Abstract:

A new inhibitory kinetic spectrophotometric method for the determination of trace copper in tea was proposed.
The method was based on the fact that in HAc-NaAc buffer solution (pH 3.5), trace amounts of copper can inhibit the
oxidative fading of bromophenol blue induced by potassium iodate in the presence of ascorbic acid as an activator.
Important experimental conditions were optimized and interference from co-existing ions was investigated. Under optimized
conditions, the linear range of the method was 0–0.058 μg/mL, and the limit of detection was 9.04 × 10-10 g/mL. The
average recoveries of copper from spiked tea samples were in the range of 94.3%－102.6% with relative standard deviations
less than or equal to 4.8% (n = 6). The method proved to be simple, rapid, sensitive and has been used to determine trace
copper in tea leaves with satisfactory results.

Key words: inhibitory kinetic spectrophotometry, bromophenol blue, copper, tea, potassium iodate