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

ICP-MS가 제공하는 이점에도 불구하고 정확한 원소 분석은 분광 및 비분광 간섭의 영향을 받습니다.
분광 간섭은 분석물 이온과 동일한 m/z 값을 가진 이온에 의해 발생합니다. 간섭 종에는 등압 종, 다원자 이온 및 내화 산화물 이온이 포함됩니다.
등압 간섭은 질량 수가 같은 다른 핵종인 분석물 isobar에서 발생하며, 이는 m/z 값이 동일하다는 것을 의미합니다.
다원자 이온 간섭은 플라즈마 종과 매트릭스 또는 대기 종의 결합으로 인해 발생하며, 다원자 종은 분석물과 동일한 m/z 값의 분자 이온으로 추가로 단편화됩니다.
중요한 간섭은 분석물 및 매트릭스 종에서 내화성 산화물 및 수산화물 종의 형성으로 인해 발생합니다. 
비분광 간섭에는 매트릭스 효과가 포함되며, 이는 매트릭스 종의 고농도와 관련이 있으며 일반적으로 분석물 신호 감소를 유발합니다.
매트릭스 효과는 적절한 내부 표준을 사용하여 크게 보상할 수 있습니다.

유도 결합 플라즈마-질량 분석법(icp-ms): 간섭

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

유도 결합 플라즈마 질량 분석기(ICP-MS)는 정확한 원소 분석을 위한 매우 선택적이고 민감한 기술입니다. ICP-MS 질량 스펙트럼 분석은 비교적 간단하지만 분광 및 비분광 간섭의 영향을 받습니다. 플라즈마에 분석물 이온과 동일한 m/z 값을 갖는 이온 종이 포함되어 있으면 분광학적 간섭이 발생합니다. 분광 간섭은 등압 이온, 다원자 이온 및 내화성 산화물 이온 간섭으로 분류될 수 있습니다.

등압 간섭은 유도 결합 플라즈마에 등압 분석물질이 포함되어 있을 때 발생합니다. 이 종은 동일한 질량수를 갖는 서로 다른 핵종이므로 동일한 전하를 가정할 때 분석물질과 동일한 m/z 값을 갖습니다. 예를 들어, 40Ar+ 및 58Fe+는 일반적으로 각각 40Ar+ 및 58Fe+의 피크와 겹칩니다. 1u 미만의 분해능을 갖는 사중극자 기반 질량 계측기는 등압 간섭의 영향을 크게 받습니다. 그러나 고해상도 장비를 사용하면 최소화할 수 있습니다.

다양한 플라즈마 구성 요소가 매트릭스 또는 대기 구성 요소와 상호 작용하여 다원자 종을 형성할 때 또 다른 분광 간섭이 관찰되며, 이는 추가 단편화를 거쳐 분석 이온과 동일한 m/z 값을 갖는 분자 이온을 형성할 수 있습니다. 40ArH+, 16O2+, and 40ArO+는 잠재적인 간섭 물질입니다. 공백 보정이나 다른 분석 동위원소를 사용하면 이러한 간섭이 제거됩니다.

또 다른 중요한 간섭은 여러 분석물 및 매트릭스 구성 요소가 피크가 분석물 이온과 겹치는 산화물 및 수산화물을 형성할 때 발생합니다. 산화물과 수산화물의 형성은 주입기 유속, 샘플 구멍 크기, 샘플러 스키머 간격 등과 같은 다양한 실험 요인에 따라 달라집니다. 이러한 간섭은 등압 및 다원자 이온 간섭보다 제거하기가 더 어렵습니다.

비분광 간섭에는 주로 매트릭스 효과가 포함됩니다. 이는 일반적으로 500~1000mg/mL의 고농도 매트릭스 종과 관련되어 분석 물질 신호 감소를 유발합니다. 특정 실험 조건은 분석물질 신호를 향상시킵니다. 분석 물질에 가까운 질량 및 이온화 전위를 갖는 내부 표준을 통합하여 매트릭스 간섭을 제거할 수 있습니다.

유도 결합 플라즈마-질량 분석법(ICP-MS): 간섭

ICP-MS가 제공하는 이점에도 불구하고 정확한 원소 분석은 분광 및 비분광 간섭의 영향을 받습니다.
...

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

Education

교육

JoVE Core

Analytical Chemistry

분석 화학

Unit 1

제1단원

Principles of Mass Spectrometry

질량 분석법의 원리

KEY TERMS AND CONCEPTS

주요 용어 및 개념

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

mass spectrometry: overview

Mass Spectrometry and Molecular Identity

Mass spectrometry helps identify a compound by measuring its molecular mass and molecular formula. It does this by turning the analyte molecule into ions and then comparing ion abundance with mass-to-charge ratio. One common ionization method is electron ionization, or EI. In EI, high-energy electron beams strike analyte molecules in the gas phase. The beam removes an electron and leaves a molecular ion behind. A molecular ion is a radical cation, so it has a positive charge and an unpaired...

mass spectrometry: isotope effect

Isotope Peaks in Mass Spectra

Isotope peaks in mass spectra show how natural isotope mixtures change the signal of a molecule. Most elements occur as a mix of isotopes, which are atoms of the same element with different numbers of neutrons. Because isotopes have different masses, the same fragment can appear at more than one position in a spectrum. The mass of a molecule depends on which isotopes are present in its atoms. The size of each isotope peak also depends on how common those isotopes are in nature. Carbon is a...

