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.

中文翻译：

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微滴融合质谱：酸诱导叶绿素脱金属的加速动力学

通过融合含有 40 µM 叶绿素的微滴流，在微滴中记录酸诱导的叶绿素脱金属动力学一种要么b用含有 35 mM 盐酸 (pH = 1·46) 的水性微滴流溶解在甲醇中。融合微滴中叶绿素脱金属的动力学（直径 14 ± 6 µm；84 ± 18 ms-1速度）通过控制融合区域和质谱仪入口之间的融合微滴的行进距离来记录。与散装溶液中报道的相比，带电微滴中酸诱导的叶绿素脱金属速率快约 960 ± 120 倍。如果没有对喷射的微滴施加电压，则加速因子约为 580 ± 90，这表明施加的电压不是决定加速的主要因素。叶绿素一种在散装溶液中比叶绿素 b 更快地脱金属约 26 倍，在带电微滴中脱金属约 5 倍。脱金属动力学在 H 中是二级的+浓度，但与本体溶液相比，微滴的加速因子在从 pH = 1·3 到 7·0 时似乎没有变化。融合的微滴的水：甲醇比例从 7:3 变化到 3:7，导致叶绿素的反应速率增加一种脱金属20%。这一观察表明，具有不同蒸发速率的溶剂组合物不会显着影响加速。我们认为加速的主要部分可归因于涉及表面反应的限制效应，而不是归因于溶剂的蒸发或将电荷引入微滴。