Optimized separation of pesticide enantiomers by chiral high-performance liquid chromatography

Summary A computer-assisted method is described for optimization of multi-component, mobile phase selection for separating enantiomers of four pesticides in normal-phase HPLC. The method is based on the triangle, solvent-selection concept using a statistical scanning method. The optimization of the separation over the experimental region is based on a special polynomial estimation from seven experimental runs, and resolution (R_s) is used as the selection criterion. Excellent agreement was obtained between predicted and experimental data.     

Optimization of multicomponent solvent selection in high-performance liquid chromatography using a statistical method

A computer-assisted method is presented for optimization of multicomponent solvent mobile phase selection for separation of O-ethyl-N-isopropyl phosphoro (thioureido) thioates in reversed-phase HPLC and four geometric isomers of pesticides Decis in normal-phase HPLC. The method is based on Snyder's solvent selection triangle concept using a statistical method. The optimization of the separation over the experimental region is based on a special polynomial estimation from seven experimental runs, and resolution (R_s) is used as the selection criterion. Excellent agreement was obtained between predicted data and experimental results.     

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～...     

Computer-assisted optimization of pesticides separation by two-dimensional high-performance thin-layer chromatography

Summary A computer-assisted method is presented for optimization of two mobile phase selection for separation of a mixture of eight pesticides in two-dimensional TLC. Optimization of the separation over the experimental region is based on two special polynomial estimations from preliminary runs of two groups. Using D (distance of two spots) as the selection criterion with a two factor statistical scanning technique excellent agreement is obtained between predicted and experimental results.     

Computer-assisted multifactor optimization of selectivity in gas chromatography

Summary A computer-assisted method is presented for the simultaneous multifactor optimization (stationary phase loading, column temperature and carrier gas flow rate) of the analytical conditions for the optimum separation of multicomponent samples in gas chromatography. The optimization of the separation over the experimental region is based on a special polynomial from twelve preliminary experiments using the resolution as the selection criterion. Computer scanning technique was used for optimum selection in three dimensions. Excellent agreement was obtained between the predicted data and the experimental results.     

Computer-assisted optimization for the selection of mobile phase in semi-preparative HPLC

A computer-assisted method is presented for optimization for the selection of mobile phasecomposition in semi-preparative HPLC.The optimization for the expected separation is based ona polynomial estimation from five preliminary runs.Statistical scanning technique was used foroptimization.Double criteria simulation system (DCSS) is established for chromatographic perfor-mance measurement in this method.The validity of the optimization strategy is confirmed by applyingit to a technical Cypermethrin separation.Excellent agreement is obtained between the predictedand experimental results.     

Optimization of the separation of a mixture of unknown composition by reversed-phase HPLC

A method is presented for the computer-assisted optimization of mobile phaseselection for the separation of a synthetic intermediate of unknown composition by reversed-phase HPLC.The method is based on recognition of the order of the peaks by comparisonof peak area ratio and followed by the BSOS-L(Binary Solvent Optimization System forHPLC)method.Excellent agreement was obtained between predicted data and experimentalresults.     

Advanced simplex optimization of two-factor selectivity by high performance thin-layer chromatography

Summary A computer-assisted mixture design simplex method is presented for optimization of the separation of a mixture of five benzoic acid derivatives in reversephase HPTLC and twelve PTH-amino acids in normal phase HPTLC. A two-factor selectivity rectangle concept was used. The method is based on a special polynomial estimated from nine experimental runs, using the R_F difference as the selection criterion, with connection to a general simplex method for optimization using a microcomputer. Excellent agreement is obtained between predicted data and experimental results, and more than half the number of experiments required in the general simplex method can be omitted.     

Computer-assisted optimization of temperature programming and flow rate in capillary gas chromatography

A computer-assisted method is presented for simultaneous optimization of three-factor of temperature programming (initial temperature, temperature rising rate and carrier gas flow rate) for the separation of eleven compounds in capillary gas chromatography. The optimization of the separation over the experimental region is based on a special polynomial from fifteen preliminary experiments using the resolution as the selection criterion. Computer scanning technique was used for optimum selection on three dimensions. Excellent agreement was found between the predicted data and the experimental results.     

Computer-assisted transposition of conditions in high-performance thin-layer chromatography to high-performance liquid chromatography for the separation of pesticides

Summary A computer-assisted method is presented for mobile phase selection for the optimal separation of pesticides by HPTLC and HPLC. The system is based on a plot of solute retention value and separation criterion vs. binary mobile phase composition for graphic optimization. The result of HPTLC can be transposed to HPLC for optimal separation. The transposition equation is given.     

A modified simplex method for multifactor optimization of selectivity in gas chromatography

A computer-assisted advanced simplex method is presented for the simultaneous optimization of multifactor ( stationary phase loading, carrier gas flow rate and column temperature ) for separation of ten compounds in gas chromatography. A three factors factorial design was used. The method was based on a special polynomial established from fifteen preliminary runs, using resolution as the selection criterion, with connection to a general simplex method. Excellent agreement is found between the predicted data and the experimental results, and most of experiments required in the general simplex method can be omitted.     

Optimization of two-factor(pH and ion concentration)simultaneous selection in HPLC using a statistical method

A computer-assisted method is presented for simultaneous optimization of pH and ion con-centration selection for the optimal separation in reversed-phase HPLC.The method is based on apolynomial estimation from nine preliminary experiments according to two-factor rectangular design.This is followed by a two-dimension computer scanning technique.Resolution is used as the selectioncriterion.Good agreement was obtained between predicted data and experimental results.     

