Quadrupole ESI

The initial studies was carried out using on-line RP-HPLC coupled with a single quadrupole ESI-MS to measure the molecular weights of IFN-a-2b components. The mass spectrum showed that other than IFN-a-2b, peak 1 in Figure 19-7c contained a protein with a MW of 19,281 Da that was 16 Da higher than the predicted MW of 19,265 Da for IFN-a-2b. This higher mass component corresponds to oxidation of one of the five methionine amino acids present in IFN-a-2b. The oxidation of a methionine is also indicated by the fact that this component elutes earlier than the parent protein. It is well known... 

F.-F. Hsu, J. Turk, Studies on GPGro with triple quadrupole ESI-MS-MS fragmentation processes and structural characterization, J. Am. Soc. Mass Spectrom., 12 (2001) 1036. 

No LC Triple quadrupole ESI and APCI negative and positive ion mode... 

Ml Milk, milk powder LC-MS/MS triple quadrupole (ESI source) Multifunction column 9-14 — 7-16 — [88]... 

GENERAL PROCEDURE FOR SINGLE QUADRUPOLE ESI-MS AND CHEMOMETRICS IN BIOFUEL RESEARCH 753... 

Mass spectrometric analysis of bio-oUs from lignocel-lulose is in an early phase. The purpose of the two studies that have been published is simply to demonstrate the presence of ionizable and detectable compounds, to clarify the possible existence of homologous series, and to determine the MW distribution. The single quadrupole ESI-MS and chemometrics were used in... 

Figure 34.6 shows a spectrum of rapeseed oil obtained with single quadrupole ESI-MS. The lines in the spectrum represent triglycerides with MW around 900. Typical FAME has a MW around 300 as shown in the positive ESI-MS spectrum in Figure 34.1. 

Because of the advances in the gas-phase ionization of biomacromolecules, such as electrospray ionization (ESI) and matrix-assisted laser desorption ionization (MALDI), mass spectrometry (MS) has become a powerful tool for detection, identification, and structural analysis of proteins, peptides, and polynucleotides. The molecules ionized in a gas phase by these methods are subsequently analyzed by sector, quadrupole, ion-trap, or time-of-flight mass spectrometers. In particular, the MS systems consisting of ESI and triple-stage quadrupole (ESI/TSQ) or ion-trap (IT) mass spectrometry and MALDI time-of-flight (MALDl/TOF) mass spectrometry have been most widely applied to the field of protein chemistry for the accurate determination of molecular mass of proteins and peptides, determination of amino acid sequence, identification of proteins by peptide mass databases, and analysis of posttranslational modifications such as phosphorylation and glycosylation. In general, current techniques allow detenni-... 

As we have seen in this book, three developments appear to have provided the necessary momentum, and all three are still works in progress . The first was the development of TOF instruments, which could accomodate electrospray ionization by using orthogonal extraction or combining ion trapping with the TOF analyzer, which led to the possibility of carrying out on-line HPLC analysis. Considerable improvements are required to enable ESI-TOF instruments to be commercially competitive with existing quadrupole (and triple quadrupole) ESI mass spectrometers, but this is sure to be a major focus of development by both University laboratories and instrument manufacturers. 

Detector UV 280 MS, Micromass Quattro II, triple quadrupole, ESI, source 150°, source capillary voltage 2500-3500 V, cone voltage 25-50 V or APCI, positive ion mode to negative ion mode at 11 min, source 150°, probe 550°, corona voltage 2500 V, cone voltage 35 V... 

Detector MS, Micromass Quattro triple-stage quadrupole, ESI, 100 ixIVmin of column effluent entered the detector, capillary 3.2 kV, source 130°, desolvation 400°, desolvation gas nitrogen 650 L/h, nebulizer gas nitrogen 75 L/h, collision gas argon, cone 30 V, collision energy 15 eV m/z 363-320... 

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