With insulin methanol water, and the ion pairing agent, hydrochloric acid and trifluroacetic acid (TFA), the character of the first plateau (FP) on the elution curve of frontal analysis in reversed phase liquid chro...With insulin methanol water, and the ion pairing agent, hydrochloric acid and trifluroacetic acid (TFA), the character of the first plateau (FP) on the elution curve of frontal analysis in reversed phase liquid chromatography (RPLC) was investigated by on line UV spectrometry and identified with nuclear magnetic resonance (NMR) spectrometry and mass spectrometry. The profile of the FP is the same as that of a usual elution curve of methanol in frontal analysis (FA). When the insulin concentration was limited to a certain range, the height of the FP was found to be proportional to the insulin concentration in mobile phase and its length companying to shorten. The FP profile on the intersection of two tangents reflects the components of the microstructure in the depth direction of the bonded stationary phase layer and the desorption dynamics of the displaced components. The displaced methanol was quantitatively determined by NMR and on line UV spectrometries. TFA with high UV absorbance can not be used as an ion pairing agent for the investigation of the FP in RPLC, but it can be used as a good marker to investigate the complicated transfer process of components in the stationary phase in RPLC. A stoichiometric displacement process between solute and solvent was proved to be valid in both usual and FA in RPLC. From the point of view of dynamics of mass transfer, the solutes can only contact to the surface of stationary phase in usual RPLC, while solute can penetrate into it in FA of RPLC. The solvation of insulin in methanol and water solution as an example indicating the usage of the FP in the FA was also investigated in this paper.展开更多
A simple frontal analysis equation to determine the adsorption parameters of solute molecules on different adsorbents was presented. It gives the relationship between the average breakthrough time and the feed solute ...A simple frontal analysis equation to determine the adsorption parameters of solute molecules on different adsorbents was presented. It gives the relationship between the average breakthrough time and the feed solute concentration, and by using its linear form, two important parameters, the thermodynamic equilibrium constant KSL for solute adsorption on the surface of adsorbent and the number nt of total adsorption sites distributed on the surface of adsorbent, can be simultaneously determined. The frontal analyses for some aromatic hydrocarbons on RP-C18 reversed-phase medium, and some protein molecules on RP-C18 reversed-phase, WCX-1 cation-exchange, PEG-400 hydrophobic and Chelating Sepharose Fast-flow separately chelated with Zn^2＋ or Cu^2＋ media, were separately carried out to test this equation and their adsorption parameters KSL and nt were separately obtained. The results show that all these frontal analysis data can be well described by this frontal analysis equation. For all of these frontal analysis systems, their parameters nt can separately approximately keep constant and they are independent of solute molecules used, while their parameters KSL are dependent upon both of the media packed in frontal analysis column and the solute molecules used.展开更多
With four kinds of mobile phases, methanol water, ethanol water, 2 propanol and acetonitrile water (all containing 0 1% triflu roacetic acid), the displacement between solute and solvent in RPLC was proved to be...With four kinds of mobile phases, methanol water, ethanol water, 2 propanol and acetonitrile water (all containing 0 1% triflu roacetic acid), the displacement between solute and solvent in RPLC was proved to be universal in frontal analysis (FA). Based on the measured Z value in usual RPLC to be a constant and the quantitative determination of methanol increment in mobile phase in FA, the stoichiometric displacement (SD) between insulin and methanol was directly proved by the experiment. The SD was also proved to occur only on about the one fourth of the maximum amount of adsorbed methanol in the bonded phase layer (BPL) without any dynamic problem of mass transfer, while in FA, the SD firstly occurs on the surface of the BPL and then gradually sinks into the deeper sites companied with a dynamic problem. Although the displaced solvent by the same solute is less in the former case, the SD is independent of how deep of the solute enters the BPL. In addition, the adsorbed amount of solute on an adsorbent not only depends on the numbers of the adsorbed layer on the adsorbent surface, but also on the extent of the complete removal of the displaceable solvent in the BPL. The physical fundamental of the SD and the methodology for investigation were also discussed.展开更多
In previous paper a new adsorption isotherm which relates the amount of solute absorbed to the solvent concentration is proposed and simplified, and it only can be used at lower solute concentration. In this article t...In previous paper a new adsorption isotherm which relates the amount of solute absorbed to the solvent concentration is proposed and simplified, and it only can be used at lower solute concentration. In this article the scope of the new adsorption isotherm is extended and the expressions with three and four parameters are obtained. The equations with multi parameters are valid when the adsorbed amounts are larger and show non linear logarithmic relationships. Tests with a homologue of aromatic alcohols by frontal analysis in reversed phase liquid chromatography demonstrate that the experimental results fit those equations well. In addition, the predicted values by the multi parameters were found to fit the experimental values well also. The parameters have physical meaning only for the two parameter equation for the aromatic alcohols.展开更多
