[Development of capillary electrophoretic method for determination of the inorganic anions in the ash of black powder].

A capillary electrophoretic method for determining the inorganic anions in the ash of black powder has been developed. The components and pH of the buffer solution, the concentration of osmotic flow modifier and the separation voltage were investigated. The optimized parameters were 5.0 mmol/L sodium chromate buffer solution (pH 8.20) containing 0.5 mmol/L cetyltrimethylammonium bromide (CTAB) as osmotic flow modifier, a separation voltage of -20 kV and a detection wavelength of 254 nm. Under the specified conditions five anions were completely separated in four minutes, and the repeatabilities (RSD) of migration time and peak area were in the range of 0.17%-1.4% and 3.9%-5.0%, respectively. The detection limits were in the range of 5.0 mumol/L to 10.0 mumol/L. To show the usefulness, the method was applied to analyze the ash of a black powder and the results showed that the relative standard deviations of the determination for Cl- and NO2- were 6.0% and 3.9%, respectively.