Development of on-site chiral switching micro columns

近年来，光学活性和生物活性化合物的外消旋或D-氨基酸等在体内的作用已被阐明。此外，由于手性药物的光学纯度的测量由于副作用等问题而变得重要，手性分离的重要性日益增加，同时，小型化的分析设备也在迅速发展。只有小型化装置中的分离系统几乎没有得到改善，因为大多数情况下分离系统和流动系统是集成在一个系统中的。本研究开发了一种可以通过光照射改变对映体洗脱顺序的微柱，分别以D-和L-缬氨酸为原料制备了两种含偶氮苯基团的光敏手性固定相(CSP(1)和CSP(2))。将制备的固定相连续填充到紫外光透过性聚合物涂层的熔融石英毛细管(100 mm，i.d.)中。分别具有20 cm的长度，并用作微柱。以3，5-二硝基苯甲酰基-D、L-亮氨酸异丙酯和3，5-二硝基苯甲酰基-D、L-丙氨酸甲酯为样品，用紫外光照射柱中CSP(1)的一部分后，按D-型和L-型洗脱。当可见光照射到CSP(1)后，紫外光照射到CSP(2)的部分，洗脱顺序变为L型和D型。可见，保留顺序的可逆变化是由于紫外光照射降低了固定相对映体选择性所致。

Recently, the racemization of optically-active and bioactive compounds or the role of D-amino acids etc. in vivo have been cleared. Additionally, the importance of chiral separation is increasing because the measurement of optical purity of chiral drug substances becomes important due to the side-effect problem etc., Meanwhile, the downsizing analytical devices are rapidly advanced. Only the separation system in the downsizing device is hardly improved because, in most case, the separation and flow systems are integrated in the same system.In this study, A micro column that is able to change the elution order of enantiomers by photo-irradiation was developed.Two photo-responsive chiral stationary phases (CSP(1) and CSP(2)) with an azobenzene moiety were prepared using D-and L-valine, respectively. Prepared stationary phases were continuously packed into a UV-permeable polymer-coated fused silica capillary tubing (100 mm, i.d.) with 20 cm of length, respectively, and used as a micro column. When 3,5-dinitrobenzoyl-D,L-leucine isopropyl ester and 3,5-dinitrobenzoyl-D,L-alanine methyl ester were used as test samples, the samples were eluted in this order, D-form and L-form, after a UV light was irradiated to only the part of CSP(1) in the column. Continuously, when a UV light was irradiated to the part of CSP(2) after a visible light was done to the CSP(1), the elution order became L-form and D-form. It can be seen that the reversible change in the retention order was caused by the reduction of the enantio-of the enantio-selectivity of the stationary phase by the UV light irradiation.