
31. Ion-Exchange Chromatography
• In ion exchange, the column packing contains
ionic groups (e.g. sulfonic, tetraalkylammonium)
and the mobile phase is an aqueous buffer (e.g.
phosphate, formate, etc.).
• Ion exchange chromatographyis used by about
20% of the liquid chromatographers
• The technique is well suited for:
o The separation of inorganic and organic anions
and cations in aqueous solution.
o Ionic dyes, amino acids, and proteins can be
separated by ion exchange.
32. Size –Exclusion Chromatography
• In size-exclusion chromatography the sample molecule
do not interact with the stationary phase, the
separation is based on the size of the sample
molecules.
• Lower molecular weight species enter the pores on the
column packing and higher molecular weight species
do not fit in these pores and thus are not retained.
• A range of stationary phases in different pore size is
available and the selection of an appropriate one for a
given separation is based on the molecular weight of
the sample.
33. • The SEC technique is used by 10-15% of
chromatographers, mainly for polymer
characterization and for proteins.
• There are two modes:
– non-aqueous SEC [sometimes termed Gel
Permeation Chromatography (GPC)] and
– aqueous SEC [sometimes referred to an Gel
Filtration Chromatography (GFC)].
34. Isocratic Vs Gradient Elusion
Isocratic Elusion: A separation in which the mobile
phase composition remains constant throughout the
procedure is termed as isocratic elusion.
• Best for simple separations
• Often used in quality control applications that support
and are in close proximity to a manufacturing process.
Gradient Elusion: A separation in which the mobile phase
composition is changed during the separation process
is described as a gradient elution.
• Best for the analysis of complex samples
• Often used in method development for unknown
mixtures.
37. The Stationary Phase
• It is the combination of a suitable stationary
phase and mobile phase that enables the
separation of a mixture and thus the analysis
of the components in the mixture.
• HPLC is characterised by the use of very small
particles of stationary phase which are fixed in
place in a HPLC column, often made of a
material such as stainless steel. A typical
column is shown in Figure.
39. 1-Packing/Matrix of the HPLC column
• The finely divided material with which the column is packed
is usually silica. It can be used as stationary phase in
adsorption chromatography or a bonded phase is attached
for use in partition chromatography.
• Silica is the most common packing material used in HPLC
columns . It is physically robust (durable, strong, long-lasting) and
chemically stable in virtually all solvents and at low pH.
• Silica consists of silicon atoms bridged three-dimensionally
by oxgen atom. The free silanol (Si-OH) groups are most
active and most of the chromatographic properties of the
silica surfaces are related to interactions with these.
• Other polar statioany phase packing include alumina and
graphitised carbon.
40. 2-Bonded Phase
• Reversed phase bonded phases
These are non-polar groups, attached to the matrix surface by
covalent bonding. The most common bonded phases are alkyl
groups. C18 is the most popular, referred as octyldecylsilane
(ODS). The silane will contain a group that can react with the
silica surface (e.g Cl).
41. • Normal phase bonded phases
The bonded phases that are used for normal phase
chromatography are polar. Typical example are cyano (CN),
amino (NH2) and diol bonded phases.
• Bonded phases for size exclusion HPLC
Silica based size-exclusion chromatography packings have
chemicals bonded to the surface to deactivate the silica but
these bonded phases do not interact with the analyte
molecules since the separation is based only on size.
• Chiral stationary phases
A large number of drugs contain chiral centers and often
only one enantiomer is pharmacologically active. Therefore
an analytical technique which separate the enantiomer is
required. To use of HPLC for this separation involves the use
of a chiral stationary phase. A large number of different
phases are available and the selection of a suitable one will
depend on the analyte.
42. 3-Particle size
• The development of finely divided stationary phase
resulted in the development of HPLC as an analytical
technique. The magnitude of these particles size is typically
in the range 1.5 to 10 microns.
• Most packings have a distribution of particle sizes, this is
inherent in the manufacturing process. A narrow
distribution gives better results and thus the high
performance column tend to have narrow distribution of
particle size.
• Over the past few years technology required to both
produce and utilize sub 2 micron particles has been
commercialized. Reduction in particle size gives benefits in
efficiency and faster analysis but also results in higher
operating pressures, this means that instrumentation is
required which can operate at ultra high pressure.
43. 4-Pore size
• Many stationary phases are porous to provide greater surface area.
Small pores provide greater surface area while larger pore size has
better kinetics, especially for larger analytes. For example, a protein
which is only slightly smaller than a pore might enter the pore but
does not easily leave once inside.
