Orthogonal acceleration time-of-flight mass spectrometry

Guilhaus, Michael; Selby, David; Mlynski, V.

doi:10.1002/(sici)1098-2787(2000)19:2<65::aid-mas1>3.0.co;2-e

Cited by 308 publications

(204 citation statements)

References 111 publications

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“…Introduction of the collisional cooling source in the prOTOF 2000 instrument allowed for stabilization of the fragile molecules on desorption from the MALDI target [10,21,22]. The time the ions spend in the instrument between desorption from the target and detection is typically several milliseconds, which is several orders of magnitude longer than the time of TOF analysis, and, therefore, metastable fragmentation under conditions of low ion source gas pressure is apparent, and stabilization of the ions becomes essential for their detection.…”

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confidence: 99%

Ganglioside analysis by thin-layer chromatography matrix-assisted laser desorption/ionization orthogonal time-of-flight mass spectrometry

Ivleva

Sapp

O’Connor

et al. 2005

J. Am. Soc. Mass Spectrom.

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Metastable decomposition of ions generated in matrix-assisted laser desorption/ionization (MALDI) mass spectrometers complicates analysis of biological samples that have labile bonds. Recently, several academic laboratories and manufacturers of commercial instruments have designed instruments that introduce a cooling gas into the ion source during the MALDI event and have shown that the resulting vibrational cooling stabilizes these labile bonds. In this study, we compared stabilization and detection of desorbed gangliosides on a commercial orthogonal time-of-flight (oTOF) instrument with results we reported previously that had been obtained on a home-built Fourier transform mass spectrometer. Decoupling of the desorption/ ionization from the detection steps resulted in an opportunity for desorbing thin-layer chromatography (TLC)-separated gangliosides directly from a TLC plate without compromising mass spectral accuracy and resolution of the ganglioside analysis, thus coupling TLC and oTOF mass spectrometry. The application of a declustering potential allowed control of the matrix cluster and matrix adduct formation, and, thus, enhanced the detection of the gangliosides. during matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) analyses of molecules having labile bonds. Although this phenomenon can be used for obtaining analyte structural information for small peptides, oligosaccharides, and some glycolipids [1-5] for larger or more fragile molecules, it can limit the mass accuracy and resolution and complicate interpretation of the spectra of heterogeneous samples. Thus, it is important to develop methods that allow control of the extent of metastable decay. In addition to the pressure of the background gas and extraction field strength in the MALDI technique, the major factors affecting metastable fragmentation are laser wavelength/pulse width and the choice of the MALDI matrix [6,7]. In addition, the presence of electrons may play a role in analyte fragmentation and may cause suppression of multiply charged ions in a spectrum [8,9].Control of the metastable fragmentation in MALDI by increasing the pressure in the ionization source and reduction of the ions internal energy was first introduced by Loboda et al. on orthogonal time-of-flight (oTOF) instruments [10] and later extended to Fourier transform mass spectrometry (FTMS) [11] and to the operation at atmospheric pressure on various types of instruments [12]. These methods have since been used for stabilization of glycolipids [13,14] and peptides and proteins [11,15]. The term vibrational cooling (VC) MALDI recently has been introduced to describe desorption in the pressure range where cooling of the excess bond energy is achieved [12]. Stabilization of the labile bonds under these conditions allows for control of the extent of fragmentation, which is particularly

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confidence: 99%

Ganglioside analysis by thin-layer chromatography matrix-assisted laser desorption/ionization orthogonal time-of-flight mass spectrometry

Ivleva

Sapp

O’Connor

et al. 2005

J. Am. Soc. Mass Spectrom.

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“…From the high duty cycle, the technique has the advantages of high efficiency, increased sensitivity, and/or rapid acquisition of mass spectra when monitoring continuous ion sources compared with conventional on-axis TOFMS. Orthogonal extraction TOFMS [3,4] is the more widely used method of achieving high duty cycle, but some trade-off must be accepted between mass range covered and duty cycle achieved. Often these trade-offs are acceptable, but some situations might benefit from the approach described here.…”

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confidence: 99%

Duty cycle and modulation efficiency of two-channel hadamard transform time-of-flight mass spectrometry

Yoon

Zuleta

Kimmel

et al. 2005

J. Am. Soc. Mass Spectrom.

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Hadamard transform time-of-flight mass spectrometry (HT-TOFMS) is based on the pseudorandom gating of ion packets into a time-of-flight mass-to-charge analyzer. In its typical implementation, the technique is able to monitor continuous ion sources with a 50% duty cycle, independent of all other figures of merit. Recently, we have demonstrated that the duty cycle can be extended to 100% using patterned, two-channel detection. Two-channel HT-TOFMS involves the simultaneous optimization of paired one-channel experiments and imposes more stringent conditions to achieve high-quality spectra. An ion modulation device, known as Bradbury-Nielson Gate (BNG), is central to HT-TOFMS. It is an ideal deflection plate, capable of transmitting or deflecting an ion beam according to a known binary sequence without changing the times-of-flight of the ions. Analytical equations are derived that accurately describe the ion modulation process of the BNG as confirmed by good agreement with SimIon simulations and ion beam imaging experiments. From these expressions, the duty cycle and ion modulation efficiency were calculated for various BNG parameters, ion beam characteristics, and detector dimensions, which permit the optimum conditions to be chosen for the two-channel experiment. We conclude that the outer detector should be three times the maximum deflection angle to detect all deflected ions (100% duty cycle) and that the difference between the modulated ion counts in the sequence elements 0 and 1 should be maximized to achieve high modulation efficiency. This condition is best achieved by tight focusing of the ion beam in the center of the inner detector. When both channels are optimized, the two-channel advantage can be exploited to achieve a further improvement over a single-channel experiment. (J Am Soc Mass Spectrom 2005, 16, 1888 -1901

