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在PH8.5-9的液中,钙可与DBC-偶氮氯膦形成一种紫色的稳定配合物。该配合物在625nm处有最大吸收,表观摩尔吸光系数为2.6×10~4L.mol~(-1).cm~(-1),配合物组成为Ca:DBC-偶氮氯膦=1:1。在Zn-DTPA和乙二胺的存在下,较大量的Y~(3+)、Fe~(3+)及Cu~(2+)、Mo(Ⅵ)、Cr~(3+)等三十余种离子不干扰钙的测定。方法的选择性较好,利用本方法,并经简单萃取分离基体后,测定了高纯氧化钇和易切削钢中的微量钙,结果令人满意。标准加入试验回收率好。方法简便实用。
In the pH 8.5-9 solution, calcium forms a purple stable complex with DBC-chlorophosphonazo. The complex has the maximum absorption at 625nm with an apparent molar absorptivity of 2.6 × 10 ~ 4L.mol -1 (cm -1). The complex has a composition of Ca: DBC-chlorophosphonazo = 1 :1. In the presence of Zn-DTPA and ethylenediamine, a relatively large amount of Y ~ (3 +), Fe ~ (3+) and Cu ~ (2 +), Mo (VI), Cr ~ (3+) Ions do not interfere with the determination of calcium. The method has good selectivity. By this method, the trace calcium in high-purity yttrium oxide and free-cutting steel was determined after simple extraction and separation of matrix. The result was satisfactory. Standard join test recovery rate is good. The method is simple and practical.