在偶氮氯瞵Ⅲ的重稀土(钆至镥)螯合物的吸收光谱中,其吸收谱带扩展至700～800毫微米间,最大吸收约在745毫微米处。这些谱带的强度随着金属对试剂的克分子比和原子序数的增大而增加,亦取决于pH值和显色时间.在相同情况下,相应的轻稀土(镧至铕)螯合物不显示相似的最大吸收。光度试剂2,7-双-(4-氯-2-膦酸基苯偶氮)-1,8-二羟基萘-3,6-二磺酸(偶氮氯膦Ⅲ)为铬变酸的对称 In the absorption spectrum of the heavy rare earth (gadolinium to chelate) chelates of azochloramine III, the absorption band is extended to 700 to 800 nm and the maximum absorption is about 745 nm. The intensities of these bands increase with increasing molar ratios and atomic numbers of the metal-to-reagent depending on the pH value and the color development time. In the same case, the corresponding light rare earth (lanthanum to europium) chelates Do not show similar maximum absorption. Photometric reagent 2,7-Bis- (4-chloro-2-phosphonophenylazo) -1,8-dihydroxynaphthalene-3,6-disulfonic acid (Chiorophosphine III) symmetry