C18 -- silica-based bonded phase with strong hydrophobicity; used to adsorb analytes of even weak hydrophobicity from aqueous solutions; typical applications include drugs and their metabolites in serum, plasma or urine, desalting of peptides, trace organics in environmental water samples, organic acids in beverages; similar in behavior to reversed-phase HPLC columns
tC18 -- silica-based bonded phase with strong hydrophobicity; trifunctional bonding chemistry gives it an increased hydrolytic stability over C18; applications similar to C18
C8 -- silica-based bonded phase with moderate hydrophobicity; use for methods requiring less retention than C18; typical applications include drugs and their metabolites in serum, plasma or urine, peptides in serum, plasma
tC2 -- silica-based bonded phase with low hydrophobic character; use for methods requiring less retention than C8; applications are similar to C18 and C8
Porapak™ RDX -- specially cleaned polymeric poly(divinylbenzene-vinylpyrrolidone) resin with hydrophobic character. Can be used as an alternative to octadecyl-bonded silica for preparation of analytes that weakly adsorb to silica-based reversed-phase sorbents. Compatible with sample or eluents at high and low pH. Specifically designed for the concentration of high explosives in aqueous samples.