Anion-exchanger packed precolumn

Figure 5. Standards recovered from 10 mL of distilled-deionized water on a strong-anion-exchanger packed precolumn. Peak identities 1, 0.87 pg of phenoxyacetic acid 2, 1.2 pg of p-chlorobenzoic acid 3, 0.33 pg of 2-naphthalenesulfonic acid and 12, 0.055 pg of pyrene. Conditions for concentration, analytical separation, mobile-phase gradient, and detection were the same as in Figure 3. (Reproduced with permission from...

The second enhancement column was constructed of plastic (4.6 x 50mm) and packed with an anion exchange resin in the OH+ form TSK SAX (5pm). The precolumn was constructed of plastic (7.5 x 100mm) and packed with an anion exchange resin in the OH+ form (TSK SAX, 5pm). 

Bonded-phase silica materials are the most widely used particles for SPE. Since the technology of bonded-phase silica packings for LC columns was already well developed, it was relatively easy for suppliers to offer similar materials in a form suitable for SPE. The most common types are listed in Table 1. Octadecylsilane, or sometimes octylsilane, particles are used for retention of relatively hydro-phobic organic analytes from predominately aqueous samples. A more polar particle, such as cyano-propylsilane, is selected for SPE of less hydrophobic analytes. Cation- and anion-exchange resins are used in small precolumns to concentrate sample ions from very dilute aqueous samples prior to their... 

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