氢化物发生-催化共振瑞利散射光谱法测定痕量砷

在硫酸介质中,以硼氢化钠(NaBH_4)为还原剂,可将As(Ⅲ)还原为砷化氢(AsH_3)气体使其逸出,用Ce(SO_4)_2-H_2SO_4-KI混合液做吸收液,在催化剂KI存在下四价铈与AsH_3气体反应生成具有共振瑞利散射(RRS)的砷微粒和具有荧光的三价铈,导致体系在370nm处的RRS信号和在351nm处的荧光强度增大。在选定条件下,As(Ⅲ)浓度分别在0.006~0.76mg·L~(-1)和0.006~0.28mg·L~(-1)范围内与RRS增加值ΔI和荧光强度增大值ΔF351呈线性关系,检出限均为3.0μg·L~(-1)。据此可建立新的检测As(Ⅲ)的催化RRS和荧光光谱法。

A Hydride Generation-Catalytic Resonance Rayleigh Scattering Method for Detection of Trace Arsenic

Arsenic is a toxic metal element and the establishment of a highly sensitive and selective method for As has great sig-nificance to human health and environment protection.In sulfuric acid medium,As(Ⅲ)was reduced by NaBH4 to form AsH3 gas that was trapped by the Ce(Ⅳ)-I- catalytic absorption solution to cause Ce(Ⅳ)concentration decreased and As particle in-creased,which resulted in the resonance Rayleigh scattering (RRS)and fluorescence increased at 370 and 351 nm respectively. The increased RRS and fluorescence intensities were linear to As(Ⅲ)concentration in the range of 0.006~0.76 and 0.006~0.28 mg·L-1 respectively,with a detection of As of 3.0μg·L-1 .The new hydride generation-catalytic RRS method was ap-plied for detection of trace As(Ⅲ)in milk samples,and the results were in agreement with that of hydride generation-atomic ab-sorption spectrometry.