Speciation of toxicologically important transition metals using ion chromatography with inductively coupled plasma mass spectrometric detection

Abstract

Speciation of vanadium(IV) and (V) using a mixed mode high-performance liquid chromatography column with inductively coupled plasma mass spectrometry detection was investigated. Nickel(II), chromium(III) and (VI) were also separated using the same column. The effect on the separation by varying the pH of the mobile phase and the ionic strength were studied. The absolute detection limits in aqueous media were 0.024 ng for vanadium(v) and 0.114 ng for vanadium(IV). The speciation of vanadium in National Institute of Standards and Technology Standard Reference Material (SRM) 2670 (Toxic metals in Freeze-Dried Urine, Elevated Level) was also accomplished. Using a slight modification of the mobile phase, the speciation of chromium(III) and (VI), as well as nickel(II) was accomplished. Absolute detection limits for chromium(III) at m/z 52 and 53 were 0.042 and 0.017 ng, respectively and for chromium(VI) at the same masses were 0.055 and 0.022 ng, respectively. Absolute limits of detection for nickel obtained were 0.031 ng and the speciation of nickel(II) in SRM 2670 was also demonstrated.