Name: how mass spectrometers sort ions
Uploaded: 2024-04-04T10:51:33.000Z
Duration: 1 min 16 s
Channel: JoVE

El espectrómetro de masas ioniza las moléculas y produce un espectro de masas a partir de la distribución de fragmentos.
Realiza tres funciones: ionización de moléculas o átomos, separación de los fragmentos de iones y detección de iones.
En la ionización de electrones, un método de ionización común, una muestra vaporizada en la cámara de ionización bombardeada con un haz de electrones de alta energía produce cationes radicales. El catión radical se fragmenta rápidamente en moléculas neutras, radicales y cationes.
A continuación, los cationes se aceleran en una cámara de análisis mediante una serie de placas aceleradoras cargadas negativamente.
Muchos analizadores comunes aplican un campo magnético o eléctrico a la cámara de análisis, que dobla las trayectorias de los iones en función de su masa y carga.
Solo los iones de valores m/z particulares tienen la trayectoria exacta para pasar a través de la estrecha rendija colocada frente al detector de iones para un campo magnético o eléctrico dado.
Al alterar el campo, el analizador de masas escanea a través de un rango de masas de iones, con sus abundancias registradas en el espectro de masas.

espectrómetro de masas

Mass Spectrometers

Esta lección detalla la instrumentación de un espectrómetro de masas, un instrumento físico para realizar espectrometría de masas en moléculas de analitos y registrar los espectros de masas característicos. Esto se logra a través de tres funciones principales:



<ol>
	<li>Conversión de los átomos/moléculas del analito en fase gaseosa en un haz de iones con carga positiva o negativa mediante ionización.</li>
	<li>Separación de las especies cargadas en función de su relación masa-carga.</li>
	<li>Registrar la abundancia relativa de cada tipo de ion.</li>
</ol>

En la cámara de ionización del espectrómetro de masas, el analito vaporizado en el vacío es golpeado con electrones de alta energía. La energía del electrón es de alrededor de 70 eV, suficiente para arrancar un electrón del analito. El ion molecular resultante se fragmenta aún más en especies cargadas y moléculas neutras. El espectrómetro de masas solo registra la masa de especies cargadas, ya que la carga permite el control de las moléculas mediante un campo eléctrico o magnético.

El ion molecular y sus fragmentos cargados son acelerados por una serie de placas aceleradoras cargadas negativamente ubicadas apropiadamente en el detector en la cámara de análisis. Se aplica un campo magnético en el camino entre la placa del acelerador y el detector, lo que provoca una curva en el camino de las especies cargadas. En un campo magnético constante, el radio de curvatura depende de la masa molecular de la especie cargada. Colocar una rendija delante del detector garantiza que solo las especies cargadas de un peso molecular particular lleguen al detector.

Variando el campo magnético, se pueden registrar en el detector las especies cargadas de todos los pesos moleculares, cada especie de peso molecular única a la vez. Al escanear todos los campos magnéticos, el espectrómetro de masas proporciona información sobre la abundancia relativa de todas las especies cargadas en forma de espectro de masas.

Espectrómetro de masas

Esta lección detalla la instrumentación de un espectrómetro de masas, un instrumento físico para realizar espectrometría de masas en moléculas de analito y registrar ...

Education

Educación

JoVE Core

Analytical Chemistry

Química Analítica

Unit 1

Unidad 1

Principles of Mass Spectrometry

Principios de la espectrometría de masas

KEY TERMS AND CONCEPTS

TÉRMINOS Y CONCEPTOS CLAVE

how mass spectrometers sort ions

A mass spectrometer sorts charged ions by their mass-to-charge ratio and records their relative abundance. It turns vaporized analyte molecules into ions, separates them, and then measures the signal from each type of ion.

The process begins in the ionization chamber. The analyte is in the gas phase inside a vacuum, and it is struck by high-energy electrons. The electrons have about 70 eV of energy, which is enough to remove an electron from the analyte and form a molecular ion.

After ionization, the molecular ion can break into charged fragments and neutral molecules. The instrument records only the charged species. Their charge allows them to be controlled by electric or magnetic fields.

Next, the molecular ion and its charged fragments are accelerated by a set of negatively charged accelerator plates. These plates move the ions toward the detector in the analyzing chamber. A magnetic field bends the path of the ions as they travel between the accelerator plate and the detector.

At a constant magnetic field, the radius of the curved path depends on the molecular mass of the charged species. A slit placed in front of the detector helps admit only ions with a particular molecular weight. By changing the magnetic field, ions of different molecular weights can reach the detector one at a time.

As the instrument scans through the magnetic fields, it records the relative abundance of the charged species. The result is a mass spectrum. This spectrum shows the ions detected across the range of molecular weights.

How Mass Spectrometers Sort Ions

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mass spectrometers

A mass spectrometer sorts charged ions by their mass-to-charge ratio and records their relative abundance. It turns vaporized analyte molecules into ions, separates them, and then measures the signal from each type of ion. The process begins in the ionization chamber. The analyte is in the gas phase inside a vacuum, and it is struck by high-energy electrons. The electrons have about 70 eV of energy, which is enough to remove an electron from the analyte and form a molecular ion. After...

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Reading Peaks in a Mass Spectrum

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Mass Analyzers and Ion Separation

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Mass Accuracy in HRMS Analysis

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key terms and concepts

Learn how a mass spectrometer ionizes analytes, bends charged ions with a magnetic field, and records a mass spectrum for each molecular weight.

How Mass Spectrometers Sort Ions | JoVE K12

analytical chemistry

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How Mass Spectrometers Sort Ions

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