Abstract: An electrochemical signal inhibition method coupled with microwave digestion was developed for ultra-sensitive determination of chromium(Ⅵ) in ell. Cr(Ⅵ) could be oxidized and the oxidation peak current was therefore inhibited. Factors affecting Cr(Ⅵ) determination such as buffer solution pH, enrichment potential, accumulation time and possible interferences were investigated. The developed method revealed excellent linearity over the Cr(Ⅵ) concentration of 0.2 to 2.6 nmol/L with a correlation coefficient 0.9977. The limit of detection was 60.2 pmol/L. This method proved ultra-sensitive and effective despite the presence of excess interference ions, thereby being applicable for the determination of Cr(Ⅵ) in eel.

Key words: microwave digestion, electrochemistry, determination, chromium(Ⅵ)