[Determination of inorganic anions in Herba Ephedrae by ion chromatography]

An ion chromatographic method for the detemination of inorganic anions in Herba Ephedrae was developed. The separation of the anions was achieved on a Shim-Pack IC-AI column with a mixture of 2.5 mmol/L phthalic acid and 2.4 mmol/L tris (hydroxymethyl) amino-methane as mobile phase, and the detection was performed by a conductivity detector. Fluoride, chloride, nitrite, bromide, nitrate and sulfate could be identified within 10 min. The method is simple and useful, and has good linearity with correlation coefficients between 0.999 2 and 0.999 7 and relative standard deviations lower than 1.92%. The recoveries of anions in the samples were between 96.6% and 100.4%.