Improvement of Chromatographic Performances of C8 Hybrid Monoliths by

Considerable attention has been paid to monolith columns for liquid chromatography (LC) system owing to their easy preparation, good permeability, fast mass transport and various kinds of surface modification. The feature of in-situ polymerization make the monolith column have significant development in capillary/nano LC and micro-fluidic system research. In the fabrication of hybrid C8 silica monoliths, the precursor undergoes an acid/base two-step reaction. Dodecylamine was added to the system after the hydrolysis in several hours to provide a basic media and also as a template [1]. In this research, surfactant Pluronic F127 and dodecylamine were used as template together, and the characteristic of monolith column was explored in detail. The most striking change is the significant improvement in column efficiency with the addition of F127 in nano-liquid chromatography mode. When 30 mg F127 was added in the system, the number of plate was increased almost 2 times of that when no F127 was used. SEM images show that the size of macropore and skeleton decreased with increasing amount of F127, which is in accordance with the results observed by Kazuyoshi et al [2]. With the addition of F127, the column efficiency was increased slightly when the dodecylamine was reduced to 6mg. The final number of plate was 28,706/meter, with the minimal plate height of 34.84 μm. Moreover, less amount of dodecylamine delay the time of sol-gel transition from almost 4 min to more than 10 min, which provide more time for filling step and improve the column-to-column reproducibility. The C8 monolith column with 100 μm i.d. was validated in nanoLC-UV system. Good peak shapes were obtained in the analysis polycyclic aromatic hydrocarbon and alkylbenzens. The monolith column with 75 μm i.d. was used in nanoLC- nanoESImass spectrometry to analysis seven kinds of microcystins in water. Without any kind of preconcentration, the limit of detections of microcystins are all below 1 μg/L given in the WHO provisional guideline for microcystin-LR in drinking water.Considerable attention has been paid to monolith columns for liquid chromatography (LC) system owing to their easy preparation, good permeability, fast mass transport and various kinds of surface modification. The feature of in-situ polymerization make the monolith column have significant development in capillary/nano LC and micro-fluidic system research. In the fabrication of hybrid C8 silica monoliths, the precursor undergoes an acid/base two-step reaction. Dodecylamine was added to the system after the hydrolysis in several hours to provide a basic media and also as a template [1]. In this research, surfactant Pluronic F127 and dodecylamine were used as template together, and the characteristic of monolith column was explored in detail. The most striking change is the significant improvement in column efficiency with the addition of F127 in nano-liquid chromatography mode. When 30 mg F127 was added in the system, the number of plate was increased almost 2 times of that when no F127 was used. SEM images show that the size of macropore and skeleton decreased with increasing amount of F127, which is in accordance with the results observed by Kazuyoshi et al [2]. With the addition of F127, the column efficiency was increased slightly when the dodecylamine was reduced to 6mg. The final number of plate was 28,706/meter, with the minimal plate height of 34.84 μm. Moreover, less amount of dodecylamine delay the time of sol-gel transition from almost 4 min to more than 10 min, which provide more time for filling step and improve the column-to-column reproducibility. The C8 monolith column with 100 μm i.d. was validated in nanoLC-UV system. Good peak shapes were obtained in the analysis polycyclic aromatic hydrocarbon and alkylbenzens. The monolith column with 75 μm i.d. was used in nanoLC- nanoESImass spectrometry to analysis seven kinds of microcystins in water. Without any kind of preconcentration, the limit of detections of microcystins are all below 1 μg/L given in the WHO provisional guideline for microcystin-LR in drinking water