The determination of V and Mo by dispersive liquid–liquid microextraction (DLLME) combined with laser-induced breakdown spectroscopy (LIBS)

Abstract

Laser-induced breakdown spectroscopy (LIBS) is a promising analytical technique with well-known advantages and limitations. However, despite its growing popularity, this technique has been applied mainly to solid samples and there have been a smaller number of studies devoted to liquid samples. This lack of studies is mainly due to experimental difficulties in the analysis of liquid matrices. Sensitivity can be improved and matrix effects minimized in the LIBS analysis of aqueous samples by using a dispersive liquid–liquid microextraction (DLLME) procedure followed by drying the extract on a suitable surface prior to laser irradiation. The combination of DLLME-LIBS is fast, easy to use, and inexpensive. The small volume of the final extract is sufficient for LIBS analysis, and the procedure generates little waste. It is likely that this combination could be automated during future work. The limits of detection (LOD) and quantification (LOQ) achieved using the proposed method were 30 and 70 μg L⁻¹ for Mo and 5 and 20 μg L⁻¹ for V, respectively. Using this method, we analyzed samples of pharmaceutical, multimineral formulation, soil, mineral water and a reference material NCS ZC 85005 (Beef Liver). In the latter, the concentration of V was below the LOQ, and the recovery of Mo was 103%.