The pH of the mobile phase in reversed-phase HPLC is an
important factor, it can affect the peak shape as well as the retention time of
the molecule as it affects the ionization state of the molecule, and therefore
the chemistry of the interactions in the HPLC column. It is therefore important
that to maintain the correct ph for the compound that may be affected by the pH
change of the mobile phase and buffer. The triethylamine and trifluoroacetic
acid are common mobile phase modifiers, but they do not maintain pH, you need
buffer solution for this. They resist a change in pH when small amounts of acid
or alkali are added. A buffer solution contains a mixture of a weak base and
its conjugate acid (or a weak acid and its conjugate base).
The effect of the pH of the mobile phase in
high-performance liquid chromatography can influence the selectivity, retention
time, and method ruggedness.
Selectivity:
Minute changes in the mobile phase pH can also have a
dramatic effect on the selectivity of weakly ionizable analytes.
The retention time of the analyte:
When the pH of the mobile phase changes a dramatic change
occurs in the retention time of acidic and basic analytes. When the ionization
of these molecules is changed it is often the result of different interactions
amongst the column and the molecules.
Method Ruggedness:
For best roughness, choose a pH for the buffer or mobile
phase where selectivity and RT do not change if the slight changes in pH.
Effect of pH on HPLC analysis
Effect of pH on HPLC columns
When a buffer is used in HPLC
Why is pH important for HPLC buffers?
How to select a pH of mobile phase in HPLC
Role of pKa in HPLC method development
Why use a buffer in the HPLC mobile phase
Why do we need buffers solution in HPLC?
Why phosphate buffer is used in HPLC
Selection of buffer in HPLC method development
HPLC buffer selection guide
What are the common buffers used in HPLC?
You may also like this
Effect of pH on HPLC columns
When a buffer is used in HPLC
Why is pH important for HPLC buffers?
How to select a pH of mobile phase in HPLC
Role of pKa in HPLC method development
Why use a buffer in the HPLC mobile phase
Why do we need buffers solution in HPLC?
Why phosphate buffer is used in HPLC
Selection of buffer in HPLC method development
HPLC buffer selection guide
What are the common buffers used in HPLC?
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