Name: icp-ms signal interference sources and fixes
Uploaded: 2024-04-04T10:51:35.000Z
Duration: 1 min 20 s
Channel: JoVE

A pesar de las ventajas que ofrece ICP-MS, el análisis elemental preciso se ve afectado por las interferencias espectroscópicas y no espectroscópicas.
La interferencia espectroscópica es causada por iones con los mismos valores m/z que los iones de analito. Las especies interferentes incluyen especies isobáricas, iones poliatómicos e iones de óxido refractario.
La interferencia isobárica surge de las isobaras del analito, que son diferentes nucleidos que tienen el mismo número de masa, lo que significa que los valores m/z son los mismos.
La interferencia de iones poliatómicos es el resultado de la combinación de especies de plasma con especies de matriz o atmosféricas para formar especies poliatómicas que se fragmentan aún más en iones moleculares del mismo valor m/z que un analito.
Surge una interferencia crítica debido a la formación de especies de óxido e hidróxido refractarios a partir del analito y las especies de la matriz. 
La interferencia no espectroscópica incluye el efecto matriz, que se asocia con una alta concentración de especies de matriz y generalmente causa una reducción de la señal del analito.
Los efectos de la matriz pueden compensarse en gran medida mediante el uso de un estándar interno apropiado.

espectrometría de masas con plasma acoplado inductivamente (icp-ms): interferencias

Inductively Coupled Plasma-Mass Spectrometry (ICP-MS): Interferences

La espectrometría de masas con plasma acoplado inductivamente (ICP-MS) es una técnica altamente selectiva y sensible para un análisis elemental preciso. Aunque el análisis de los espectros de masas ICP-MS es comparativamente sencillo, se ve afectado por interferencias espectroscópicas y no espectroscópicas. Las interferencias espectroscópicas surgen cuando el plasma contiene especies iónicas con un valor m/z igual que el ion analito. La interferencia espectroscópica se puede clasificar como interferencias isobáricas, de iones poliatómicos y de iones de óxido refractario.

La interferencia isobárica se produce cuando el plasma acoplado inductivamente contiene especies isobáricas de analitos. Estas especies son nucleidos diferentes con el mismo número de masa y, por lo tanto, tienen los mismos valores m/z que el analito, asumiendo la misma carga. Por ejemplo, 40Ar+ y 58Fe+ generalmente se superponen a los picos de 40Ca+ y 58Ni+, respectivamente. Los instrumentos de masa basados ​​en cuadrupolo, que tienen una resolución inferior a 1 u, se ven sustancialmente afectados por la interferencia isobárica. Sin embargo, se puede minimizar utilizando instrumentos de mayor resolución.

Otra interferencia espectroscópica se observa cuando varios componentes del plasma interactúan con la matriz o los componentes atmosféricos para formar especies poliatómicas, que pueden sufrir una mayor fragmentación para formar iones moleculares que tienen el mismo valor m/z que el ion analito. 40ArH+, 16O2+ y 40ArO+ son algunas posibles interferencias. Una corrección en blanco o el uso de un isótopo de analito diferente elimina dichas interferencias.

Otra interferencia crítica ocurre cuando varios componentes del analito y de la matriz forman óxidos e hidróxidos cuyos picos se superponen con los iones del analito. La formación de óxidos e hidróxidos depende de varios factores experimentales, como el caudal del inyector, el tamaño del orificio de la muestra, el espaciado del skimmer del muestreador, etc. Estas interferencias son más difíciles de eliminar que las interferencias de iones isobáricos y poliatómicos.

Las interferencias no espectroscópicas incluyen principalmente el efecto matriz. Se asocia con una alta concentración de especies de la matriz (generalmente, de 500 a 1 000 mg/ml), lo que provoca una reducción de la señal del analito. Las condiciones experimentales específicas mejoran la señal del analito. Las interferencias de la matriz se pueden eliminar incorporando un estándar interno con masa y potencial de ionización cerca del analito.

Espectrometría de masas con plasma acoplado inductivamente (ICP-MS): Interferencias

A pesar de las ventajas que ofrece ICP-MS, el análisis elemental preciso se ve afectado por las interferencias espectroscópicas y no espectroscópicas.
...

inductively-coupled-plasma-mass-spectrometry-icp-ms-interferences

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

icp-ms signal interference sources and fixes

Inductively coupled plasma-mass spectrometry (ICP-MS) is a sensitive method for elemental analysis, but its spectra can be affected by interferences. These interferences can make the mass signal less accurate, even when the instrument is working well.

Spectroscopic interferences happen when ions in the plasma have the same mass-to-charge ratio, or m/z, as the analyte ion. This group includes isobaric interferences, polyatomic ion interferences, and refractory oxide ion interferences. Isobaric interference occurs when different nuclides share the same mass number and therefore the same m/z value if the charge is the same. For example, 40 Ar+ can overlap with 40 Ca+, and 58 Fe+ can overlap with 58 Ni+.

Quadrupole-based mass instruments, which have a resolution of less than 1 u, are strongly affected by isobaric interference. Using a higher-resolution instrument can help reduce this problem. Polyatomic interferences can appear when plasma species react with matrix or atmospheric components to form molecular ions. Examples include 40 ArH+, 16 O2+, and 40 ArO+.

These polyatomic interferences can be reduced with a blank correction or by choosing a different analyte isotope. Another important spectroscopic problem is the formation of oxides and hydroxides. These peaks can overlap with analyte ions. Their formation depends on experimental conditions such as injector flow rate, sample orifice size, and sampler-skimmer spacing. These interferences are often harder to remove than isobaric and polyatomic interferences.

Non-spectroscopic interferences mainly involve the matrix effect. A matrix is the other material in the sample, and a high matrix concentration of about 500 to 1000 mg/mL can reduce the analyte signal. Certain experimental conditions can improve the analyte signal. Matrix interference can also be reduced by using an internal standard with a mass and ionization potential close to the analyte.

ICP-MS Signal Interference Sources and Fixes

icp-ms-signal-interference-sources-and-fixes

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inductively coupled plasma-mass spectrometry (icp-ms): interferences

Inductively coupled plasma-mass spectrometry (ICP-MS) is a sensitive method for elemental analysis, but its spectra can be affected by interferences. These interferences can make the mass signal less accurate, even when the instrument is working well. Spectroscopic interferences happen when ions in the plasma have the same mass-to-charge ratio, or m/z, as the analyte ion. This group includes isobaric interferences, polyatomic ion interferences, and refractory oxide ion interferences. Isobaric...

key terms and concepts

Learn how ICP-MS signals can be affected by isobaric, polyatomic, oxide, and matrix interferences, and how blank correction and internal standards help.

ICP-MS Signal Interference Sources and Fixes | JoVE K12

analytical chemistry

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ICP-MS Signal Interference Sources and Fixes

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