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Abstract by Jiuzhi Gao

Personal Infomation

Presenter's Name

Jiuzhi Gao

Degree Level



Ames Ettinger

Abstract Infomation


Chemistry and Biochemistry

Faculty Advisor

Daniel Austin


Opposite polarity electrical charge on electrosprayed bacterial spores: implications for electrospray mechanism


Electrospray ionization (ESI) is a commonly used soft ionization technique in mass spectrometry. Maze et al. observed a phenomenon of bipolar fission in which about 1% of the droplets in a positive electrospray were measured to have a negative charge. We have previously demonstrated that ESI can produce desolvated, de-agglomerated, bacterial spores with either positive or negative charges on their surface. However, under some conditions, we observe as many as 23.7% of electrosprayed spores carry a charge with polarity opposite to the ESI tip.  This effect is present for both positive spray and negative spray.  An asymmetric 2-stage image charge detector eliminates ambiguity of charge measurement.  ESI experiments with amino-terminated polystyrene beads of similar size showed no such characteristics.