5-Length
• The length of the column influences the extent of the separation of
the components in the mixture.
• A longer column enables more separation. The time taken to
perform the separation will increase as the length increases since it
takes longer to travel through the column.
• Also as the column length increases the backpressure experienced
will also increases.
• Another problem with increasing the column length is that the
spread of the components of the mixture in the column will
increases, this will result in difficulties during detection and
quantification.
44. 6-Diameter
The internal diameter of the column usually measured
in mm.
7-Hardware
The material used to construct the external tubing and
end fitting of the column
• Stainless steel (the most popular; gives high pressure
capabilities)
• Glass (mostly for biomolecules)
• PEEK (Polyether ether ketone) polymer (biocompatible
and chemically inert to most solvents)
8-Manufacturer
The name of manufacturer of the column.
46. The Mobile Phase
• The mobile phase for HPLC is the liquid phase which is
continually flowing through the stationary phase and which
carries the analyte through with it. The composition of the
mobile phase which is used is dependent on both the
stationary phase and the nature of the compounds being
analysed.
• The different properties of solvents define whether they
are suitable for use as a mobile phase either under
reversed phase or normal phase conditions.
• The most common solvents used for HPLC are listed below
in order of increasing polarity: n-hexane, methylene
chloride, chloroform, methyl-t-butyl ether, tetrahydrofuran
(THF), isopropanol (IPA), acetonitrile (MeCN or ACN),
methanol (MeOH), water.
47. • A blend of two (or more) of these solvents is used as
the mobile phase in a HPLC analysis. The proportions
of the different solvents in the blend act to adjust the
polarity of the mobile phase. This is combined with a
suitable stationary phase to achieve the separation of a
mixture. Ideally, the components in the mixture will be
separated fully and will all elute within a practical time
scale.
• By convention, chromatographers usually refer to the
strong solvent in a mobile phase as the 'B' solvent and
the weak solvent as the 'A' solvent. Generally, solvent
strength is related to polarity, with non-polar solvents
being 'strong' solvents for reversed phase HPLC and
polar solvents being 'strong' for normal phase HPLC.
48. • A binary mixture is a mixture of two solvents and is the
most common type of mobile phase. However ternary
mixtures, where three solvents are blended, are also
used. The choice of the solvents in the mobile phase,
and the proportions of each, will be selected during
method development.
• The most important property of the solvent is its ability
to interact with both the stationary phase and the
analytes in the mixture, resulting in the desired
separation. However, there are other important
properties that need to be considered. An ideal solvent
will be readily available in high purity, relatively
inexpensive, safe to use routinely, and compatible with
the entire HPLC system including the detector.
49. Mobile Phase Preparation
1-Quality
All reagents and solvents should be of the highest quality it should
contain no impurities. De-ionized water often contains trace levels
of organic compounds and therefore it is not recommended for
HPLC use. Ultra pure water is generated by passing de-ionized water
through an ion exchange bed.
2-Buffer
All buffers should be prepared freshly. Buffer reagents can contain a
stabilizing agent. They may affect the chromatographic behavior of
the buffer solution so reagents that are free of stabilizer are
preferred.
3-Filtration
All HPLC solvents should be filtered through a 0.45 micrometer
filter before use. This removes any particulate matter that may
cause blockage. After filtration, the solvents should be stored in a
covered reservoir to prevent contamination with dust.
50. 4-Degassing
Before the freshly prepared mobile phase is pumped around the HPLC system , it
should be thoroughly degassed to remove all dissolved gasses. Dissolved gas can be
removed from solution by:
• bubbling with Helium
• sonication
• vaccum filtration
If the mobile phase is not degassed,
air bubbles can form high pressure
in the system resulting in system
instability and spurious baseline.
The most efficient form of degassing
is bubbling with helium or another
low solubility gas.
52. Selecting a Stationary and mobile
phase
• The selection of a suitable column and the mobile
phase for an analysis of a mixture of components
is very difficult.
• This decision is made during HPLC method
development, which is the process of selecting a
suitable column and mobile phase for a given
separation.
• The best choice will depend on both the nature
of the analyte and the aim of the analysis.
54. The HPLC System
Instrumentation is required to enable the flow of the mobile phase
through the stationary phase and also to convert the separated
components into meaningful information. A typical configuration of a
HPLC system is shown in Figure:
55. Main components of a HPLC system
1. Pump
The role of the pump is to force mobile phase through the liquid
chromatograph at a specific flow rate, expressed in milliliters per
min (mL/min). Normal flow rates in HPLC are in the 1- to 2-mL/min
range. Typical pumps can reach pressures in the range of 6000-9000
psi (400- to 600-bar). During the chromatographic experiment, a
pump can deliver a constant mobile phase composition (isocratic
elusion) or an increasing mobile phase composition (gradient
elusion).
