酮洛芬对映体在Chiralpak AD上具有连续温度相关参数的竞争吸附平衡模型

结晶原理和色谱原理是拆分手性药物用到的两大主要原理,而高效液相色谱法和模拟移动床(SMB)色谱分离技术是利用色谱原理拆分手性药物的两大重要手段。本研究用高效液相色谱法测定了酮洛芬对映体在Chiralpak AD柱中,以正己烷和乙醇(体积比80∶20)为流动相,多温度下的流出曲线。并以此为基础用拟合度最好的八参数bi-Langmuir模型,运用逆向法来考察该药物对映体在不同温度下,温度对竞争吸附等温线参数的影响,并对3温度下的酮洛芬过载曲线同时拟合,确定出bi-Langmuir中受温度影响的模型参数。     

逆向法测定氨氯地平在色谱柱Chiralpak OD-H上的竞争吸附等温线

使用逆向法测定氨氯地平在色谱柱Chiralpak OD-H上的竞争吸附等温线,先用泵进样的方式在高效液相色谱上测定氨氯地平的过载流出曲线,再选用5参数Bi-langmuir吸附等温线模型对过载流出曲线进行拟合,确定吸附等温线模型及模型参数,并验证参数准确性。     

西酞普兰对映体的手性色谱拆分及吸附平衡

以添加醇类和二乙胺的正己烷为流动相,考察了多糖类、酒石酸类和环糊精类手性固定相对西酞普兰外消旋体的拆分效果,优选合适的手性固定相、流动相和温度等色谱条件,在此基础上利用前沿色谱法测定了西酞普兰对映体的吸附等温线。优化的色谱操作条件为：Chiralpak AD-H柱为固定相,正己烷∶异丙醇∶二乙胺（95∶5∶0.1,体积比）为流动相,柱温35℃。西酞普兰对映体的吸附等温线为优惠型,采用Langmuir方程拟合,效果较好。本研究为模拟移动床（SMB）制备西酞普兰对映体提供重要的基础数据。     

柚皮素对映体在Chiralpak AD柱上吸附平衡的测定

柚皮素对映体是一种抗炎、抗癌类药物,在医药和食品领域具有重要作用。调查结果表明(R)-柚皮素和(S)-柚皮素在医药方面具有不同的作用,所以拆分柚皮素对映体有重要的应用价值。柚皮素对映体在Chiralpak AD柱上以甲醇为流动相可以得到很好的分离。用逆向法测定了25℃下柚皮素对映体在Chiralpak AD柱上的吸附等温线及其参数。     

不同流动相组成对雌马酚对映体拆分的影响

要对雌马酚对映体进行大量的拆分及制备,需要通过高效液相色谱法对雌马酚的拆分条件进行探索,雌马酚拆分条件的确定是进行后续实验的基础。通过高效液相色谱,选取Chiralpak AD柱,用正己烷和乙醇作为流动相,对正己烷和乙醇的不同配比进行拆分雌马酚对映体,主要测定在线性条件下,流动相的配比对色谱柱参数及各个吸附常数的影响。     

前沿分析法测定葡萄糖在制备色谱柱上的吸附等温线

吸附等温线对模拟移动床色谱操作参数的模拟和优化具有重要的指导意义。以前沿分析法测定65℃下葡萄糖在离子树脂色谱柱上的吸附等温线,实验结果表明该行为符合anti-langmuir吸附模型。用所求模型参数预测脉冲实验,模拟结果较好,验证了测定的模型参数准确可靠。     

模拟移动床色谱拆分酮洛芬对映体的模拟研究

利用平衡扩散模型对酮洛芬对映体在4区模拟移动床上的拆分进行模拟研究,考察了主要操作参数对分离效能的影响,具体包括:(a)切换时间对纯度、回收率的影响;(b)各区色谱柱配置对分离的影响;(c)Ⅱ区和Ⅲ区流量对纯度和回收率的影响。验证了模拟移动床操作参数的敏感性,对酮洛芬的中试生产具有一定的指导意义。     

迎头色谱法测定人参皂苷Rg1和Re的吸附量

制备色谱分离条件优化的基础是吸附等温线的测定及保留时间的预测。本文以人参皂甙Rg₁、Re为研究对象，用色谱单柱制备了人参粗粉中的人参皂甙Rg₁、Re,以迎头法测定了人参皂甙Rg₁、Re在C₁₈球形固定相中的吸附等温线，在竞争Langmuir模型基础上确定了吸附参数G和b，并应用非线性色谱理论的结果预测了人参皂甙Re的保留时间，上述结果与实验值进行了比较，平均相对误差为3.68%。在实验中发现了运用竞争Langmuir模型进行拟合的一些问题并进行了讨论。     

