Samples was digested by HNO_3, to detect Ca, Mg, K, Cu, Fe, Mn in flame atomic absorption, to detect Cr and Ni in graphite atomic absorption.

• 样品用硝酸消解,用火焰原子吸收法测定钙、镁、钾、铜、铁、锰,用石墨炉原子吸收法测铬和镍。