what is the general mechanism of high performance liqiud
chromatography?
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Answer Posted / nabil
Confusigly,there are two variants in use in HPLC depending
on the relative polarity of the solvent and the stationary
phase.
1-Normal Phase HPLC
The column is with tiny silica particles, and the solvent
is non polar hexane for example, Polar cpds in the mix
being passed through the column will stick longer to the
polar silica than the non polar cpds will, the non polar
ones will therefore pass more quickly through the column.
2-Reversed phase HPLC
In this case the silica is modified to make it non polar by
attacheing hydrocarbon chains to its surface typically with
either 8 or 18 carbon atomsin them. A polar solvent is used.
In this case there will bestrong attraction between polar
solvents and polar molecules will pass through
thecolumntherewon't be much attractoin between the
hydrocarbon chain and the polar solvent.
Non polar cpds in the mix will tend to form attractions
with the hydrocarbons gps because of van der waals forces
they will be also less soluble in the solvent because the
need to break the hydrogen bonds,they spend less time in
solution in the solvent, that mean the polar molecules that
will travel through the column more quickly.
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