Selection of internal standards for quantitative analysis by matrix-assisted laser desorption-ionization (MALDI) time-of-flight mass spectrometry

Wilkinson, William B.; Gusev, Arkady I.; Proctor, Andrew; Houalla, Marwan; Hercules, David M.

doi:10.1007/s002160050148

Cited by 45 publications

(49 citation statements)

References 19 publications

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“…In the cases examined, the two peptides were of similar molecular mass (1385.56 versus 1046.48 Da) but of different composition. Several studies reported the use of structural analogues (8,22), derivatives (8,10,11,19), functional analogues (9), molecules of similar hydrophobicity (12), or isotopically labeled derivatives (5,6,8,11) of the analyte as internal standards. Some of these have indeed published calibration lines with quite small mean relative standard deviations (6,12).…”

Section: Examining the Correlation Between The Relative Signal Intensmentioning

confidence: 99%

“…A variety of stable isotope labeling methods have recently been developed for relative quantitation, including isotope-coded affinity tags (ICAT), isobaric tags for relative and absolute quantitation (iTRAQ), stable isotope labeling with amino acids in cell culture (SILAC) (35)(36)(37)(38)(39), 18 O (40 -42), and absolute quantitation of abundance (AQUA) (43). iTRAQ labeling is unique in this list because the differently labeled components yield the same nominal masses, and thus the quantitation can be accomplished only from MS/MS data.Another phenomenon hindering the use of MALDI for quantitative measurements is the suppression effect, which has also been discussed in a number of publications (19,29,30,32,33,44). Suppression can especially distort the data when complex biological samples are analyzed that contain thousands of components in a wide concentration range.…”

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confidence: 99%

“…At the same time, several studies discuss the non-quantitative nature of MALDI-TOF MS (7, 8, 13, 19, 22, 26 -30). The main problem of MALDI is its poor reproducibility (sample to sample and shot to shot), which makes most quantitative measurements quite difficult at best (19,27,31). This is especially true for complex samples.…”

mentioning

confidence: 99%

“…Another phenomenon hindering the use of MALDI for quantitative measurements is the suppression effect, which has also been discussed in a number of publications (19,29,30,32,33,44). Suppression can especially distort the data when complex biological samples are analyzed that contain thousands of components in a wide concentration range.…”

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confidence: 99%

“…Lately MALDI-TOF MS has become a popular method for quantitative analysis of biomolecules (oligonucleotides, proteins, glycoproteins, etc.) originating from various sample types (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22) or even for imaging tissue sections (13)(14)(15)(16)(17)(18)(23)(24)(25)(26). At the same time, several studies discuss the non-quantitative nature of MALDI-TOF MS (7, 8, 13, 19, 22, 26 -30).…”

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Investigating the Quantitative Nature of MALDI-TOF MS

Szaéjli

Feheér

Medzihradszky

2008

Molecular & Cellular Proteomics

138

116

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MALDI-TOF MS has been applied by several groups to relative quantitative measurements. At the same time, the non-quantitative character of this method has been widely reported. We conducted experiments to test the reliability of this technique for quantitation using the statistical method of inverse confidence limit calculation for the first time in this context. The relationship between relative intensities of known amounts of standard peptides and their concentration ratios was investigated. We found that the concentration ratios determined by relative intensity measurements were highly inaccurate and strongly influenced by the molecular milieu of the sample analyzed. Thus, we emphasize the necessity of using the sample itself for calibration. We also performed experiments using an isotope-labeled derivative of the analyte as an internal standard for calibration line generation. As expected, the use of such standard led to a dramatic increase in precision and a less pronounced improvement in accuracy. We recommend performing a similar statistical analysis as a demonstration of reliability for every system where MALDI-TOF MS is used for quantitative measurements. Molecular & Cellular Proteomics 7: 2410 -2418, 2008.MALDI-TOF MS is a widely used analytical technique because of its excellent sensitivity, relatively high speed, and simplicity. As a consequence of producing mostly singly charged ions (1, 2) MALDI is especially suitable for mixture analysis. It is commonly used in proteomic studies (3) frequently without any prefractionation (4) as well as in the analysis of other biomolecules. Lately MALDI-TOF MS has become a popular method for quantitative analysis of biomolecules (oligonucleotides, proteins, glycoproteins, etc.) originating from various sample types (5-22) or even for imaging tissue sections (13)(14)(15)(16)(17)(18)(23)(24)(25)(26). At the same time, several studies discuss the non-quantitative nature of MALDI-TOF MS (7, 8, 13, 19, 22, 26 -30). The main problem of MALDI is its poor reproducibility (sample to sample and shot to shot), which makes most quantitative measurements quite difficult at best (19,27,31). This is especially true for complex samples. The presence of so-called hot spots or sweet spots is the main cause of the poor reproducibility and is therefore a factor strongly increasing measurement times and complicating automated measurements. Furthermore this phenomenon is one of the major factors hampering the use of MALDI MS for spatially resolved imaging (27). The reasons for sweet spot formation are not completely understood. It could be caused by variation in the amount and the crystallization of the matrix, the latter being a function of local analyte concentration. Dependence of signal intensities on the orientation of the matrix-analyte crystals relative to the spectrometer axis is also possible (27). The extent of hot spot formation depends strongly on the matrix used. For example, preparations with ␣-cyano-4-hydroxycinnamic acid (CHCA) 1 deliver relatively homogenous samples (...

