Adsorbent carbons are frequently used in analytical techniques including chromatographic separations. Sigma-Aldrich®/Supelco®’s carbon technology development efforts have been critical to the advancement of chromatography and sample preparation applications. Supelco® offers over 85 different carbon products including custom materials, ranging in particle size from 1–1000 microns and surface areas from 1–1500 m2/g. These adsorbent carbons include:
Graphitised Carbon Black (GCB)
Generally, these are non-porous and non-specifi c adsorbents that exhibit high surface homogeneity. The high purity of these adsorbents ensures effective desorption of the analyte of interest. These adsorbents are suitable for gas-solid chromatography, even for eluting polar compounds. GCBs exhibit hydrophobic surface characteristics and, therefore, can be effectively used in trapping organic compounds in humid streams. Their hydrophobic nature minimises sample displacement by water, so accurate samples can be obtained despite levels of high levels of humidity. Trapped compounds can be desorbed by a solvent or thermal desorption at 100 % desorption effi ciency. These adsorbents offer excellent thermal stability, ensure minimal bleed at thermal desorption temperatures, and prevent high pressure-drop.
Carbotrap B, -C, and -F trap a wide range of airborne organics (C4-C5 hydrocarbons) to polychlorinated biphenyl and other large molecules
Carbon Molecular Sieve (CMS)
A carbon molecular sieve (CMS) also called molecular sieve carbon, is a specialised carbon that has a tailored porosity for selective adsorption. 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 pore entrances in the CMS particle, determine how well the analyte is adsorbed and desorbed.
As our CMSs are prepared from high-purity polymers, resulting material is a high-purity carbon that allows effective adsorption of an analyte, and its effi cient desorption for quantifi cation. Carbosieve S-III and Carboxen CMS have upper temperature limits of at least 400 ºC.
These CMS materials are hydrophobic in nature, thus ensuring accurate sampling at high humidity levels.
Carboxen-563 and Carboxen-564:
Carboxen-572: most effi cient for purge & trap, and air sampling applications.
Carboxen-100: trap and retain small compounds.
Carboxen-1003: large surface area for effi cient adsorption/desorption and good hydrophobicity.
Carboxen-1012: highly-activated with large micropores; effective for aqueous phase adsorption of organic compounds, or for air sampling of C4-C6 compounds.
Carboxen-1016: analyte group of permanent gases.
Carboxen-1018: narrow (~6–7 Aº) micropores for adsorption/ desorption of small analytes such as, ethane, acetylene, ethylene and the C3 hydrocarbons. Hydrophobic.
Carboxen-1021: for air sampling of small molecules.
Activated Carbons and Charcoals
Activated coconut charcoal has been used extensively as a general purpose adsorbent due to its ability to adsorb/desorb a wide range of volatile analytes.
Carbon Adsorbent Sampler Kits
Choosing the right adsorbent or combination of adsorbents can often be diffi cult. Selecting a suitable adsorbent means an adsorbent that can retain a specifi c analyte, or group of analytes, for a specifi c sample volume, and also able to release the analyte(s) during the desorption process.
By using one of the Supelco® Carbon Adsorbent Kits, the method developer obtains a cost-effective process to evaluate several carbon adsorbents when designing adsorbent-based applications and products. Once the appropriate material has been identified, we will work with you to produce larger quantities to your specifi cations.
Carbon Adsorbent Selection Guide
For multi-bed tubes, use the weaker adsorbent in front of the stronger adsorbent. For example, use Carbopack C in front of Carbopack B.