Spectrophotometric determination of Cu(II) with sequential injection analysis.

A sequential injection system, based on the reaction of Cu(II) with diethyldithiocarbamate (DDTC), was developed for the determination of Cu(II) in plant food and water samples. The extraction procedure, generally used to extract the Cu(II)-DDTC complex for subsequent analysis was eliminated in this procedure. The complex was detected spectrophotometrically in aqueous solutions at 460 nm. The physical and chemical parameters depicting the system were studied to obtain optimum conditions for sample analysis. The system developed is fully computerized and able to monitor Cu(II) in samples at seven samples per hour with a relative standard deviation of <4.50%. The calibration curve is linear from 0.5-5.0 mg/l with a detection limit of 0.2 mg/l. Interferences were reduced by introducing multiple flow reversals, to increase mixing between the reagent and sample zones, and subsequently enhance working of the masking agents (EDTA/citrate).