Restricted accessed material-copper(II) ion imprinted polymer solid phase extraction combined with inductively coupled plasma-optical emission spectrometry for the determination of free Cu(II) in urine and serum samples

A novel restricted accessed material (RAM)—Cu(II) ion imprinted polymer (IIP) was synthesized by the surface imprinted-emulsion method, and possessed a high selectivity to Cu(II) and good macromolecules exclusion property. And a novel method of RAM-IIP packed microcolumn solid phase extraction (SPE) combined with inductively coupled plasma-optical emission spectrometry (ICP-OES) was developed for the determination of trace free Cu(II) in human body fluids. Under the optimized conditions, the adsorption capacity of RAM-IIP for Cu(II) was 15.9 mg g−1. With a preconcentration factor of 30, the limit of detection was 0.17 µg L−1, and the relative standard deviation was 2.2% (n=7, c=1 µg L−1). The developed method was validated by the analysis of two Certified Reference Materials, and the determined values were in good agreement with the certified values. This method was also successfully applied for the direct analysis of free Cu(II) in human urine and serum samples. While the total Cu can be determined by the proposed method after microwave digestion. The concentrations of free Cu(II) were much lower than that of total Cu, indicating that Cu is mainly coordinated with macromolecules in these biological samples. From this point of view, the developed method exhibits application potential in speciation of free metal ions and metallic complex molecules in biological samples.