Stereo- and enantioselective determination of pesticides in soil by using achiral and chiral liquid chromatography in combination with matrix solid-phase dispersion

The separation of enantiomers and diastereomers of 8 commonly used pesticides was investigated by liquid chromatography (LC) using a Chiralcel OD column (cellulose tris-3,5-dimethylphenylcarbamate as the chiral stationary phase) and a Pirkle-type Chirex 3020 column (urea derivative from the reaction of (R)-1-(alpha-naphthyl)ethylamine with (S)-tert-leucine, chemically bonded to 3-aminopropylsilanized silica as the chiral stationary phase). The pesticides studied included one organophosphorus insecticide (phenthoate), 3 triazole fungicides (uniconazole, diniconazole, and propiconazole), and 4 pyrethroids (fenpropathrin, beta-cypermethrin, beta-cyfluthrin, and alpha-fenvalerate). The enantiomers were separated within 20 min with a resolution of > or = 1.5 using a mixture of n-hexane and 2-propanol as the mobile phase for all the pesticides studied except propiconazole, for which only the 2 diastereomers were baseline separated. This method allows determination of the enantiomers or stereoisomers of the above pesticides in soil. The strategy was as follows: (1) First, the total concentration(s) of the enantiomer pair(s) of a chiral pesticide in soil was (were) determined by a newly developed matrix solid-phase dispersion (MSPD) procedure, followed by silica-based LC quantification. The recoveries ranged from 76.5 to 93.6% with relative standard deviations of 6.0%. (2) Second, the enantiomeric ratio(s) (ER(s)) of the chiral pesticide was (were) determined by LC with a chiral stationary phase after fractionation of the MSPD extract by silica-based LC. The determined ERs or stereoisomeric ratio(s) (SR(s); for propiconazole, only the SR of the 2 diastereomers was determined) in soil samples spiked with the above 8 racemic pesticides agreed with those of the corresponding standard solutions. (3) Third, based on the total concentrations and the corresponding ERs, the concentration of each enantiomer in soil was calculated. The proposed method is rapid, precise, and sensitive, and is appropriate for the investigation of the stereo- and enantioselective degradation of pesticides in environmental media.     

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 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.     

衍生化环糊精键合固定相色谱保留和手性识别机理的研究(Ⅰ)

合成了苯基氨基甲酸酯衍生化β-环糊精键合固定相,14个α-氨基膦酸酯类化合物首次在该固定相和商品化的(S)-(+)-萘乙基氨基甲酸酯衍生化β-环糊精固定相上进行液相色谱手性拆分.通过定量结构-对映异构体保留关系对比研究了两种不同的环糊精类固定相上可能的色谱保留和手性识别机理.     

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～...     

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.     

计算机辅助合成最优化方法研究(I)——Azodrin合成反应优化条件选择

本文提出了一种计算机辅助有机合成条件(摩尔比,反应物浓度,处理时间)最优化选择方法.方法的基础是通过15个预实验建立一个多项式,然后用计算机扫描技术来优化,含量与得率作为优化指标.方法用于工业久效磷的合成,结果表明预示与实验结果非常一致.     

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.     

反相薄层色谱法测定1-1,2,4-三唑类杀菌剂的疏水性

1-1 ,2 ,4-三唑类农药是本世纪 60年代初期发展起来的新型杀菌剂 ,具有广谱、高效和内吸等优点 ,一直是农药研究的热门课题 [1] .多年的研究表明 ,其疏水性与活性有很好的相关性 ,因此快速准确地测定其疏水性显得十分重要 .与传统的振荡方法测定化合物的疏水性相比 ,反相高效液相色谱法( RP-HPLC) [2～ 4 ] 和反相薄层色谱法 ( RP-TL C) [5,6 ] 简单、快速、经济 ,所需样品量很少 ,对样品纯度要求也不高 .尤其是薄层色谱法所需仪器简单 ,耗时更短 .本文以甲醇 -水混合物为展开剂测定了我们合成的 2 3种新型三唑类化合物在 C2高效薄层板…     

The correlation between molecular structure parameters of O-ethyl N-isopropyl phosphoro(thioureido)thioates and their retention data in RP-HPLC

A retention prediction system(RPS)of seven O-ethyl N-isopropyl phosphoro(thioureido)-thioates in reversed phase HPLC was investigated.The system is based on the solvent selectivitytriangle concept.Three molecular structure parameters(hydrophobicity Ⅱ,substituent length L,and substituent maximum width B_5)were used to describe the quantitative structure-retention relation-ships.With these quantitative relationships,the retention behaviours of other eight homologsfor different mobile phase composition were predicted.The predicted values were consistent with themeasured values within relative error of 10%,which means that it is possible to apply the reportedmethod to predict retention values for qualitative purposes for different mobile phase compositions.