27种手性化合物的拆分研究

采用配位体交换手性柱(Chiralpak WH)以0.25 MmCuSO_4溶液作为流动相,对氟比洛芬、酮洛芬、扁桃酸、布洛芬、萘普生、DNB-亮氨酸等6个酸性手性药物和21个氨基酸手性化合物进行拆分研究。一定色谱条件下,被测样品中大部分手性药物的两个对映体实现了较好分离,扁桃酸、DNB-亮氨酸、氟比洛芬、缬氨酸、丙氨酸、对羟基苯甘氨酸、丝氨酸、苏氨酸、、甲硫氨酸、天冬酰胺、赖氨酸、精氨酸、苯甘氨酸等均得到分离。建立的手性HPLC能有效拆分氟比洛芬、酮洛芬等13个手性对映体。     

沸石ZSM-5吸附回收低浓度煤层气中CH_4

利用高硅疏水性沸石ZSM-5吸附回收低浓度煤层气中的甲烷,对其吸附平衡、吸附动力学以及真空变压吸附分离过程进行了理论和实验研究。通过重量法和穿透曲线法测定了CH_4/N2单组分及双组分的竞争吸附平衡数据,并采用Multisite Langmuir吸附等温线模型对其进行拟合。结合CH_4和N2稀释穿透曲线实验数据和等温无动量损失的双分散二级孔结构扩散模型,获得CH_4和N_2在沸石ZSM-5上的微孔扩散系数。建立并求解包含质量、动量及能量传递的固定床吸附分离模型方程,预测了CH_4和N2在沸石ZSM-5上的竞争吸附穿透曲线。进一步采用ZSM-5吸附剂填充床单柱四步真空变压吸附实验考察了进料浓度、进料流速、进料时间以及吹扫比对分离效果的影响。结果发现沸石ZSM-5对CH_4具有较好的选择性,沸石晶粒内的微孔扩散为吸附速率控制步骤,真空变压吸附工艺可将模拟煤层气中20%的CH_4提纯至31%~41%,回收率为93%~98%。     

Comparison of adsorption equilibrium of glycyrrhizic acid and liquiritin on C18 column

The adsorption isotherms of glycyrrhizic acid (GA) and liquiritin (LQ) on a C₁₈ column were compared and the competitive adsorption of the two compounds was investigated. The experimental parameters in the equilibrium isotherms were estimated by linear and nonlinear regression analyses. The adsorption equilibrium data were correlated into the linear, Langmuir, competitive Langmuir, Freundlich, and Langmuir–Freundlich isotherm models. Over a moderate concentration range, the competitive Langmuir isotherm provided the best fit to the experimental data. The regression coefficients of the competitive Langmuir adsorption isotherms were 0.9754 and 0.9855 for the mixtures of GA and LQ, respectively. The coefficients obtained for the five isotherm models confirmed the superiority of the competitive Langmuir isotherm for analyzing the adsorption data of solutes.     

Competitive adsorption of protocatechuic acid and caffeic acid on C18 particles

Comparisons of protocatechuic acid (PA) and caffeic acid (CA) adsorption isotherm on C₁₈ column and competitive adsorption of the two compounds were investigated. By linear and nonlinear regression analysis, the experimental parameters in the equilibrium isotherms were estimated. Adsorption equilibrium data of the two compounds were investigated using six different models including linear, Langmuir, Freundlich, Langmuir-Freundlich, competitive Langmuir and Quadratic. In the moderate range of concentrations, the competitive Langmuir isotherm proved to be the best model for these experimental data. The regression coefficients of the competitive Langmuir adsorption isotherms were 0.9860 for PA and 0.9898 for CA, respectively. The coefficients obtained for the six isotherm models confirmed the superiority of the competitive Langmuir isotherm for analyzing the competitive adsorption data of solutes.     

Single component and competitive adsorption of propane, carbon dioxide and butane on Vycor glass

Equilibrium of gas phase adsorption on Vycor glass has been investigated. Adsorption isotherms for propane, carbon dioxide and butane as pure gases, binary mixtures and ternary mixtures were determined experimentally as a function of temperature using a volumetric method. The single-component isotherms were described with the Langmuir and Freundlich equations. Additionally, a second order isotherm based on statistical thermodynamics and an isotherm equation based on vacancy solution theory taking into account real phase behavior were used for fitting single-component equilibrium data. In order to describe the measured partial isotherms for binary mixtures, at first simple extensions of the single-component isotherm models were used, i.e., the conventional competitive Langmuir model and a multi-Freundlich equation based on the ideal adsorbed solution theory (IAS). Since these two simple isotherm models failed to represent the unusual competitive behavior observed, three model extensions using additional mixture parameters were applied, i.e., two modified multi-Langmuir equations based on: (a) statistical thermodynamics and (b) vacancy solution theory and a modified multi-Freundlich IAS model correcting spreading pressure uncertainties. These three model equations were found to be capable to describe the observed behavior better. Finally, the measured partial adsorption equilibrium data of the ternary system were correlated based on the extended equations using the determined additional binary parameters. The results obtained reveal the difficulty to predict accurately multi-component adsorption equilibria.     

