In order to check pH effect, I want to use only one type buffer in pH ranges from 2 to 10. Can Robinson's Buffer be used as a mobile phase in HPLC? Specially for the zwitterionic columns.
In general, yes. Since many molecules are amphoteric, pH control is important. Therefore, just use 1 pH probably on the acidic side.
Can Robinson's buffer be prepared at concentrations less than 0.04 M?
Maybe. But the concentration of 0.04M or 40 mM can be tolerated quite well by an HPLC. pH control of a molecule is demonstrated around 20 mM to 50 mM (0.05 M).
Be sure to select a pH at least 2.5 pKa units away from the molecule since you don't want at least 2 peaks due to ionization of the molecule.
Thank you so much. But in HILIC mode, due to a higher concentration of acetonitrile (>90%), buffer solubility is very important. I tried this, but in the concentration of upper than 10 mM, Robinson's Buffer is immiscible with acetonitrile.
pH Buffers (particularly phosphate) precipitate at high concentrations of ACN. Try not to go above 50% ACN.
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