2. Injector
The injector serves to introduce the liquid sample into the flow
stream of the mobile phase. Typical sample volumes are 5- to 20-
microliters (µL). The injector must also be able to withstand the
high pressures of the liquid system. An autosampler is the
automatic version for when the user has many samples to analyze
or when manual injection is not practical.
56. 3. Column
Considered the "heart of the HPLC" the column's
stationary phase separates the sample components of
interest using various physical and chemical
parameters. The small particles inside the column are
what cause the high backpressure at normal flow
rates. The pump must push hard to move the mobile
phase through the column and this resistance causes a
high pressure within the chromatograph.
4. Detector
There are many detection principles used to detect the
compounds eluting from an HPLC column.
The most common are:
Spectroscopic Detection
Refractive Index Detection
Fluorescence Detection
57. Spectroscopic Detection
i-Ultraviolet (UV) Absorption
• An ultraviolet light beam is directed through a flow cell
and a sensor measures the light passing through the
cell.
• If a compound elutes from the column that absorbs
this light energy, it will change the amount of light
energy falling on the sensor.
• The resulting change in this electrical signal is amplified
and directed to a recorder or data system.
• An UV spectrum is sometimes also obtained which
may aid in the identification of a compound or series of
compounds.
58.
59. ii-Mass Spectroscopy (MS)
• A MS detector senses a compound eluting from
the HPLC column first by ionizing it then by
measuring it's mass and/or fragmenting the
molecule into smaller pieces that are unique to
the compound.
• The MS detector can sometimes identify the
compound directly since its mass spectrum is like
a fingerprint and is quite unique to that
compound.
60. Refractive Index (RI) Detection
• The ability of a compound or solvent to deflect
light provides a way to detect it.
• The RI is a measure of molecule's ability to
deflect light in a flowing mobile phase in a flow
cell relative to a static mobile phase contained in
a reference flow cell.
• The amount of deflection is proportional to
concentration.
• The RI detector is considered to be a universal
detector but it is not very sensitive.
61.
62. Fluorescence Detection
• Compared to UV-Vis detectors fluorescence
detectors offer a higher sensitivity and
selectivity that allows to quantify and identify
compounds and impurities in complex
matrices at extremely low concentration levels
(trace level analysis).
• Fluorescence detectors sense only those
substances that fluoresce
63.
64. 5.Computer
The computer controls all the modules of the HPLC
instrument but it takes the signal from the detector
and uses it to determine the time of elution
(retention time) of the sample components
(qualitative analysis) and the amount of sample
(quantitative analysis).
66. Operating Procedure for HPLC
Start-up
1. Switch on the computer.
2. Switch on the detector and HPLC pump.
3. Double click on the HPLC software icon on the desktop.
4. Check there is sufficient elution solvents. Please top-up if there is insufficient.
Use only HPLC grade solvents to prevent clogging of the system.
5. If HPLC has not been in use for a while, air bubbles in the system are needed to
purge out. Turn the knob on HPLC a quarter and press Purge. The purging
process will take 10 minutes.
6. Once the purging is finished, turn the knob back.
7. Attach the column in the correct flow direction.
8. Open the required method file or build a new method file. Ensure that the
wavelength, flow rate, elution time and elution proportion are correct.
9. Monitor the baseline by clicking the Baseline icon in the program. Check tubing
connection, ensure that there is no leakage.
10. Once the baseline is flat, the system is ready for sample injection.
67. Sample preparation and injection
1. Prepare the sample in the appropriate solvent. Ensure there is no
particulate by filtering the sample solution through a membrane.
2. Wash the syringe thoroughly with the appropriate solvent (at least three
times).
3. Wash the syringe with the sample solution (at least three times).
4. Draw up the sample. Ensure there is no bubble in the syringe.
5. Click the Single Run icon once ready.
6. Insert the syringe and lift up the injection valve anticlockwise (LOAD
position).
7. Inject the sample and turn down the injection valve clockwise (INJECT
position). The elution begins.
8. Withdraw the syringe and wash it with the appropriate solvent (at least
three times). After the run is finished, flush the system with the
appropriate solvent for at least 10 minutes.
68. Temperature control in HPLC
Reasons for temperature control :
Reproducibility
• Retention in HPLC is temperature dependent
• If temperature varies , then it is difficult to assign peaks to specific
compounds in chromatogram and the peak areas/heights may vary.
