Abstract：The indirect determination method of chlorine in limestone was proposed by flame atomic absorption spectrometry after dissolving the sample with nitric acid. In this method, the same amount of chlorine was firstly added into both sample ion and calibration curve solution. Then, excessive silver ion was added to form silver chloride saturated solution, eliminating the interference of micro suspended silver chloride and its solubility during the determination of chlorine by indirect flame atomic absorption spectrometry. In the proposed method, ammonium persulfate was added in sample preparation process to oxidize and remove interference ions such as S2-, I- and most of Br-, avoiding the filtration and distillation operation procedures which were complicated and polluted easily. The relative standard deviation (RSD, n=9) of method was 0.3 %~7.0 %. This method was verified with national certified reference material, and the determination results were basically consistent with the certified values.
