• Mass Spectrometry Letters
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• 제7권4호
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• pp.91-95
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• 2016

In recent years, matrix-free laser desorption ionization (LDI) for mass spectrometry of thermally labile molecules has been an important research subject in the pursuit of new ionization methods to serve as alternatives to the conventional matrix-assisted laser desorption ionization (MALDI) method. While many recent studies have reported successful LDI of thermally labile molecules from various surfaces, mostly from surfaces with nanostructures, understanding of what drives the LDI process still requires further study. This article briefly reviews the thermal aspects involved in the LDI mechanism, which can be characterized as rapid surface heating. The thermal mechanism was supported by observed LDI and postsource decay (PSD) of peptide ions produced from flat surfaces with special thermal properties including amorphous Si (a-Si) and tungsten silicide ($WSi_x$). In addition, the concept of rapid surface heating further suggests a practical strategy for the preparation of LDI sample plates, which allows us to choose various surface materials including crystalline Si (c-Si) and Au tailorable to specific applications.

• Journal of Photoscience
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• 제8권2호
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• pp.83-86
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• 2001

Structural analyses of oligosaccharide-malononitrile derivatives were conducted by matrix-assisted laser desorption/ionization post-source decay (MALDI-PSD) analysis in positive ion mode. The malononitrile derivatives of oligosaccharides, which were developed for highly sensitive detection of multi-component oligosaccharides by negative ion electrospray ionization mass spectrometry (ESI MS), were detected by positive-ion MALDI with the detection limit of 2 pmol level from the crude derivatization sample. The used matrix affected drastically the analytical results of oligosaccharide-malononitrile derivative by matrix-assisted laser desoprtion/ionization mass spectrometry (MALDI MS). The malononitrile derivatization of oligosaccharide also affect the patterns of MALDI-PSD spectra and give much more structural information than the free oligosaccharide.

• Mass Spectrometry Letters
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• 제6권2호
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• pp.27-30
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• 2015

This article reviews the fundamentals of sample preparation used in matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS). MALDI is a soft ionization method used to generate analyte ions in their intact forms, which are then detected in MS analysis. MALDI-MS boasts fast analysis times and easy-to-use operation. The disadvantages of MALDI-MS include the occurrence of matrix-associated peaks and inhomogeneous distribution of analyte within the matrix. To overcome the disadvantages of MALDI-MS, various efforts have been directed such as using different matrices, novel matrix systems, various additives, and different sample preparation methods. These various efforts will be discussed in detail. This article will benefit those who would like to obtain basic knowledge of MALDI sample preparation and those who would like to use MALDI-MS in their chemical analyses.

• Bulletin of the Korean Chemical Society
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• 제33권3호
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• pp.987-992
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• 2012

Magnetic nanoparticles (MNPs) treated with phosphoric acid were used to improve sequence coverage in protein identification by matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS). Sample solution of tryptic peptides from proteins was mixed with the MNPs, and the MNPs were separated from the supernatant using a magnet. MALDI mass spectra obtained separately from the supernatant and the MNPs were distinctly different and complementary to each other. Combination of the two spectra led to a significantly increased sequence coverage.

• Bulletin of the Korean Chemical Society
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• 제34권3호
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• pp.907-911
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• 2013

Numbers of matrix- and analyte-derived ions and their sum in matrix-assisted laser desorption ionization (MALDI) of a peptide were measured using 2,5-dihydroxybenzoic acid (DHB) as matrix. As for MALDI with ${\alpha}$-cyano-4-hydroxy cinnamic acid as matrix, the sum was independent of the peptide concentration in the solid sample, or was the same as that of pure DHB. This suggested that the matrix ion was the primary ion and that the peptide ion was generated by matrix-to-peptide proton transfer. Experimental ionization efficiencies of $10^{-5}-10^{-4}$ for peptides and $10^{-8}-10^{-7}$ for matrices are far smaller than $10^{-3}-10^{-1}$ for peptides and $10^{-5}-10^{-3}$ for matrices speculated by Hillenkamp and Karas. Number of gas-phase ions generated by MALDI was unaffected by laser wavelength or pulse energy. This suggests that the main role of photo-absorption in MALDI is not in generating ions via a multi-photon process but in ablating materials in a solid sample to the gas phase.

