▎ 摘　　要

Vanadium (V) and vanadium (IV) in the presence of a small concentration of graphene oxide (0.05 mg mL(-1)) are quantitatively transferred to the coacervate obtained with Triton X-l14 in a cloud point microextraction process. The surfactant-rich phase is directly injected into the graphite atomizer of an atomic absorption spectrometer. Using a 10-mL aliquot sample and 150 mu L of a 15% Triton X-114 solution, the enrichment factor for the analyte is 103, which results in a detection limit of 0.02 mu g L-1 vanadium. The separation of V(V) and V(IV) using an ion-exchanger allows speciation of the element at low concentrations. Data for seven reference water samples with certified vanadium contents confirm the reliability of the procedure. Several beer samples are also analyzed, those supplied as canned drinks showing low levels of tetravalent vanadium. (C) 2018 Elsevier B.V. All rights reserved.