Study of speciation of aluminum in human serum using capillary electrophoresis separation with on-line UV and off-line fluorination-assisted electrothermal vaporization (FETV)-ICP-MS detection

A new method has been developed for the speciation of Al in human serum using capillary electrophoresis (CE) separation with on-line UN and off-line fluorination-assisted electrothermat vaporization inductively coupled plasma mass spectrometry (FETV)-ICP-MS detection. A synthetic human serum solution was used as the model sample to study the effects of nature, pH, concentration of buffer, and operation voltage on the separation of different Al species (Al-citrate, Al-transferrin, and Al-albumin) with UV detection. Under optimum conditions, baseline separation,if the above three species was obtained. Various Al species were collected after separation into 50 mu L 6% (m/v) polytetrafluoroethylene(PTFE) emulsion (60% commercial PTFE emulsion diluted with water), and detected by FEW ICP-MS. A mass detection limit of 5.0 pg (106 nL of injection volume) and recovery of 90 similar to 110% were achieved. The proposed method was applied to the analysis of Al speciation in spiked real human serum, and the results indicate that Al-citrate, Al-transferrin, and Al-albumin were found at the percentages of 0-5%, 75-84%, and 15-21%, respectively. This method has the following advantages: minimal sample volume requirements, making it suitable for micro sample analysis, highspeed separation, and high absolute sensitivity. However, this method is not applicable to real human serum due to insufficient sensitivity. (The distribution of these Al species could be obtained by analyzing the real human serum spiked with Al.) To understand Al metabolism, toxicity, and the transport mechanism in the human body, developing an easy, rapid, sensitive, and reliable method for Al speciation analysis in serum has become one of the most challenging problems to analytical chemists (11-16). To understand the toxicity of Al in humans and its transport through the body, it is important to identify and quantify the Al species in serum. It is believed today (16) that 'basal' Al concentrations in blood serum are less than or equal to 2 mu g/L, and most of the Al in human serum is bound to Al-transferrin. But the content of low molecular mass (LMM) Al varied in some investigations (11, 15, 16).