德国MN液相色谱柱产品特点:
Nucleodex 环糊精类型手性柱
环糊精是含葡糖单元的环状低聚糖。zui常见的有α、β和γ环糊精，它们都是手性结构。β环糊精有35个手性点，如下图，环糊精是一种穴状结构，含有七个葡糖单元，大小是7.5Å；α环糊精有六个葡糖单元，大小是5.7Å；γ环糊精有八个葡糖单元，大小是9.5Å；由于环糊精的内部是亲脂性的，非极性的样品（如含苯或萘结构），并具有合适的大小能够穿透这种穴的结构。这种现象称为包含配位（inclusion complex），而样品穿过环糊精结构时产生的各种作用力，达到了手性分离的结果。
Nucleodex 液相色谱柱的手性基团如下
定相组成
Nucleodex是在高性能5um，100 A规格Nucleosil球形硅胶上衍生环糊精系列液相手性色谱柱。包括β-OH、α-PM、β-PM、和γ-PM四个系列。能够满足农药和医药领域大量手性化合物的反相分离。MN商品名称 | 德国MN液相色谱柱定相组成 | 分离原理 |
Nucleodex β-OH | 化学键合相：β-环糊精 | 立体对位原理（Cavity） |
Nucleodex α-PM | 化学键合相：预甲基化α-环糊精 |
Nucleodex β-PM | 化学键合相：预甲基化β-环糊精 |
Nucleodex γ-PM | 化学键合相：预甲基化γ-环糊精 |
PM系列中的环糊精所有羟基被羟甲基所取代，产生了不同的选择特性。如下图所示，由于PM环糊精与被测样品的共价作用只有氧，所以通常条件下，PM环糊精对样品的保留时间比OH环糊精要短。例如在常见的巴妥类样品Prominal，PM甲基化的环糊精就能够得到满意的分析结果。
 β-OH中的羟基不能对样品手性分离产生作用，结果只是增加保留时间，不提高手性分离度。NUCLEODEX | 
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Cyclodextrin-modified silica phases
for HPLC enantiomer separation |
Features |
| Base material NUCLEOSIL® silica, particle size 5 μm, pore size 100 Å
modified cyclodextrins as chiral selectors |
| NUCLEODEX β-OH: β-cyclodextrin (R = H; n = 2) ? USP L45
Separation based on hydrogen bonds and dipole interactions between functional groups of the analyte and hydroxyl groups of the cyclodextrin
Examples for successful enantiomer separations: chlorthalidone and other compounds, which require free hydroxyl groups for enantioselective interactions
Eluent in column CH3OH – 0.1 % TEAA pH 4 (55:45) |
| NUCLEODEX α-PM: permethylated α-cyclodextrin (R = CH3; n = 1)
For all permethylated phases the ability to form hydrogen bonds is reduced, the hydrophobicity of the phase is increased compared to β?OH, resulting in shorter retention times .
Examples for successful enantiomer separations: mecoprop and dichlorprop as free carboxylic acids,trans-stilbene oxide and styrene oxide
Eluent in column CH3OH – 50 mM phosphate pH 3 (70:30) |
| NUCLEODEX β-PM:
permethylated β-cyclodextrin (R = CH3; n = 2) ? USP L45
Examples for successful enantiomer separations:
mephobarbital (prominal), pesticides derivatives mecoprop-methyl etfenoxaprop-ethyl
Eluent in column CH3OH – 0.1 % TEAA pH 4 (65:35) | 
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| NUCLEODEX γ-PM:
permethylated γ-cyclodextrin (R = CH3; n = 3)
Examples for successful enantiomer separations:
steroids or other larger molecules
Eluent in column CH3OH – 0.1 % TEAA pH 4 (55:45) |
| NUCLEODEX phases are especially suited for the control of optical purity, but also for semipreparative separations and for the analysis of positional and cis-trans isomers.
For more applications click here. |
