Anion-trap column

Roethig, J. and Smith, G., Auto-regeneration of anion-trap columns for improved determination of silica by ion chromatography. Journal of Chromatography A (2004), 1039(1-2), 23-25. 

Fig. 7.16. (A) Schematic diagram of SFE-HPLC coupled systems. (Al) SFE system 1 CO, cylinder, 2 filter, 3 cooler, 4 SFE pump, 5 tee connector, 6 six-port valve, 7 modifier pump, 8 oven for extraction chamber, 9 mixing column, 10 six-port valve, 11 extraction cell. (A2) Interface 12 restrictor, 13 six-port valve, 14 oven for the six-port valve, 15 cell trap, 16 liquid trap. (A3) HPLC system 17 HPLC pump for H,0 or HCl/MeOH, 18 six-port valve, 19 anion-exchange column, 20 HPLC column, 21 diode array detector, 22 computer. (B) Exploded view of the valves. (Reproduced with permission of Pergamon Press.)...

Among the three-dimensional silicates are the zeolites, which contain cavities or tunnels in which Na+ or Caz+ ions may be trapped. Synthetic zeolites with made-to-order holes are used in home water softeners. When hard water containing Ca2+ ions flows through a zeolite column, an exchange reaction occurs. If we represent the formula of die zeolite as NaZ, where Z represents a complex, three-dimensional anion, the water-softening reaction can be represented by the equation... 

As mentioned in the historical synopsis (Section 5.1), Levine121 perfected the compendial partition column procedure in which aspirin in chloroform is first trapped in an immobile phase of sodium bicarbonate on a column of siliceous earth (celite) then eluted with a solution of acetic acid in chloroform and measured spectrophotometrically. This has been also used for separation in combination products.80 For the determination of salicylic acid in presence of aspirin by this method, see Section 5.61. Ion exchange columns filled with strongly or weakly basic anion exchange resin in the acetate or chloride cycle have also been used for separation of aspirin in combination products. 122 123/l2lf This has also been adapted for a student experiment.125 A Sepha-dex-G25 column has been used for the separation of aspirin from salicylic acid.126... 

In a more recent work Ito [101] has described a simple and highly sensitive ion chromatographic method with ultraviolet detection for determining iodide in seawater. A high-capacity anion exchange resin with polystyrene-divinylbenzene matrix was used for both preconcentration and separation of iodide. Iodide in artificial seawater (salinity, 35 % ) was trapped quantitatively (98.8 0.6%) without peak broadening on a preconcentrator column and was separated with 0.35M sodium perchlorate+ 0.10M phosphate buffer (pH 6.1). On the other hand, the major anions in seawater, chloride and sulphate ions, were partially trapped (5-20%) and did not interfere in the determination of iodide. The detection limit for iodide was 0.2pg L 1 for 6mL of artificial seawater. This method was apphed to determination of iodide (ND-18.3pg L ) and total inorganic iodine (I +I03 -I, 50.0-52.7pg L 1) in seawater samples taken near Japan. 

---