Bond Elut C18 is the most hydrophobic, bonded silica sorbent available in the Bond Elut family. It is considered to have the broadest retention spectrum among bonded silica sorbents. C18 is the most popular SPE sorbent because of its extreme retention of nonpolar compounds.;Bond Elut C18 retains most organic analytes from aqueous matrices. When analyzing small to intermediate molecules, Bond Elut C18 can be used for desalting aqueous matrices before ion exchange, as salts pass through the sorbent unretained.