Name: how maldi turns samples into ions
Uploaded: 2025-12-15T15:55:27.000Z
Duration: 1 min 8 s
Channel: JoVE

매트릭스 보조 레이저 탈착 이온화 분광법 또는 MALDI는 분자량이 몇 십만 달톤에 이르는 극성 바이오 폴리머에 대한 정확한 분자량 데이터를 획득하는 데 사용되는 이온화 기술입니다.
샘플 준비 공정에는 분석물 용액을 2,5-디하이드록시벤조산과 같은 매트릭스 물질과 혼합하는 작업이 포함됩니다. 그런 다음 이 혼합물을 질량 분석기에 삽입된 프로브에 증착합니다.
자외선 또는 적외선 레이저 빔이 표면에 집중되면 매트릭스는 레이저 에너지를 흡수하여 매트릭스에서 분석물 분자로의 양성자 전달을 통해 샘플 분자의 탈착 및 이온화를 유도하여 양성자 이온을 생성합니다.
새로 형성된 이온은 전기장에 의해 가속되고 ToF(Time-of-Flight) 질량 분석기에서 질량 대 전하 비율에 따라 분리됩니다.
결과 질량 스펙트럼을 분석하여 조사중인 생체 분자의 분자 질량을 결정할 수 있습니다.

매트릭스 보조 레이저 탈착 이온화(maldi)

Matrix-Assisted Laser Desorption Ionization (MALDI)

MALDI(Matrix-assisted laser desorption ionization)는 질량 분석에 사용되는 강력한 분석 기술입니다. 이를 통해 단백질, 펩타이드, 핵산 및 탄수화물을 포함한 다양한 생체 분자를 식별하고 특성화할 수 있습니다. MALDI 분광법은 약리학 및 생화학과 같은 분야뿐만 아니라 생물학 및 의학 연구에서 널리 사용됩니다.
관심 분석물, 생체 분자 또는 생체 분자의 혼합물은 적절한 매트릭스 물질과 혼합됩니다. 매트릭스는 일반적으로 이온화를 촉진하는 작은 유기산 또는 결정질 물질과 같은 유기 화합물입니다. 그런 다음 이 분석물-매트릭스 혼합물을 대상 표면에 증착하고 질량 분석기에 삽입하고 건조합니다. 건조하는 동안 매트릭스는 구조 내에 분석물 분자를 통합하는 작은 결정을 형성합니다.
샘플이 준비되면 펄스 레이저가 대상 표면으로 향합니다. 매트릭스 분자는 레이저 빔 에너지를 흡수하여 빠르게 가열되고 기화합니다. 이 과정을 레이저 탈착이라고 합니다. 매트릭스 분자는 기화하면서 내장된 분석물 분자를 운반합니다. 기화된 분석물 분자는 양성자 전달(proton transfer)이라는 과정을 통해 이온화됩니다. 양성자 전달은 매트릭스와 분석물 분자 사이에서 발생합니다. 매트릭스 분자는 분석물 분자에 양성자를 기증하여 양성자화된 이온을 형성합니다. 그런 다음 분석물 이온은 전기장에 의해 가속되고 비행 시간 질량 분석기에서 질량 대 전하 비율에 따라 추가로 분리됩니다.
MALDI 분광법에서 얻은 질량 스펙트럼은 분석된 생체 분자의 질량 및 상대적 존재비에 대한 귀중한 정보를 제공합니다.

매트릭스 보조 레이저 탈착 이온화(MALDI)

MALDI(Matrix-assisted laser desorption ionization)는 질량 분석에 사용되는 강력한 분석 기술입니다. 그것은 식별을 가능하게 하고 ...

matrix-assisted-laser-desorption-ionization-maldi

Education

교육

JoVE Core

Analytical Chemistry

분석 화학

Unit 1

제1단원

Mass Spectrometry Fragmentation Methods

질량 분석법의 단편화 방법

KEY TERMS AND CONCEPTS

주요 용어 및 개념

how maldi turns samples into ions

Matrix-assisted laser desorption ionization (MALDI) is a mass spectrometry technique that turns biomolecules into ions for analysis. It is used to identify and characterize proteins, peptides, nucleic acids, and carbohydrates. Because of this, it is common in biological and medical research, as well as pharmacology and biochemistry.

In MALDI, the analyte of interest is mixed with a matrix material. The matrix is usually an organic compound, such as a small organic acid or a crystalline substance, that helps ionization. The analyte-matrix mixture is placed on a target surface, inserted into the mass spectrometer, and dried. As the sample dries, the matrix forms small crystals that trap the analyte molecules inside them.

A pulsed laser is then aimed at the target surface. The matrix absorbs the laser energy, heats up, and vaporizes quickly. This step is called laser desorption. As the matrix leaves the surface, it carries the embedded analyte molecules with it.

