Chromatography-electrospray Ion Trap Mass Research Articles

Determination of aristolochic acids in medicinal plant and herbal product by liquid chromatography–electrospray–ion trap mass spectrometry

This paper describes a liquid chromatography–electrospray–ion trap mass spectrometry (LC–ES–ITMS) method for the determination of aristolochic acid I and II (AA-I and AA-II) in medicinal plants and Chinese herbal remedies. A reversed phase C 18 column with gradient elution was utilized. The effects of mobile phase additives, acetic acid and ammonium acetate, on LC separation and ES ionization were investigated. For both AA-I and AA-II, the [M+NH 4] + ion was found to be the precursor ion for target MS/MS analysis. The MS/MS product ion, [M+H−44] +, was used for the quantitative measurement of AA-I and AA-II. The linearity was good from 0.03 to 5 μg ml −1 and good correlation ( r 2=0.999) over the range examined was determined for both AA. The detection limit based on a signal-to-noise ratio of three was 0.012 and 0.015 μg ml −1 for AA-I and AA-II, respectively. Various Chinese herbal remedies obtained from renal failure patients and medicinal plants were examined by this newly developed method.

Complete sequencing of anti-vancomycin fab fragment by liquid chromatography–electrospray ion trap mass spectrometry with a combination of database searching and manual interpretation of the MS/MS spectra

Sequencing of anti-vancomycin monoclonal antibody (mAb) Fab region (48,000 Da) was carried out using liquid chromatography–electrospray ionization ion trap mass spectrometry (LC/ESI-MS). Comprehensive strategies were employed to ensure complete sequence coverage. The sequence information was obtained from the spectra of collision-induced dissociation (CID) (MS/MS) of the protonated proteolytic peptides resulting from multiple enzymatic digestions of reduced/ S-carboxymethylated (RCM) light chain and Fd fragment. Database searching of the spectra against the published immunoglobulin G (IgG) sequences allowed the identification of all the peptides in constant domains as well as partial sequences in variable domains. The rest of the sequences were deduced by manual interpretation of the peptide tandem mass spectrometry (MS/MS) spectra. The analysis showed that the N-terminus of the heavy chain was modified by the conversion of a glutamine residue to pyroglutamic acid.

Speciation and detection of organotins from PVC pipe by micro‐liquid chromatography–electrospray–ion trap mass spectrometry

AbstractThis paper describes the application of a micro‐liquid chromatography–electrospray–ion trap mass spectrometry (µ‐LC–ES–ITMS) method for separation and detection of organotin compounds leached from potable‐water polyvinyl chloride (PVC) pipe. Dibutyltin (DBT) is added as a heat stabilizer to PVC. DBT was determined in 1 l water samples that had remained static in PVC pipes over several days (totaling 96 h). Other organotin compounds in the leachate were screened for, by using µ‐LC–ES–ITMS. An initial level of approximately 1 µgl−1 of DBT resulted within 24 h, with a subsequent drop and then a rise in DBT levels over the next 96 h to 0.8 µgl−1. Published in 2001 by John Wiley & Sons, Ltd.

Study for Catecholamine-2'-Deoxyguanosine Adduct Formation under Biomimetic Conditions Using Liquid Chromatography-Electrospray Ionization-Ion Trap Mass Spectrometry.

The adduct formation of 2'-deoxyguanosine (dG) with L-adrenaline under biomimetic conditions (pH 7.5, 37°C) with or without oxidant (MnO2) was demonstrated in order to clarify the reaction mechanism and the structure. At least two adducts have been observed by liquid chromatography-electrospray ionization-ion trap mass spectrometry (LC-ESI-ion trap MS) and LC-photodiode array detection (LC-PAD) (compound a: more polar than dG, m/z 463(M+H)+, λmax: 230, 320 nm; compound b: less polar than dG, m/z 445 (M+H)+, λmax: 220, 240, 320, 405 nm). Compound a appeared only in the early stage of the reaction prior to formation of compound b.

Direct analysis of microcystins by microbore liquid chromatography electrospray ionization ion-trap tandem mass spectrometry

Microcystins are a group of structurally similar cyclic heptapeptide hepatotoxins and tumor promoters, produced by cyanobacteria. A microbore liquid chromatography electrospray ionization ion-trap mass spectrometry (LC-ESI-ITMS) method has been developed which is capable of separating and detecting trace amounts of microcystin variants in environmental samples. Extracted water sample was loaded onto a LC trapping column and, using a column switching technique, the compounds of interest were back-flushed onto a 1-mm LC column. Structural elucidation was achieved using ion-trap with tandem mass spectrometry in the data dependent scan mode. Collision-induced dissociation to MS 3 allowed tentative identification of these cyclic peptides. Full-scan LC-ESI-MS mass spectrum was obtained when 250 pg of the authentic compound was injected onto the HPLC column, which represents the detection limit for microcystin-LR. This study demonstrated that LC-ESI-ITMS is a reliable and sensitive technique for analysing trace levels of microcystins.

Identification of two-dimensional electrophoresis-separated proteins in human hepatoma cell by electrospray ion trap mass spectrometry

As one of the most important analytical methods in proteome research, mass spectrometry was utilized to identify proteins separated by two-dimensional electrophoresis in the human hepatoma cell line BEL-7404. The protein spots were excised from the gel, followed by in-gel digestion, and the peptide mappings were analyzed by liquid chromatography electrospray ion trap mass spectrometer. Nine proteins were identified via database searching, according to the molecular weights and amino acid sequences of peptides, among which two proteins have not been identified in the other liver-cell database. The sequence coverage was 21% –72%. Furthermore, the relationship between the expressed proteins and the liver carcinoma was discussed.

イオントラップＭＳによるＬＣ／ＭＳ／ＭＳを用いた抗体の糖鎖構造の解析

Precise and rapid glyco-mapping of a mouse monoclonal immunoglobulin G2b (IgG2b) was carried out by liquid chromatography-electrospray ionization ion trap-mass spectrometry/mass spectrometry (LC/ESI IT-MS/MS). It was possible to obtain spectra of minor glycopeptides with a quantity as low as 1.8 pmol. Reduced and carboxymethylated mouse antidansyl monoclonal IgG2b (RCM-IgG2b) was digested with Lys-C. Proteolytic peptides were subjected to capillary HPLC separation followed by analysis with an ion trap mass spectrometer. The structures of twelve different types of O-linked oligosaccharides attached to Thr-221AH in the hinge region and those of three major types of N-linked oligosaccharides attached to Asn-297H have been characterized.