人参皂苷正相薄层色谱二维分离的优化

 在薄层色谱分离人参皂苷的两种互补性的流动相组分比例与皂苷比移值呈相关关系的基础上 ,以薄层色谱分离中距离最小的两点之间的距离Dmin为优化标准 ,对人参皂苷的二维分离结果进行预测和优化。通过计算机扫描不同流动相组成下的Dmin值得到的三维网络图显示出的最大Dmin下的二维流动相的组成 ,即为达到最佳二维分离结果的流动相组成。以优化的流动相对皂苷进行二维展开 ,分离结果与预测结果吻合 ,且比一维展开分离出了更多的新的皂苷组分。     

计算机辅助高效液相色谱梯度洗脱的优化

本文介绍了计算机辅助反相高效液相色谱梯度洗脱优化分离的方法。首先采用混合设计法，通过９个预试验建立目标函数，然后运用双因素（初始流动相组成Ｃ和梯度时间Ｔ）扫描技术，由计算机给出优化分离条件，实验结果和预示完全一致。     

Statistical scanning method for the optimization of gradient elution high performance liquid chromatography

Summary A computer-assisted method is presented for the optimization of separation in gradient elution reversed-phase HPLC. The method is based on a polynomial estimation from nine preliminary experiments according to a two-factor (initial solvent composition C and gradient time T) rectangular design. This is followed by a two-dimension computer scanning technique. Resolution is used as the selection criterion. Good agreement was obtained between predicted data and experimental results.     

Computer-assisted optimization of mobile phase compositions and development distance selectivity in gradient two-step development high-performance thin-layer chromatography

A computer-assisted method is presented for optimization of mobile phase compositions and development distance in gradient two-step development HPTLC. The method is based on a system which can predict the final Rf values for gradient two-step development from values measured using five preliminary runs. The statistical scanning method is then used for optimization, using Rf difference as the selection criterion. The method was evaluated using a mixture of eight components. Excellent agreement was obtained between predicted and experimental results. Gradient two-step development HPTLC, mobile phase composition optimization, velopment distance optimizationde-     

Development and validation of an improved method for the analysis of vancomycin by liquid chromatography selectivity of reversed-phase columns towards vancomycin components

The current method prescribed in official monographs for the purity control of vancomycin is inappropriate in that several components are not separated from each other and other components are coeluted with the main component vancomycin B. The method uses an ODS column at pH 3.2. In this study, several changes were introduced in order to improve the separation. The optimization of the separation method at low pH indicated that pH 1.7 was optimum and that the use of dioxane as organic modifier drastically improved the separation. These conditions were used to test a set of more than 40 reversed-phase columns for their selectivity towards vancomycin components. The selection of the most suitable columns was performed by means of principal component analysis. Most of these columns did not allow the separation of didechlorovancomycin from monodechlorovancomycin 1. It was found that neutral to slightly alkaline mobile phases allowed better separation. Further optimization of the separation method and a robustness study were performed by means of experimental design. This optimization indicated that pH 7.7 was optimum and gradient elution was also used to effect complete analysis. The final method uses a Kromasil column and the mobile phase comprises dioxane, water and ammonium formate solution pH 7.7. The separation of monodechlorovancomycin 2 and of some unknown impurities from the main component vancomycin B is described for the first time. The method shows good repeatability, linearity and sensitivity.     

Solvent optimization of reversed-phase high-performance liquid chromatography for polar adrenal steroids using computer-predicted retentions

Computer-aided optimization of a mobile phase has been applied to the isocratic reversed-phase separation of ten polar adrenocortical steroids, including aldosterone and reduced metabolites of cortisol and cortisone. A method based on a seven-step procedure for calculation of the Chromatographic Optimization Function (COF) has been used. Logarithmically transformed retention indices were used for computing multiple polynomial regressions for the retention times of compounds as a function of solvent composition, with the resultant COF as a dependent parameter used for selection of the better mobile phase. Peak crossovers and overlaps are accommodated in this method and the maximum acceptable analysis time factor is incorporated as well as weighting factors for priority separations. The utility of this procedure for complex mixtures of closely eluting compounds is discussed with respect to the Overlapping Resolution Map method and with the COF method of Glajch and Kirkland as used for automated optimization. Its application to aldosterone-containing samples from human adrenocortical tumours is illustrated.     

A method for characterization and optimization of reversed-phase liquid chromatographic separations based on the retention behaviour in homologous series

Summary A method based on the use of the members of homologous series as the calibration standards is suggested for prediction of retention in reversed-phase liquid chromatography. The method respects the dependence of retention on the composition of the mobile phase and makes possible distinguishing between the contributions of non-specific (hydrophobic) and specific (polar) interactions to the retention. The selection of calibration homologous series is described, the method is verified for a number of compounds and compared to the calculations based on the model of interaction indexes. The method suggested can be used for prediction of retention in mobile phases with different compositions and for the optimization of separation conditions. Presented at the 15th International Symposium on Chromatography, Nürnberg, October 1984     

Optimization of Solvent Composition for High Performance Thin-Layer Chromatography

Abstract

The methodology of mixture experiments has been applied to optimize the multicomponent solvent composition for high performance thin-layer chromatography (HPTLC). In this study, a mixture of five solvents for the mobile phase was maximized for the separation of twelve structurally related B(a)P metabolites on normal phase HPTLC plates. Volume fractions (rather than absolute quantities) of the mobile phase solvents were constrained by upper bounds by considering solvent strength. These restrictions defined an experimental region that is an irregular polyhedron formed from a truncated 4-dimensional simplex. The optimization of the expected separation response over the experimental region was based on a second-order Scheffé polynomial estimated from twenty-five experimental runs. Six functions for measuring separation based on R_f values were evaluated. A new response function is proposed that overcomes the difficulties of previously published criteria.