Real time monitoring of accelerated chemical reactions by ultrasonication-assisted spray ionization mass spectrometry

2017

Mass Spectrometry

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Generation of analyte ions in gas phase is a primary requirement for mass spectrometric analysis. One of the ionization techniques that can be used to generate gas phase ions is electrospray ionization (ESI). ESI is a so ionization method that can be used to analyze analytes ranging from small organics to large biomolecules. Numerous ionization techniques derived from ESI have been reported in the past two decades.ese ion sources are aimed to achieve simplicity and ease of operation. Many of these ionization methods allow the exibility for elimination or minimization of sample preparation steps prior to mass spectrometric analysis. Such ion sources have opened up new possibilities for taking scienti c challenges, which might be limited by the conventional ESI technique. us, the number of ESI variants continues to increase. is review provides an overview of ionization techniques based on the use of electrospray reported in recent years. Also, a brief discussion on the instrumentation, underlying processes, and selected applications is also presented.

Section: Acousticsmentioning

confidence: 76%

Section: Acousticsmentioning

confidence: 99%

Electrospray Modifications for Advancing Mass Spectrometric Analysis

Meher

2017

Mass Spectrometry

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“…It is understandable because applying direct electric‐contact on the capillary outlet can lead to generation of solvent background ions through electrochemical reaction. It is also the reason why we usually did not apply any electric contact directly on the emitter in our approaches . That is, to apply any electric contact on the capillary outlets is not necessary.…”

Section: Resultsmentioning

confidence: 99%

“…Cortisone contains several ketone functional groups. Thus, Girard T reagent is usually used to derive cortisone to improve detection limit in MS analysis . In this study, we selected these reactions as the model reactions to demonstrate the suitability of our approach in monitoring reaction species by MS in real time.…”

Section: Introductionmentioning

confidence: 99%

Ultrasonication‐assisted spray ionization‐based micro‐reactors for online monitoring of fast chemical reactions by mass spectrometry

2018

J Mass Spectrom

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Microfluidics can be used to handle relatively small volumes of samples and to conduct reactions in microliter‐sized volumes. Electrospray ionization can couple microfluidics with mass spectrometry (MS) to monitor chemical reactions online. However, fabricating microfluidic chips is time‐consuming. We herein propose the use of a micro‐reactor that is sustained by two capillaries and an ultrasonicator. The inlets of the capillaries were individually immersed to two different sample vials that were subjected to the ultrasonicator. The tapered outlets of the two capillaries were placed cross with an angle of ~60° close to the inlet of the mass spectrometer to fuse the eluents. On the basis of capillary action and ultrasonication, the samples from the two capillaries can be continuously directed to the capillary outlets and fuse simultaneously to generate gas phase ions for MS analysis through ultrasonication‐assisted spray ionization (UASI). Any electric contact applied on the capillaries is not required. Nevertheless, UASI spray derived from the eluents can readily occur in front of the mass spectrometer. That is, a micro‐reactor was created from the fusing of the eluent containing different reactants from these two UASI capillaries, allowing reactions to be conducted in situ. The solvent in the fused droplets was evaporated quickly, and the product ions could be immediately observed by MS because of the extreme rise in the concentration of the reactants. For proof of concept, pyrazole synthesis reaction and cortisone derivatization by Girard T reagent were selected as the model reactions. The results demonstrated the feasibility of using UASI‐based micro‐reactor for online MS analysis to detect reaction intermediates and products.

“…High electric field applied in the mass spectrometer can be used to induce polarization of sample droplets without direct application of a high electric voltage on the sample emitter. As a result, analyte ions in gas phase can be generated via polarization induced ESI processes . For example, in ultrasonication‐assisted spray ionization MS, ultrasonic transducers were used to generate gas‐phase ions from liquid samples in the proximity of a mass spectrometer.…”

Section: Introductionmentioning

confidence: 99%

Polarization induced electrospray ionization mass spectrometry for the analysis of liquid, viscous and solid samples

Meher

2015

J. Mass Spectrom.

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In this study, a polarization-induced electrospray ionization mass spectrometry (ESI-MS) was developed. A micro-sized sample droplet was deposited on a naturally available dielectric substrate such as a fruit or a stone, and then placed close to (~2 mm) the orifice of a mass spectrometer applied with a high voltage. Taylor cone was observed from the sample droplet, and a spray emitted from the cone apex was generated. The analyte ion signals derived from the droplet were obtained by the mass spectrometer. The ionization process is similar to that in ESI although no direct electric contact was applied on the sample site. The sample droplet polarized by the high electric field provided by the mass spectrometer initiated the ionization process. The dielectric sample loading substrate facilitated further the polarization process, resulting in the formation of Taylor cone. The mass spectral profiles obtained via this approach resembled those obtained using ESI-MS. Multiply charged ions dominated the mass spectra of peptides and proteins, whereas singly charged ions dominated the mass spectra of small molecules such as amino acids and small organic molecules. In addition to liquid samples, this approach can be used for the analysis of solid and viscous samples. A small droplet containing suitable solvent (5-10 µl) was directly deposited on the surface of the solid (or viscous) sample, placed close the orifice of mass spectrometer applied with a high voltage. Taylor cone derived from the droplet was immediately formed followed by electrospray processes to generate gas-phase ions for MS analysis. Analyte ions derived from the main ingredients of pharmaceutical tablets and viscous ointment can be extracted into the solvent droplet in situ and observed using a mass spectrometer.