Solubility
• Certain chemical compounds may have low solubility in the HPLC
mobile phase
• If they are injected into the flow stream they may precipitate or
other difficulties may arise.
Stability
• Certain chemical compounds especially biological compounds such
as enzymes or proteins may not be stable at room temperature or
higher. The temperature needs to be much lower down to 4 ͦc.
69. Retention time
• The time taken for a particular compound to travel through
the column to the detector is known as its retention time.
• This time is measured from the time at which the sample is
injected to the point at which the display shows a maximum
peak height for that compound.
• Different compounds have different retention time.
For a particular compound, the retention time will vary
depending on:
1. The pressure used (because that affects the flow rate of the
solvent)
2. The nature of the stationary phase (not only what material it
is made of, but also particle size)
3. The exact composition of the solvent
4. The temperature of the column.
71. 1-Separation and analysis of non-volatile or
thermally-unstable compounds
• HPLC is optimum for the separation of chemical and
biological compounds that are non-volatile
Typical non-volatile compounds are
– Pharmaceuticals like aspirin, ibuprofen, or acetaminophen
– Salts like sodium chloride and potassium phosphate
– Organic chemicals like polymers
– Many natural products such as ginseng, herbal medicines,
plant extracts
– Thermally unstable compounds such as enzyme
• If a compound is volatile (i.e. a gas, fragrance,
hydrocarbon in gasoline, etc.), gas chromatography is a
better separation technique.
72. 2-Qualitative analysis
• The aim of qualitative analysis is to answer the question
'What' is in the sample?
• Two discrete situations exist for qualitative analysis:
– the sample components are known and peaks within the
chromatogram need to be assigned to the known components
– the sample is a completely unknown which you are attempting
to characterize
• In the former case, it might be possible to inject standards
of the pure compound, and assign the peaks in the
chromatogram based on the retention time of the
standard. Having a selective detector, such as diode-array
UV or Fluorescence detector, which assists in identification
by producing spectra or a specific response, can assist in
peak assignment.
• In the second case, it may be necessary to employ
detectors that can be used to aid in identification, such as
mass spectrometers.
73. • Perhaps the most straightforward way to assign peaks
within the chromatogram of a sample solution is to
inject standard solutions under identical analytical
conditions. By comparing the retention factor (k) and
response of the peak in the chromatogram of the
standard solution, with the sample chromatogram,
peaks may be tentatively assigned.
• It is important that the concentration of the standard
solution is matched to the sample solution as closely as
possible. This avoids peak mis-assignment due to peak
shape effects.
75. 2-Qualitative analysis
• After the peaks have been integrated and identified, the next step in the
analysis is quantification. Quantification uses peak areas or heights to
determine the concentration of a compound in the sample.
• The external standard (ESTD) procedure is the basic quantification
procedure in which both standard and unknown sample are analysed
under the same conditions.
• The result (usually peak height or peak area measured using a data
system) from the unknown sample is then related to that of a standard, to
calculate the amount in the sample.
• The ESTD procedure uses absolute response factor. The response factor is
normally calculated as:
• The sample amount can be calculated as:
76.
77. 4-Preparation of Pure Compound(s)
• By collecting the chromatographic peaks at the
exit of the detector,
• and concentrating the compound (analyte) by
removing/evaporating the solvent,
• a pure substance can be prepared for later use
(e.g. organic synthesis, clinical studies, toxicology
studies, etc.).
This methodology is called preparative
chromatography
78. 5-Trace analysis
A trace compound is a compound that is of interest to the analyst but it's
concentration is very low, usually less than 1% by weight, often parts per
million (ppm) or lower;
• the determination of trace compounds is very important in
pharmaceutical, biological, toxicology, and environmental studies since
even a trace substance can be harmful or poisonous;
• in a chromatogram trace substances can be difficult to separate or detect;
• high resolution separations and very sensitive detectors are required.
79. References
• An Introduction to HPLC for Pharmaceutical Analysis by Oona
Mcpolin.
• HPLC Basics: Fundamentals of Liquid Chromatography (HPLC)
Courtesy of Agilent Technologies, Inc.
• Standard Operating Procedure for SHIMADZU Prominence HPLC
(http://medchem.science.nus.edu.sg)
• High performance liquid chromatography by Veronika R.Meyer.
• Practical HPLC method development by Lioyd R.Synder.
• Remington (the science and practice of pharmacy) 21st edition.
• High performance liquid chromatography in biotechnology by
Agnes Henschen.
• Quantitative & Qualitative HPLC www.chromacademy.com