Analytical Sciences

Determination of Traces of Cadmium in Natural Water Samples by Flow Injection On-line Preconcentration-Graphite Furnace Atomic Absorption Spectrometry

Yoshihiro HIRANO,* Junichi NAKAJIMA,* Koichi OGUMA,* and Yasushi TERUI**

*Department of Materials Technology, Faculty of Engineering, Chiba University, Yayoi-cho, Inage, Chiba 263-8522, Japan
**Instruments Group, Analytical Systems Center Design Department, Hitachi, Ltd., Ichige, Hitachinaka 312-8504, Japan

A flow injection on-line preconcentration-graphite furnace atomic absorption spectrometric method was developed for the determination of traces of cadmium in natural water samples. Cadmium in samples was adsorbed on an iminodiacetate-type chelating resin, Muromac A-1 microcolumn (3 mm i.d. and 10 mm long), and then eluted with 2 mol l^-1 HNO₃. The eluate was introduced into the injection tip of an autosampler. The eluate zone with the highest analyte concentration was injected into the graphite furnace by cooperation of a peristaltic pump and a syringe pump of the autosampler, which were controlled by a programmable controller. The present system was successfully applied to the determination of cadmium in natural water samples. A detection limit of 0.2 ng^l-l was obtained with 12 ml sample loading. The recoveries were 99 and 108% for tap water (4 ml loading) and underground water (12 ml loading), respectively. Analytical results obtained for a river water reference material (JAC-0031, Japan Society for Analytical Chemistry) were close to the reference value.

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