The vaporized analyte molecules become ionized by proton transfer. In this step, the matrix donates a proton to the analyte molecule. This forms protonated ions, which can then be accelerated by an electric field. The ions are separated in a time-of-flight mass analyzer based on their mass-to-charge ratio, and the resulting mass spectrum shows the mass and relative abundance of the biomolecules studied.

How MALDI Turns Samples Into Ions

mass spectrometry: long-chain alkane fragmentation

mass-spectrometry-long-chain-alkane-fragmentation

Mass Spectra of Linear Alkane Chains

Mass spectra of linear alkanes show a clear fragmentation pattern. The molecular ion often breaks at a carbon-carbon bond away from the end of the chain. This cleavage forms a stable carbocation and a stable radical, so the middle of the mass-to-charge plot usually has the strongest signals while the ends are weaker. As each bond breaks, a methyl group is lost and the main peaks in the spectrum appear 14 u apart. Smaller peaks near each main signal can also appear. These come from secondary...

mass spectrometry: branched alkane fragmentation

mass-spectrometry-branched-alkane-fragmentation

Branched Alkanes in Mass Spectra

Branched alkanes in mass spectrometry fragment quickly because branching can create stable carbocations. When cleavage happens at a branching point, a secondary or tertiary carbocation may form. That stability helps explain why the molecular ion peak is often very weak or missing compared with a linear alkane. The lesson uses 2-methylbutane, neopentane, and n-pentane to show how this pattern appears in mass spectra. 2-methylbutane and neopentane break apart to form secondary and tertiary...

mass spectrometry: cycloalkane fragmentation

mass-spectrometry-cycloalkane-fragmentation

Cycloalkane Ions and Mass Peaks

Cycloalkane ions in mass spectrometry often give strong peaks because the ring structure helps stabilize the molecular ion. Compared with linear or branched alkanes, this added stability changes how the molecule breaks apart. As a result, cycloalkanes can produce prominent signals in the mass spectrum. Cyclohexane is a clear example. Its molecular ion has an m/z of 84, and this peak is often stronger than the signal from hexane, a linear alkane. The closed ring helps hold the ion together,...

mass spectrometry: alkene fragmentation

Alkene Ion Fragmentation Patterns

Alkene ion fragmentation patterns in mass spectrometry begin when the molecule loses one electron from the unsaturated π bond. This ionization forms a stable molecular ion. The ion can then break apart by three main reaction pathways. The most common pathway is cleavage at the allylic position, which is the carbon next to the double bond. This produces an allylic carbocation that is stabilized by resonance. In terminal alkenes, this fragment appears at a mass-to-charge ratio of 41. In internal...

mass spectrometry: cycloalkene fragmentation

mass-spectrometry-cycloalkene-fragmentation

Cycloalkene Side-Chain Cleavage in Mass Spectra

Cycloalkenes can break apart in a mass spectrometer through retro-Diels–Alder fragmentation. In this process, two carbon-carbon bonds in the ring split, and ethene is released. The remaining fragment is a dienyl radical cation that is 28 u less than the molecular ion. This pathway is similar to the fragmentation of cycloalkanes that also releases ethene. The difference is the type of charged fragment that remains. Cycloalkanes form an alkyl species, while cycloalkenes form a dienyl species.

mass spectrometry: alkyne fragmentation

Alkyne Mass Spectra and Key Peaks

Alkyne mass spectra often show strong peaks from two main fragmentation paths. One path breaks the carbon-carbon bond between the alpha and beta carbons of the alkyne bond. This produces a 3-propynyl cation, also called a propargyl cation. In terminal alkynes, this is the only fragmentation path that gives the 3-propynyl cation. The unsubstituted 3-propynyl cation appears at a mass-to-charge ratio of 39. In internal alkynes, the 3-propynyl cation is substituted. For example, 2-pentyne forms a...

mass spectrometry: alcohol fragmentation

Alcohol Fragmentation Patterns in Mass Spectra

Alcohols fragment in mass spectrometry in predictable ways. When an alcohol, written as R-OH, ionizes, it can lose one non-bonded electron from the oxygen atom. That forms a molecular ion, but the molecular ion peak is often weak or may not appear because alcohols break apart quickly. Two main fragmentation routes are important for alcohols: β-cleavage and dehydration. In β-cleavage, the bond at the β-position next to the hydroxyl group breaks. This gives a resonance-stabilized cation and a...

