德國MN液相色譜柱產品特點:
Nucleodex 環糊精類型手性柱
環糊精是含葡糖單元的環狀低聚糖。zui常見的有α、β和γ環糊精，它們都是手性結構。β環糊精有35個手性點，如下圖，環糊精是一種穴狀結構，含有七個葡糖單元，大小是7.5Å；α環糊精有六個葡糖單元，大小是5.7Å；γ環糊精有八個葡糖單元，大小是9.5Å；由于環糊精的內部是親脂性的，非極性的樣品（如含苯或萘結構），并具有合適的大小能夠穿透這種穴的結構。這種現象稱為包含配位（inclusion complex），而樣品穿過環糊精結構時產生的各種作用力，達到了手性分離的結果。
Nucleodex 液相色譜柱的手性基團如下
定相組成
Nucleodex是在高性能5um，100 A規格Nucleosil球形硅膠上衍生環糊精系列液相手性色譜柱。包括β-OH、α-PM、β-PM、和γ-PM四個系列。能夠滿足農藥和醫藥領域大量手性化合物的反相分離。MN商品名稱 | 德國MN液相色譜柱定相組成 | 分離原理 |
Nucleodex β-OH | 化學鍵合相：β-環糊精 | 立體對位原理（Cavity） |
Nucleodex α-PM | 化學鍵合相：預甲基化α-環糊精 |
Nucleodex β-PM | 化學鍵合相：預甲基化β-環糊精 |
Nucleodex γ-PM | 化學鍵合相：預甲基化γ-環糊精 |
PM系列中的環糊精所有羥基被羥甲基所取代，產生了不同的選擇特性。如下圖所示，由于PM環糊精與被測樣品的共價作用只有氧，所以通常條件下，PM環糊精對樣品的保留時間比OH環糊精要短。例如在常見的巴妥類樣品Prominal，PM甲基化的環糊精就能夠得到滿意的分析結果。
 β-OH中的羥基不能對樣品手性分離產生作用，結果只是增加保留時間，不提高手性分離度。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. |
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