Analytical Sciences

Simultaneous Determination of TraceCadmium and Mercury in Chinese Herbal Medicine by Non-dispersive AtomicFluorescence Spectrometry Using Intermittent Flow VaporGenerator

Hanwen SUN,*  RanSUO,*^,** and Yunkai LU*

*Key Laboratory of Analytical Science ofHebei Province, College of Chemistry and Environmental Science, HebeiUniversity, Baoding 071002, Hebei Province, China
**College of FoodScience, Hebei Agricultural University, Baoding 071001, Hebei Province,China

A method was proposed for the simultaneousdetermination of trace cadmium and mercury by vapor generationnondispersive atomic fluorescence spectrometry using an intermittent flowsystem. The effects of the parameters on the performance were studiedsystematically. The parameters such as acid concentration of the reactionmedium, flow rate of the carrier gas and shield gas, the observation heightand the atomizer temperature, etc. which affected the sensitivity,were optimized. Ascorbic acid, cobalt ion and thiourea were used asenhancement reagents or masking agents to enhance the generation efficiencyof the volatile species of Cd and Hg. The mechanisms of their effects onvapor generation were investigated. In the presence of thiourea andascorbic acid, the influences of some coexisting elements on thedetermination of cadmium and mercury were investigated. The detectionlimits (3σ) were 0.010 µg l^-1 for Cd and 0.019µg l^-1 for Hg, respectively. The relative standarddeviations for Cd and Hg at 1.00 µg l^-1 were 2.6% and 0.97%(n = 11), respectively. The proposed method has been satisfactorilyapplied to the determination of trace cadmium and mercury in Chinese herbalmedicine.

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