Liquid chromatography with post-column electrochemical treatment and mass spectrometric detection of non-polar compounds

J. Am. Soc. Mass Spectrom.

2008

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A method for the simultaneous determination of the number of free cysteine groups and disulfide-bound cysteine groups in proteins has been developed based on the sequential labeling of free and bound thiol functionalities with two ferrocene-based maleimide reagents. Liquid chromatography/electrochemistry/mass spectrometry was used to assign the N-(2-ferroceneethyl)maleimide (FEM) labeled free cysteine functionalities in a tryptic digest mixture, whereas a precursor ion scan enables the detection of peptides with ferrocenecarboxylic acid-(2-maleimidoyl)ethylamide (FMEA) labeled disulfide-bound cysteine groups after reduction. Fragment spectra of the labeled peptides yield an excellent coverage of b-type and y-type ions. The ferrocene labeled cysteines were fragmented as 412 Da (FEM) and 455 Da (FMEA). These fragment masses are significantly higher than unlabeled amino acids or dipeptides and are easily detected. The position of free and disulfide-bound cysteine may therefore be assigned in an amino acid sequence. (J

Section: Identification Of Ferrocene-labeled Peptides By Lc/ec/msmentioning

confidence: 78%

Section: Chemicalsmentioning

confidence: 99%

Differential labeling of free and disulfide-bound thiol functions in proteins

Seiwert

Hayen

J. Am. Soc. Mass Spectrom.

2008

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“…The first step consisted of the reaction of the commercially available ferrocenecarboxylic acid to the respective ferrocenecarboxylic acid chloride (FCC) by using oxalyl chloride and catalytic amounts of N,Ndimethylaminopyridine. This procedure was introduced by Rolfes and Andersson [23,24], but for this work, a slightly modified version by Karst et al [40] was applied. FCC was then reacted with an excess of piperazine under formation of Fc-PZ.…”

Section: Resultsmentioning

confidence: 99%

“…Ferrocenecarboxylic acid chloride was prepared according to literature [23,24,40]: At room temperature, a solution of 1.43 mL (16.6 mmol) of oxalyl chloride in 30 mL of toluene was added to a stirred suspension of 3.0 g (13.0 mmol) of ferrocene carboxylic acid and catalytic amounts (3.5 mg) of DMAP in 35 mL of toluene. The reaction mixture was stirred for 1 h at room temperature.…”

Section: Synthesis Of the Derivatizing Agentmentioning

confidence: 99%

“…None of these studies involved a separation. Karst et al used the combination of pre-column derivatization with ferrocenecarboxylic acid chloride, LC separation, electrochemical conversion, and MS detection for the determination of alcohols and phenols [40]. The method could be combined with rapid separations on very short LC columns [41] and was applied for the analysis of alcohols and phenols in mineral oils [42].…”

mentioning

confidence: 99%

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Ferrocenoyl piperazide as derivatizing agent for the analysis of isocyanates and related compounds using liquid chromatography/electrochemistry/mass spectrometry (LC/EC/MS)

Seiwert

Henneken

J. Am. Soc. Mass Spectrom.

2004

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Ferrocenoyl piperazide is introduced as a new pre-column derivatizing agent for the analysis of various isocyanates in air samples using reversed-phase liquid chromatographic separation, electrochemical oxidation/ionization, and mass spectrometry. The nonpolar derivatives can be separated well using a phenyl-modified stationary phase and a formic acid/ammonium formate buffer of pH 3, which yields excellent separations, especially for one problematic group of isocyanates consisting of 2,4-and 2,6-toluylenediisocyanate (2,4-and 2,6-TDI) and hexamethylenediisocyanate (HDI). Electrochemical oxidation at low potentials (0.5 V versus Pd/H 2 ) leads to formation of charged products, which are nebulized in a commercial atmospheric pressure chemical ionization (APCI) source, with the corona discharge operated only at low voltage. Limits of detection between 6 and 20 nmol/L are obtained for the isocyanate derivatives, and calibration is linear over at least two decades of concentration. The method is applied for the analysis of air after thermal degradation of a polyurethane foam, and it is demonstrated that it is suitable as well for the analysis of carboxylic acid chlorides and of

Elektrochemie/Massenspektrometrie (EC/MS) – eine Technik für Metabolismusstudien und die Untersuchung von Reaktionsmechanismen

2004

Angewandte Chemie

Kombiniere: Die Kopplung von Elektrochemie und Massenspektrometrie (EC/MS) eröffnet neue Möglichkeiten für die Analytik – nicht nur in der Biochemie bei der Untersuchung von Naturstoffen und Metabolismen, sondern auch beim Screening kombinatorischer Bibliotheken und bei der Charakterisierung von Übergangsmetallverbindungen. Funktionsweise, Anwendungsbreite und Perspektiven der wichtigsten aktuellen EC/MS‐Methoden sind das Thema dieses Highlights.