Countercurrent chromatographic separation of hippuric acid and related compounds using cross-axis coil planet centrifuge with eccentric coil assemblies

Countercurrent chromatographic separation of hippuric acid (HA) and related compounds was performed using the cross-axis coil planet centrifuge equipp ed with a pair of eccentric coil assemblies mounted in an off-center positi on. Partition coefficients of HA and a set of related compounds were determ ined on a polar two-phase solvent system composed of methyl t-butyl ether, 1-butanol, acetonitrile and aqueous 0.1% trifluoroacetic acid at various vo lume ratios. The optimal volume ratio of 1 : 0 : 0 : 1 was successfully use d to resolve p-amino HA, HA, p-methyl HA, and (+/-)-mandelic acid by the lo wer aqueous phase mobile, and benzoic acid, p-methyl HA and HA by the upper organic phase mobile.