Carbon Molecular Sieve (CMS)

Carboxen materials have through-pore structures. That is, the majority of the pores pass entirely through the particles. Additionally, the specially designed pores taper from macro- to meso- to micropores, resulting in materials with excellent thermodynamic properties for both adsorption and desorption processes. As such, no other CMS materials on the market can match the performance of our Carboxen materials. When protected properly with weaker adsorbents upstream, the Carboxen materials provide great performance for a very wide range of small C2-C5 analytes.

Fifteen Carboxen materials are offered:

• Carboxen 563 is useful for collecting volatile organic compounds (VOCs) from water or air.
• Carboxen 564 is effective for collecting VOCs from air. It has a greater capacity than Carboxen 563.
• Carboxen 569 is a highly hydrophobic material, making it useful for sampling in high humidity environments. Relative to Carboxen 563 and Carboxen 564, Carboxen 569 has a greater capacity for organic molecules and a lower capacity for water.
• Carboxen 572 is a highly efficient CMS material and compares directly to Carboxen 1000. The primary difference between Carboxen 572 and Carboxen 1000 is the particle size distribution (Carboxen 572 is only available in 20/45 mesh whereas Carboxen 1000 is available in 40/60, 60/80, and 80/100 mesh).
• Carboxen 1000 has a large surface area and optimized microporosity, which enable it to effectively and efficiently adsorb and desorb smaller molecular size compounds, providing excellent chromatography without a need for cryogenic cooling. One of our most efficient CMS materials, it is widely used in purge traps and as air sampling media. It is also used for low volume sampling of very volatile compounds, such as vinyl chloride
• Carboxen 1001 is used to trap and retain very small compounds. It is often used as the final bed in multi-bed adsorbent tubes, to minimize breakthrough. It is similar to Carboxen 569 in strength and hydrophobicity. Note that bulk Carboxen 1001 material is only available as a custom item.
• Carboxen 1003, with a large surface area and hydrophobic surface characteristics, provides a desirable combination of efficient adsorption/desorption and good hydrophobicity.
• Carboxen 1006 is only available as 2 µm particles. It is used as an adsorbent in porous layer open tubular (PLOT) capillary GC columns. Note that bulk Carboxen 1006 material is only available as a custom item.
• Carboxen 1010, also only available as 2 µm particles, is used as an adsorbent in PLOT capillary GC columns. Note that bulk Carboxen 1010 material is only available as a custom item.
• Carboxen 1012 is a highly activated, inert CMS possessing large mesopores. It can be used effectively for aqueous phase adsorption of organic compounds, or for air sampling of C4-C6 compounds. Note that bulk Carboxen 1012 material is only available as a custom item.
• Carboxen 1016 is unlike most other CMSs because it is non-porous. Its adsorptive strength it slightly stronger than that of Carboxen 1017.
• Carboxen 1017 is also non-porous. With the weakest adsorptive strengths of our CMSs, it provides a unique bridge between the GCB and CMS materials. This highly engineered material has traveled to space on several missions, used to collect samples for evolved gas analysis. Note that bulk Carboxen 1017 material is only available as a custom item.
• Carboxen 1018, possessing a large percentage of narrow (6-7 Å) micropores, is useful for the adsorption/desorption of small analytes, such as C2 (ethane, ethylene, acetylene) and C3 hydrocarbons. This hydrophobic, inert, and strong adsorbing porous carbon is used in sampling tubes to collect ethane, acetaldehyde, and other small molecules present in exhaled breath samples. Note that bulk Carboxen 1018 material is only available as a custom item.
• Carboxen 1021 is another highly-microporous CMS designed for air sampling of small molecules. It is similar to Carboxen 1018 in that is has a large percentage of small micropores. Compared to Carboxen 1018, it has smaller micropores (5-6 Å), and is more hydrophobic. Note that bulk Carboxen 1021 material is only available as a custom item.
• Supelcarb™ material is based on Carboxen 1003 material. It is primarily used in gas purification applications to retain hydrocarbons. Note that bulk Supelcarb material is only available as a custom item.

Carbosieve materials have closed-pore structures. That is, the pores do not pass through the particles. These materials tend to have very strong adsorptive strengths due to being predominately microporous. However, the lack of tapered pores may result in larger (>C5) analytes blocking pores, preventing smaller analytes from reaching available pore sites. When protected properly with weaker adsorbents upstream, the Carbosieve materials provide great performance for many small, volatile analytes that most adsorbents have trouble retaining.

Three Carbosieve materials are offered:

• Carbosieve G is mainly used in GC columns for analyzing C1-C3 hydrocarbons.
• Carbosieve S-II is mainly used in GC columns for analyzing mixtures of permanent gases (oxygen, nitrogen, carbon monoxide, and carbon dioxide) and C1-C2 hydrocarbons (methane, ethane, ethylene, and acetylene).
• Carbosieve S-III is excellent for trapping small airborne molecules, such as chloromethane. Although hydrophobic, it retains slightly more water during sampling than does Carboxen 569.

1. While these carbon materials are stable to above 400 °C, the temperature actually used at depends on the application. For example, thermal desorption unit (TDU) tubes are typically desorbed at 330 °C, purge traps containing just our specialty carbons typically use a 250 °C desorption temperature, and GC column applications may work best with final oven temperatures of 225 °C. For assistance in determining the proper temperature for your application, contact Technical Service at techservice@sial.com.