在 pH2 0时 ,La(Ⅲ )　Ce(IV)和Nd(Ⅲ )均与CPAⅢ发生高灵敏的显色反应 ,形成稳定的二元络合物 ,其λmax分别为 6 73、6 73和 6 70nm ,表明吸收光谱严重重叠 ;在相应λmax处 ,其表观摩尔吸光系数分别为 7 6 0× 10 4 、6 76×10 4 和 7 80× 10 4 L·mol-1·cm-1。本文采用迭代目标转换因子分析法辅助分光光度法对模拟样和大米样中痕量镧、铈和钕进行了同时测定 ,结果具有满意的准确度和精密度。 At pH 20, La (Ⅲ) Ce (IV) and Nd (Ⅲ) reacted with CPA Ⅲ in a highly sensitive manner to form stable binary complexes with λ max of 6 73, 6 73 and 6 70 nm , Indicating a serious overlap of the absorption spectra. At the corresponding λmax, the apparent molar absorptivities were 7 6 × 10 4, 6 76 × 10 4 and 7 80 × 10 4 L · mol -1 · cm -1, respectively. In this paper, Iterative target conversion factor analysis assisted spectrophotometry for simultaneous determination of trace amounts of lanthanum, cerium and neodymium in simulated and rice samples with satisfactory accuracy and precision.