Synthesis and evaluation of NA-PHEMAH polymer for use as a new stationary phase in high-temperature liquid chromatography

In order to develop more stable packing materials for high-temperature liquid chromatography (HTLC), a new stationary phase, 1-naphthyl attached poly(2-hydroxyethylmethacrylate-N-methacryloyl-(L)-histidine-methyl-ester) (NA-PHEMAH) polymer was synthesized in this work. The NA-PHEMAH polymer particles with 2.0-2.1 mu m in diameter were then evaluated for use as a stationary phase in high-temperature liquid chromatography. Separation of vanillin, ethyl vanillin, coumarin, 6-methylcoumarin, and 7-methylcoumarin was achieved on this NA-PHEMAH column using HTLC at 125-200 degrees C with 2% or 5% methanol in the mobile phase. Successful separation of the test analytes was also obtained using subcritical water chromatography (SBWC) at 200 degrees C. Evaluation of the long-term stability of the NA-PHEMAH stationary phase revealed that the column was stable for over 500 h at 150 degrees C. These results demonstrate that the new NA-PHEMAH stationary phase is suitable for high-temperature liquid chromatography separations due to its excellent stability at high temperatures.