Determination of Cadmium by Electrothermal Atomic Absorption Spectrometry Using Single Drop Micro Extraction in Real Samples

Abstract

In this investigation a novel and extremely sensitive method for extraction and determination of cadmium in aqueous samples by liquid phase micro extraction combined with electrothermal atomic absorption spectrometry using a new ligand is described. In this method Cd²⁺ in pH 4 during 20 min extraction time at 20 ºC is reacted with S-methyl-3-salicylidene dithiocarbazate dissolved in 4 μL of chloroform micro drop. After extraction, the micro drop was retracted and directly transferred into a graphite tube coated by palladium as chemical modifier. In this investigation the type of organic solvent, volume of organic solvent, pH, temperature and extraction time were optimized. Using 10 mL sample solution an enrichment factor of 100 was obtained. The detection limit was calculated to be 6 pg mL^-1 based on 3Sb and relative standard deviation for five replicate analysis of 0.2 ng mL^-1 Cd²⁺ was 4.9 % .The calibration curve was liner in the range of 6 pg mL^-1 to 1.0 ng mL^-1 with a sensitivity of 1.0 pg mL^-1. This method was used for determination of cadmium in tap water, waste water, sea water, soil and reliability of the method was evaluated using two reference materials.