Application of the general rate model with the Maxwell-Stefan equations for the prediction of the band profiles of the 1-indanol enantiomers

The adsorption isotherm data of R- and S-1-indanol and of their racemic mixture on cellulose tribenzoate were measured by frontal analysis. These experimental data were fitted to the single-component and the modified competitive Bilangmuir isotherms. The overloaded elution profiles of bands of the pure enantiomers and of the racemic mixture were calculated for different sample sizes, using the best competitive isotherm model and the General Rate Model of chromatography coupled with the generalized Maxwell-Stefan equation that describes the surface diffusion flux. The calculated and the experimental profiles were found to be in excellent agreement in all cases. The parameters of the model of the mass transfer kinetics were derived from the band profiles obtained for the pure enantiomers. The same values of these parameters give an excellent prediction of the profiles of multicomponent bands. The new model described here allows a satisfactory interpretation of the competitive mass transfer kinetics.     

Prediction of the band profiles of the mixtures of the 1-indanol enantiomers from data acquired with the single racemic mixture

The adsorption isotherm data of R- and S-1-indanol and of their racemic mixture on cellulose tribenzoate were measured by frontal analysis. These data were then fitted to the Langmuir, the Bilangmuir, the Toth, and the Langmuir-Freundlich isotherm models. The single component data fitted well to both the Bilangmuir and the Toth models. Combined with the lumped pore diffusion model (POR) of chromatography, these isotherms were used to calculate overloaded elution profiles of the pure enantiomers. The calculated and the experimental profiles agree excellently in all cases if the former are derived from the Bilangmuir model. The competitive experimental data also gave excellent agreement with the Bilangmuir model. The simultaneous fit of all the data, for the single components and the racemic mixture, gave again superior agreement with the bilangmuir model. The overloaded elution profiles of samples of the racemic mixture calculated with the Bilangmuir isotherm model combined with the POR model of chromatography gave results in very good agreement with the experimental band profiles of large samples of the racemic mixture. This confirms that in numerous cases the whole set of competitive isotherms of two enantiomers can be derived from the experimental data obtained only with the racemic mixture.     

Competitive adsorption of phenol and resorcinol onto rice husk ash

The present study deals with the adsorptive removal of phenol and resorcinol from aqueous solution onto rice husk ash. The competitive adsorption equilibrium of the binary mixtures (phenol/resorcinol) was determined by conducting batch experiments with initial concentration varying in the range of 50 to 1000 mg/L. In order to evaluate multicomponent adsorption isotherm parameters, individual adsorption equilibrium studies were also carried out. Langmuir, Freundlich and Redlich-Peterson equilibrium isotherm models were used for single compound equilibrium sorption data modeling. All three models almost similar fit for single compound equilibrium data. Binary equilibrium adsorption data and the parameter evaluated from single adsorption data were fitted to various multicomponent isotherm models by minimizing the sum of square of error. The extended Langmuir model gave the better fit to the experimental adsorption data of phenol and resorcinol from binary systems onto rice husk ash. It seems that both phenol and resorcinol compete for the same adsorption sites on rice husk ash. The net interactive effect of phenol and resorcinol on the adsorption of resorcinol by rice husk ash was found to be antagonistic.     

PREDICTION OF THE ASYMMETRIC PEAK PROFILE USING A MATHEMATICAL METHOD WITH A COMPETITIVE LANGMUIR ISOTHERM

The adsorption characteristics of a single component and a binary component in the stationary phase using preparative chromatography were investigated with a six-adsorption isotherm model. These analyses were based on the Langmuir model. Each parameter of the adsorption isotherm was obtained with the adsorption raw data that was calculated by frontal analysis (FA). The experimental data and the values calculated using the adsorption isotherm model were compared. The bi-Langmuir model showed good agreement for phenol while the tri-Langmuir model showed good agreement for caffeine. Each characteristic of adsorption was obtained from these results. The effect of competitive adsorption was investigated using the parameters of the adsorption isotherm model with a single component. There was good agreement between the experimental data and the calculated values.     

PREDICTION OF THE ASYMMETRIC PEAK PROFILE USING A MATHEMATICAL METHOD WITH A COMPETITIVE LANGMUIR ISOTHERM

The adsorption characteristics of a single component and a binary component in the stationary phase using preparative chromatography were investigated with a six-adsorption isotherm model. These analyses were based on the Langmuir model. Each parameter of the adsorption isotherm was obtained with the adsorption raw data that was calculated by frontal analysis (FA). The experimental data and the values calculated using the adsorption isotherm model were compared. The bi-Langmuir model showed good agreement for phenol while the tri-Langmuir model showed good agreement for caffeine. Each characteristic of adsorption was obtained from these results. The effect of competitive adsorption was investigated using the parameters of the adsorption isotherm model with a single component. There was good agreement between the experimental data and the calculated values.