Determination of Copper in Tobacco by Spectrophotometry Using 1-(2-Pyridine azo)-2-naphthol as a Color Reagent

The determination of copper in tobacco by coloration using 1-(2-pyridine azo)-2-naphthol as a color reagent was studied.In the HAc-NaAc buffer medium with a pH value of 4.0, a stable complex was formed by reaction of Cu²⁺ with 1-(2-pyridine azo)-2-naphthol, and the maximum absorption of the complex was at wavelength of 552nm.When the concentration of copper was in the range of zero to 15μg per 25 milliliter, the relationship between the absorption of the complex and the concentration of Cu²⁺ observed the Beer's law.Being used for determining the content of copper in tobacco, the recovery of copper standard was from 97.89%to 101.35%, and the requirements of sensitivity and selectivity were fulfilled.The relative standard deviation between this method and the atomic absorption was from 1.7% to 2.6%.No significant difference was found.