智能多柱系统选择性优化研究

复杂混合物样品分高应采用统一方法、多柱系统。多元切换或多柱串联调节选择性在仪器和操作上均不适合作为通用方法。因此提出了智能多柱系统的概念,探讨了智能多柱系统选择性优化原则和多柱系统选择性优化方法。对多种官能团取代基化合物混合物样品,最佳多柱系统是针对其中的特殊重叠组分进行的,一般采用选择性有足够差别的弱极性柱子组成最佳多柱系统。对同族化合物异构体复杂混合物,多拄系统一般采用作用距离和分子构型差别大的柱子组成多柱系统,对光学异构体则必须采用相应的手性柱子组成多柱系统。     

Modelling the gas chromatographic separation of multicomponent samples on a system of three open-tubular columns coupled in series

A procedure was developed for modelling the gas chromatographic separation on a system of columns coupled in series. This procedure can be used for computer based optimization of lengths and order of serially coupled columns at isothermal conditions. The sample component retention factors and column resistances needed for the model can easily be measured on each individual column. The proposed procedure was verified by analyzing a 52 component hydrocarbon mixture on three columns of different polarity coupled in series by various column orders. Good agreement between experimental and calculated retention data was found. The procedure is also well suited for optimization of the chromatographic selectivity by coupling columns with different selectivity in series.Dedicated to Professor Dr. h.c. mult. J.F.K. Huber on the occasion of his 70th birthday     

Automated liquid chromatographic analysis of drugs in urine by on-line sample cleanup and isocratic multi-column separation

A multi-column system has been developed for automated analysis of basic drugs in urine. Two polymeric pre-columns, containing PRP-1 and Aminex A-28, were used to isolate the drugs. A short reversed-phase column, coupled to a 150 x 4.6 mm I.D. silica column, produced the analytical separation. Sample preparation consisted of dilution and centrifugation. The entire procedure required less than 30 min. Careful optimization of mobile phase conditions led to retention of benzoylecgonine and barbiturates. For most drugs, levels of 0.3 mg/l were sufficient to produce peaks that could be matched against stored spectra with a computerized library search program.     

Optimization and characterization of the chiral separation of citalopram and its demethylated metabolites by response-surface methodology

Summary Response-surface modelling and sequential optimization have been used for optimization and characterization of the separation of the enantiomers of citalopram, desmethylcitalopram, and didesmethylcitalopram on an acetylated β-cyclodextrin column. In the model chosen the separation conditions mobile phase methanol content, buffer concentration, column temperature, and pH were varied to investigate their influence on the chromatography. It was found that what is good for selectivity within an enantiomer pair is bad for selectivity between enantiomer pairs. Because within-pair and between-pair selectivity does not reach its optimum at the same conditions, a middle course approach has to be followed. Use of an experimental design for this investigation enabled understanding of the mechanisms of within- and between-pair separation for citalopram, desmethylcitalopram, and didesmethylcitalopram. Sequential optimization can be a quicker means of optimizing a chromatographic separation; response-surface modelling, in addition to enabling optimization of the chromatographic process, also serves as a tool for leaming more about the separation mechanism.     

Optimization of simulated moving bed and Varicol processes

A new continuous chromatographic process (Varicol) has been presented recently. Its basic principle consists, in contrast to the traditional simulated moving bed (SMB) technology, of an asynchronous shift of the inlet/outlet lines in a multi-column system with a recycle loop. Due to the stronger influence of the discrete dynamics on the plant behavior, the design of a Varicol process requires the use of model-based optimization to take advantage of the very high flexibility of this process. The equilibrium theory which has been successfully applied to SMB by many practitioners fails to predict the region of complete separation accurately. In this paper, we present a rigorous model-based optimization framework, which can handle the SMB and the novel Varicol process in a systematic manner. The feasibility of the approach is demonstrated by the separation of a mixture of propranolol isomers which exhibits a highly non-linear multi-component adsorption behavior. Experimental results are presented and discussed.     

