Ms1 Full Scan Acquisition Simulation

MS1 Full-Scan Acquisition Simulation

Summary

Simulate full-scan MS1 (parent ion) acquisition on known chemical compounds using ViMMS, generating realistic LC-MS chromatograms and MS1 spectra without fragmentation. This skill enables prototyping and optimization of MS acquisition strategies in a virtual environment before testing on real mass spectrometry hardware.

When to use

When you need to prototype, test, or benchmark MS1-only acquisition strategies on a defined set of metabolites (e.g., sampled from HMDB) without access to real LC-MS equipment, or when you want to generate synthetic full-scan MS1 data for method validation or comparative studies of fragmentation strategies.

When NOT to use

• When you need MS/MS fragmentation data — use a TopN or data-dependent controller instead of FullScanController.
• When your input is real measured MS data that you wish to replay or re-acquire — use ChemicalMixtureFromMZML to extract chemicals from an existing mzML, then simulate with a different controller.
• When you require instrument-specific hardware simulation (e.g., Thermo Tribrid tuning parameters) — IAPI provides direct hardware control and is outside the scope of ViMMS simulation.

Inputs

• List of chemical formulas or KnownChemical objects (with retention times, m/z values, intensities)
• HMDB database or local metabolite list (for sampling)
• Acquisition time bounds (min_time, max_time in seconds)
• Ionization polarity setting (positive or negative)

Outputs

• mzML file containing full-scan MS1 spectra and chromatograms
• Simulation evaluation data (if save_eval=True) for scan-level metrics

How to apply

First, sample or define a set of chemical compounds with known m/z values (typically 100–1000 m/z range) using ViMMS DatabaseFormulaSampler or ChemicalMixtureCreator. Create KnownChemical objects with retention times and MS1 intensities. Instantiate an IndependentMassSpectrometer with polarity='positive' (or negative) and supply the chemicals list. Configure a FullScanController (or SimpleMs1Controller) with the same polarity to acquire only MS1 scans, disabling any MS/MS fragmentation. Initialize an Environment object with the spectrometer, controller, and set time bounds (e.g., min_time=0, max_time=1200 seconds). Execute env.run() to simulate the full LC-MS acquisition loop, which generates scan-by-scan MS1 data. Finally, export the acquired scans to mzML format using Environment.write_mzML(), which produces a standards-compliant mzML output file suitable for downstream peak picking and analysis.

Related tools

• ViMMS (Core simulation framework; provides SimpleMs1Controller and FullScanController for MS1-only acquisition, IndependentMassSpectrometer for virtual instrument, Environment for run loop, and write_mzML for output export) — https://github.com/glasgowcompbio/vimms
• Python (Programming language for instantiating ViMMS classes and executing simulation workflows)
• Poetry (Dependency management tool for installing and configuring ViMMS and its dependencies) — https://python-poetry.org/
• OpenMS (Post-simulation peak picking and fragmentation coverage analysis on the exported mzML files)

Examples

from vimms.ChemicalMixtureCreator import ChemicalMixtureCreator
from vimms.MassSpectrometer import IndependentMassSpectrometer
from vimms.Controller import FullScanController
from vimms.Environment import Environment
from vimms.Common import POSITIVE
cmc = ChemicalMixtureCreator(formula_sampler, ms_levels=2)
chemicals = cmc.sample(100)
ms = IndependentMassSpectrometer(polarity=POSITIVE, chemicals=chemicals)
controller = FullScanController(polarity=POSITIVE)
env = Environment(ms, controller, min_time=0, max_time=1200, save_eval=True)
env.run()
env.write_mzML('output.mzML')

Evaluation signals

• mzML file is valid and parseable by standard tools (OpenMS, pymzML) without schema errors
• mzML contains MS1 scans only (no MS2 scans), with m/z and intensity arrays matching the input chemical parameters
• Retention time coverage spans the configured time window (min_time to max_time) with scan-level timestamps monotonically increasing
• Peak picking on the mzML (using MZMine parameters or OpenMS) recovers chemical signals at or near input m/z values and retention times within expected tolerance (typically ≤ 1 ppm for m/z, ≤ 30 s for retention time)
• Comparison of simulation output (number of detected peaks, intensity distribution, chromatographic profile) to input chemical list shows expected overlap and absence of artifactual peaks

Limitations

• ViMMS simulation assumes idealized peak shapes and does not model instrumental noise, calibration errors, or hardware-specific artifacts that occur on real mass spectrometers.
• The DatabaseFormulaSampler relies on HMDB metabolite coverage; m/z ranges outside 100–1000 and rare metabolites may be underrepresented or absent.
• Full-scan MS1-only simulations do not generate fragment ion (MS/MS) data, so they cannot be used to optimize or validate fragmentation-dependent identification strategies.
• Chromatographic overlap and ion suppression effects are not modeled; all sampled chemicals are assumed to ionize with specified intensity regardless of co-eluting compounds.

Evidence

• [other] The ViMMS framework includes a SimpleMs1Controller that can generate full-scan MS1 data from simulated chemicals, with the Environment class providing write_mzML functionality to export generated scans as mzML files.: "SimpleMs1Controller that can generate full-scan MS1 data from simulated chemicals, with the Environment class providing write_mzML functionality to export generated scans as mzML files"
• [other] Sample 100 chemical formulas from HMDB database within m/z range 100–1000 using DatabaseFormulaSampler. Generate KnownChemical objects with retention times, intensities, and MS1 chromatograms using ChemicalMixtureCreator with ms_levels=2.: "Sample 100 chemical formulas from HMDB database within m/z range 100–1000 using DatabaseFormulaSampler. Generate KnownChemical objects with retention times, intensities, and MS1 chromatograms"
• [other] Configure FullScanController with polarity='positive' to acquire only MS1 scans without fragmentation. Create an Environment with the mass spectrometer, controller, min_time=0, max_time=1200, and enable save_eval=True. Execute env.run() to simulate the LC-MS acquisition loop.: "Configure FullScanController with polarity='positive' to acquire only MS1 scans without fragmentation. Create an Environment with the mass spectrometer, controller, min_time=0, max_time=1200"
• [readme] a flexible and modular framework designed to simulate fragmentation strategies in tandem mass spectrometry-based metabolomics: "flexible and modular framework designed to simulate fragmentation strategies in tandem mass spectrometry-based metabolomics"
• [readme] devising new methods is often challenging due to the absence of a structured environment where researchers can prototype, compare, and optimize strategies before testing on real equipment: "absence of a structured environment where researchers can prototype, compare, and optimize strategies before testing on real equipment"