mass spectrometry: aromatic compound fragmentation

mass-spectrometry-aromatic-compound-fragmentation

Mass Spectra of Benzene and Toluene

Mass spectra of aromatic compounds show a strong molecular ion peak. In ionization, the molecule becomes a molecular ion, which appears as a prominent peak in the spectrum. Benzene gives a molecular ion at m/z 78, and toluene gives one at m/z 92. Benzene’s molecular ion is especially stable. It does not fragment readily because breaking the aromatic benzene ring requires a large amount of energy. Alkyl-substituted benzenes behave differently in mass spectrometry. Toluene can lose a hydrogen...

mass spectrometry: amine fragmentation

Amines in Mass Spectra: Nitrogen Rule

Amines can be identified in mass spectrometry by their fragmentation patterns and by the nitrogen rule. The molecular ions of amines often break apart through β-cleavage, which cuts a carbon-carbon bond next to the nitrogen. This process forms an alkyl radical and a resonance-stabilized nitrogen-containing cation. The nitrogen rule helps predict the mass of the molecular ion. A compound with one nitrogen atom, or any odd number of nitrogen atoms, gives a molecular ion with an odd molecular...

mass spectrometry: alkyl halide fragmentation

mass-spectrometry-alkyl-halide-fragmentation

Mass Spectra of Alkyl Halides

Mass spectra of alkyl halides show clear isotope patterns from the halogen atom. Chlorine has two common isotopes, 35Cl and 37Cl, in a 3:1 ratio. Bromine has two common isotopes, 79Br and 81Br, in a 1:1 ratio. These isotope ratios create two molecular ion peaks, [M] and [M + 2], with relative heights that match the halide abundance. This pattern is easy to see in examples such as 2-chloropropane and 1-bromopropane. 2-Chloropropane gives peaks in a 3:1 ratio. 1-Bromopropane gives peaks in a 1:1...

mass spectrometry: aldehyde and ketone fragmentation

mass-spectrometry-aldehyde-and-ketone-fragmentation

Carbonyl Fragment Patterns in Mass Spectra

Aliphatic aldehydes and ketones break apart in mass spectrometry through a few key carbonyl fragment patterns. The main pathways are alpha-cleavage, inductive cleavage, and the McLafferty rearrangement. These patterns help chemists read the mass spectrum and spot a carbonyl group. Alpha-cleavage is a common break next to the carbonyl group. The bond beside the carbonyl splits, and this forms an alkyl radical and an acylium cation. The acylium cation is often seen in the spectrum because it is...

mass spectrometry: carboxylic acid, ester, and amide fragmentation

mass-spectrometry-carboxylic-acid-ester-and-amide-fragmentation

Mass Spectra of Carboxylic Compounds

Mass spectra of carboxylic acids, esters, and amides often show two key fragmentation routes: β-cleavage and McLafferty rearrangement. In β-cleavage, the carbon-carbon bond at the β-position next to the carboxylic group breaks. This produces a neutral radical and a cation. Long-chain compounds can also fragment by McLafferty rearrangement if they have a hydrogen on the γ-carbon. The γ-carbon is the third carbon away from the carboxylic group. This rearrangement gives a radical cation and a...

chemical ionization (ci) mass spectrometry

Using Reagent Gas in CI Mass Spectrometry

Chemical ionization mass spectrometry uses a reagent gas to help detect molecules that break apart too quickly in electron impact ionization. It is a milder ionization method that can extend the life of the ionized analyte, which makes molecular identification easier. In chemical ionization, the sample is mixed with an excess reagent gas. This setup makes the electron impact occur mainly on the reagent gas instead of on the analyte. The charged species formed from the reagent then protonates...

electrospray ionization (esi) mass spectrometry

electrospray-ionization-esi-mass-spectrometry

How ESI Turns Biomolecules Into Ions

Electrospray ionization, or ESI, is a mass spectrometry method used to detect biomolecules that are too large or nonvolatile for conventional electron impact ionization. These molecules may break down before they can ionize or evaporate. ESI helps prevent rapid fragmentation and lets scientists record a mass signal for the whole biomolecule. ESI uses electrical energy to move ions from the liquid phase into the gas phase. The analyte biomolecule is mixed with an ionic liquid, which is a...

matrix-assisted laser desorption ionization (maldi)

Matrix-assisted laser desorption ionization (MALDI) is a mass spectrometry technique that turns biomolecules into ions for analysis. It is used to identify and characterize proteins, peptides, nucleic acids, and carbohydrates. Because of this, it is common in biological and medical research, as well as pharmacology and biochemistry. In MALDI, the analyte of interest is mixed with a matrix material. The matrix is usually an organic compound, such as a small organic acid or a crystalline...

key terms and concepts

Learn how MALDI uses a matrix, laser desorption, and proton transfer to create ions for mass spectrometry analysis of biomolecules.

How MALDI Turns Samples Into Ions | 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.

How MALDI Turns Samples Into Ions

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