How to turn a CAS list into a GC-QQQ transition list
The practical workflow is: normalize the list, check coverage, confirm family and method support, then review vendor-neutral transitions before export. A clean CAS list speeds the process up, but it does not remove the need to validate RT behavior and transition suitability in the lab.
Direct answer
Converting a CAS list into a usable GC-QQQ transition list is not just a file-format step. The process requires compound normalization, coverage review, method-aware matching, and review of unsupported or unmatched compounds before export.
In practice, the safest workflow is to start with a canonical CAS or well-formed name list, run a coverage check, confirm the correct family, inspect matched and unmatched entries, and only then build the transition table. This reduces silent misses and makes the final review auditable.
Prepare the list
Start with a clean list of CAS numbers, names, or a mixed panel. Remove obvious spreadsheet artifacts and decide which family the list belongs to before building.
Normalize the inputs
Resolve each entry to a canonical internal compound record. This is where duplicates, aliases, and unmatched inputs should be surfaced instead of hidden.
Check coverage and method support
Confirm which compounds are actually supported in the selected workflow and, for odor/VOC work, whether the selected method supports them in WAX or 5ms.
Build and review transitions
Generate vendor-neutral Q1/Q3 rows with method metadata, then review RT windows, qualifier logic, and unsupported compounds before export.
Step-by-step workflow
1. Start with the cleanest list available. If you already have canonical CAS numbers, use them. If you have names only, keep common aliases but expect a normalization pass before building.
2. Run a coverage check before export. This tells you which entries match the active library and which require correction or manual handling.
3. Confirm family and method context. Pesticide and environmental workflows currently share the main GC dataset path, while odor/VOC workflows use a separate odor dataset with explicit WAX vs 5ms support differences.
4. Review transitions, not just export them. Check quantifier and qualifier roles, relative intensity, RT windows, and unsupported compounds before treating the list as method-ready.
What the exported rows typically include
- compound name and CAS
- Q1 and Q3 ions
- quantifier / qualifier role
- relative intensity and RT window context
- method fingerprint fields such as column, carrier, flow, and oven program
Common failure points
CAS formatting problems. Extra spaces, spreadsheet artifacts, or old aliases can prevent a match even when the target compound exists in the dataset.
Wrong family selection. A list that belongs in an odor workflow should not be treated as a general pesticide or environmental panel.
Method support assumptions. In odor/VOC work, some compounds may be present in WAX but not in 5ms. That should be reviewed explicitly rather than assumed away.
Export without review. A generated table is a fast starting point, not an excuse to skip RT, qualifier, or matrix-fit checks.
Validation limits
A transition list is only part of a working GC-QQQ method. Final method suitability still depends on instrument setup, RT behavior, matrix effects, collision settings, and acceptance criteria.
Use the exported list to accelerate method drafting, then validate it under your own laboratory conditions.
Use the trust pages together
This guide explains the workflow. For current dataset scope, read the coverage page. For the current normalization and build logic, read the methodology page.
If you already know the list family you are working with, you can also start from the category pages for pesticides, environmental, or odor/VOCs.
FAQ
Do I need to start with CAS numbers only?
No. A practical workflow can start with CAS numbers, compound names, or a mixed list. CAS numbers are usually cleaner, but the platform can also normalize supported names and aliases.
What if some CAS numbers do not match?
Unmatched inputs should stay visible during review. That lets you correct formatting, replace an alias with a canonical CAS, or continue with only the supported compounds.
Does the output create a vendor-specific instrument method?
No. The output is a vendor-neutral transition table intended for review, export, and downstream method preparation rather than a final instrument-specific acquisition file.
Do I still need to validate RT and transitions in the lab?
Yes. Transition lists accelerate preparation, but users still need to validate retention behavior, ion ratios, matrix effects, and acceptance criteria on their own instrument and method.
Ready to turn your list into transitions?
Paste your CAS numbers or names, review coverage first, then build export-ready GC-QQQ transition rows for the workflow you are actually running.