Study on speciation of aluminum in human serum using zwitterionic bile acid derivative dynamically coated C18 column HPLC separation with UV and on-line ICP-MS detection

A C18 column dynamically coated with zwitterionic bile acid derivative, 3-[(3-cholamidopropyl)-dimethylammonio]-1-propanesulfonate (CHAPS), was used for direct injection high performance liquid phase chromatography (HPLC)–ultraviolet visible (UV)/inductively coupled plasma mass spectrometry (ICP-MS) speciation of aluminum in non-spiked human serum. Small-molecule Al-complex compounds of Al-citrate (Al-Cit) and large-molecule Al-protein compounds of Al-transferrin (Al-Tf) were chosen as the model species and their retention behaviors on CHAPS modified C18 column were studied with UV and on-line ICP-MS detection in detail. Under the optimal conditions, large-molecule Al-protein compounds and small-molecule Al-complex compounds could be separated in 4 min, and their concentrations were on-line determined by ICP-MS. The detection limits of the method were 0.74 and 0.83 ng mL−1 with the RSD of 2.8% and 3.0% (n = 7) for Al-Tf and Al-Cit, respectively. The developed method was applied to the speciation of Al in healthy human serum and chronic hemodialysis patient serum. To the best of our knowledge, this is the first report on the simultaneous quantification of both Al-protein compounds (e.g. Al-Tf) and small-molecule Al-complex compounds (e.g. Al-Cit) in healthy human serum at low concentration levels. Compared with the reported methods in the literature, this method has several attractive features such as simplicity, rapidness, no sample preparation required, and it provides a new strategy for the speciation of trace elements in human body fluids.