Coupling of an atmospheric pressure microplasma ionization source with an Orbitrap Fusion Lumos Tribrid 1M mass analyzer for ultra-high resolution isotopic analysis of uranium

Abstract

Ultra-high resolution is achieved in the LS-APGD/Orbitrap Fusion Lumos Tribrid 1M coupling, with no sacrifice in sensitivity or precision.

Improved Uranium Isotope Ratio Analysis in Liquid Sampling–Atmospheric Pressure Glow Discharge/Orbitrap FTMS Coupling through the Use of an External Data Acquisition System

“…Perhaps the lower field orbitrap cell employed here, accompanied by its tuning state, is unable to hold the ions in a coherent packet for as long as a high field orbitrap. 28,44,53 As such, the quality of the signal (actually the SNR) diminishes at transient times of greater than 1 s, though still much improved over the best cases of previous efforts using the standard DAQ system on this instrument. The transient length has a much greater effect on the middle-valued peak area isotope ratio, 238 U 17 O 16 O/ 238 UO 2 , than it has on the 235 UO 2 / 238 UO 2 .…”

“…Using peak areas in the case of the most abundant 235 UO 2 / 238 UO 2 ratio, the raw accuracy is slightly improved over previous works on this instrument using the standard acquisition system where the best 235 UO 2 / 238 UO 2 values were generally biased to lower values of 0.0066−0.0068. 24,25,27,28 The variation in the determined values is minimal across the longer transients but then deviates in the negative direction at more extended transient lengths, most likely due to the decay in the ion packet density in the orbitrap. Perhaps the lower field orbitrap cell employed here, accompanied by its tuning state, is unable to hold the ions in a coherent packet for as long as a high field orbitrap.…”

“…This is different from shown previously on an Orbitrap Fusion Lumos 1M, where increasing the transient length (increasing resolution) up to 2 s resulted in an increase in the 235 UO 2 / 238 UO 2 measurement precision. 28 The lack of improved precision with transient length (here) is most likely due to the (relative) inability to maintain a stable ion packet for the duration of the transients employed on this low field orbitrap cell and the employed ion optics tuning parameters. That said, it is very interesting to note that the differences in the measurement precision between the two transient lengths become smaller as the ratios decrease, where there is virtually no difference in precision performance for the transients for 234 UO 2 / 238 UO 2 measurements.…”

“…In this work, precision is defined as the percent relative standard deviation (%RSD) of determined values, and error is defined as the percentage deviation from the accepted IR values, as done in previous efforts for uranium isotope ratio analysis. 23,28 ■ RESULTS AND DISCUSSION Improvements in Mass Resolution. The advanced DAQ system (FTMS Booster X2) allows the collection of ion signal transients of an arbitrary length (not limited to a 2-fold transient length increment step) and for extended periods of time, resulting in resolution beyond what is implemented using the standard acquisition/processing system.…”

Mass spectrometry-based structure elucidation of small molecule impurities and degradation products in pharmaceutical development

“…More recently, FT-ICR and orbitrap mass analyzers with "ultra"-high resolving power became available. In 2011, the high-field orbitrap was commercialized with a resolving power of 240,000 FWHM [52], which was further improved to 1,000,000 FWHM in 2015 [53]. These instruments can resolve the isotopic fine-structure of small molecules, a feature that is extremely powerful in structure elucidation.…”