Application of a flow-tunable, serially coupled gas chromatographic capillary column system for the analysis of complex mixtures

Summary A capillary column gas chromatographic system employing two serially coupled fused-silica columns and a simple coupling element is described. The system is operated in flow-tunable mode (flow-tunable tandem system). The very fact of continuous tuning over a large polarity (selectivity) range, ultimately determined by the two constituent columns, offers several possibilities in the analysis of complex mixtures. In this paper two applications are discussed in detail: optimization of peak separation and peak identification. For these applications it is feasible to use, retention data collected from experiments on the tandem system, and empirical formulas. A relatively simple theoretical mathematical model valid for the flow-tunable tandem system, however, furnishes an easy way of calculating retention data on the system from data collected from the individual single columns, thus, creating a new possibility for optimization and peak identification. Optimization and peak identification processes using the empirical and theoretical models are both demonstrated by analysis of solvent mixtures. Dedicated to the memory of Dr. Tibor Tóth Presented at Balaton Symposium on High-Performance Separation Methods, Siófok, Hungary, September 1–3, 1999     

Artificial neural networks modeling in ultra performance liquid chromatography method optimization of mycophenolate mofetil and its degradation products

The study of experimental design in conjunction with artificial neural networks for optimization of isocratic ultra performance liquid chromatography method for separation of mycophenolate mofetil and its degradation products has been reported. Experimental design showed to be suitable for selection of experimental scheme, while Kennard‐Stone algorithm was used for selection of training data set. The input variables were column temperature and composition of mobile phase including percentage of acetonitrile, concentration of ammonium acetate in buffer, and its pH value. The retention factor of the most retentive component and selectivity factors were used as the dependent variables (outputs). In this way, artificial neural network has been applied as a predictable tool in solving a method optimization problem using small number of experiments. Network architecture and training parameters were optimized to the lowest root‐mean‐square error values, and the network with 5‐4‐4‐4 topology has been selected as the most predictable one. Predicted data were in good agreement with experimental data, and regression statistics confirmed good ability of trained network to predict compounds retention. The optimal chromatographic conditions included column temperature of 40°C, flow rate of 700 µl min⁻¹, 26% of acetonitrile and 9 mM ammonium acetate in mobile phase, and buffer pH of 5.87. The chromatographic analysis has been achieved within 5.2 min. The validation of the proposed method was also performed considering selectivity, linearity, accuracy, precision, limit of detection, and limit of quantification, and the results indicated that the method fulfilled all required criteria. The method was successfully applied to the analysis of commercial dosage form. Copyright © 2014 John Wiley & Sons, Ltd.     

Diffusion coefficients in liquids by HPLC and the respective calibration factors

When an analyte can be chromatographed on a HPLC column using a suitable solvent, the diffusion coefficient of this analyte into the solvent can easily and accurately be determined, together with the calibration factor of the detector for this analyte. The experimental arrangement needed is based on a slight modification of the HPLC valve so that the analyte is introduced into the chromatographic column via a short diffusion column filled with the solvent. The new method is theoretically developed and the required mathematical relations have been derived. As an example, the diffusion coefficient of liquid benzene in chloroform, together with its calibration factor, are measured, under various experimental conditions, and the values found compare very well with that calculated by Wilke-Chang formula. Diffusivities and calibration factors of ions in aqueous liquid systems can also be determined by the new method.Dedicated to Professor Dr. Dr. h.c. mult. J. F. K. Huber on the occasion of his 70th birthday     

Evaluation of a complete HPLC solvent optimization system involving piece-wise quadratic modelling

Summary Interpretive methods are accepted to give the best possible results for selectivity optimization in HPLC. However the methods are very complex, and most work so far has been detailed academic studies. This paper describes an evaluation of a complete integrated system incorporating peak labelling, modelling of retention behaviour and calculation of response surfaces, with particular emphasis on the retention modelling. The peak labelling section has been discussed previously.A piece-wise quadratic function is investigated for the modelling of retention times across an isoeluotropic plane to effect selectivity optimization in HPLC. This requires 10 data-points on the isoeluotropic plane. The predicted global optimum and local optima are evaluated by comparison of calculated and experimental retention data, for a nine component sample. Seven interstitial points, distributed across the whole plane between the data-points, are similarly evaluated for a related sample. The typical error (in retention time) is less than 2%, often 1%, and the maximum error is 4.2%. At the global optimum the error was found be less than 1.3% for all 9 peaks.     

计算机辅助柱色谱最优化分离氨基酸

计算机辅助柱色谱最优化分离氨基酸王琴孙，颜炳文，王寿亭，陶雪（南开大学元素有机化学研究所，天津，３０００７１）（南开大学高分子化学研究所）关键词计算机，色谱最优化，柱色谱微型计算机的发展推动了整个色谱优化领域的发展，也陆续出现了一些优化分离方法［１～...     