mass spectrometry: molecular fragmentation overview

mass-spectrometry-molecular-fragmentation-overview

Mass Spectrometry Fragmentation Patterns

Mass spectrometry fragmentation patterns show how a molecular ion breaks apart after ionization. When a molecule loses an electron inside the mass spectrometer, its structure becomes unstable. The ion then fragments at bonds that often produce the most stable pieces. One common pattern is cleavage of a single bond in the molecular ion. This break forms a radical and a cation. The bond can split in more than one way, but the favored path is the one that gives the more stable carbocation rather...

mass spectrometers

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...

mass spectrum

Reading Peaks in a Mass Spectrum

A mass spectrum shows the charged fragments in an analyte as peaks plotted by mass-to-charge ratio, or m/z. The x-axis gives the mass of each charged fragment divided by the number of charges it carries. The y-axis shows the relative abundance of each charged species based on the signal intensity recorded at the detector. The tallest peak is called the base peak. It is assigned an abundance of 100%, and the other peaks are scaled against it. The peak from the molecular ion is called the parent...

mass spectrum: interpretation

Decoding Molecular Ions in Mass Spectra

Mass spectra help scientists identify an unknown compound by finding the molecular ion peak. The molecular ion peak shows the mass of the intact molecule, but it is often weak or missing because high-energy electron beams cause strong fragmentation. When that happens, a soft-energy electron beam can be used to scan the spectrum and improve the molecular ion signal. Other ionization methods can also give a stronger molecular ion peak. Chemical ionization, field ionization, and desorption...

mass analyzers: overview

Mass Analyzers and Ion Separation

Mass analyzers separate ions by their mass-to-charge ratio, or m/z, in a mass spectrometer. After a sample is vaporized in the ionization chamber, it is hit with a high-energy electron beam. This creates a radical cation and also produces neutral molecules, radicals, and cations. Negatively charged accelerator plates then push the cations into the mass analyzer, where they are sent on to the detector. Several mass analyzer designs are commonly used. These include magnetic sector,...

mass analyzers: common types

Quadrupole, TOF, and Ion Trap Analyzers

Quadrupole, time-of-flight, and ion trap mass analyzers each separate ions in a different way. They are common tools in mass spectrometry and help sort ions by their mass-to-charge ratio, or m/z. A quadrupole mass analyzer uses four cylindrical metal rods arranged in a diamond shape. The rods carry a direct current, or DC, voltage and a radio-frequency AC voltage. Ion motion depends on the field strength, so only ions with a certain m/z resonate and reach the detector at that setting. This...

high-resolution mass spectrometry (hrms)

Mass Accuracy in HRMS Analysis

High-resolution mass spectrometry separates ions by very small differences in mass. This matters because atomic masses are not always exact whole numbers, even though they are often rounded for simple calculations. Atomic mass is usually estimated by adding the masses of protons and neutrons. In reality, the proton and neutron do not have exactly the same mass. That creates small differences when atomic masses are compared to the simplest hydrogen atom. Helium, for example, is made of 2...

mass spectrometry: complex analysis

Hyphenated Mass Spectrometry Methods

Mass spectrometry can be paired with separation methods to study complex mixtures. This combination is called a hyphenated method. It helps when a pure mass spectrum is too hard to read because a mixture causes too much fragmentation and too many overlapping signals. GC-MS is one common hyphenated method. GC stands for gas chromatography, which separates volatile, thermally stable compounds in narrow capillary columns before they enter the mass spectrometer. This approach is widely used in...

tandem mass spectrometry

MS/MS Scan Modes and Fragment Ions

Tandem mass spectrometry uses two or more mass analyzers in series to improve selectivity and lower chemical noise during analyte detection. A set of analyzers separated by an interaction cell lets the instrument break ions apart and study the fragment ions that form. Fragmentation happens in the interaction cell and can be caused in several ways. Collision-induced dissociation, or CID, uses inert gases such as nitrogen, argon, or helium. Other methods include surface-induced dissociation...

gas chromatography&ndash;mass spectrometry (gc&ndash;ms)

How GC-MS Separates and Identifies Compounds

Gas chromatography-mass spectrometry (GC-MS) separates compounds in a mixture and then identifies them. A gas chromatograph first splits the mixture into its parts. A mass spectrometer then analyzes each part on its own to determine molecular masses and molecular structures. The gas chromatograph uses a long, narrow capillary column. The inner wall of the column has a polysiloxane coating. This coating serves as the stationary phase. It has a high boiling point, low viscosity, and low polarity.

inductively coupled plasma&#8211;mass spectrometry (icp&#8211;ms): overview

inductively-coupled-plasmamass-spectrometry-icpms-overview

ICP-MS Sample Ionization and Detection

ICP-MS uses an inductively coupled plasma torch to turn samples into ions for mass analysis. Solid samples are first dissolved and volatilized before they enter the hot argon plasma. Solution samples are nebulized, which means they are converted into a fine spray, and then passed through the same plasma. Inside the plasma, the analytes break apart. Their atoms become positively charged ions, along with some molecular species. These positive ions are sent to the mass spectrometer, where they...

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

JoVE Core Analytical Chemistry simplifies complex chemical principles by breaking them down into clear, engaging animations, making topics from SI Units to NMR spectroscopy more accessible and straightforward. Additionally, the scientist-in-action videos highlight the application of these concepts in real-world research conducted in laboratories globally.

ICP-MS Signal Interference Sources and Fixes

Description

Transcript