Effective Enrichment and Simultaneous Quantitative Analysis of Trace Heavy Metal Ions Mixture in Aqueous Samples by the Combination of Radial Electric Focusing Solid Phase Extraction, UV-Vis Spectrophotometric Determination and Partial Least Squares Regression

An efficient and stable preconcentration method for ionic and ionizable analytes, named radical electric focusing solid phase extraction (REFSPE), was proposed here for enriching trace Cu(II), Ni(II), and Co(II) from water samples. In REFSPE, radical electric field was introduced into solid phase extraction system to enhance the mass transfer rate of heavy metal ions in aqueous solution and shorten the extraction time obviously. The concentration of mixed heavy metal ions were predicted using partial least squares (PLS) regression by analyzing ultraviolet and visible spectrum efficiently. By optimizing chromogenic agent, pH values, extraction voltage, extraction time, and PLS parameters, the proposed method had higher figures of merit. The comparison of the determination data and the calculation results showed that the proposed method can provide a favorite quantitative precision with expanded measuring range. The limit of detection (LOD) for Cu(II), Ni(II), and Co(II) were 0.10, 0.13, and 0.15 μg L−1, respectively. The reliability was confirmed by the RSD lower than 5% and the recovery of 95–102%. The novel enrichment method has a great potential for applications in detecting different ionic and ionizable analytes with the help of spectrometry determination and chemometrics calculation.