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“…Este último é construído de maneira a direcionar os íons ortogonalmente do quadrupolo ao tempo de voo, através de um acelerador de íons, para análises no modo de espectrometria de massas em série (MS/ MS) com varredura dos íons produtos. 84,85 A grande vantagem destes analisadores está no fato de oferecerem informações espectrais completas com resolução de média a alta, medida de massa exata e excelente sensibilidade no modo de varredura total. Não há dúvida de que os espectrômetros QqQ e QLIT são superiores para a quantificação, mas os dados adquiridos nestes analisadores são limitados à natureza das transições SRM e às m/z nominais dos íons precursores e produtos, desta forma, parte da informação qualitativa para elucidação estrutural e identificação de compostos é perdida.…”

Section: Tempo De Voo (Time Of Flight -Tof) E Quadrupolo -Tempo De Vounclassified

Aspectos analíticos e regulatórios na determinação de resíduos de macrolídeos em alimentos de origem animal por cromatografia líquida associada à espectrometria de massas

Sismotto¹,

Paschoal²,

Reyes³

2013

Quím. Nova

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Recebido em 25/7/12; aceito em 17/10/12; publicado na web em 20/2/13 ANALYTICAL AND REGULATORY ASPECTS FOR DETERMINATION OF MACROLIDE RESIDUES IN ANIMAL-DERIVED FOODS BY LIQUID CHROMATOGRAPHY ASSOCIATED WITH MASS SPECTROMETRY. This is an overview of LC-MS techniques applied for macrolide determination in food, including sample preparation and method validation, as well as the policies adopted by international agencies regarding their presence in food. Techniques for the analysis of macrolides in food normally include solid phase or liquid-liquid extraction followed by HPLC. UHPLC presents advantages in running time, detectability and solvent consumption. Triple-quadrupoles are the most common analyzers in instruments used for the determination of contaminants in food, but time-of-flight and ion-trap spectrometers have been successfully applied for analyses focusing on the investigation of structural formula or the presence of degradation products.Keywords: macrolides; liquid chromatography; mass spectrometry. INTRODUÇÃOOs antimicrobianos são compostos que inibem o crescimento de determinados microrganismos, podendo ser, de modo geral, utilizados na produção animal para tratar enfermidades (aplicação terapêutica), prevenir contra enfermidades causadas pela presença de organismos patogênicos (aplicação profilática) e melhorar a taxa de crescimento e/ou conversão alimentar (utilizados como promotores de crescimento). Uma grande variedade de substâncias antimicrobianas é usada na produção animal em todo o mundo. A presença de resíduos dessas substâncias em produtos alimentícios é uma questão de grande interesse dos órgãos governamentais responsáveis pela saúde pública e das indústrias de alimentos, pois representa riscos à saúde dos consumidores, ressaltando-se a seleção de formas resistentes de microrganismos, a carcinogenicidade, mutagenicidade, teratogenicidade e a hipersensibilidade. [1][2][3][4][5][6] Sendo o Brasil um país de expressiva atividade pecuária no cenário mundial, é fundamental que estejam em vigor programas eficientes que garantam a qualidade de alimentos desta origem. Para atender a essa demanda, é necessário o desenvolvimento de métodos analíticos confiáveis que possibilitem a determinação de medicamentos veterinários em níveis residuais (na ordem de ng g -1 ), haja vista que são substâncias potencialmente tóxicas para a saúde humana e para o meio ambiente.Segundo Mellon et al., 7 estima-se que nos Estados Unidos cerca de 70% da produção anual de antimicrobianos (considerando um total de 16000 t) tenham sido utilizadas na pecuária com fins não terapêuticos.Dentre as diferentes classes de antimicrobianos existentes, destacam-se os macrolídeos por serem altamente potentes contra uma grande variedade de bactérias Gram-positivas e Gram-negativas. A Organização Mundial para a Saúde Animal (Office International dés Épizoties -OIE) considera alguns macrolídeos, como a eritromicina, espiramicina, tilmicosina e tilosina, como criticamente importantes na pecuária de bovinos, suínos e aves, já que existem p...

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Orthogonal acceleration time-of-flight mass spectrometry

Cited by 308 publications

References 111 publications

Ganglioside analysis by thin-layer chromatography matrix-assisted laser desorption/ionization orthogonal time-of-flight mass spectrometry

Ganglioside analysis by thin-layer chromatography matrix-assisted laser desorption/ionization orthogonal time-of-flight mass spectrometry

Duty cycle and modulation efficiency of two-channel hadamard transform time-of-flight mass spectrometry

Aspectos analíticos e regulatórios na determinação de resíduos de macrolídeos em alimentos de origem animal por cromatografia líquida associada à espectrometria de massas

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