Fabrication of spherical silica amino-functionalized microporous organic network composites for high performance...

Microporous organic networks (MONs) are a potential class of microporous materials in analytical chemistry. As great efforts have been made in sample pretreatment and gas chromatography, the application of MONs in high performance liquid chromatography (HPLC) has largely lagged and has never been investigated. In addition, directly packing of MONs into columns for HPLC is impractical due to the high column pressure and low column efficiency resulted from the sub-micron sized and irregular MONs. To solve these issues and uncover the possibility of MONs in HPLC, here we report the fabrication of spherical silica amino-functionalized MON (SiO₂@MON-NH₂) composite as a novel stationary phase for HPLC. Neutral, acidic and alkaline probes were evaluated on SiO₂@MON-NH₂ packed column. A column efficiency of 21,246 plates per meter was obtained for n-propylbenzene. The results revealed the hydrophobic interaction was the main separation mechanism on SiO₂@MON-NH₂ packed column. Baseline separation of benzenediol, dichlorophenol, chlorophenol and phenylenediamine position isomers, deoxynucleosides and nucleosides was also achieved on SiO₂@MON-NH₂ packed column. The relative standard deviations of retention time, peak height and peak area for the studied position isomers, deoxynucleosides and nucleosides were 0.2-0.7%, 0.3-3.7% and 1.7-3.5%, respectively. The SiO₂@MON-NH₂ packed column also offered better resolution for dichlorophenol isomers, deoxynucleosides and nucleosides than SiO₂-NH₂ and commercial C18 columns. These results revealed the potential of MONs in HPLC and also provided a new way for the use of nano-sized or irregular MONs in HPLC.