HF-LPME as a green alternative for the preconcentration of nickel in natural waters

In the last years, some analytical methodologies have been identified as a source of pollution, receiving increasing attention to decrease their impact on the environment. In this sense, the so-called solvent-less methodologies appear as a green alternative to reduce the volume of solvents used in many sample treatment procedures and, consequently, the volume of toxic wastes produced. Among these techniques, analytical methodologies based on liquid-phase microextraction are being continuously developed, although most applications are focused on organic compounds. In this work, a three-phase hollow-fibre liquid-phase microextraction (HF-LPME) system has been developed for the preconcentration of nickel in natural waters, prior to the analysis by atomic absorption spectrometry. Under optimum conditions, the new system allowed an enrichment factor of 29.80 to be obtained after 60 min of experiment, and it was successfully applied to the determination of nickel in both saline and non-saline water samples, at ppb and ppt levels. The results were compared with those obtained using a well-established methodology based on liquid solvent extraction showing no significant differences (α = 0.05) between both values. In addition, the new HF-LPME presents the advantages of a green analytical technique, as its greenness profile shows, with the additional reduction of sample manipulation and time cost.