Direct Determination of Trace Chloride Ion in Polymeric Grade Ethylene Glycol by Ion Chromatography

With KOH solution and Na₂CO₃/NaHCO₃ solution as eluents, two methods were developed for the direct determination of trace chloride ion in polymeric grade ethylene glycol (EG) by ion chromatography, respectively. Vacuum manual sample introduction mode was used. Chloride ion in the sample was seperated on IonPac AS19 analytical column (4 mm×250 mm) and IonPac AG19 guard column (4 mm×50 mm) with 5 mmol·L^-1 KOH solution for elution, or on IonPac AS23 analytical column and IonPac AG23 guard column (4 mm×50 mm) with 4.5 mmol·L^-1 Na₂CO₃-0.8 mmol·L^-1 NaHCO₃ solution for elution, and detected by conductivity detector. In the two methods, linear ralationships were found between the peak area and the mass ratio of chloride ion in definite ranges, with detection limits (10S/N) of 0.002, 0.006 mg·kg^-1, respectively. Recovery rates obtained by standard addition method were 94.7%-100%, 92.3%-99.8%, respectivly, and RSDs (n=3) were both less than 5.0%. The determination results of trace chloride ion in polymeric grade ethylene glycol by the two methods were consistent.