Column preconcentration and spectrophotometric determination of ziram and zineb in commercial samples and foodstuffs using (1,2′-pyridylazo)-2-naphthol (PAN)-naphthalene as adsorbate

A procedure has been developed for the determination of zinc(II) bis(dimethyldithiocarbamate) (ziram) and zinc(II) ethylenebis(dithiocarbamate) (zineb) after preconcentration on a column using naphthalene-(1,2'-pyridylazo)-2-naphthol (PAN) as adsorbent. Ziram and zineb are quantitatively retained on the column in the pH range of 9.0-12.5 and at a flow rate of 1-2 mL/min. The solid mass consisting of the Zn-PAN complex along with naphthalene is dissolved from the column with 5 mL of dimethylformamide (DMF). Absorbance of the complex was measured at 550 nm; Beer's law is obeyed over the concentration ranges of 2.0-22.0 mug of ziram and 5.0-19.8 mug of zineb in 10 mL of the final DMF solution. Ten replicate determinations on a sample solution containing 20 mug of ziram and 18 mug of zineb gave a mean absorbance of 0.33 with relative standard deviations of 0.80 and 0.70%, respectively. The interference of various ions has been studied. The method has been employed for the determination of ziram and zineb in commercial samples and in various foodstuffs, and the results were compared with the earlier reported methods.