Tandem mass spectrometry data interpretation

tandem-mass-spectrometry-data-interpretation

License: restricted — no clear open-source license detected for the underlying tool; verify licensing before commercial use or redistribution. <!-- asb-license-banner -->

Summary

Automated structure annotation of lipid A from high-resolution tandem mass spectrometry (MS2) data using LipidA-IDER, an open-source tool that identifies and classifies lipid A molecular species at systems scale. This skill enables conversion of raw MS2 spectral data into annotated lipid structure outputs.

When to use

You have high-resolution MS2 data (.ms2 format) from tandem mass spectrometry analysis of lipid A-containing samples and need to perform automated structure annotation and identification at systems scale. You lack established lipid A reference libraries or wish to standardize annotation across large sample batches. You want to avoid manual peak assignment and structural hypothesis generation.

When NOT to use

• Input data is in formats other than .ms2 (e.g., raw vendor formats, mzML, NetCDF) without prior conversion
• Running on MacOS or Linux systems, as LipidA-IDER has only been tested and validated on Windows
• Data consists of MS1 spectra only or does not include tandem MS2 fragmentation data

Inputs

• .ms2 format mass spectrometry data files
• LipidAIDER_AnalysisParam.csv configuration file (optional custom parameters)
• LipidAIDER_BatchAnalysisFiles.csv batch definition file (for CLI mode)

Outputs

• Annotated lipid A structure assignments
• Batch output files in Logger/<YYYYMMDD_HHMMSS>/Batch Output directory
• Per-spectrum annotation records with lipid A molecular identities

How to apply

First, prepare input data by converting raw mass spectrometry files to .ms2 format using MSConvert (ProteoWizard) with peak picking (CWT algorithm) and MS level 2 filtering. Clone the LipidA-IDER repository and install Python dependencies. Configure analysis parameters in the LipidAIDER_AnalysisParam.csv settings file to match your data characteristics (e.g., m/z accuracy, fragment ion thresholds). Execute LipidA-IDER via either the GUI ($ python LipidAIDER_GUI.py) for interactive file selection and parameter adjustment, or CLI ($ python LIPIDAIDER_main.py -m <PATH_TO_MS2_FILE>) for batch processing. Monitor the Logger directory for timestamped output folders containing annotated lipid structures. Verify output completeness by checking that all input .ms2 records generated corresponding structure annotations.

Related tools

• MSConvert (ProteoWizard) (Converts raw mass spectrometry data to .ms2 format with peak picking and MS level 2 filtering) — https://proteowizard.sourceforge.io/download.html
• Python (Runtime environment for executing LipidA-IDER GUI and CLI interfaces)
• git (Version control tool for cloning the LipidA-IDER repository)

Examples

$ python LIPIDAIDER_main.py -m /path/to/sample.ms2

Evaluation signals

• Output directory exists in Logger with correctly formatted YYYYMMDD_HHMMSS timestamp
• Batch Output folder contains annotation records for all input .ms2 files without truncation or errors
• Annotated lipid A structures include defined molecular identities with m/z values and fragment ion assignments consistent with input spectra
• Parameter values in settings file align with expected MS data characteristics (e.g., instrument resolution, ion mode)
• No error logs or warnings in stdout/stderr indicating failed spectrum processing or missing required input files

Limitations

• LipidA-IDER has only been tested on Windows; use on MacOS and Linux has not been tested and is unsupported
• Accepts only .ms2 format input; conversion from other formats (raw vendor data, mzML) is required beforehand
• Output quality and annotation accuracy depend on proper configuration of analysis parameters in LipidAIDER_AnalysisParam.csv; misaligned parameters may produce spurious or incomplete annotations
• Tool is optimized for lipid A structures specifically; applicability to other lipid classes or modified lipid A species is not documented

Evidence

• [readme] LipidA-IDER is an automated structure annotation tool for systems-level scale identification of lipid A from high resolution tandem mass spectrometry (MS2) data: "LipidA-IDER is an automated structure annotation tool for systems-level scale identification of lipid A from high resolution tandem mass spectrometry (MS2) data"
• [readme] As of current, LipidA-IDER has only been tested on Windows. Use of LipidA-IDER on MacOS and Linux has not been tested.: "As of current, LipidA-IDER has only been tested on Windows. Use of LipidA-IDER on MacOS and Linux has not been tested."
• [readme] LipidAIDER currently accepts data in .ms2 format. To convert to .ms2, use MSConvert (ProteoWizard) (download from: https://proteowizard.sourceforge.io/download.html) Settings: Output format: .ms2, Filters: Peak Picking, Algorithm: CWT, MS Levels: 2: "LipidAIDER currently accepts data in .ms2 format. To convert to .ms2, use MSConvert (ProteoWizard) Settings: Output format: .ms2, Filters: Peak Picking, Algorithm: CWT, MS Levels: 2"
• [readme] Upon completion of the analysis. the generated output will be found in the '\Logger<YYYYMMDD_HHMMSS>\Batch Output' subfolder.: "Upon completion of the analysis. the generated output will be found in the '\Logger<YYYYMMDD_HHMMSS>\Batch Output' subfolder."
• [readme] In the event that you do not have initial .ms2 data, we have provided the some demo input files for your use here: [\Source\demo_input_files]: "In the event that you do not have initial .ms2 data, we have provided the some demo input files for your use"