Simultaneous Determination Of Lead And Cadmium With Sequential Injection Hydride Generation-atomic Fluorescence Spectrometry

Lead and cadmium are both detrimental to human health. Lead can cause harmful effect on the nervous system and deteriorate the development of the intelligence of childhood. Cadmium has been classified as the first category carcinogens by the International Agency for Research on Cancer (IARC). It is, therefore, highly desirable to develop accurate, fast and sensitive methods for the determination of ultra-trace lead and cadmium.Hydride generation atomic fluorescence spectrometry (HG-AFS) is one of the most suitable approaches for measuring ultra-trace lead and cadmium and some other hydride forming elements. In this work, a novel hydride generation system was reported for the simultaneous hydride generation of lead and cadmium, i.e., the system of K3Fe(CN)6-(NH4)2Ce(NO3)6-NaBH4, where 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)2Ce(NO3)6, meanwhile, the K3Fe(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)2Ce(NO3)6 serves as a sensitizer. A sequential injection-hydride generation-atomic fluorescence spectrometric procedure was thus developed for simultaneous determination of lead and cadmium. When employing the following experimental parameters, i.e.,2.0% NaBH4-3.0% HC1-0.6% K3Fe(CN)6-0.3%(NH4)2Ce(NO3)6, a 0.5 ml sampling volume, linear ranges of 0.4～15μg 1-1 (Pb) and 0.5～20μg 1-1 (Cd) were achieved, respectively, along with limits of detection of 0.09μg 1-1 (Pb) and 0.17μg 1-1 (Cd). The precisions of the procedure were characterized by RSD values of 0.5%(8.0μg 1-1 Pb, n=9) and 1.0%(6.0μg 1-1 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.