Speciation of chromium dyes by high-performance liquid chromatography with inductively coupled plasma mass spectrometric detection.

High-performance liquid chromatography (HPLC) coupled to inductively coupled plasma mass spectrometry (ICP-MS) was employed for the separation and detection of chromium species in azo dyes, Acid blue 158 and Acid Blue 193; mainly Cr(III) and Cr(VI). The dyes were first analyzed for total metal content using ICP-MS and their stability in solution was studied by measuring their absorbance through a range of pH values. Then an isocratic chromatographic method employing reversed-phase liquid chromatography with mass spectrometric detection was developed. Applying this method to the separation of these dyes, the absolute detection limits of Acid Blue 158 and 193 were 1 and 5 ng respectively. Additionally, Acid Blue 158 did not contain any chromium species. On the other hand, Acid Blue 193 contained uncomplexed and potentially bioavailable Cr(III). Acid Blue 193 did not have any toxic Cr(VI) present in the samples.