Determination of cadmium and zinc in vegetables with online FAAS after simultaneous pre-concentration with 1,5-diphenylthiocarbazone immobilised on naphthalene

The concentration of cadmium and zinc in vegetables was determined by using an online flame atomic absorption spectrophotometer after simultaneous pre-concentration based on the complexation of Cd and Zn with 1,5-diphenylthiocarbazone immobilised on naphthalene. The effect of pH, sample flow rate and amount of 1,5-diphenylthiocarbazone on adsorption was investigated. After pre-concentration, Cd and Zn were eluted from the sorbent with hydrochloric acid. A pre-concentration factor of 20 and 33 was achieved for Cd and Zn, respectively. The calibration curve was linear in the range of 0.21 mu g?ml-1 for Cd and Zn. The regression coefficients for the lines were 0.9914 and 0.9989 for Cd and Zn, respectively. The detection limits were calculated as three times the standard deviation of nine replicates of blanks: 0.00123 mu g?ml-1 for Cd and 0.00176 mu g?ml-1 for Zn.