Eluents hydrofluoric acid

Borate is selectively concentrated on Amberlite XE-243 ion exchange resin and converted to tetrafluoroborate using 10% hydrofluoric acid. Tetrafluoroborate is strongly retained by the resin, thus allowing excess fluoride to be eluted without loss of boron. The tetrafluoroborate is eluted with lmol L 1 sodium hydroxide and is determined in the eluent by ion chromatography. Boron is quantified to a lower limit of 0.05mg L 1. 

A similar example represents the determination of borate that is usually analyzed with ion-exclusion chromatography. However, when borate is converted into tetrafluoro-borate by reacting with hydrofluoric acid [107], upon application of an anion exchanger indirect borate determination together with other inorganic anions becomes possible. Tetrafluoroborate is a polarizable anion therefore, when using the suppressor technique some p-cyanophenol is added to the carbonate/bicarbonate eluent to improve the peak shape of the ion that elutes after sulfate. 

With the anion detection system on the ion chromatograph and sodium carbonate solutions in various pH ranges as an eluent, an effort was made to distinguish the 0x0 phosphorus acids that existed in a hydrofluoric acid solution of PSG films. The phosphate and phosphite ions were readily detected and quantitated when compared with known standards of these ions, as shown in Figure 6 (a) - (i). 

Figure 5.22 Separation of chloride, nitrate, and sulfate in 24.5% hydrofluoric acid (w/w) after preseparation on an lonPac ICE-AS6. Eluent for the preseparation deionized water flow rate 0.55 mL/min concentrator column lonPac AG9-HC (4 mm) separator column ...

---