文摘With insulin methanol water, and the ion pairing agent, hydrochloric acid and trifluroacetic acid (TFA), the character of the first plateau (FP) on the elution curve of frontal analysis in reversed phase liquid chromatography (RPLC) was investigated by on line UV spectrometry and identified with nuclear magnetic resonance (NMR) spectrometry and mass spectrometry. The profile of the FP is the same as that of a usual elution curve of methanol in frontal analysis (FA). When the insulin concentration was limited to a certain range, the height of the FP was found to be proportional to the insulin concentration in mobile phase and its length companying to shorten. The FP profile on the intersection of two tangents reflects the components of the microstructure in the depth direction of the bonded stationary phase layer and the desorption dynamics of the displaced components. The displaced methanol was quantitatively determined by NMR and on line UV spectrometries. TFA with high UV absorbance can not be used as an ion pairing agent for the investigation of the FP in RPLC, but it can be used as a good marker to investigate the complicated transfer process of components in the stationary phase in RPLC. A stoichiometric displacement process between solute and solvent was proved to be valid in both usual and FA in RPLC. From the point of view of dynamics of mass transfer, the solutes can only contact to the surface of stationary phase in usual RPLC, while solute can penetrate into it in FA of RPLC. The solvation of insulin in methanol and water solution as an example indicating the usage of the FP in the FA was also investigated in this paper.
基金Project supported by the Natural Science Foundation of Shaanxi Province （No. 2001K10-G3-3）.
文摘A simple frontal analysis equation to determine the adsorption parameters of solute molecules on different adsorbents was presented. It gives the relationship between the average breakthrough time and the feed solute concentration, and by using its linear form, two important parameters, the thermodynamic equilibrium constant KSL for solute adsorption on the surface of adsorbent and the number nt of total adsorption sites distributed on the surface of adsorbent, can be simultaneously determined. The frontal analyses for some aromatic hydrocarbons on RP-C18 reversed-phase medium, and some protein molecules on RP-C18 reversed-phase, WCX-1 cation-exchange, PEG-400 hydrophobic and Chelating Sepharose Fast-flow separately chelated with Zn^2＋ or Cu^2＋ media, were separately carried out to test this equation and their adsorption parameters KSL and nt were separately obtained. The results show that all these frontal analysis data can be well described by this frontal analysis equation. For all of these frontal analysis systems, their parameters nt can separately approximately keep constant and they are independent of solute molecules used, while their parameters KSL are dependent upon both of the media packed in frontal analysis column and the solute molecules used.
文摘With four kinds of mobile phases, methanol water, ethanol water, 2 propanol and acetonitrile water (all containing 0 1% triflu roacetic acid), the displacement between solute and solvent in RPLC was proved to be universal in frontal analysis (FA). Based on the measured Z value in usual RPLC to be a constant and the quantitative determination of methanol increment in mobile phase in FA, the stoichiometric displacement (SD) between insulin and methanol was directly proved by the experiment. The SD was also proved to occur only on about the one fourth of the maximum amount of adsorbed methanol in the bonded phase layer (BPL) without any dynamic problem of mass transfer, while in FA, the SD firstly occurs on the surface of the BPL and then gradually sinks into the deeper sites companied with a dynamic problem. Although the displaced solvent by the same solute is less in the former case, the SD is independent of how deep of the solute enters the BPL. In addition, the adsorbed amount of solute on an adsorbent not only depends on the numbers of the adsorbed layer on the adsorbent surface, but also on the extent of the complete removal of the displaceable solvent in the BPL. The physical fundamental of the SD and the methodology for investigation were also discussed.
基金ProjectsupportedbytheNationalNaturalScienceFoundationofChina (No .2 0 175 0 16)
文摘In previous paper a new adsorption isotherm which relates the amount of solute absorbed to the solvent concentration is proposed and simplified, and it only can be used at lower solute concentration. In this article the scope of the new adsorption isotherm is extended and the expressions with three and four parameters are obtained. The equations with multi parameters are valid when the adsorbed amounts are larger and show non linear logarithmic relationships. Tests with a homologue of aromatic alcohols by frontal analysis in reversed phase liquid chromatography demonstrate that the experimental results fit those equations well. In addition, the predicted values by the multi parameters were found to fit the experimental values well also. The parameters have physical meaning only for the two parameter equation for the aromatic alcohols.
