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Microdroplet fusion mass spectrometry: Accelerated kinetics of acid-induced chlorophyll demetallation
- Microdroplet fusion mass spectrometry: Accelerated kinetics of acid-induced chlorophyll demetallation
- Lee, Jae Kyoo; Nam, Hong Gil; Zare, Richard N.
- DGIST Authors
- Nam, Hong Gil
- Issue Date
- Quarterly Reviews of Biophysics, 50, 1-7
- Article Type
- Charged Microdroplets; Electrospray; Neat Water; Water Surface
- Kinetics of acid-induced chlorophyll demetallation was recorded in microdroplets by fusing a stream of microdroplets containing 40 μM chlorophyll a or b dissolved in methanol with a stream of aqueous microdroplets containing 35 mM hydrochloric acid (pH = 1-46). The kinetics of the demetallation of chlorophyll in the fused microdroplets (14 ± 6 μm diameter; 84 ± 18 m s-1 velocity) was recorded by controlling the traveling distance of the fused microdroplets between the fusion region and the inlet of a mass spectrometer. The rate of acid-induced chlorophyll demetallation was about 960 ± 120 times faster in the charged microdroplets compared with that reported in bulk solution. If no voltage was applied to the sprayed microdroplets, then the acceleration factor was about 580 ± 90, suggesting that the applied voltage is not a major factor determining the acceleration. Chlorophyll a was more rapidly demetallated than chlorophyll b by a factor of ∼26 in bulk solution and ∼5 in charged microdroplets. The demetallation kinetics was second order in the H+ concentration, but the acceleration factor of microdroplets compared with bulk solution appeared to be unchanged in going from pH = 1-3 to 7-0. The water:methanol ratio of the fused microdroplets was varied from 7:3 to 3:7 causing an increase in the reaction rate of chlorophyll a demetallation by 20%. This observation demonstrates that the solvent composition, which has different evaporation rates, does not significantly affect the acceleration. We believe that a major portion of the acceleration can be attributed to confinement effects involving surface reactions rather than either to evaporation of solvents or to the introduction of charges to the microdroplets. © Cambridge University Press 2017.
- Cambridge University Press
- Related Researcher
Nam, Hong Gil
CBRG(Complex Biology Research Group)
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