Criteria for judging the quality of separation in chromatograms containing solvent peaks

Summary Formal procedures used for optimizing chromatographic selectivity require objective, numerical functions to assess the quality of each chromatogram obtained during the process. Many of such optimization criteria have been suggested for chromatograms in which all or a number of well-shaped peaks need to be separated. This paper describes a method by which resolution can be measured in chromatograms in which very large, highly non-symmetrical background peaks,e.g. typical solvent peaks, are present. Using this method, various optimization criteria can be calculated. The method is evaluated using a simulation program which constructs chromatograms from the recorded profiles of individual experimental peaks. It is also demonstrated for use in an experimental optimization procedure in reversed-phase liquid chromatography.     

Simulated moving bed chromatography for the separation of enantiomers

Simulated moving bed (SMB) chromatography, a continuous multi-column chromatographic process, has become one of the preferred techniques for the separation of the enantiomers of a chiral compound. Several active pharmaceutical ingredients, including blockbuster drugs, are manufactured using the SMB technology. Compared to single column preparative chromatography, SMB separations achieve higher productivity and purity, while reducing the solvent consumption. The SMB technology has found applications both at small and large scales. Design methods have been developed for robust operation and scale-up, using data obtained from analytical experiments. In the last few years, rapid developments have been made in the areas of design, improved process schemes, optimization and robust control. This review addresses these developments, as well as both the fundamentals of the SMB science and technology and some practical issues concerning the operation of SMB units. Particular emphasis is placed on the consolidation of the “triangle theory”, a design tool that is used both in the academia and industry for the design of SMB processes.     

多柱色谱技术进展

在色谱分析过程中，利用串联、并联或串并联结合的方式将多根色谱柱组合起来，可以实现高通量和高分辨的分离效果。相比于传统单柱色谱技术，多柱技术很好地满足了批量样品分析和复杂生物样品分离分析的需求，因此引起了广泛关注。该文对多柱技术在多维分离、芯片色谱、毛细管电泳、固定相筛选以及串联色谱等领域的应用进行了综述，并对其发展前景进行了展望。     

Rapid method development for chiral separation in drug discovery using multi-column parallel screening and circular dichroism signal pooling

A novel strategy for rapid chiral method development has been developed using multi-column parallel screening and circular dichroism (CD) signal pooling. Described is the first use of a customized HPLC system that integrates an HPLC auto-sampler, one pump and five divided channels with five columns and five UV detectors to screen five chiral stationary phases (CSPs) simultaneously in parallel. A high-pressure semi-prep on-line pre-filter, a six-port manifold and five individually adjusted backpressure restrictors were installed in the system which allowed the sample and mobile phase to be evenly distributed over the five columns and UV detectors. The five CSPs, namely Chiralpak AD and AS, Chiralcel OJ and OD and Whelk-O1, were screened. The system guarantees a five-fold increase in speed for chiral column scouting compared with the widely used automated sequential column switching approach, and does not have the limitations of the coupled column screening approach for enantiomers whose elution order could be reversed on CSPs. Furthermore, the five channels after the UV detectors were recombined using a reversed flow splitter into a CD detector. The pooled CD signal from the five channels was recorded to track the elution order of the resolved enantiomers and to determine their sign, positive or negative. The signal pooling allows for the effective use of a single CD detector for multiple columns since unresolved racemate has little CD signal, and observing the sign of CD signal for one of the two enantiomer UV peaks is sufficient for tracking the enantiomeric elution order.     

Comparison of polymer resolution in thermal field-flow fractionation and size-exclusion chromatography

A comparison of the resolving power of themal field-flow fractionation (thermal FFF) and size-exclusion chromatography (SEC) has been made by the experimental operation of a high-resolution system from each category. For the experimental systems used, the measured resolution for thermal FFF was found to be higher than that for SEC for three different binary polymer mixtures. Only for a single low-molecular-weight mixture falling outside the optimal operating range of thermal FFF did SEC show better resolution. The experimental resolution values were broken down into selectivity and column efficiency parameters. While selectivity was easily obtained, column efficiency required a correction for polydispersity effects. With the polydispersity correction made on the basis of thermal FFF data, true resolution values were calculated to replace the apparent or experimental resolution levels. Overall, the corrected resolution values showed that thermal FFF had a significant advantage over SEC. Prospects for future advances in these two techniques are discussed.     

