A kinetic experiment using a spring powered, stopped-flow apparatus

Morelli, Basilio

doi:10.1021/ed053p119

Cited by 8 publications

(8 citation statements)

References 8 publications

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“…We also observe this strong enhancement of the reaction rate in the systems we investigated. For example, in the reaction of DCIP with ascorbic acid the bulk reaction rate has been measured to be 1.16 ± 0.03 × 10 2 s −1 (17) and 1.12 ± 0.02 × 10 2 s −1 (18), which should be compared with our measured value 1.0 ± 0.2 × 10 5 s −1…”

Section: Discussionsupporting

confidence: 68%

“…To ensure that solution mixing was complete before the initiation of kinetic measurements in fused droplets, the reaction rate in the droplets was measured using a standard chemical reaction for characterizing the performance of the kinetic apparatus. The reaction between 2, 6-dichlorophenolindophenol (DCIP) and ascorbic acid has been used widely to measure reaction rates in the liquid phase (17)(18)(19). Water droplets containing 1 μM DCIP were fused with water droplets containing 100 μM ascorbic acid to provide pseudo-first-order kinetics based on the excess concentration of ascorbic acid compared with DCIP.…”

Section: Resultsmentioning

confidence: 99%

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Microdroplet fusion mass spectrometry for fast reaction kinetics

Lee

Kim

Nam

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

208

258

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We investigated the fusion of high-speed liquid droplets as a way to record the kinetics of liquid-phase chemical reactions on the order of microseconds. Two streams of micrometer-size droplets collide with one another. The droplets that fused (13 μm in diameter) at the intersection of the two streams entered the heated capillary inlet of a mass spectrometer. The mass spectrum was recorded as a function of the distance x between the mass spectrometer inlet and the droplet fusion center. Fused droplet trajectories were imaged with a high-speed camera, revealing that the droplet fusion occurred approximately within a 500-μm radius from the droplet fusion center and both the size and the speed of the fused droplets remained relatively constant as they traveled from the droplet fusion center to the mass spectrometer inlet. Evidence is presented that the reaction effectively stops upon entering the heated inlet of the mass spectrometer. Thus, the reaction time was proportional to x and could be measured and manipulated by controlling the distance x. Kinetic studies were carried out in fused water droplets for acid-induced unfolding of cytochrome c and hydrogen-deuterium exchange in bradykinin. The kinetics of the former revealed the slowing of the unfolding rates at the early stage of the reaction within 50 μs. The hydrogendeuterium exchange revealed the existence of two distinct populations with fast and slow exchange rates. These studies demonstrated the power of this technique to detect reaction intermediates in fused liquid droplets with microsecond temporal resolution.mass spectrometry | liquid microdroplets | reaction kinetics | protein unfolding | hydrogen-deuterium isotope exchange T ime-resolved measurements of reaction intermediates are crucial for understanding the fast kinetics of chemical reactions. Various approaches have been implemented to improve the temporal resolution of kinetic measurements in liquid reactions (1, 2), which are often limited by the mixing time. One approach for improving the mixing time involves the use of turbulent flow to increase the shear stress in fluid channels (3). Another approach is to stimulate the rapid initiation of a reaction by photo-triggered initiation (4), electron transfer (5), or temperature jump/rise (6). A small-size reactor was also used for rapid mixing so that the time required for diffusion-dependent mixing is minimized (7-10).Among various methods for detecting reaction intermediates, mass spectrometry has been a powerful tool for probing reaction products because it can discriminate similar species by their mass-to-charge ratio while simultaneously measuring multiple species. Time-resolved mass spectrometry (11) has been widely used for measuring the kinetics of protein-ligand complexation, organometallic compound formation, and enzyme-catalyzed processes. Despite these efforts for improving temporal resolution, time-resolved mass spectrometry has been limited to the millisecond timescale, with a recent achievement of 300 μs (12).A major obstacle for imp...

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Section: Discussionsupporting

confidence: 68%

Section: Resultsmentioning

confidence: 99%

Microdroplet fusion mass spectrometry for fast reaction kinetics

Lee

Kim

Nam

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

208

258

View full text Add to dashboard Cite

show abstract

“…Although this approach requires large amounts of reagents, it is very convenient because the concentrations are constant at each point along the tube and, thus, signals can be averaged to get good signal-to-noise ratio [121,122]. Measurements at different distances along the flow tube yield concentrations at different reaction times.…”

Section: Slow To Moderately Fast Reactionsmentioning

confidence: 99%

“…In this method, solutions of reactants are mixed rapidly in a special chamber (typical mixing, or "dead" time of a few ms) and flowed through a detection cell. As long as the reactants are flowing steadily, no change in the composition of the mixture in the detection chamber appears [121,122]. When the flow is suddenly stopped, the composition begins to change and this is monitored as a function of time by a fast-response detector.…”

Section: Stopped-flow Techniquementioning

confidence: 99%

Practical Chemical Kinetics in Solution

Seoud

Baader

Bastos

2016

Encyclopedia of Physical Organic Chemistry, 5 Volume Set

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“…For example, in 1976 this reaction was used to demonstrate the capabilities of a home-built spring-loaded stopped-flow apparatus. 6 At first glance the reaction may seem problematical for an undergraduate experiment due to the multiple ionization states possible for the reactants (Table 1).…”

mentioning

confidence: 99%

A Stopped-Flow Kinetics Experiment for the Physical Chemistry Laboratory Using Noncorrosive Reagents

Prigodich

2014

J. Chem. Educ.

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Stopped-flow kinetics techniques are important to the study of rapid chemical and biochemical reactions. Incorporation of a stopped-flow kinetics experiment into the physical chemistry laboratory curriculum would therefore be an instructive addition. However, the usual reactions studied in such exercises employ a corrosive reagent that can over time cause damage to sensitive and expensive components of a stopped-flow apparatus. The reduction of the dye 2,6-dichlorophenolindophenol by L-ascorbic acid at a pH of 8.5 is a reaction that provides accurate and reproducible data in the physical chemistry laboratory. Furthermore, these reagents are noncorrosive and protect instrumentation from damage.

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A kinetic experiment using a spring powered, stopped-flow apparatus

Cited by 8 publications

References 8 publications

Microdroplet fusion mass spectrometry for fast reaction kinetics

Microdroplet fusion mass spectrometry for fast reaction kinetics

Practical Chemical Kinetics in Solution

A Stopped-Flow Kinetics Experiment for the Physical Chemistry Laboratory Using Noncorrosive Reagents

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