ORGANIC-HIGH IONIC STRENGTH AQUEOUS SOLVENT SYSTEMS FOR SPIRAL COUNTER-CURRENT CHROMATOGRAPHY: GRAPHIC OPTIMIZATION OF PARTITION COEFFICIENT

Abstract

A new series of organic-high ionic strength aqueous two-phase solvents systems was designed for separation of highly polar compounds by spiral high-speed counter-current chromatography. A total of 21 solvent systems composed of 1-butanol-ethanol-saturated ammonium sulfate-water at various volume ratios are arranged according to an increasing order of polarity. Selection of the two-phase solvent system for a single compound or a multiple sample mixture can be achieved by two steps of partition coefficient measurements using a graphic method. The capability of the method is demonstrated by optimization of partition coefficient for seven highly polar samples including tartrazine (K = 0.77), tryptophan (K = 1.00), methyl green (K = 0.93), tyrosine (0.81), metanephrine (K = 0.89), tyramine (K = 0.98), and normetanephrine (K = 0.96). Three sulfonic acid components in D&C Green No. 8 were successfully separated by HSCCC using the graphic selection of the two-phase solvent system.

Keywords:

• catecholamines
• graphic optimization of partition coefficient
• organic-high ionic strength aqueous solvent system series
• spiral high-speed counter-current chromatography
• sulfonic acids
• zwitter ions

ACKNOWLEDGMENT

This work was supported by the Intramural Research Program (IRP) of the National Institutes of Health (NIH). The work also was partially supported by projects (No. 09ZA036, KFJJ0905/0807, and 2011JQ0032) of Sichuan Province and National Natural Science Foundation of China (81101101).

Notes

*Saturated ammonium sulfate stock solution.