Evaluation of a modified Orbitrap Astral Mass Spectrometer for label-free quantitation of proteomic samples

Significance of the Topic

The ability to perform accurate and precise label-free quantitation in complex proteomic samples is critical for biological research, biomarker discovery, and quality control in pharmaceutical and clinical laboratories. Advances in mass spectrometer design that increase sensitivity, acquisition speed, and spectral clarity directly impact the depth of proteome coverage and the reliability of quantitative data across a wide dynamic range.

Objectives and Study Overview

This study evaluates the performance of the new Thermo Scientific Orbitrap Astral Zoom mass spectrometer in a label-free quantitation (LFQ) workflow. Using defined mixtures of human, yeast, and E. coli proteomes at known ratios, samples spanning four orders of magnitude (100 pg to 1 µg) were analyzed. Results from the Zoom variant were compared to those from the standard Orbitrap Astral instrument to assess gains in identification rates, quantitative precision, and accuracy.

Methodology and Instrumentation

Samples comprising two mixtures (Mix A: H65-Y15-E20 and Mix B: H65-Y30-E5) were prepared at high (10–1000 ng) and low (100 pg–10 ng) loads. Peptides were separated using a Vanquish Neo UHPLC system in direct injection mode with a 25 cm × 75 µm ID Aurora Ultimate XT column. High-load runs employed a 37 min gradient (30 SPD) and low-load runs a 20 min gradient (50 SPD). Data were acquired in data-independent acquisition (DIA) mode with variable window sizes and injection times, and processed using Spectronaut 19.5 (DirectDIA) or Proteome Discoverer 3.3 with CHIMERYS.

Used Instrumentation

• Vanquish Neo UHPLC
• Aurora Ultimate XT 25 cm × 75 µm ID column (IonOpticks)
• Orbitrap Astral and Orbitrap Astral Zoom mass spectrometers
• FAIMS Pro Duo (low-load analyses)
• Spectronaut 19.5 DirectDIA software
• Thermo Scientific Proteome Discoverer 3.3 with CHIMERYS 4.0

Main Results and Discussion

• Identification Gains at High Loads: Orbitrap Astral Zoom MS delivered on average 5–7% more protein group identifications and 10–15% more peptide identifications compared to standard Astral MS.
• Identification Gains at Low Loads: Precursor-level gains of 4–14%, peptide-level gains of 10–15%, and protein-level gains of 2–8% were observed, highlighting enhanced sensitivity for low-abundance species.
• MS2 Data Density: Median number of data points per peak increased by approximately 15%, supporting improved quantitation precision.
• Quantitation Precision and Accuracy: Coefficients of variation (CVs) at the protein level remained below 5% across loads, with median log2 ratio errors within 10% of theoretical values. Zoom MS achieved a single ion detection probability increase from 85% to 95% at low input levels.
• Software Consistency: Both Spectronaut and Proteome Discoverer/CHIMERYS pipelines reflected similar trends, confirming robustness of the Zoom hardware and spectral processing enhancements.

Benefits and Practical Applications

The Orbitrap Astral Zoom MS provides deeper proteome coverage and robust label-free quantitation over a wide dynamic range, making it suitable for high-throughput proteomics, biomarker validation, QA/QC in biomanufacturing, and exploratory research. Its enhanced sensitivity for low-input samples enables studies in limited material scenarios, such as microdissected tissues or precious clinical specimens.

Future Trends and Opportunities

Ongoing developments may integrate real-time spectral deconvolution algorithms and machine learning to further boost identification rates and quantitation accuracy. The Zoom concept can be extended to single-cell proteomics, spatial proteomics, and clinical workflows requiring ultra-low input. Enhanced ion optics and software-driven acquisition schemes will continue to push the boundaries of depth, speed, and reproducibility in proteomic analysis.

Conclusion

The Thermo Scientific Orbitrap Astral Zoom mass spectrometer demonstrates significant improvements in label-free proteomic workflows, delivering higher identification rates, increased data density, and maintained quantitative precision across sample loads from 100 pg to 1 µg. These advances position the Zoom MS as a powerful tool for comprehensive and reliable proteome profiling.