Abstract:

A new flow-injection catalytic kinetic spectroscopy was developed for the determination of Cu²⁺ based on its catalytic activity on the oxidation of safranine T by potassium bromate in sulfuric acid solution. Cu²⁺ can be separated and enriched on-line by using a customer designed 1,5-diphenylcarbazone grafted silica gel micro-column coupled with flow injection technology. The determination conditions including the enrichment time, coil length, flow rates of sample, type of eluent, reaction medium, amounts of all reagents, reaction temperature and effects of external ions, were optimized. Under these conditions, the linear range of the concentration determination curve is 0.0010~0.60 mg/L and the detection limit is 7.9×10^-4 mg/L. The sensitivity was improved by 20 times and the permitted amounts of some external ions were enhanced at least 10 times than that of a non-preconcentrated step method. The relative standard deviation of eleven replicate measurements is less than 2.6%. One assay cycle only takes 6 min and the total volume of reagents consumed is 6.0 mL. This established method has been applied for the determination of trace amounts of copper in Chinese traditional medicine and tea.

Key words: Solid-phase extraction, catalytic kinetic, flow injection spectrophotometry, copper