Effect of Latex Functional Group on Selectivity

Two important conclusions may be drawn from these tables. One is that the hydroxide ion is a much weaker eluent for anion chromatography than carbonate. The second is that the eluting power of sodium hydroxide is enhanced considerably by using latexes with one or two hydroxyethyl groups instead of those containing only alkyl groups. 

Surprisingly good ion exchangers can be prepared simply by coating an ordinary HPLC material, such as C18 silica or PS-DVB, with a hydrophobic molecule containing an ionic functional group. Table 3.8 lists a number of coating materials that have been used [19]. 

The actual coating may be done statically by equilibrating the particles of bonded-phase silica or polymeric resin with a solution of the coating material in methanol- 

4) was used as the mobile phase. Separation of anions on a PS-DVB (Hamilton PRP-1) coated column required an aqueous mobile phase containing 1-S% acetonitrile. The acetonitrile was needed to make good surface contact with the very hydro-phobic PRP-1. 

Other authors have used coated columns successfully for ion chromatography. Polymer-based packing or a C18 silica packing coated with methyl green or ethyl violet [4] has been used to coat substrates for the separation of anions. Several dyes httvc been used to coat substrates for separation of various metal ions [5]. 

---