Highly sensitive determination of copper in HeLa cell using capillary electrophoresis combined with a simple cell extraction treatment

A new separation system of capillary electrophoresis (CE1) for the highly sensitive determination of copper was established by using ethylenediaminetetraacetic acid (EDTA) as a complexing agent and employing cetyltrimethylammonium chloride (CTAC) as a capillary inner wall modifier. Benefitted from the combination of field-enhanced sample injection (FESI) method, a limit of detection (LOD) of 2.7 nM was obtained, which was much lower than that of the conventional methods. This made it possible to determine trace copper in HeLa cell only by a simple cell extraction (CE2) treatment. Two copper-extraction methods—acid-hydrolysis and freeze–thaw—were compared. Limited by the requirement of low ion strength in FESI, only the extract using freeze–thaw could be successfully applied in the determination. The effectiveness assessment of this CE2–FESI method was adopted by inductively coupled plasma-atomic emission spectrometry (ICP-AES) as a gold standard.