Separation of Alkaloids from Datura Metel. and Sophora Flavescens Ait by High-Speed Countercurrent Chromatography

Cai, D.-G.; Gu, Min; Zhang, J.-D.; Zhu, Guanghui; Zhang, T.-Y.; Li, N.; Ito, Yoichiro

doi:10.1080/01483919008049041

Cited by 10 publications

(4 citation statements)

References 2 publications

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“…The extraction equilibrium based on these dependencies is shown in eq 1, and the relationship of the extraction equilibrium constant K ex to the distribution constant of the metal complex K DC , the distribution constant of the ligand K DR , the acid dissociation constant of the ligand K a , and the stability constant of the ML 3 complex β LL is given in eq 2 The averages of log K ex from batch and CPC experiments, and log β LL calculated from the K ex values, using the K DR , K DC , and K a values determined independently, are listed in Tables and , respectively, where it can be seen that these values increase with the atomic numbers of the lanthanides, similar to previous observations with other ligands. ,,− ,, It is also evident that the tervalent lanthanides have better extractabilities with HPMBP than with HPMCP, but the separation factors with the two ligands for a given pair of lanthanides, as indicated by the differences in their log K ex values, are about the same. The log β LL values, shown in Table , for the HPMCP complexes are 3 orders of magnitude larger than those for the HPMBP complexes, indicating that HPMCP forms much stronger complexes than does HPMBP.…”

Section: Resultsmentioning

confidence: 99%

“…The CPC cartridges were loaded with the toluene stationary phase and equilibrated with the aqueous mobile phase at a rotational speed of 200 rpm, with the total internal volume in the present studies being 125 mL. The separation experiments were conducted under conditions optimized in our previous studies, , with organic and aqueous phase volumes of 25 and 100 mL, respectively, at a rotational speed of 800 rpm and a mobile phase flow rate of 1 mL/min. Sample solutions (4 × 10 -4 −2 × 10 -3 M) of Pr, Eu, Tb, and Yb were prepared by dilution of their stock solutions with the equilibrated mobile phase.…”

Section: Methodsmentioning

confidence: 99%

“…Their separation is complicated by the similarities of their properties and requires the employment of multistage methods such as continuous ion exchange, cation exchange chromatography, , micellar high-performance chromatography, capillary zone electrophoresis, and supported liquid membranes − CPC is distinctly different from the various conventional liquid chromatographic (LC) methods mentioned in that it is a multistage countercurrent distribution technique involving two immiscible liquid phases, usually an organic phase and an aqueous phase, with the organic phase usually serving as the stationary phase by the action of a centrifugal force and the aqueous phase serving as the mobile phase. As a result, CPC is a multistage solvent extraction method employing two bulk phases, unlike conventional LC techniques, which employ a solid stationary phase and a liquid mobile phase, where separations are predominantly effected by physical and chemical interactions at the solid−liquid interface.…”

mentioning

confidence: 99%

“…The acylpyrazolone family of ligands, with their low p K a values (∼4), are ideally suited for the extraction and separation of tervalent lanthanides. − Even though batch extraction experiments indicate that their selectivities for a given pair of lanthanides are not as good as the phosphinic acids, which possess some of the best selectivities, complete separation of the tervalent lanthanides using the acylpyrazolones is still possible using multistage methods such as CPC. We have conducted a systematic study of the kinetics of formation and dissociation of the tervalent lanthanide complexes (ML 3 ) of 1-pheny-3-methyl-4-benzoyl-5-pyrazolone (HPMBP, HL) and 1-phenyl-3-methyl-4-capryloyl-5-pyrazolone (HPMCP, HL) in the toluene−water phase pair and found these reactions to occur exclusively at the toluene−water interface .…”

mentioning

confidence: 99%

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Centrifugal Partition Chromatographic Separation of Tervalent Lanthanides Using Acylpyrazolone Extractants

Freiser

Muralidharan

1997

Anal. Chem.

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The separation of tervalent lanthanides (M 3+ ) by centrifugal partition chromatography (CPC) with the extractants 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (HPMBP, HL) and 1-phenyl-3-methyl-4-capryloyl-5-pyrazolone (HPM-CP, HL) in the toluene-water phase pair and the factors influencing the separation efficiencies have been investigated. The CPC efficiencies are mainly limited by the slow dissociation of the M 3+ -acylpyrazolone complexes (ML 3 ) occurring exclusively at the toluene-water interface, as indicated by a direct linear correlation between the reduced plate heights (CETP ck ) and the half-lives (t 1/2 ) of the dissociation of the ML 3 complexes determined by independent kinetic studies. The lanthanide-acylpyrazolone system represents the first example of a separation by multistage countercurrent distribution wherein the efficiencies are mainly limited by interfacial processes analogous to conventional liquid chromatographic systems. Dramatic improvements in the efficiencies of these separations could be obtained by the addition of the neutral surfactant Triton X-100 to the toluene phase and the metallochromic indicator Arsenazo III (AZ) to the aqueous phase. The improvement in the efficiencies with Triton X-100 was due to the increased interfacial areas resulting from the adsorption of the surfactant, and that in the case of AZ was due to the increased interfacial area and interfacial catalysis of the formation and dissociation of the ML 3 complexes. As a result, the addition of AZ provided much higher efficiencies than did the addition of Triton X-100. Further, the addition Triton X-100 did not significantly alter the selectivities of the ligands for M 3+ , but the addition of AZ resulted in much poorer selectivities. Significant differences were observed in the efficiencies of separations with HPMBP and HPMCP under various experimental conditions, which stem from differences in the interfacial dissociation rate constants of ML 3 complexes and the interfacial areas generated, indicating that CPC separation of tervalent lanthanides with acylpyrazolones in the toluene-water phase pair is driven mainly by interfacial processes.

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