Mass Spectrometry Transition Data Formatting

mass-spectrometry-transition-data-formatting

Summary

Conversion and validation of raw mass spectrometry transition data (precursor m/z, product m/z, intensity, retention time, compound identifiers) into the EISA-EXPOSOME tabular schema (.xlsx or .csv) to enable suspect chemical screening and database compatibility. This is a prerequisite data preparation step that ensures input files conform to the expected column structure and data types required by the EISA-EXPOSOME platform.

When to use

When you have raw mass spectrometry transition data from a triple-quadrupole or other tandem MS instrument and need to prepare it for suspect chemical screening using EISA-EXPOSOME, or when merging custom compound libraries into the T3DB format. Specifically apply this skill when your data is in instrument-native, unstructured, or non-standard tabular formats and must be integrated into an EISA-EXPOSOME workflow.

When NOT to use

• Input is already a validated EISA-EXPOSOME-compliant database file (.xlsx or .csv with correct schema) — skip to import step.
• You are working with full-scan or data-independent acquisition (DIA) spectra rather than targeted multiple reaction monitoring (MRM) transitions — EISA-EXPOSOME expects discrete precursor–product ion pairs.
• Retention time data is entirely absent and your use case requires RT-based peak extraction and feature disambiguation; RT is optional but strongly recommended for filtering and confidence.

Inputs

• Raw mass spectrometry transition data (precursor m/z, product m/z, intensity, retention time, compound identifiers)
• Instrument-native or unstructured tabular data (e.g., CSV, TSV, Excel, XML from MS software)
• Reference T3DB database file (.xlsx format) for cross-validation

Outputs

• Formatted transition database file (.xlsx or .csv) with columns: NAME, PrecursorMZ, ProductMZ, Intensity, RT, ID
• Validated database ready for import into EISA-EXPOSOME R Shiny application
• Data integrity report confirming schema compliance and reference compound validation

How to apply

Obtain or prepare raw mass spectrometry transition data containing precursor m/z, product m/z, intensity, retention time (optional), and compound identifiers. Restructure the data into a tabular format with exactly six columns: NAME, PrecursorMZ, ProductMZ, Intensity, RT (optional but recommended for peak extraction), and ID. Cross-reference formatted entries against the compiled T3DB reference database (provided in .xlsx format) to verify column alignment, data type consistency (numeric m/z and intensity values; string identifiers), and entry completeness. Validate the presence and correct formatting of reference compounds (e.g., Methamidophos with PrecursorMZ 142.0086, ProductMZ 94.0046, Intensity 100, RT 2.182, ID 1) as a sanity check. Export the validated table as .xlsx or .csv format and confirm file integrity by reloading into the R Shiny interface to verify all rows parse and filter operations function without error.

Related tools

• R Shiny (Interactive interface for uploading, importing, and validating the formatted transition database; supports real-time schema checking and result filtering) — https://github.com/Lab-XUE/EISA-EXPOSOME
• EISA-EXPOSOME (Downstream platform that consumes the formatted database for targeted peak extraction and suspect chemical screening; requires strict column schema compliance) — https://github.com/Lab-XUE/EISA-EXPOSOME

Evaluation signals

• File contains exactly six column headers: NAME, PrecursorMZ, ProductMZ, Intensity, RT, ID (case-sensitive); no extra or missing columns.
• All PrecursorMZ and ProductMZ values are numeric and within expected m/z ranges (typically 50–2000 m/z); no text or missing values in these columns.
• All Intensity values are non-negative numbers; zero intensity is acceptable but may indicate low-abundance transitions.
• RT (retention time) values, where present, are numeric and within expected range (typically 0–60 minutes); absence of RT is acceptable.
• File successfully imports into R Shiny EISA-EXPOSOME interface without parsing errors; reference compound entries (e.g., Methamidophos) match T3DB reference values exactly; filtering and visualization functions operate without exception.

Limitations

• RT (retention time) is not essential but is strongly recommended; absence of RT may reduce the effectiveness of targeted peak extraction and feature disambiguation in chromatography-rich samples.
• The schema assumes one precursor–product ion pair per row; multiple product ions from a single precursor must be formatted as separate rows with the same NAME and PrecursorMZ but different ProductMZ and ID values.
• No built-in handling for isomers or isobars; users must ensure NAME identifiers are unique or clearly distinguish stereoisomers and regioisomers within the ID or NAME field.
• Cross-referencing against T3DB is manual; no automated duplicate or conflict detection is described; users must verify that custom entries do not contradict or redundantly re-enter T3DB compounds.

Evidence

• [readme] Database schema requirement: "your file (.xlsx /.csv) must contain the following columns:|NAME|PrecursorMZ|ProductMZ|Intensity|RT|ID|, RT is not essential."
• [readme] Reference compound format and values: "Methamidophos|142.0086|94.0046|100|2.182|1"
• [other] Data preparation workflow: "1. Obtain or prepare raw mass spectrometry transition data (precursor m/z, product m/z, intensity, retention time, and compound identifiers). 2. Format the data into a tabular structure with required"
• [other] Validation and export step: "5. Export the validated database as .xlsx or .csv format and verify file integrity."
• [readme] R Shiny tool integration: "We provide a Rshiny program for EISA-EXPOSOME, which runs with the interface shown below, and you can filter the results according to the visualisation interface"