Recently, there is growing interest in single cell elemental analysis, especially, in the fields of drug discovery and regenerative medicine. In this study, we have developed a highly selective single cell elemental analysis system, that enables selective analysis of target cells, using a cell sorter and Inductively Coupled Plasma-Time of Flight-Mass Spectrometer (ICP-TOF-MS) and analysed single HeLa cells.

　The developed analysis system consists of a cell sorter (FENIX, Allied Flow Inc.) as a high speed droplet injection system, a desolvation device, and an ICP-TOF-MS (icpTOF R, TOFWERK). Droplets 70 µm in diameter containing single cell are ejected at a frequency of about 40 kHz by the cell sorter. Cell samples are measured their presence, size, type, and other characteristics by a laser. Droplets are charged positively or negatively by applying voltage to the sheath fluid in accordance with the laser measurement results. Charged droplets are deflected in their trajectory by deflection plates to which voltages of +1,500 V and -1,500 V are applied, respectively. This allows only droplets containing the target cells to be introduced into the plasma. And the cell introduction frequency can be controled up to 1,000 Hz, which is the highest throughput without signal overlap. In the desolvation device, solvent in the droplets are removed for improving analytical sensitivity. After desolvation, cell samples are introduced into ICP-TOF-MS for simultaneous multi elemental analysis.

　Using this system, HeLa cells derived from cervical cancer were analyzed. The cells were suspended with sheath fluid (IsoFlow Sheath Fluid CE, Beckman Coulter, Inc.). We were able to obtain the single cell derived mass spectra of Magnesium, Aluminum, Potassium, Calcium, Iron, Copper, etc.

　In the presentation, the details of the system and the analysis results will be discussed.