5-Br-PADAP共振光散射法测定水中镉

Determination of Cadmium in Water by Resonance Light Scattering with 5-Br-PADAP

建立了一种快速、准确测定水中镉含量的共振光散射(RLS)方法。在pH=9.0的氨-氯化铵缓冲介质及表面活性剂十二烷基硫酸钠(SDS)存在下,镉(II)与2-(5-溴-2-吡啶偶氮)-5-二乙氨基酚(5-Br-PADAP)可形成复合物,导致体系共振光散射强度显著增加,据此建立了利用共振光散射技术测定镉含量的分析方法。在优化条件下,依次加入0.40mL的pH=9.0的NH3-NH4Cl缓冲溶液,0.10mL的1.0mmol/L5-Br-PADAP溶液,适量镉(II)标准使用液,以及0.40mL的1.0mmol/LSDS水溶液,并定容至10.0mL,于室温下反应10min,在最大散射峰604nm处测定共振光的散射信号。结果表明,共振光散射强度与镉(II)质量浓度在5.3~200.0μg/L范围内呈线性关系,检出限(3Sd/K)为0.1μg/L。

A resonance light scattering (RLS) method for the rapid and accurate determination of Cadmium in water was developed.In an ammonia-ammonium chloride buffer medium at pH 9.0 and in the presence of surfactant sodium dodecyl sulfate (SDS),Cadmium(II) reacted quickly with 2-:(5-bromine-2-pyridine)-azo:-5-diethylaminophenol(5-Br-PADAP) and formed a complex,which led to a distinctly enhancement of resonance light scattering signal of system.Accordingly,an analysis method of Cadmium content using resonance light scattering was established.Under optimized conditions,0.40 mL of ammonia-ammonium chloride buffer solution at pH 9.0,0.10 mL of 1.0 mmol/L 5-Br-PADAP solution,proper amount of Cadmium(II) standard solution and 0.40 mL of 1.0 mmol/L SDS were added successively into a colorimetric tube and diluted to 10.0 mL.After reaction at room temperature for 10 min,the resonance light scattering signals were determined at maximum scattering peak of 604nm in 1cm quartz cuvette.The results indicated that in the largest scattering peak at 604 nm,the resonance light scattering intensity was directly proportional to the mass concentration of Cadmium(II) in the range of 5.3 μg/L to 200.0 μg/L with a detection limit (3 S d / K ) of 0.1 μg/L.