• 대한임상검사과학회지
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• 제55권4호
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• pp.244-252
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• 2023

검사 결과의 적시성과 정확성은 임상의가 특히 생명을 위협하는 감염이나 시력과 같은 중요한 장기 및 기능이 위험에 처한 경우, 효과적이고 표적화된 항균 요법을 결정하고 즉시 시행하는데 중요한 요소이다. 가능한 한 최단 시간 내에 정확하고 신뢰할 수 있는 결과를 얻기 위해 matrix assisted laser desorption/ionization time-of-flight (MALDI-TOF) 질량분석기기반 분석을 개선하고 최적화하기 위한 추가 연구 노력이 이루어져야 할 것이다. MALDI-TOF 질량분석기기반 세균 식별은 주로 임상 시료에서 병원체를 분리 및 정제하는 기술, 스펙트럼 라이브러리 확장 및 소프트웨어의 업그레이드에 중점을 둔다. 기술이 발전함에 따라 많은 MALDI-TOF 기반 미생물 동정 데이터베이스 및 시스템이 허가되어 임상에 사용되고 있다. 그럼에도 불구하고, 포괄적인 임상미생물의 특성화를 위해서는 MALDI-TOF 질량분석기 기반 항균제 내성 분석을 개발하는 것이 여전히 필요하다. 특정 적용 범주, 일반적인 분석물질, 주요 수행방법, 한계 및 해결점을 포함하여 임상 연구에서 MALDI-TOF의 적용이 중요하다. 임상 미생물 검사실에서 업무 활용을 위해 임상병리사들의 교육 및 훈련을 통한 전문성 확보가 필수적이며, 데이터베이스 구축과 경험을 극대화하여야 할 것이다. 향후 더 강력한 데이터베이스의 활용으로 다양한 분야에서 MALDI-TOF 질량분석기가 적용될 것으로 보인다.

• 광학과기술
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• 제9권1호
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• pp.29-35
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• 2005

• 분석과학
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• 제8권4호
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• pp.865-868
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• 1995

The method of matrix-assisted laser desorption ionization mass spectrometry has been used to solve some bioanalytical problems, which is difficult to analyse by general methods. For the selection of proper laser wavelength and matrices, eight matriees was used with laser wavelength of 226 and 355nm. The result shows that with wavelength of 355nm better results could be obtained with most of the matrices. The molecular weight of eytochrome C, which was seperated by gel electrophoresis and electro-blotted onto NC membrane is determined by MALDI. The accuracy is better than 0.1%, which is much higher than that of SDS-PAGE. Protein mixture extracted from crude peanut oil is directly determined by MALDI. The molecuiar weight of its three components are determined, and the result also demonstrated that these proteins are in free manner. As proteins arc in 2S bond, with the traditional method, SDS-PAGE, it is not able to decide whether protein exists in combination mode or in free manner. In the technique of two phase aquesous solution, which is used for separating biomaterials, water soluble polymers stained with dyes are used in this technique. By the use of MALDI the number or the dye molecules react with the polymer PEG molecule are determined, and that is difficult to determined by other methods.

• Mass Spectrometry Letters
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• 제8권4호
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• pp.105-108
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• 2017

Recently, deciduous teeth have been proposed as a promising biomatrix for estimating internal and external chemical exposures of an individual from prenatal periods to early childhood. Therefore, detection of organic chemicals in teeth has received increasing attention. Organic materials in tooth matrix are mostly collagen type proteins, but lipids and other small organic chemicals are also present in the tooth matrix. In this study, matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) was employed to obtain lipid fingerprints from deciduous teeth. Phospholipids and triacylglcerols (TAGs) from deciduous teeth were successfully detected by MALDI MS with 2,5-dihydroxybenzoic acid (DHB) or gold nanoparticle (AuNP) as a matrix.

• Bulletin of the Korean Chemical Society
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• 제26권5호
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• pp.763-768
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• 2005

An improved tandem time-of-flight (TOF) mass spectrometer for the photodissociation (PD) study of ions generated by matrix-assisted laser desorption ionization (MALDI), MALDI-TOF-PD-TOF, has been designed and constructed. Recording a full spectrum with better than unit mass resolution even in low mass range has been achieved without reflectron voltage stepping which was needed in the previous version. Other aspects of the improvement, such as those in the data system which now allow 10-100 times faster spectral acquisition than with the previous instrument, are described. Rationale for the ideas which have led to the improvements is presented also.