UHPLC AND HPLC COLUMN PERFORMANCE continued Table 1 – Supelco silica platforms with monodisperse particles


Year Particle* Design Pore size, Å


2013 Titan


2007 Ascentis Express


Totally porous


Fused- Core


2012 BIOshell Fused- Core


90


160, 400


Particle size, µm


80, 120 1.9 2.0, 2.7, 5 2.7, 3.4 3


Current phases 3


8 Application Small


molecules Small


molecules Larger


molecules (peptide/ protein)


*Titan, Ascentis and BIOshell are trademarks of Sigma-Aldrich Co. LLC.


future should also see more use of elevated temperature and multidimen- sional column techniques in HPLC and UHPLC to solve the most difficult separation problems.


Acknowledgments The efforts of the large Supelco team who developed the Ecoporous process for synthesizing monodisperse Titan particles are acknowledged and greatly appreciated. Regular communication and support from Drs. Jack Kirkland, Joseph DeStefano, Stephanie Schuster and others at AMT concerning Fused-Core particle technology from 2006 until the present were valuable as well. The assistance and column performance evalu- ations of academic collaborators Professors Luigi Mondello and Paola Dugo at the University of Messina and Francesco Gasparrini at Sapienza University of Rome are also appreciated. Column evaluations and discus- sions with Professors Gert Desmet and Ken Broeckhoven, Free University of Brussels, and Professors Fabrice Gritti and Georges Guiochon, University of Tennessee, were very valuable.


References 1. Knox, J.H. and Saleem, M. J. Chromatogr. Sci. 1969, 7, 614–22. 2. Nguyen, D.; Guillarme, D. et al. J. Sep. Sci. 2006, 29, 1836–48. 3. Schwartz, M. Special Issue of LC GC May 2005, 8–14. 4. Kirkland, J.J.; Langlois, T.J. et al. Am. Lab. Feb 2007, 39, 18–21. 5. Chester, T.L. Am. Lab. Mar 2009, 41, 11–15. 6. Giddings, J.C. Dynamics of Chromatography. Marcel Dekker, Inc.: New York, NY, 1965, Chapter 2.


Figure 6 – High-speed separations showing greater retention of 1.9-µm porous Titan C18 column compared to 1.7-µm core-type C18 column for benzodiazepines and metabolites by gradient LC/MS. Columns: 5 cm × 3.0 mm; mobile phase: a) 0.1% formic acid in 95:5, water:acetonitrile; b) 0.1% formic acid in 5:95, water:acetonitrile; gradient: 35% B to 60% B in 1 min; 60% B held for 0.5 min; flow rate: 0.6 mL/min; column temp.: 35 °C; detector: MS-TOF, ESI+.


Summary and conclusion Analytical HPLC/UHPLC columns filled with both porous and core-type


particles should continue to improve in efficiency and ruggedness to ad- dress the demand for higher sample throughput. Analysts will eventually become less concerned about the type of particle inside as long as the column demonstrates stable, reproducible separation performance. The desire to improve column performance, increase column lifetime and minimize particle waste should continue to drive the production of silica particles toward narrower particle-size distribution. Recent intense de- velopment has greatly improved the efficiency of modern spherical silica particles; however, development of interesting new phases has slowed down during this period. Now that new particle designs are becoming widely accepted and readily available, research should shift toward de- veloping new stationary phases to meet the challenge of increasingly complex separations. Selective new phases should be added to proven ones, especially for high-speed resolution of closely related species. The


7. Knox, J.H. J. Chromatogr. A 1999, 831, 3–15. 8. Knox, J.H. J. Chromatogr. A 2002, 960, 7–18. 9. Henry, R.A. LC GC 2014 North America Apr 2014, 32(4), 12–19.


10. Cabooter, D.; Fanigliulo, A. et al. J. Chromatogr. A 2010, 1217, 7074–81. 11. Betz, W.R.; Campbell, W.H. Development of a New Monodisperse Porous Silica for UHPLC. Poster presented at 38th International Sym- posium on High Performance Liquid Phase Separations and Related Techniques (HPLC 2012), June 16–21, 2012, Anaheim, Calif.


12. Gritti, F.; Bell, D.S. et al. J. Chromatogr. A 2014, 1355, 179–92. 13. Gritti, F. and Guiochon, G. J. Chromatogr. A 2014, 1355, 164–78. 14. Horváth, K.; Lukács, D. et al. J. Chromatogr. A 2014, 1361, 203–8. 15. Gritti, F. and Guiochon, G. J. Chromatogr. A (2014). 16. Neue, U.D. HPLC Columns; Wiley-VCH: New York, NY, 1997, p 14. 17. Antia, F.D. and Horvath, C. J. Chromatogr. 1988, 435, 1–15. 18. Henry, R.A. et al. Achieving Maximum Kinetic Performance from UHPLC Columns, Oral Paper, Eastern Analytical Conference, Somerset, NJ, Nov 18, 2014.


Richard A. Henry is a Consultant, State College, Penn., U.S.A. Paul Ross, William R. Betz, Gaurang Parmar and Wayne K. Way (wayne.way@sial.com) are with Supelco, Div. of Sigma Aldrich, 595 North Harrison St., Bellefonte, PA 16823- 0048, U.S.A.; tel.: 814-359-3441/800-247-6628.


AMERICAN LABORATORY • 12 • AUGUST 2015


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