本文利用FIA的pH梯度技术,以Na_2HPO_1-KH_2PO_4缓冲体系在流路中建立起pH—4.47～6.47的稳定的pH梯度,用微机采集梯度内多个不同pH点上的显色配合物的吸光度数据,然后用多元线性回归法处理以求得各待测组份的浓度。利用本法,以XO为显色剂,对Cu~(2+)、Co~(2+)、Cd~(2+)中的任意两组份进行了同时测定。结果的相对误差≤4.0%. In this paper, the pH gradient of FIA was used to establish a stable pH gradient from pH 4.47 to 6.47 in the flow path of Na_2HPO_1-KH_2PO_4 buffer system. The absorbance data of chromogenic complex at different pH points , And then treated with multiple linear regression method to obtain the concentration of each component to be tested. Using this method, XO is used as a reagent to simultaneously measure any two components of Cu ~ (2 +), Co ~ (2 +) and Cd ~ (2+). The relative error of the result is ≤4.0%.