Determination of chloride ion in additives of concrete by flame atomic absorption spectrometry

Flame atomic absorption spectrometry due to its high sensitivity and selectivity has been widely used for the determination of micro levels of metal elements in various materials. But this method can not be used for the determination of Cl- directly. In this paper the determination of Cl- in additives of concrete by flame atomic absorption spectrometry was studied. Adding superfluous standard solution of Ag+ to the sample solution, the results were obtained by determining the remanent content of Ag+ having reacted with Cl- quantitatively. The acidity of the sample solution and the precision were studied. The standard rate of recovery obtained was in the range of 96% -104%. By the determination of actual samples it was proved that the method features simple sample preparation, fast determination, and little interference, especially for those samples which contain micro levels of Cl-. The procedure is as follows: weigh 0.05-2 g of sample, dissolve it in water and adjust the acidity with nitric acid, add proper standard solution of Ag+, and after 2 h, measure the remanent Ag* content by atomic absorption spectrometry. A GBC902 atomic absorption spectrometry was employed.