Titration Determination of Trace Copper in Vegetables

This study aimed to establish a new method using thiourea and EDTA titration for the determination of trace copper in vegetables. Samples were dry-digested, and KBr was then added to one portion of the digestion solution (pH 5-6) to mask Hg2+, and the total metal ions were tested by titration with standard EDTA solution using pyridylazo naphthol as an indicator. Subsequently, other metal ions except Cu2+ masked by thiourea in another portion were titrated with standard EDTA solution. Finally, the amount of copper was calculated by the volume difference of EDTA solution expended in titration of the two portions. The relative standard deviation was less than 2.50% and the spiked recovery was 96.8%-100.4%. This method has many advantages including simple and fast operation and little interference.