Separation of Pharmaceutical Counter-Ions
Method:
Buffers from a CElixirOA™ pH 5.4 Kit for anion analysis, a Beckman P/ACE MDQ™ CE Instrument and a 75um ID bare
fused silica capillary were used for the analysis and separation of over 10 anions and organic acids. The sample was
hydro-dynamically injected for 5 seconds and the capillary conditioned as per the CElixirOA™ manual. The separation
was easily achieved in a run time of less than 7 minutes. Please note: in reverse polarity the sample is introduced at
the cathode and will migrate to the anode. (Octanoic Acid can be used as an internal standard.)
Discussion and Rationale:
Pharmaceutical compounds are often charged and have counter-ions. These counter-ions are an important part of the formula
weight and may have a significant impact on the effective concentration of the API (active pharmaceutical ingredient) in
the drug’s formulation. As regulatory agencies (such as the FDA) require full testing of the composition of all
pharmaceutical ingredients it is important to determine the presence of these analytes. CElixirOA™ is an easy to use
pre-made dynamic coating/buffer system that separates and detects these negatively charged counter-ions (organic acids or
inorganic ions) that do not absorb UV light. It is fast, economical, reliable and runs in reverse polarity.
