MPIC is a method in which an ion-pairing agent in the eluent enhances retention for charged analytes on a hydrophobic column, and then is removed by the suppressor to provide selective, sensitive detection of the analytes. For analysis of cations, heptafluorobutyric acid is one such agent that is amenable to suppression. Main column features include:
Eluent Operational Guidelines
- Excellent resolution
- Good peak shape
- High efficiency
- Rugged packed bed
Anions typically use 5–10mM sodium borate, 0.5–5mM TPA, or TBA borate pH 8–9 prepared from boric acid and the corresponding hydroxide. When using gradient elution with a Thermo Scientific™ Dionex™ ASRS™ Anion Self-Regenerating Suppressor, we recommend maintaining constant sodium/TBA concentration and varying the organic solvent.
Cations typically use 0.5–10 mM TFA, HFBA, HSA or OSA. When using gradient elution with a Thermo Scientific™ Dionex™ CSRS™ Cation Self-Regenerating Suppressor, we recommend maintaining constant acid concentration and varying the organic solvent.
Solvent composition is limited based on the solvent compatibility of the suppressor. Flush all solvents out of the suppressor with DI water before shutting down the system. See suppressor manuals for detailed instructions and solvent compatibility limits. Suppressor Operational Guidelines
- The 4mm Thermo Scientific™ Dionex™ AERS™ Anion Electrolytically Regenerated Suppressors, Dionex ASRS suppressors, Thermo Scientific™ Dionex™ CERS™ Cation Electrolytically Regenerated Suppressors, and Dionex CSRS suppressors are compatible with ≤40% acetonitrile and require operation in the external water mode.
- Thermo Scientific™ Dionex™ AMMS™ Anion MicroMembrane™ Suppressors are compatible with all solvent conditions with 5–50mN sulfuric acid at 2–10mL/min.
- Thermo Scientific™ Dionex™ CMMS™ Cation MicroMembrane™ Suppressors are compatible with all solvent conditions with 20–100mM tetrabutylammonium hydroxide at 2–10mL/min.
- See suppressor manuals for detailed instructions and solvent compatibility limits.