Determination of copper in urine and water samples using a simple led-based colorimeter

چکیده مقاله

A cheap and simple colorimetric assay based on the reaction with sodium 8-aminoquinoline-5-azobenzene-4'-sulfonate (SPAQ) is applied to the determination of copper in urine and water samples. The proposed technique employs a light emitting diode (LED) as a light source and a cheap common light dependent resistor (LDR) as a detector. This device functions on the basis of the level of light received by photoresistor (LDR), which is connected to a digit multimeter yielding resistance readings increasing with the in- crease in light absorption by sample solution. Experimental variables affecting the complex formation were optimized applying the Taguchi method. Under the optimum conditions, calibration plot was linear in the analyte concentration range of 0.1-2 μg/mL. The stoichiometry of metal/ligand ratio, the stability constant, and molar absorptivity (ε) of Cu(II)-SPAQ complex were also found. The relative standard deviation for five replicate determinations of 1 μg/mL Cu(II) was 3.64% and the corresponding limit of detection was 35 μg/L. © Pleiades Publishing, Ltd., 2010.