Determination of Glycolate Acid, Mono- and Dichloroacetic Acids in Synthetical Betaine by Anion-exchange Chromatography

An anion-exchange chromatography method combined solid phase extraction (SPE) was developed for the simultaneous analysis of glycolate acid (GL), monochloroacetic acid (MCA) and dichloroacetic acid (DCA) in synthetical betaine products. The analytes and unknown anionic impurities were well separated on a Metrosep A supp5 anion-exchange column (150 mm×4 mm) with 2.0 mmol/L Na 2 CO 3 +2.0 mmol/L NaHCO 3 solution as eluent. Suppressed conductivity detection was used. A strong cation exchange (SCX) solid phase extraction (SPE) cartridge was used to reduce the concentration of matrix betaine and a Cleanert IC-Ag pretreatment cartridge was used to remove high Cl − concentration. The detection limits of GL, MCA and DCA were 0.09, 0.017 and 0.05 µg/L, respectively. The relative standard deviations (RSDs) of the retention times and peak areas were less than 0.09% and 0.49%, respectively. The recoveries of the three analytes were between 90.6% and 100.8%. The analytical results showed that GL and DCA were present in high concentration and no MCA was found when the proposed ion chromatography method was applied to three synthetical betaine samples. The proposed method is simple, sensitive and timesaving, and is also suitable for routine analysis in quality control of synthetical betaine products.