The use of phenylfluorone in the presence of cetylpyridinium chloride and Triton X-100 for the spectrophotometric determination of copper(II) in blood serum

A simple and sensitive spectrophotometric method for determination of copper(II) is based on the formation of a blue coloured complex of Cu(II) with 9-phenyl-2,3,7-trihydroxy-6-fluorone (PF) in the presence of cetylpyridinium chloride (CP) and Triton X-100, has been developed. Optimum concentrations of PF, CP, Triton X-100 and pH ensuring maximum absorbance were defined. The complex Cu(II)–PF–CP–Triton X-100 shows maximum absorbance at 595 nm with a molar absorptivity value of 9.67×104 l mol−1 cm−1. The detection limit of the method is 0.028 μg ml−1. Beerʹs law is obeyed for copper concentrations in the range 0.04–0.4 μg ml−1. The studies of the effect of foreign ions on determination of copper, show that the selectivity of the method is poor. The cations of alkali metals and anions Br−, Cl−, I−, F−, NO2−, NO3−, CH3COO−, SO42−, S2O32−, PO43−, citrates (examined in 1000-fold molar excess over copper) do not affect the determination. All cations forming complexes with PF have an interfering effect. The statistical evaluation of the method was carried out for six determinations using 10 μg of Cu and the following results were obtained: the standard deviation, SD=0.042, the confidence interval μ95=10.1±0.1 μg Cu. The method has been applied for determination of copper in blood serum.