甲基蓝探针瑞利光散射测定奶制品中Cu(Ⅱ)

Determination of C(Ⅱ) in Milk Products by Rayleigh Light Scattering Method with Methyl Blue as a Probe

建立了检测奶制品中Cu(Ⅱ)的瑞利散射(RLS)法,探讨了适宜反应条件、反应机理、共存物质的影响及RLS光谱特征。在pH=5.50的Tris-HCl缓冲介质中,溴化十六烷基三甲基铵(CTMAB)增敏甲基蓝(MEB)使RLS信号显著增强,而Cu(Ⅱ)的加入则使体系的瑞利散射猝灭。在最大瑞利散射峰348nm处,Cu(Ⅱ)的质量浓度在0.007~0.13mg/L范围内与体系的RLS猝灭程度呈线性关系,检出限为0.0058mg/L,定量限为0.069mg/100g。方法用于奶制品中Cu(Ⅱ)的测定,加标回收率为98.4%~103%,相对标准偏差(RSD,n=6)为2.2%~2.8%。

A new Rayleigh scattering（RLS）method for the determination of Cu（Ⅱ）in milk products was established.The optimum reaction conditions,reaction mechanism,the effects of coexistent substances and the spectrum characteristics of Rayleigh scattering of ternary complex were discussed.In a Tris-HCl acid buffer medium of pH=5.5,the RLS signal of mythyl blue（MEB）was significantly enhanced in the presence of cetyltrimethylammonium bromide（CTMAB）,while the addition of Cu（Ⅱ）resulted in the quenching of the RLS signal.The maximum Rayleigh scattering peak was located at 348 nm.At this wavelength,the mass concentration of Cu（Ⅱ）in the range of 0.007-0.13 mg/L was directly proportional to quenching intensity of Rayleigh scattering of system with the detection limit of 0.0058 mg/L and limit of quantitation of 0.069 mg/100 g.The method has been applied to the determination of copper in milk products with the standard addition recovery and RSDs（n=5）found were in the ranges of98.4%-103% and 2.2%-2.8%,respectively.