Lin C E, Chen H W, Lin E C, Lin K S, Huang H C
Department of Chemistry, National Taiwan University, Taipei.
J Chromatogr A. 2000 May 26;879(2):197-210. doi: 10.1016/s0021-9673(00)00301-0.
The influences of buffer pH, buffer concentration and buffer electrolyte on the migration behavior and separation of 12 cephalosporin antibiotics in capillary zone electrophoresis using three different types of buffer electrolyte, including phosphate, citrate, and 2-(N-morpholino)ethanesulfonate (MES), were investigated. The results indicate that, although buffer pH is a crucial parameter, buffer concentration also plays an important role in the separation of cephalosporins, particularly when cefuroxime and cefazolin, cephalexin and cefaclor, or cefotaxime and cephapirin are present as analytes at the same time. The electrophoretic mobility of cephalosporins and electroosmotic mobility measured in citrate and MES buffers are remarkably different from those measured in phosphate buffer. With citrate buffer, optimum buffer concentration is confined to a small range (35-40 mM), whereas buffer concentrations up to 300 mM can be used with MES buffer. Complete separations of 12 cephalosporins could be satisfactorily achieved with these three buffers under various optimum conditions. However, the separability of 12 cephalosporins with citrate or MES buffer is better than that with phosphate buffer. As a consequence of a greater electrophoretic mobility of cephalosporins than the electroosmotic mobility with citrate buffer at pH below about 5, some cephalosporins are not detectable. The cloudiness of the peak identification and of the magnitudes of the electrophoretic mobility of cefotaxime and cefuroxime reported previously are clarified. In addition, the pKa values of cephradine, cephalexin, cefaclor, and cephapirin attributed to the deprotonation of either an amino group or a pyridinium group are reported, and the migration behavior of these cephalosporins in the pH range studied is quantitatively described.
研究了缓冲液pH值、缓冲液浓度和缓冲电解质对12种头孢菌素抗生素在毛细管区带电泳中迁移行为和分离效果的影响，其中使用了三种不同类型的缓冲电解质，包括磷酸盐、柠檬酸盐和2-（N-吗啉代）乙磺酸盐（MES）。结果表明，尽管缓冲液pH值是一个关键参数，但缓冲液浓度在头孢菌素的分离中也起着重要作用，特别是当头孢呋辛和头孢唑林、头孢氨苄和头孢克洛，或头孢噻肟和头孢匹林同时作为分析物存在时。在柠檬酸盐和MES缓冲液中测得的头孢菌素电泳迁移率和电渗迁移率与在磷酸盐缓冲液中测得的显著不同。对于柠檬酸盐缓冲液，最佳缓冲液浓度限制在一个较小的范围内（35 - 40 mM），而MES缓冲液可使用高达300 mM的缓冲液浓度。在各种最佳条件下，使用这三种缓冲液均可令人满意地实现12种头孢菌素的完全分离。然而，12种头孢菌素在柠檬酸盐或MES缓冲液中的可分离性优于在磷酸盐缓冲液中的可分离性。由于在pH值低于约5时，头孢菌素的电泳迁移率大于柠檬酸盐缓冲液中的电渗迁移率，一些头孢菌素无法检测到。澄清了先前报道的头孢噻肟和头孢呋辛峰识别的模糊性以及电泳迁移率的大小。此外，报道了头孢拉定、头孢氨苄、头孢克洛和头孢匹林由于氨基或吡啶鎓基团去质子化而产生的pKa值，并定量描述了这些头孢菌素在所研究pH范围内的迁移行为。
