氢化物发生新体系-原子荧光法同时测定铅和镉

A Novel Hydride Generation System for the Simultaneous Determination of Lead and Cadmium Using Atomic Fluorescence Spectrometry

报道了Pb和Cd同时氢化物发生的K3Fe（CN）6-（NH4）2Ce（NO3）6-NaBH4-HCl新体系，并探讨了相关反应机理。（NH4）2Ce（NO3）6作为氧化剂将Pb（Ⅱ）氧化为Pb（Ⅳ），Fe（CN）^3-6与Pb（Ⅳ）络合促进了Pb的氢化物发生。同时，体系中的（NH4）2Ce（NO3）6作为Cd氢化物发生过程中的增敏剂使荧光信号显著增强。在该体系中，Pb和Cd的氢化物发生不产生相互干扰。本实验据此建立了顺序注射-氢化物发生-双道原子荧光同时测定Pb和Cd的方法。所采用的实验条件包括NaBH4、HCl、K3Fe（CN）6和（NH4）2Ce（NO3）6的浓度分别为2％、3％、0．6％和0．3％。以125μL／s进样500μL，得到的线性范围分别为0．4-15μg／L（Pb）和0.5-20μg/L（Cd）；对应的检出限分别为0.09μg／L（Pb）和0．17μg／L（Cd）；方法的精密度为0．5％（6．0μg／L Pb，n=9）和1．0％（6．0μg／L Cd，n=9）。将本法应用于国家标准样品GBW08608中Pb和Cd的检测。检测值与标准值相符；对河水及海水中Pb和Cd进行了同时测定，加标回收率合格。

A novel hydride generation system was developed for the simultaneous hydride generation of lead and cadmium, i.e., the system of K3 Fe （CN） 6- （ NH4 ） 2 Ce （ NO3 ） 6-NaBH4-HCl, which no interfering effects from the hydride generation of the two species were identified. The mechanisms of the hydride generation process include the oxidation of Pb （Ⅱ） by （ NH4 ） 2 Ce （ NO3 ） 6, meanwhile, the K3 Fe （CN） 6 was used as a coordinating reagent to form a complex with Pb（ Ⅳ ） which facilitates its ensuing hydride generation. Cadmium hydride generation follows the conventional process with （NH4 ）2 Ce（ NO3 ）6 serves as a sensitizer. A sequen- tial injection-hydride generation-atomic fluorescence spectrometric procedure was developed for the simultaneous determination of lead and cadmium. When employing the following experimental parameters, i. e. , 2% NaBH4o3% HCl -0. 6% K3Fe（CN） 6-0. 3% （NH4） 2 Ce（ NO3 ）6, a 500-μL sampling volume at a flow rate of 125 μL/s, the obtained linear ranges were 0. 4 - 15 μg/L （Pb） and 0. 5 -20 μg/L （Cd） respectively, along with limits of detection of 0. 09 μg/L （Pb） and 0. 17 μg/L （Cd）. The RSDs of the procedure were derived as 0.5% （6.0 μg/L Pb, n =9） and 1.0 % （6.0 μg/L Cd, n =9）. The present procedure was applied for the determination of lead and cadmium in a certified reference material of water sample, GBW08608, a coastal sea water and a riverine water sample, with satisfactory spiking recoveries.