Adsorbents

Carbon based adsorbents, such as Carbopack™ graphitized carbon blacks and Carboxen™ carbon molecular sieves, exhibit unique and superior performance characteristics for a wide range of applications. Because Supelco manufactures these materials on-site, quality and availability can be assured. Additionally, custom solutions are available for special application requirements.

Unlike activated charcoals, which are porous, graphitized carbon blacks (GCBs) are generally non-porous. Consequently, the entire surface of these materials is available for interactions that depend solely on dispersion (London) forces. Because we prepare our GCBs at temperatures >2500 °C, the high purity nature of the resulting carbon material ensures effective release/desorption of the analyte of interest. Carbotrap™ signifies material that is 20/40-mesh size, whereas Carbopack™ signifies material that is 60/80-mesh size (or smaller particle size).

Carbotrap B, Carbotrap C, and Carbotrap F graphitized carbon blacks trap a wide range of airborne organic compounds, from C4-C5 hydrocarbons to polychlorinated biphenyls and other large molecules. Carbotrap adsorbent has a surface area of 100m²/g and can be used for monitoring many airborne C5-C12 compounds. The smaller surface areas of Carbotrap C and Carbotrap F adsorbents, 10m²/g and 5m²/g, respectively, make these materials useful for trapping and efficiently releasing larger molecules, in the C9-C30 range.

Carbopack B, Carbopack C, and Carbopack F GCBs are essentially the same adsorbents as Carbotrap B, Carbotrap C, and Carbotrap F, respectively, but in a 60/80 mesh size. These materials often are used in narrow bore tubes (1- 2mm ID), for sample refocusing or very low flow sampling (e.g., <20mL/min).

Unlike most GCBs, Carbopack X is porous. Its surface area of 240m²/g provides greater adsorption strength than other GCBs; hence it is a unique bridge between GCBs and carbon molecular sieves. Carbopack Y, with a surface area of 24m²/g, bridges the characteristics of Carbopack B and Carbopack C.
These adsorbents offer excellent thermal stability, which ensures minimal bleed at thermal desorption temperatures, and their coarse 20/40 and 40/60 mesh particle size prevents high pressure drop across the tube. Hydrophobic properties minimize sample displacement by water, enabling accurate sampling despite high humidity. Trapped compounds can be desorbed by solvent or thermal desorption, at virtually 100% desorption efficiency.

A carbon molecular sieve (CMS) particle is the carbon skeletal framework remaining after the pyrolysis of a polymeric precursor. These materials are primarily used for collecting very small molecular-sized compounds (C2–C5). The size and shape of the analyte molecule and the size and shape of the pores in the CMS particle determine how well the analyte is adsorbed and desorbed. Because our CMSs are prepared from high purity polymers, the resulting material is a high purity carbon, effective in the release/desorption of adsorbed analytes for quantification. Our Carbosieve™ S-III and Carboxen™ carbon molecular sieves have upper temperature limits of at least 400°C.

Carbosieve-SIII is a large surface area (approximately 975m²/g) and 15-40Å pores make this spherical carbon molecular sieve excellent for trapping small airborne molecules, such as chloromethane. Although hydrophobic, it retains slightly more water during sampling than Carboxen-569. The pure carbon framework permits thermal desorption of analyte molecules without loss.
Carbosieve-SII is recommended for analyzing mixtures of permanent gases (H₂, O₂, Ar, CO and CO₂) and C1-C2 hydrocarbons (methane, ethane, ethylene, acetylene). Maximum temperature 225°C with oxygen-free carrier gas.
Carbosieve-G is recommended for analyzing C1-C3 hydrocarbons. Maximum Temperature <200°C with oxygen free carrier gas.

Carboxen - Carboxen carbon molecular sieves are highly hydrophobic, ensuring accurate sampling at high humidities.
Carboxen-563 and Carboxen-564 are our preferred versions of Ambersorb® XE-340 and Ambersorb XE-347 adsorbents – the Carboxen adsorbents have higher capacity (breakthrough volume) for many volatile organic compounds (VOCs).
Carboxen-563 is used for analyzing water quality or airborne compounds. Its range for airborne compounds is similar to that of Carboxen-564, but with a somewhat lower capacity.
Carboxen-564 is effective for monitoring many C2-C5 VOCs.
Carboxen-569 is a 20/45-mesh material with no Ambersorb® equivalent. High hydrophobicity makes it useful for sampling in high humidity (use a 4mm ID or larger tube). Relative to Carboxen-563 and Carboxen-564, Carboxen-569 has greater capacity for organic molecules and less capacity for water.
Carboxen-572 is a CMS possessing tapered pore structure with open, throughput micropores. It is a highly efficient CMS and compares direclty to the Carboxen-1000 (one of our most efficient CMS carbons used for purge-trap and air sampling applications). The primary difference between the Carboxen-572 and Carboxen-1000 is the particle size distribution (Caboxen-572 = 20/45 mesh, and Carboxen-1000 = 60/80 mesh).
Carboxen-1000 is for low volume sampling of very volatile compounds, such as vinyl chloride. Its large surface area and optimized microporosity enable it to effectively and efficiently adsorb and desorb smaller molecular size compounds, providing excellent chromatography without a need for cryogenic cooling. This 60/80-mesh adsorbent is used primarily in narrow bore tubes that are desorbed directly into the chromatographic column.
Carboxen-1001 is a 60/80-mesh material used to trap and retain small compounds. It often is used as the final bed in multi-bed adsorbent tubes, to minimize breakthrough. It is similar to Carboxen-569 in strength and hydrophobicity.
Carboxen-1003 is a carbon molecular sieve with a large surface area and hydrophobic surface characteristics, which provide a combination of efficient adsorption/ desorption and good hydrophobicity.
Carboxen-1012 is a highly-activated (i.e., super activated), inert CMS possessing large micropores. It has been used effectively for aqueous phase adsorption of organic compounds, or for air sampling of C4-C6 compounds.
Carboxen-1018 is a microporous CMS possessing a large percentage of narrow (~6-7 angstrom) micropores for adsorption/desorption of small analytes such as ethane, acetylene, ethylene and C3 hydrocarbons. This CMS is a hydrophobic, inert, strong adsorbing porous carbon, as is the Carboxen-1021. BOth are used in breath sampling tubes developed for ethane, acetaldehyde and other small molecules present in exhaled breath samples.

Often choosing the right adsorbent or combination of adsorbents can be difficult. The goal in selecting the proper adsorbent is to choose one or more that can retain a specific analyte, or group of analytes, for a specific sample volume. However, equally important is that the adsorbent(s) must also be able to release the analyte(s) during the desorption process.

By using one of the Supelco Carbon Adsorbent Sampler Kits, the method developer obtains a cost-effective way to evaluate several carbon adsorbents when designing adsorbent-based applications and products. Once the appropriate material has been identified, Supelco is ready to work with you to produce larger quantities to your specifications.