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Frequently Asked Questions

High-Pressure Liquid Chromatography (HPLC)


Q: Why use diamond as a stationary phase support?

A: Diamond is the hardest material known to man and an inert material that is stable at high temperatures and pH.  It is also a much better thermal conductor than silica. According to published thermal conductivity values(1,2) the thermal conductivity of diamond is about 1000x that of silica which may allow for faster thermal equilibration times for LC. Further, diamond is not easily fouled up as very few compounds stick to its surface. The inertness of diamond may allow it to be used with biologically sensitive samples which are often pH sensitive and can easily foul a column.

Q: What is the pH stability of your diamond-based chromatographic materials?

A: Our materials should be stable over the entire pH range (0 – 14), but we have empirically proven(3) their stability over long periods of time from pH 1 to pH 13.

Q: What is the temperature stability of your diamond-based chromatographic materials?

A: We have tested the stability of our diamond-based particles at temperatures up to 120 ºC where they show very little degradation over extended periods of time.

Q: What differences exist between your diamond-based materials and a standard reversed-phase, silica-based column?

A: Our phases exhibit similar selectivity to traditional silica-based reversed-phases; however, we can typically use less organic modifier, when performing separations, to achieve similar retention factors to those obtained on traditional silica-based materials. Furthermore, we have greater pH and temperature stability than a silica-based (non-hybrid) material.

Q: What types of separations have been performed using your diamond-based materials?

A: We have performed separations of alkylbenzenes, phenols, pharmaceuticals, and some proteins with our reversed-phase, diamond-based particles(3).

Q: What makes your carbon/diamond-based materials different from carbon/polymer-based materials already available?

A: While typical carbon-based materials are based off of polymer beads, usually divinylbenzene (DVB), our stationary phases are built off of diamond and a thin polymer layer. Unlike DVB phases, our materials do not swell or shrink when exposed to organic solvents, and our diamond-based HPLC phases give efficiencies at or greater than 100,000 N/m, which is on par with other reversed-phase HPLC phases.

Q: What can I do if my column fouls or gets plugged with a biological sample?

A: Just flush it with either a harsh acidic or basic solution that will digest the sample and flush it off the column. The performance of the phase will remain unaffected because of the extreme pH stability of our materials.

Q: Why should I choose a diamond-based column for use in my laboratory?

A: With an outstanding pH range and thermal stability that will be stable under any condition, we recommend our diamond-based phases if you prefer to cater your separations to your analytes.

Q: How are your phases created?

A: We coat spherical carbon with poly(allylamine) (PAAm), which deposits on the particles in a self-limiting fashion. We then apply nanodiamond, which also adheres to the surface in a self-limiting deposition. We alternate application of PAAm and nanodiamond until we reach the desired shell thickness. Our particles are then functionalized using a C18 epoxide and a crosslinker. The particles are then packed into a column(3).

1CRC Materials Science and Engineering Handbook
2Netzsch Periodic Table of the Elements
3Anal. Chem., 2011, 83 (14), pp 5488–5501

 

Thin-Layer Chromatography (TLC)


Q: Why use microfabricated TLC (M-TLC) plates?

A: To briefly review, M-TLC uses processes, similar to those used to build computer chips, that allow for the precise placement of the chromatographic media. This precision in placement of the chromatographic media allows for an increase in separation efficiency and allows for shorter development distances which, in return, increases sample throughput. 

Q: How does the chromatographic efficiency of M-TLC compare to HPTLC?

A: The quick answer is that M-TLC is more efficient. The higher efficiency of M-TLC is because of two aspects: (1) the M-TLC plates have a smaller “particle” size that allows for improved mass transfer (C-term in van Deemter equation) of the analytes during chromatography; (2) the effects of “eddy” diffusion (A-term in van Deemter equation) are reduced due to the precisely placed adsorbent materials.

Q: Is the development time for M-TLC plates faster or slower than HPTLC?

A: M-TLC, over the same development distance, is faster than HPTLC. This phenomena can be explained through the microfabrication process. The microfabrication process allows for efficient designs to be used that can both increase the speed of analysis and the separation efficiency by changing either the capillary width of the chromatographic media or the “particle” size of the media or both.

Q: What material is used to produce the M-TLC plates?

A: The M-TLC plates are composed of the same material HPTLC plates use, which is silica. Because M-TLC is a silica-based material, this allows for direct transfer of HPTLC type analyses to M-TLC analyses.

Q: How could your lab benefit from M-TLC?

A: How does an increase in sample throughput sound? Because M-TLC gives improved chromatographic efficiencies and the development times are faster than conventional. This allows for an increase in sample throughput.


For further support, please email us at info@diamond-analytics.com. Thank you.