The determination of neodymium content in the wastewater from production of RE cis-1,4-polybutadiene rubber in pilot-scale by absorption spectrometry was studied.The determination conditions were as follows:the maximum absorption wavelength was 674 nm;Nd3+ standard solution,CPAⅢ and buffer solution were added in turn,upper limit ofρ(Nd3+) was 2.0 mg/L,dosage of 0.500 g/L CPAⅢ anhydrous ethanol solution was 3.0 mL and pH was 2.0,dosage of hydrochloric acid-glycin buffer solution was 9.0 mL.The slope of standard curve was 0.428 2,the recovery of standard curve was in the range of 97.5%～102.4%,which can meet the requirement that measurement error was not more than ±5%.The metal element analysis was carried out by ICP-AES,concentration of calcium was 10.85 mg/L.The correction equation of determining neodymium was regressed by Origin under 0～20 mg/L calcium co-exist.Then,the determined concentration of neodymium in the waste water was 3.35 mg/L,whose concentration was in the micro-level.

Stability of chlorophosphonazo Ⅲ as a chromogenic reagent for determination of Nd by spectrophotometry was studied by tracking the change of the absorbency and the slope of the standard curve every two days during 62 days.Results indicate the standard curve is stable basicaly because fluctuation intensity is LT 3%.So if precision requirement of measurement is lower,k is 0.4345.Otherwise duration of the chromogenic reagent is LE 30 days,and k is 0.4260.