Chiral Countercurrent Chromatography

Enantiomers may be resolved by CCC if an appropriate chiral selector is present in the stationary phase. Figure 10 shows the separation of four enantiomeric

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Time (min)

Figure 8 Analysis of rare earth elements by pH gradient elution with a ligand in the stationary phase. Apparatus, HSCCC centrifuge with 7.5 cm revolution radius; column, three multilayer coils, 1.1mm i.d. x300m, 270 mL capacity; stationary phase, 0.003 mol L_1 di-(2-ethylhexyl)phosphoricacid in n-heptane; mobile phase, exponential gradient of 0-0.4 mol L_1 HCl; sample, 0.001 mol L_1 each of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu in 100 ^L; revolution, 900 rev min~1; flow rate, 5 mL min~1; pressure, 300 psi (& 2070 kPa).

100 150 200 250

Time (min)

Figure 8 Analysis of rare earth elements by pH gradient elution with a ligand in the stationary phase. Apparatus, HSCCC centrifuge with 7.5 cm revolution radius; column, three multilayer coils, 1.1mm i.d. x300m, 270 mL capacity; stationary phase, 0.003 mol L_1 di-(2-ethylhexyl)phosphoricacid in n-heptane; mobile phase, exponential gradient of 0-0.4 mol L_1 HCl; sample, 0.001 mol L_1 each of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu in 100 ^L; revolution, 900 rev min~1; flow rate, 5 mL min~1; pressure, 300 psi (& 2070 kPa).

pairs of dinitrobenzoyl amino acids using a chiral selector, N-dodecanoyl-l-proline-3,5-dimethylanilide in the stationary phase. When the separation is performed without the chiral selector, all components elute near the solvent front, resulting in poor separation (Figure 10A). The addition of the chiral selector to the stationary phase results in excellent separation with only one overlapping peak under otherwise identical experimental conditions (Figure 10B). Gram quantities of ionic enantiomers can be purified by means of the pH-zone-refining CCC technique described below.

Figure 9 Separation of catecholamine and related compounds by high speed CCC using a ligand, triethylamine, in the stationary phase. The left chromatogram (A) obtained without ligand shows no evidence of separation. All components were completely resolved by introducing the ligand in the stationary phase, as shown in part (B).

Figure 9 Separation of catecholamine and related compounds by high speed CCC using a ligand, triethylamine, in the stationary phase. The left chromatogram (A) obtained without ligand shows no evidence of separation. All components were completely resolved by introducing the ligand in the stationary phase, as shown in part (B).

Figure 10 Separation of four enantiomeric dinitrobenzoyl (DNB) amino acids by high speed CCC, with (B), and without (A), a chiral selector, N/-dodecanoyl-L-proline-3,5-dimethylanilide (DPA). In the upper chromatogram obtained without chiral selector, all components eluted near the solvent front with poor peak resolution. Introduction of 1.6 g of DPA in the stationary phase under otherwise identical experimental conditions resulted in a remarkable improvement in peak resolution.

Figure 10 Separation of four enantiomeric dinitrobenzoyl (DNB) amino acids by high speed CCC, with (B), and without (A), a chiral selector, N/-dodecanoyl-L-proline-3,5-dimethylanilide (DPA). In the upper chromatogram obtained without chiral selector, all components eluted near the solvent front with poor peak resolution. Introduction of 1.6 g of DPA in the stationary phase under otherwise identical experimental conditions resulted in a remarkable improvement in peak resolution.

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