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

ICP-MS'nin sunduğu avantajlara rağmen, doğru element analizi spektroskopik ve spektroskopik olmayan girişimlerden etkilenir.
Spektroskopik girişim, analit iyonları ile aynı m/z değerlerine sahip iyonlardan kaynaklanır. Enterferans yapan türler arasında izobarik türler, poliatomik iyonlar ve refrakter oksit iyonları bulunur.
İzobarik girişim, aynı kütle numarasına sahip farklı nüklidler olan analit izobarlarından kaynaklanır - yani m/z değerleri aynıdır.
Çok atomlu iyon girişimi, bir analit ile aynı m/z değerine sahip moleküler iyonlara daha fazla parçalanan çok atomlu türler oluşturmak için plazma türlerinin matris veya atmosferik türlerle kombinasyonundan kaynaklanır.
Analit ve matris türlerinden refrakter oksit ve hidroksit türlerinin oluşumu nedeniyle kritik bir girişim ortaya çıkar. 
Spektroskopik olmayan girişim, yüksek konsantrasyonda matris türleri ile ilişkili olan ve genellikle analit sinyalinin azalmasına neden olan matris etkisini içerir.
Matris etkileri, uygun bir iç standart kullanılarak büyük ölçüde telafi edilebilir.

İndüktif eşleşmiş plazma-kütle spektrometresi (icp-ms): etkileşimler

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

İndüktif olarak eşleşmiş plazma-kütle spektrometresi (ICP-MS), kesin element analizi için oldukça seçici ve hassas bir tekniktir. ICP-MS kütle spektrumlarının analizi nispeten basit olmasına rağmen, spektroskopik ve spektroskopik olmayan girişimlerden etkilenir. Plazma, analit iyonuyla aynı m/z değerine sahip iyonik türler içerdiğinde spektroskopik girişimler ortaya çıkar. Spektroskopik girişim izobarik, çok atomlu iyonlar ve refrakter oksit iyonu girişimleri olarak kategorize edilebilir.

İndüktif olarak eşleşmiş plazma izobarik analit türleri içerdiğinde izobarik girişim meydana gelir. Bu türler aynı kütle numarasına sahip farklı nüklitlerdir ve dolayısıyla aynı yükü varsayarsak analitle aynı m/z değerlerine sahiptirler. Örneğin 40Ar+ ve 58Fe+ genel olarak sırasıyla 40Ca+ ve 58Ni+ 'nın tepe noktalarıyla örtüşür. Çözünürlüğü 1 u'dan düşük olan dört kutuplu kütle aletleri, izobarik girişimden büyük ölçüde etkilenir. Ancak daha yüksek çözünürlüklü cihazlar kullanılarak bu durum en aza indirilebilir.

Başka bir spektroskopik girişim, çeşitli plazma bileşenleri, analit iyonu ile aynı m/z değerine sahip moleküler iyonlar oluşturmak için daha fazla parçalanmaya maruz kalabilecek çok atomlu türler oluşturmak üzere matris veya atmosferik bileşenlerle etkileşime girdiğinde gözlemlenir. 40ArH+, 16O2+ ve 40ArO+ bazı potansiyel girişimlerdir. Boş düzeltme veya farklı bir analit izotopunun kullanılması bu tür etkileşimleri ortadan kaldırır.

 Bir başka kritik girişim, çeşitli analit ve matris bileşenlerinin, zirveleri analit iyonlarıyla örtüşen oksitler ve hidroksitler oluşturması durumunda ortaya çıkar. Oksitlerin ve hidroksitlerin oluşumu, enjektör akış hızı, numune deliği boyutu, numune alıcı kepçe aralığı vb. gibi çeşitli deneysel faktörlere bağlıdır. Bu girişimlerin ortadan kaldırılması, izobarik ve çok atomlu iyon girişimlerinden daha zordur.

Spektroskopik olmayan girişimler esas olarak matris etkisini içerir. Bu, analit sinyalinin azalmasına neden olan yüksek konsantrasyondaki matris türleri (genellikle 500 ila 1000 mg/mL) ile ilişkilidir. Spesifik deney koşulları analit sinyalini artırır. Analite yakın kütle ve iyonizasyon potansiyeline sahip bir iç standart dahil edilerek matriks girişimleri ortadan kaldırılabilir.

İndüktif Eşleşmiş Plazma-Kütle Spektrometresi (ICP-MS): Etkileşimler

ICP-MS'nin sunduğu avantajlara rağmen, doğru element analizi spektroskopik ve spektroskopik olmayan girişimlerden etkilenir.
...

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

Education

JoVE Core

Analytical Chemistry

Analitik Kimya

Unit 1

Ünite 1

Principles of Mass Spectrometry

Kütle Spektrometrisi İlkeleri

KEY TERMS AND CONCEPTS

TEMEL TERİMLER VE KAVRAMLAR

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

JoVE Core Analitik Kimya, karmaşık kimyasal prensiplerini anlaşılır, ilgi çekici animasyonlara dönüştürerek basitleştirir ve SI Birimlerinden NMR spektroskopisine kadar konuları daha erişilebilir ve anlaşılır hale getirir. Buna ek olarak, bilim insanlarının yer aldığı videolar, bu kavramların dünya çapındaki laboratuvarlarda yürütülen gerçek dünya araştırmalarındaki uygulamalarını gösterir.

analytical chemistry

ICP-MS Signal Interference Sources and Fixes

Description

Transcript

Tags