Dynamic range of mass accuracy in LTQ orbitrap hybrid mass spectrometer

Self Cite

173

231

While allowing analysis of intact proteins without a theoretical upper mass limit, the Orbitrap mass analyzer demonstrates reduced resolving power as ion mass increases even at a constant mass-to-charge ratio. It is shown that this effect comes from the effects of ion scattering on background gas molecules. The main mechanisms causing decay of acquired transient appear to be fragmentation as well as accelerated dephasing of ion packets. Isotopic resolution of proteins including bovine serum albumin (MW 66.4 kDa) and transferrin (MW 78 kDa) has also been demonstrated. As a part of this study, detection of individual multiply-charged ions of myoglobin (MW 16.9 kDa) has been demonstrated. Quantized distribution of signal intensities for ϩ20 myoglobin ions well above the noise threshold was observed, with high mass accuracy and resolution of recorded individual ions used as an independent confirmation of correct assignment of signal to ions rather than to noise. The latter also allowed us to benchmark the sensitivity of image-current detection and explore in detail factors responsible for signal decay. (J Am Soc

Section: Resultssupporting

confidence: 86%

Dynamics of ions of intact proteins in the Orbitrap mass analyzer

Makarov

Denisov

2009

Self Cite

173

231

“…A recent study [12] demonstrated that an Orbitrap mass resolving power of 25,000 to 40,000 was essential to obtain sufficient selectivity to enable the detection and quantification of N-nitrosamines in drink-N N ing water and wastewater samples at low ng/L level. The larger dynamic range over which accurate masses can be determined of LTQ Orbitrap MS could be a distinct advantage over TOFMS [13].…”

mentioning

confidence: 99%

Full-scan accurate mass selectivity of ultra-performance liquid chromatography combined with time-of-flight and orbitrap mass spectrometry in hormone and veterinary drug residue analysis

Heeft¹,

Bolck²,

Beumer³

et al. 2009

128

The applicability of ultra-performance liquid chromatography (UPLC) combined with fullscan accurate mass time-of-flight (TOF) and Orbitrap mass spectrometry (MS) to the analysis of hormone and veterinary drug residues was evaluated. Extracts from blank bovine hair were fortified with 14 steroid esters. UPLC-Orbitrap MS performed at a resolving power of 60,000 (FWHM) enabled the detection and accurate mass measurement (Ͻ3 ppm error) of all 14 steroid esters at low ng/g concentration level, despite the complex matrix background. A 5 ppm mass tolerance window proved to be essential to generate highly selective reconstructed ion chromatograms (RICs) having reduced background from the hair matrix. UPLC-Orbitrap MS at a lower resolving power of 7500 and UPLC-TOFMS at mass resolving power 10,000 failed both to detect all of the steroid esters in hair extracts owing to the inability to mass resolve analyte ions from co-eluting isobaric matrix compounds. In a second application, animal feed extracts were fortified with coccidiostats drugs at levels ranging from 240 to 1900 ng/g. UPLC-Orbitrap MS conducted at a resolving power of 7500 and 60,000 and UPLC-TOFMS detected all of the analytes at the lowest investigated level. Thanks to the higher analyte-to-matrix background ratio, the utilization of very narrow mass tolerance windows in the RIC was not required. This study demonstrates that even when the targeted sample preparation from conventional LC-MS/MS is applied to UPLC with full-scan accurate mass MS, false compliant (false negative) results can be obtained when the mass resolving power of the MS is insufficient to separate analyte ions from isobaric co-eluting sample matrix ions. The current trend towards more generic and less selective sample preparation is expected to aggravate this issue further. (J Am Soc Mass Spectrom 2009, 20, 451-463)

“…It has many parallels with the LIT/FT-ICR, substituting the orbitrap mass analyzer for the FT-ICR spectrometer [82]. A schematic [83] of the LIT/orbitrap is shown in Figure 6. This design has some analogies to the beam-beam instruments (e.g., Q/TOF) in that the ions are transferred from one analyzer to another, but rather than being a continuous stream, the ions are moved in packets after they have been accumu- lated in the LIT.…”

Section: Trap-beam Hybrid Instrumentsmentioning

confidence: 99%

Hybrid mass spectrometers for tandem mass spectrometry

Glish

Burinsky

2008

102

Mass spectrometers that use different types of analyzers for the first and second stages of mass analysis in tandem mass spectrometry (MS/MS) experiments are often referred to as "hybrid" mass spectrometers. The general goal in the design of a hybrid instrument is to combine different performance characteristics offered by various types of analyzers into one mass spectrometer. These performance characteristics may include mass resolving power, the ion kinetic energy for collision-induced dissociation, and speed of analysis. This paper provides a review of the development of hybrid instruments over the last 30 years for analytical applications. (J Am Soc Mass Spectrom 2008, 19, 161-172) © 2008 American Society for Mass Spectrometry T andem mass spectrometry (MS/MS), in a very generic description, is a process in which an ion formed in an ion source is mass-selected in the first stage of analysis, reacted, and then the charged products from the reaction are analyzed in the second stage of analysis. The type and quality of data that is obtained can vary greatly depending upon the type of analyzer used in the first and second stages of analysis, and the type of reaction performed between the stages of analysis. The reactions that can be done also can depend upon the type of analyzer. Over the years there have been a variety of means developed to measure the mass-to-charge ratio of gas-phase ions. The most common methods involve: dispersion based on ion momentum or kinetic energy (magnetic and electric sector instruments); separation in time based on ion velocity (time-of-flight); transmission through an electrodynamic field (quadrupole mass filter); and periodic motion in a magnetic or electrodynamic field (ion traps). There are differences in the experimental parameters associated with these various analysis methods that are pertinent to the MS/MS experiment. Some parameters are obvious, typically related to the performance of the mass analyzer while others are more subtle, related to the reactions/chemistry occurring between the stages of analysis. Many times these different parameters are used to categorize MS/MS experiments.One parameter is the ion kinetic energy. Sector and time-of-flight (TOF) instruments typically operate at "high" ion kinetic energies (5-20 keV), whereas "low" ion kinetic energies (Ͻ50 eV) are typical in quadrupole mass filters and ion traps. The ion kinetic energy is an important parameter in MS/MS experiments because the most common reaction involves colliding the ion of interest with a target gas atom or molecule. When performing ion-neutral collision experiments, the possible reactions that can be accessed (e.g., collisioninduced dissociation, collisional cooling, charge permutation, ion/molecule reaction) depends upon the ion kinetic energy. The appearance of the MS/MS spectrum can change drastically as a function of the collision (ion kinetic) energy. A related factor that is equally important, but often not considered, is the time frame of the experiment, that is, the elapsed time bet...