Carr Research Group

EDUCATION:

M.S., Iowa State University, 2000

B.S., University of Science and Technology of China, 1997;

RESEARCH PROJECT DESCRIPTION:

Microparticulate silica is currently the most widely used stationary phase support for reverse phase high-performance liquid chromatography. It is easy to produce monodisperse, mechanically strong silica-based micro particles with high surface area and narrow pore size distributions. Secondly, a large variety of silanes are available for surface modification which offers a wide range in chromatographic selectivities. However, the poor chemical and thermal stability of silica-based stationary phases at low and high pH limits their long term use to a narrow range of pH (typically 3-8) and to temperature < 60 - 80 °C.

To simultaneously address both the low and high pH stability problems, we have developed an approach for synthesizing hyper crosslinked stationary phases on silica. In this approach, dimethyl-(chloromethyl)phenylethyl)-trichlorosilane (DM-CMPES) covalently bonded to silica surface is both self-condensed and hyper cross-linked by addition of a multi-valent crosslinker (e.g. styrene heptamer. Elemental analysis data confirms the high degree of cross-linking of the surface groups and the cross-linking agent. This extensively cross-linked material exhibits enhanced stability at low pH compared to a sterically protected C18 phase. The base stability of this phase will be compared to the best available phase, i.e. bidentate C18. Additionally, we will compare the efficiency for basic drugs, the flow curve, and the pore accessibility of this highly crosslinked phase to sterically protected and bidentate C18 phases

PUBLICATIONS:

1. Ma, Lianjia; Dai, Jun; Luo, Hao; Carr, Peter W. Synthesis optimization of hyper-crosslinked Phases-a new generation of acid stable hyper-crosslinked phases with superb efficiency. In preparation

2. Ma, Lianjia; Dai, Jun; Luo, Hao; Carr, Peter W. The applications of the new generation of acid stable hyper-crosslinked phases with superb efficiency. In preparation

3. Yang, Xiqin; Ma, Lianjia; Carr, Peter W. High temperature fast chromatography of proteins using a silica-based stationary phase with greatly enhanced low pH stability Journal of Chromatography, A. In press

4. Trammell, Brian C.; Ma, Lianjia; Luo, H; Hillmyer, Marc A.; Carr, Peter W. Synthesis and characterization of hypercrosslinked, surface-confined, ultra-stable silica-based stationary phases Journal of Chromatography, A 2004, 1060(1-2), 61-76

5. Carr, Peter W.; Trammell, Brian C.; Ma. Lianjia.; Luo, H.; Liu, H.; Hillmyer, M. A. Silica-based materials and methods U.S. patent application serial No.:10/386,904 March 2003

6. Trammell, Brian C.; Ma, Lianjia; Luo, H.; Hillmyer, M. A.; Carr, Peter W. An ultra acid stable reversed stationary phase Journal of American Chemical Society, 2003, 125, 10504-10505

7. Trammell, Brian C.; Ma, Lianjia; Luo, H.; Jin, D. and Carr, Peter W. Hyper crosslinked stationary phases: a new approach for greatly enhancing the pH stability of silica-based RPLC stationary phase Analytical Chemistry, 2002, 74, 4634-4639

8. Ma, Lianjia; Gong, Xiaoyi; Yeung, Edwards S. Combinatorial Screening of Enzyme Activity by Using Multiplexed Capillary Electrophoresis. Analytical Chemistry, 2000, 72, 3383-3387

PRESENTATIONS:

1. Ma, Lianjia; Luo, Hao; Dai, Jun.; Carr, Peter W., Silanophilicity study and synthesis optimization of hyper-crosslinked phases-a new generation of acid stable hyper-crosslinked phases with superb efficiency The Pittsburgh Conference 2005, Orlando, FL, Feb 2005

2. Luo, Hao; Ma, Lianjia; Carr, Peter W., Hyper-Crosslinked Phases--A Novel Silica-Based Platform for a Family of Reversed and Ion Exchange Phases The Pittsburgh Conference 2005, Orlando, FL, Feb 2005

3. Ma, Lianjia; Dai, Jun.; Luo, Hao; Carr, Peter W., Silanophilicity study and synthesis optimization of hyper-crosslinked phases-a new generation of acid stable hyper-crosslinked phases with superb efficiency Eastern Analytical Symposium 2004, Sommerset, NJ, November 2004, Oral Presentation

4. Ma, Lianjia; Dai, Jun.; Luo, Hao; Yang, Xiqin; Trammell, Brian C.; Carr, Peter W., Devolvement of Hyper-Crosslinked Acid Stable Silica Based Phases for Protein and Peptide Separations, HPLC 2004, June 12-18 2004, Philadelphia, PA, Oral Presentation

5. Ma, Lianjia; Yang Xiqin; Carr, Peter W., High temperature fast chromatography of proteins using a silica-based stationary phase with greatly enhanced low pH stability, HPLC 2004, June 12-18 2004, Philadelphia, PA

6. Ma, Lianjia; Trammell, Brian C.; Dai, Jun.; Luo, Hao; Yang, X.; Hillmyer, M.C. Carr, Peter W., Surface Confined Polymer Networks Based on Orthogonal Reaction Chemistry: A Novel Approach to High Efficiency Stable Silica-Based Reversed Phase Media, The Pittsburgh Conference 2004, March 7-12 2004, Chicago, IL, Oral Presentation

7. Dai, Jun.; Ma, Lianjia; Trammell, Brian C.; Hillmyer, M. A.; Carr, Peter W., Chromatographic Characterization of Hyper Crosslinked Reversed Phases, The Pittsburgh Conference 2004, March 7-12 2004, Chicago, IL, Oral Presentation

8. Ma, Lianjia; Luo, Hao; Trammell, Brian C.; Liu, Huqun; Carr, Peter W., Hyper crosslinked stationary phases: a new approach to greatly enhancing the pH stability of RPLC silica stationary phase Eastern Analytical Symposium 2003, Sommerset, NJ, November 2003

9. Ma, Lianjia, Luo, Hao, Liu; Huqun; Peter W. Carr, Hyper crosslinked stationary phases: a new approach to greatly enhancing the pH stability of RPLC silica stationary phase, HPLC 2003, June 15-19 2003, Nice, France.

10. Ma, Lianjia; Trammell, Brian C.; Luo, Hao; Liu, H.; Carr, P. W., Highly Crosslinked Stationary Phases: A New Approach for Greatly Enhancing the Acid Stability of RPLC Silica The Pittsburgh Conference 2003, Orlando, FL , March 2003, Oral Presentation

11. Trammell, Brian C.; Ma, Lianjia; Luo, Hao; Jin, Dihua.; Carr, Peter W., Highly crosslinked self-assembled monolayer stationary phases: a new approach to greatly enhancing the pH stability of RPLC silica, HPLC 2002, Montreal, Canada, Jun. 2002

12. Trammell, Brian C.; Ma, Lianjia; Luo, Hao; Jin, Dihua; Carr, Peter W., Highly crosslinked self-assembled monolayer stationary phases: a new approach to greatly enhancing the pH stability of RPLC silica New Orleans, LA, The Pittsburgh Conference 2002 Mar. 2002, Oral Presentation

Email: lma@chem.umn.edu

Address: 321 Smith Hall

Phone: (612) 624-5870

Modified by Hao Luo --- hluo@chem.umn.edu