Matrix-assisted laser detection limit

Matrix-assisted laser desorption/ionization (MALDI) is widely used for the detection of organic molecules. One of the limitations of the method is a strong matrix background in low-mass (up to 500-700 Da) range. In present work an alternative approach based on the application of rough matrix-less surfaces and known as surface-assisted laser desoi ption/ionization (SALDI), has been applied. 

Liquid chromatography/mass spectrometry Lower limit of detection Limit of detection Limit of quantitation Florseshoe crab hemocyanin Liquid scintillation counting Matrix-assisted laser desorption/ ionization mass spectrometry m -Maleimidobenzoy 1-A -Hydroxysuccinimide 1 -Cyclohexyl-3-(2-Morptiolino-ethyl)carbodiimide rnetlio-/ -Toluenesulfonate (same as CDI)... 

In 1974, Comarisov and Marshall60 developed Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS). This technique allows mass spectrometric measurements at ultrahigh mass resolution (R = 100000-1000000), which is higher than that of any other type of mass spectrometer and has the highest mass accuracy at attomole detection limits. FTICR-MS is applied today together with soft ionization techniques, such as nano ESI (electrospray ionization) or MALDI (matrix assisted laser/desorption ionization) sources. 

FAB and PD have been replaced by electrospray ionization (ESI) and matrix-assisted laser desorption ionization (MALDI) in the analytical mass spectrometry laboratory, because both of these newer techniques have a wider mass range of analysis and have lower detection limits. ESI and MALDI have become invaluable ionization techniques for nonvolatile components. This is particularly true for a wide range of biological molecules including proteins, peptides, nucleic acids, etc. Samples can be analyzed by ESI using either direct injection or introduction through liquid chromatography. 

Abbreviations AOD, Acousto-optical deflection BCB, bisbenzyocyclobutadiene CCD, indirect contact conductivity detection CL, chemiluminescence ECD, electron capture detector FCS, fluorescence correlation spectroscopy FRET, fluorescence resonance energy transfer ICCD, integrated contact conductivity detection GMR, giant magnetoresistive LED-CFD, light emitting diode confocal fluorescence detector LIF, laser-induced fluorescence LOD, limit of detection MALDI, matrix-assisted laser desorption ionization PDMS, poly(dimethylsiloxane) PMMA, poly(methylmetha-crylate) SPR, surface plasmon resonance SVD, sinusoidal voltammetric detection TLS, thermal lens spectroscopy. 

Matrix-assisted laser desorption >230,000 Highest achieved mass range for proteins and glycoproteins relatively insensitive to salts ability to analyze mixtures simple to operate Very low resolution limits ability to detect structural variants not presently adapted for LC/MS limited structural information... 

Concentration detection limits in CE-MS with the ESI interface are similar to those with UV detection. Sample sensitivity can be improved by using ion-trapping or time-of-flight (TOE) mass spectrometers. MS analysis can also be performed off-line, after appropriate sample collection, using plasma desorption-mass spectrometry (PD-MS) or matrix-assisted laser desorption-mass spectrometry (MALDI-MS). 

The unimolecular fragmentation of calixarene-derived ions will not be treated here, especially as studies on this topic are much restricted due to the fact that classical El and Cl techniques cannot be applied to these mvolatile and often quite polar polyphenols. Rather, mass spectrometric analysis is limited to the detection of positively or negatively charged quasi-molecular ions, such as [M + H]+ and [M — H], or molecular adduct ions, such as [M + NR4]+ and [M - - metal]+. In general, these ions can be readily generated by using matrix-assisted laser desorption (MALDI) and/or electrospray ionization (ESI) mass spectrometry. 

Wei, H. Nolkrantz, K. Powell, D.H. Woods, J.H. Ko, M.-C. Kennedy, R.T. Electrospray Sample Deposition for Matrix-Assisted Laser Desorption/lonization (MALDI) and Atmospheric Pressure MALDI Mass Spectrometry With Attomole Detection Limits, Rapid Commun. Mass Spectrom. 18, 1193-1200 (2004). 

MS, especially in combination with advanced separation techniques, is one of the most powerful and versatile techniques for the structural analysis of bacterial glycomes. Modern mass spectral ionization techniques such as electrospray (ESI) and matrix-assisted laser desorption/ionization (MALDI) provide detection limits in the high atto- to low femto-mole range for the identification of peptides and complex carbohydrates. Structural characterization of these trace level components can be achieved using tandem MS. This provides a number of specific scanning functions such as product, precursor ion, and constant neutral loss scanning to... 

Muller, M., Schiller, J., Petkovic, M., Oehrl, W., Heinze, R., Wetzker, R., Arnold, K. and Arnhold, J., Limits for the detection of (poly-)phosphoinositides by matrix-assisted laser desorption and ionization time-of-flight mass spectrometry (MALDITOF MS), Chem Phys Lipids, 110 (2001) 151-164. 

Pastor, S. J., Wood, S. H., and Wilkins, C. L., "Poly(ethylene glycol) Limits of Detection Using Internal Matrix-assisted Laser Desorption/Ionization Fourier Transform Mass Spectrometry," /. Mass Spectrom., 33, 473—479,1998. 

Mass spectrometry currently has assumed a central role in protein sequencing. This development has been possible with the introduction of two highly sensitive ionization techniques electrospray ionization (ESI) and matrix-assisted laser desorption and ionization (MALDI) and the advent of improved instrumentation capable of high-mass and high-sensitivity detection. Currently, biopolymers with a molecular mass over 100,000 Da are analyzed routinely. In the past, fast atom bombardment (FAB) [6,7] and Cf plasma desorption (PD) ionization [8] also played a limited role in protein sequencing. Mass spectrometry now has assumed... 

L.-K. Zhang and M. L. Gross, Matrix-assisted laser desorption/ionization mass spectrometry methods for oligonucleotide improvements in matrix, detection limits, quantification, and sequencing, J. Am. Soc. Mass Spectrom. 11, 854-865 (2000). 

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