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Section: Examining the Correlation Between The Relative Signal Intensmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Investigating the Quantitative Nature of MALDI-TOF MS

Szaéjli

Feheér

Medzihradszky

2008

Molecular & Cellular Proteomics

138

116

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The determination of non-ionic surfactants in surface waters by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry

Willetts

Clench

Greenwood

et al. 1999

Rapid Commun. Mass Spectrom.

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Matrix‐assisted time‐of‐flight mass spectrometry (MALDI‐TOFMS) has been shown to be a useful tool for the analysis of a wide range of biological and synthetic polymers. This has included the analysis of some commercial formulations of some non‐ionic surfactants. But, as yet, no one has reported the use of MALDI‐TOFMS for the analysis of surfactants in environmental matrices. Here we report the use of MALDI‐TOFMS for the qualitative and quantitative determination of nonylphenol ethoxylate surfactants in environmental surface waters. Following extraction/preconcentration by C18 solid phase extraction, the sample is mixed with a standard MALDI matrix (2,5‐dihydroxybenzoic acid). The mixture is then crystallised on a stainless steel target for introduction into the mass spectrometer. The limit of detection is 40 µg/L based on a 250 mL sample. Copyright © 1999 John Wiley & Sons, Ltd.

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Analysis of erlotinib and its metabolites in rat tissue sections by MALDI quadrupole time‐of‐flight mass spectrometry

et al. 2007

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A qualitative and quantitative analysis of erlotinib (RO0508231) and its metabolites was carried out on rat tissue sections from liver, spleen and muscle. Following oral administration at a dose of 5 mg/kg, samples were analyzed by matrix-assisted laser desorption ionization (MALDI) with mass spectrometry (MS) using an orthogonal quadrupole time-of-flight instrument. The parent compound was detected in all tissues analyzed. The metabolites following drug O-dealkylation could also be detected in liver sections. Sinapinic acid (SA) matrix combined with the dried-droplet method resulted in better conditions for our analysis on tissues. Drug quantitation was investigated by the standard addition method and liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis on the tissue extracts. The presence of the parent compound and of its O-demethylated metabolites was confirmed in all tissue types and their absolute amounts calculated. In liver the intact drug was found to be 3.76 ng/mg tissue, while in spleen and muscle 6- and 30-fold lower values, respectively, were estimated. These results were compared with drug quantitation obtained by whole-body autoradiography, which was found to be similar. The potential for direct quantitation on tissue sections in the presence of an internal standard was also investigated using MALDI-MS. The use of alpha-cyano-4-hydroxycinnamic acid (CHCA) as the matrix resulted in better linearity for the calibration curves obtained with reference solutions of the drug when compared to SA, but on tissue samples no reliable quantitative analysis was possible owing to the large variability in the signal response. MS imaging experiments using MALDI in MS/MS mode allowed visualizing the distribution of the parent compound in liver and spleen tissues. By calculating the ratio between the total ion intensities of MS images for liver and spleen sections, a value of 6 : 1 was found, which is in good agreement with the quantitative data obtained by LC-MS/MS analysis.

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Selection of internal standards for quantitative analysis by matrix-assisted laser desorption-ionization (MALDI) time-of-flight mass spectrometry

Cited by 45 publications

References 19 publications

Investigating the Quantitative Nature of MALDI-TOF MS

Investigating the Quantitative Nature of MALDI-TOF MS

The determination of non-ionic surfactants in surface waters by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry

Analysis of erlotinib and its metabolites in rat tissue sections by MALDI quadrupole time‐of‐flight mass spectrometry

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