[Determination of anions in recycle sodium formate from sodium hydrosulfite industry with single column ion...

The analysis of recycle materials from industrial waste water of sodium hydrosulfite production was made by single-column anion exchange chromatography. The recycle material was sodium formate (HCOONa) in which various anions, such as SO(3)2-, Cl-, thiosulfate, hydroxyethyl sulfonate (HOC2H4SO3-), hydroxyethyl thiosulfate (HOC2H4S2O3-), SO(4)2- and NO3- as impurities were existed simultaneously. Except hydroxyethyl sulfonate anion, all other ions can be separated by using anion exchange column Shim-pack IC-Al (4.6 mm i.d. x 100 mm) with the mixture of 1.8 mmol/L of phthalic acid and 1.35 mmol/L of Tri(hydroxymethyl) aminomethane as eluent. The flow rate of mobile phase is 1.0 mL/min. The injection volume was 20 microL. The column oven temperature was controlled at 40 degrees C. Hydroxyethyl sulfonate anion and SO(3)2- could not be separated at the above conditions, but they did not interfere the determination of HCOO-. The detection limits for HCOO-, SO(3)2-, NO3-, S2O(3)2-, HOC2H4S2O3-, Cl- and SO(4)2- were 1.0, 0.7, 1.4, 5.0, 0.7, 0.2 and 2.0 mg/L, respectively. The recoveries were between 96%-102%, and the relative standard deviations (RSD) were lower than 6.0% (n = 5) for all seven ions. This method is characterized by rapidity, sensitivity and simultaneous determination of several kinds of ions.