Spectrophotometric Determination of Calcium in Tobacco with m-Chloroantipyrylazo

A spectrophotometric method for the determination of calcium in tobacco with m-chloroantipyrylazo was studied.In the sodium hydroxide solution medium, a blue complex was formed by Ca²⁺ with the chromogenic reagent, which had a maximum absorption at wavelength of 630nm, and an apparent molar absorptivity of 2.6×10⁴ L·mol^-1·cm^-1.The calibration curve was a straight line when the concentration of Ca²⁺ was in the range of zero to 40μg/25mL.Other metallic cations in tobacco did not interfere with the determination of Ca²⁺.The average recovery of this method was between 96.2% to 99.3% and RSD was 2.8%.