双波长共振瑞利散射法测定皮蛋中的汞

Determination of trace mercury in preserved eggs by dual-wavelength resonance rayleigh scattering method

建立了测定皮蛋中Hg的双波长共振瑞利散射新方法,研究了共振瑞利散射的光谱特征、共存物质的影响及反应机理。在pH 6.58的Tris-HCl缓冲介质中,Hg(Ⅱ)与快绿-溴代十六烷基吡啶结合生成三元络合物,使体系的双波长-共振瑞利散射(DWO-RRS)光谱显著增强,最大和次大的共振瑞利散射峰分别位于344 nm和470 nm波长处。当用双波长-共振瑞利散射(DWO-RRS)法测定时,Hg(Ⅱ)的质量浓度在0.005~0.50 mg/L范围内与体系的共振瑞利散射增强强度△I_(RRS)呈线性关系,检出限(3σ/S)为1.4 ng/mL,定量限为0.034 mg/kg。方法用于皮蛋中Hg的测定,回收率为98.2%~102%,相对标准偏差(n=5)为2.1%~2.7%。

A new dual-wavelength overlapping resonance Rayleigh scattering （DWO-RRS） method for the determination of trace mercury in preserved eggs was developed. The spectral characteristics of resonance Rayleigh scattering and the effects of coexistent substances and reaction mechanism of ternary complex were discussed. In a Tris-hydrochloric acid buffer of pH 6. 58, mercury（ Ⅱ ） can be bound with fast green-hexadecylpyridinium bromide to form a ternary complex. As a result, the new spectrum of DWO-RRS appeared and its intensities were enhanced greatly. The two largest resonance Rayleigh scattering peaks were located at 344 nm and 470 nm respectively. When DWO-RRS method was used to determine the concentrations of Hg （ Ⅱ）, RRS enhanced intensity A IRas was directly proportional to the mercury （ Ⅱ ） concentration in a range of 0. 005 to 0. 50 mg/L with the limit of detection （3σ/S） of 1.4 ng /mL and the limit of quantitation of 0. 034 mg/kg. The method was applied to determine the content of trace mercury in preserved eggs with recovery and relative standard deviation （n =5） found in the ranges of 98.2% - 102% and 2. 1% -2. 7% , respectively.