Catalytic-fluorimetric determination of copper at the nanograms per millilitre level by flow injection analysis

Abstract

A catalytic-fluorimetric method for the determination of copper(II) at the nanograms per millilitre level is proposed, based on the catalytic action of the copper(II) cation on the oxidation of 2,2′-dipyridyl ketone hydrazone (DPKH) by dissolved oxygen. In order to obtain the maximum analytical signal, two steps are necessary: oxidation of DPKH (basic medium) and development of fluorescence (strongly acidic medium). Flow injection analysis is very suitable for this determination as it is sensitive and rapid. The calibration graph shows two linear intervals, between 8 and 30 ng ml^–1[relative standard deviation (r.s.d.) 2.3%] and 40 and 300 ng ml^–1(r.s.d. 2.0%). The sampling frequency is 100 h^–1 for an injected volume of 60 µl. A study of interferences is reported. The use of “reverse” flow injection analysis makes the method more sensitive.