Determination of sulfur dioxide in traditional Chinese medicine by alkaline solution extraction and ion chromatography

Abstract

An ion chromatographic method was developed to analyze sulfur dioxide in traditional Chinese medicine (TCM). The samples were extracted with alkaline solution and reacted with formaldehyde to form hydroxymethyl sulfonic acid. The extracts were cleaned by C18 column and SO3(2-) was determined with ion chromatography equipped with a conductance detector. In the method, AS11-HC chromatographic column was used and the mobile phase was 15 mmol x L(-1) KOH. The calibration curve was in good linearity in the range of 1 to 100 microg (r =0.9992). The detection limit was 0.53 mg x kg(-1) and the average recovery was 103.7%. The method is simple, sensitive, precise, short-time-consuming, and the random error is smaller, which is applicable to the testing of large quantity batches of TCM.