Performance optimisation of a new‐generation orthogonal‐acceleration quadrupole‐time‐of‐flight mass spectrometer

Abstract

Orthogonal-acceleration quadrupole time-of-flight (oa-QTOF) mass spectrometers, employed for accurate mass measurement, have been commercially available for well over a decade. A limitation of the early instruments of this type was the narrow ion abundance range over which accurate mass measurements could be made with a high degree of certainty. Recently, a new generation of oa-QTOF mass spectrometers has been developed and these allow accurate mass measurements to be recorded over a much greater range of ion abundances. This development has resulted from new ion detection technology and improved electronic stability or by accurate control of the number of ions reaching the detector. In this report we describe the results from experiments performed to evaluate the mass measurement performance of the Bruker micrOTOF-Q, a member of the new-generation oa-QTOFs. The relationship between mass accuracy and ion abundance has been extensively evaluated and mass measurement accuracy remained stable (+/-1.5 m m/z units) over approximately 3-4 orders of magnitude of ion abundance. The second feature of the Bruker micrOTOF-Q that was evaluated was the SigmaFit function of the software. This isotope pattern-matching algorithm provides an exact numerical comparison of the theoretical and measured isotope patterns as an additional identification tool to accurate mass measurement. The smaller the value, the closer the match between theoretical and measured isotope patterns. This information is then employed to reduce the number of potential elemental formulae produced from the mass measurements. A relationship between the SigmaFit value and ion abundance has been established. The results from the study for both mass accuracy and SigmaFit were employed to define the performance criteria for the micrOTOF-Q. This provided increased confidence in the selection of elemental formulae resulting from accurate mass measurements.

Kinetic Control of Protonation in Electrospray Ionization

“…Data processing was performed using Bruker DataAnalysis software, including the chemical formula assignment software, SmartFormula (SF) [15][16][17][18][19] and SmartFormula3D (SF3D) [20,21] …”

Spectral accuracy of molecular ions in an LTQ/Orbitrap mass spectrometer and implications for elemental composition determination

“…This may include the SigmaFit approach in Bruker Daltonics software, of which the exact details are unknown to the authors due to the proprietary nature of the algorithms, although a reference to a patent for the purpose of precise mass positioning is available [9]. An extensive evaluation of the SigmaFit approach was recently published by Bristow et al [10]. A similar approach was independently proposed by Fernandez-de-Cossio et al [11].…”

Non-targeted screening approaches for contaminants and adulterants in food using liquid chromatography hyphenated to high resolution mass spectrometry

“…Both q-TOF and Orbitrap mass analyzers generally have mass accuracies below 5 ppm [54][55][56][57][58] and have been routinely employed in the analysis of food. While the specified measured mass accuracies for these instruments are sufficient for non-targeted analysis, impaired data quality can occur, especially when analyzing complex sample matrices [58].…”