Determination of the fungicide ferbam in wheat grains after adsorption onto microcrystalline naphthalene.

A procedure was developed for the determination of iron(III) dimethyldithiocarbamate by converting it into iron(II)-bathophenanthroline-tetraphenylborate complex, which was then adsorbed onto microcrystalline naphthalene. The absorbance was measured at 534 nm against a reagent blank. Beer's Law was obeyed over the concentration range of 0.4-20 microg mL in final solution. Ten replicate determinations on 70 microg ferbam solutions gave a mean absorbance of 0.36, with a relative standard deviation of 0.91%. The method is sensitive and highly selective. It was applied for the determination of ferbam in a commercial sample and in mixtures with various dithiocarbamates (ziram, zineb, maneb) and wheat grains.