Ghanem Ashraf
Biomedicinal Chemistry Unit, Biological and Medical Research Department, King Faisal Specialist Hospital and Research Centre, (MBC-03-95), Riyadh, Saudi Arabia.
J Sep Sci. 2007 May;30(7):1019-28. doi: 10.1002/jssc.200600357.
Chiralpak IB, a new chiral stationary phase (CSP) containing cellulose tris(3,5-dimethylphenylcarabamate) immobilized onto silica gel, is investigated for the direct enantioselective separation of a set of racemic N-alkylated barbiturates and analogs of thalidomide alkylated in position 3 of the piperidin-2,6-dione ring using different nonstandard solvents such as dichloromethane (DCM), ethyl acetate, THF, methyl tert-butyl ether as an eluent and diluent, respectively, in HPLC. The separation, resolution, and elution order of the investigated compounds were compared on both immobilized and coated cellulose tris(3,5-dimethylphenylcarbamate) CSPs (Chiralpak IB and Chiralcel OD, respectively) using a mixture of n-hexane/2-propanol (90:10 v/v) as mobile phase with different flow-rates and fixed UV detection at 254 nm. The effect of the immobilization of the cellulose tris-(3,5-dimethylphenylcarbamate) CSP on silica (Chiralpak IB) on the chiral recognition ability was noted as the coated phase (Chiralcel OD) possesses a higher resolving power in some cases than the immobilized one (Chiralpak IB). However, a few racemates, which were not or poorly resolved on the immobilized Chiralpak IB or the coated Chiralcel OD when using standard solvents were most efficiently resolved on the immobilized Chiralpak IB upon using nonstandard solvents. Furthermore, the immobilized phase withstands the nonstandard (prohibited) HPLC solvents mentioned previously when used as eluents or as a dissolving agent for the analyte itself. An example of inversion or apparent inversion of elution order on Chiralpak IB is reported. The direct analysis of a spiked plasma sample extracted using DCM on Chiralpak IB is also shown.
手性固定相Chiralpak IB是一种将三（3,5-二甲基苯基氨基甲酸酯）纤维素固定在硅胶上的新型手性固定相（CSP），本文研究了它用于直接对映选择性分离一组外消旋N-烷基化巴比妥酸盐以及沙利度胺在哌啶-2,6-二酮环3位烷基化的类似物，在高效液相色谱（HPLC）中分别使用不同的非标准溶剂如二氯甲烷（DCM）、乙酸乙酯、四氢呋喃、甲基叔丁基醚作为洗脱剂和稀释剂。使用正己烷/2-丙醇（90:10 v/v）混合物作为流动相，在不同流速下并固定紫外检测波长为254 nm，比较了在固定化和涂覆型三（3,5-二甲基苯基氨基甲酸酯）纤维素手性固定相（分别为Chiralpak IB和Chiralcel OD）上所研究化合物的分离、拆分及洗脱顺序。注意到将三（3,5-二甲基苯基氨基甲酸酯）纤维素手性固定相固定在硅胶上（Chiralpak IB）对其手性识别能力的影响，因为在某些情况下涂覆型固定相（Chiralcel OD）比固定化固定相（Chiralpak IB）具有更高的拆分能力。然而，一些外消旋体在使用标准溶剂时在固定化的Chiralpak IB或涂覆型的Chiralcel OD上未得到拆分或拆分效果不佳，但在使用非标准溶剂时在固定化的Chiralpak IB上得到了最有效的拆分。此外，当用作洗脱剂或分析物本身的溶解剂时，固定化固定相能耐受前面提到的非标准（禁用）HPLC溶剂。报道了在Chiralpak IB上洗脱顺序反转或明显反转的一个例子。还展示了在Chiralpak IB上对用DCM萃取的加标血浆样品的直接分析。