Optimizing the gas chromatographic separation and detection of polychlorinated biphenyls by use of electronic pressure programming and experimental design

The applicability of electronic pressure control and Taguchi L₂₇ experimental design to the optimization of the gas chromatographic separation and detection of polychlorinated biphenyls has been evaluated. The influence of several experimental variables, column temperature program, carrier gas pressure program, on-column injector temperature program, and make-up gas pressure program, was studied using analysis of variance. Simultaneous optimization of sample introduction, column efficiency, and detector performance could be achieved without compromising system performance. The relationships between system performance and experimental variables were established using regression analysis. Agreement between the simulated and experimental results obtained using suggested optimum conditions demonstrated the applicability of the technique developed in this study. The improvement achieved in the chromatographic separation of PCBs is presented.     

反相高效液相三元流动相台阶梯度分离条件的快速优化方法

 根据溶质在柱内的迁移规律 ,建立了一种利用线性梯度实验快速获得溶质保留值方程系数 ,然后以串行响应函数为优化指标进行多台阶梯度分离条件优化的方法。与利用等度实验获得保留值方程的方法相比 ,该法可以大大缩短优化时间。通过该方法对芳香胺和衍生化氨基酸样品进行了分离 ,获得了满意的分离度 ,表明该方法的预测精度很好。     

万古霉素及其杂质的亲水作用色谱分析

目前,万古霉素色谱分析方法主要为反相色谱法,该法分离万古霉素及其杂质时,存在极性选择性不足以及所使用的流动相体系与质谱兼容性差等问题。基于亲水作用色谱(HILIC)对糖肽类物质的色谱保留和极性选择性,本文选取万古霉素及其常见杂质为对象,考察了HILIC固定相、流动相组成比例、缓冲盐添加剂浓度和pH值等色谱条件,对万古霉素及其主要杂质进行了HILIC分离方法研究。确立了以Click XIon色谱柱为固定相,以甲酸铵为流动相添加剂的亲水作用色谱条件,实现了万古霉素及主要杂质的分离,为万古霉素类化合物的分离提供了新的途径。     

Polarity change in capillary GC by serial-column temperature optimization (SECAT mode in capillary GC)

GC, including capillary GC, is rather inflexible, if a certain column length and stationary phase has been fixed for a given analytical problem. If the sample composition changes, one often has to change the column length and/or stationary phase, at least when something like optimum analytical conditions are needed. Temperature changes (or heating rates) can change the selectivity of a given column only within very limited ranges, due to the exponential effect of temperature on retention time. By serial coupling two chemically different capillaries, each run at another temperature, even the slightest changes of these two temperature values have a dramatic effect on the selectivity of the system for polar substances. We call this technique the SECAT mode of GC. Results are reported as retention index shifts, dependent on SECAT temperature data. This technique can in future easily be automated, thus enabling the analyst, for polar sample analysis, to adjust a given chroma-tographic system to his specific sample composition without touching the instrument.     

Chiral separation of amino-alcohols using extractant impregnated resins

The performance of extractant impregnated resin (EIR) technology for chiral separation of amino-alcohols has been investigated. Phenylglycinol was selected as an archetype model enantiomer and azophenolic crown ether was used as a versatile enantioselective extractant. 1-Phenyloctane was selected as a suitable solvent for this application because of its very low solubility in water. The extraction system was first evaluated by liquid-liquid equilibrium experiments. It was shown that crown ether dissolved in 1-phenyloctane has an intrinsic selectivity of 11.5. However, due to very low solubility of phenylglycinol in 1-phenyloctane, the overall capacity of the crown ether solution in 1-phenyloctane is limited. The extractant solution was immobilized in macroporous polypropylene particles. Competitive sorption isotherms were obtained from batch experiments and successfully described with a predictive model based on the complexation constants and partitioning ratios, either obtained from literature or from independent experiments. The equilibrium selectivity of these EIRs approaches the intrinsic selectivity for low phenylglycinol concentrations. The dynamic behaviour and stability of the system were examined in column experiments. Breakthrough profiles as well as the elution curves of the R enantiomer are less sharp than those of the S enantiomer proving that the R enantiomer is strongly retained on the column. Separation of phenylglycinol enantiomers is favoured by using lower feed flow rates. The column was regenerated by water with only atmospheric carbon dioxide dissolved which proved to be sufficient. After several cycles the breakthrough profiles remain unchanged suggesting that these EIRs will be sufficiently stable.