Determination of Copper, Nickel and Cadmium in Waste Gas Samples from Stationary Pollution Sources by Graphite Furnace Atomic Absorption Spectrometry with Microwave Digestion

Waste gas samples from stationary pollution sources were collected by filter cartridges, and the filter cartridges were cut into pieces and placed into microwave digestion tubes. 5.0 mL of a mixture of hydrochloric acid and nitric acid at a volume ratio of 3:1 and 20.0 mL of water were added, and the mixture was digested at 200℃ for 15 min. 10 mL of water was added into the digestion solution obtained, settling for 0.5 h. After filtration, the solution was made its volume up to 50 mL with water. Copper, nickel and cadmium in the sample solution were determined by graphite furnace atomic absorption spectrometry. The optimized determination conditions of copper, nickel and cadmium were as follows:the ashing temperatures were 1 100, 1 200, 500℃, with the same ashing time of 20 s; the atomization temperatures were 2 000, 2 400, 1 500℃, with the atomization time of 5, 5, 4 s, respectively. As shown by the results, linear relationships between values of absorbance and mass concentration of copper, nickel and cadmium were found in definite ranges, with detection limits (3.143s) of 2, 3, 0.06 μg·L^-1, respectively. This method was applied for determination of the reference material (total amount) (RMU010) for heavy metal composition analysis in coal fly ash, and the determined values were basically consistent with the certified values. An actual coal fly ash sample was determined 6 times in parallel, with RSDs of the determined values in the range of 2.6%-7.0%. Seven waste gas samples from a stationary pollution source were collected and determined by this method, with RSDs of the determined values less than 20%, and it was shown that the collection method had certain stability.