Among them, the colour reaction of bibromo-caboxy-4-chloroarsenazo ( CAsA- DBE ) has the advantages of great contrast, high sensitivity and good selectivity.

• 其中的二溴羧基偶氮氯肿(CAsA-DBK)与稀土元素反应具有对比度大、灵敏度高、选择性好等优点。