Speciation of Chromium(vi) and Chromium(iii) Using Pneumatically Assisted Electrospray Mass Spectrometry

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Abstract
Mass spectra can be obtained from aqueous solutions containing both Cr 3+ and Cr 2 O 7 2- as negative ions under the same spray conditions. An excess of HCl is used so that Cr 3+ sprays as an anionic chloro complex. Moderately energetic collision conditions produce CrO 3 - from Cr VI and CrOCl 2 - from Cr III . Detection limits are 100 and 60 ppb for Cr III and Cr VI , respectively. Reasonable calibration curves are provided by plotting the ratio of the analyte signal to that for 37 Cl - .