Determination of Trace Amount of Cu(II) Using UV-Vis. Spectrophotometric Method.

Abstract

Trace amount of Copper(II) has determined by spectrophotometric technique using 1-(2-pyridylazo)-2-naphthal (PAN), as a new spectrophotometric reagent which is insoluble in water. PAN reacts in highly acidic solution at pH 2.40 to 2.50 with Cu(II) to give a pink chelate which has an absorption maximum (λmax.) at 550nm. The reaction is instantaneous and absorbance remains stable for over 48 hrs. The average molar absorption co-efficient (e) was found to be 2.05×104 L mol-1cm-1 and Sandell sensitivity is 3.23×10−4 μg cm−2. Linear calibration graphs were obtained for 0.1-4.0 μg mL-1 of Cu(II) and RSD (%) is 1.16. The stoichiometric composition of the chelate is 1:2 (Cu:PAN). Large excess of over 50 cations, anions, and some common complexing agents (e.g. oxalate, phosphate, tartarate, thio-urea) do not interfere in the determination. The method was successfully used in the determination of Cu(II) in Several Standard Reference Materials as well as in some environmental and industrial waste water. The method has high precision and accuracy.